Non-invasive sensor for determining heartbeats and / or heart rate in a segment of an extracorporeal blood circuit

Abstract

Non-invasive heartbeat sensor for determining the heart rate in a catheter of an extracorporeal blood treatment device, comprising a source for directing an optical signal towards blood flowing in a segment, a detector for receiving an optical information signal and emitting a corresponding output signal, the optical information signal comprising a signal emitted by the source after passing through the blood, a controller receiving the corresponding output signal and deriving a heartbeat frequency and a heart rate value based on the output signal, wherein the information signal is altered by a flow disturbance of the blood caused by a flow pulse originating from the heart.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the general field of signal processing and optical measurement of physical quantities. In detail, the present invention relates to a device, a sensor and a process for determining at least heart beat and / or heart rate. BACKGROUND

[0002] In devices for renal care purposes (hemodialysis for chronic renal care or acute renal failure treatment, or during extracorporeal plasma treatment (e.g. hemodialysis, hemofiltration, hemodiafiltration, plasma exchange, etc.)), the patient's hemodynamic parameters are measured indirectly through the blood line (e.g. arterial and venous mean pressure are measured with semi-invasive sensors that are part of the blood line itself) or occasionally with a traditional pneumatic cuff arranged on the patient's arm. The use of a traditional pneumatic cuff does not allow continuous reading of the blood pressure, since its operation involves temporary occlusion of the patient's arm arteries and veins. Moreover, the measurement is very uncomfortable and can be painful for the patient, making it unacceptable to repeat it continuously during the dialysis treatment. Heart beat and / or heart rate can also be detected through the blood pressure cuff, but only during the measurement period (which lasts about 1 minute). Known semi-invasive pressure sensors are usually installed on the blood line, in a position close to the pump and far from the patient. Those semi-invasive pressure sensors are usually provided with a membrane in contact with the blood or fluid circulating in the device's conduit. Therefore, particular care should be taken in the choice of the design and materials used for their implementation, to reduce the risk of impact on the health of the patient receiving treatment.

[0003] It has been noted that the intensity and / or energy of the pulse provided by the heart to the blood decreases along the path from the fistula channel towards the conduit up to the device for extracorporeal blood treatment.

[0004] Moreover, the pump operatively actuated on the device usually generates unwanted pressure peaks (or flow rate peaks) on the blood or fluid circulating in the conduit, since the pump is usually a pulsatile pump, in particular a peristaltic pump. This causes the precision and reliability of the pressure readings to worsen, since unwanted noise is always added to the useful signal; the pressure peaks (or flow rate peaks) provided by the pump can sometimes be of the order of magnitude of the values of the heart pulses. The pressure peaks (or flow rate peaks) provided by the pump are related to the flow rate of the pump itself in terms of amplitude and / or frequency. The higher the flow rate, the faster the pump rotates, and usually the higher the frequency at which the peaks occur. This is particularly true for peristaltic pumps, whose operation causes the flow rate / pressure to be provided discontinuously in the conduit along the operating cycle, due to the cyclic compression of the segments of the conduit of the blood circuit, which is plastically deformed due to the action of the rollers of the pump on the contrasting wall.

[0005] It has also been noted that for blood treatment by an extracorporeal blood treatment apparatus, in particular for the typical flow rates involved in dialysis procedures, the frequency of the peaks provided by the pump is very close to the frequency of the heart rate, which in the resting state is typically between 50 bpm (or typically 60-70 bpm, the first figure referring to a well-trained athlete) and 100 bpm, resulting in a peak frequency of approximately between slightly less than 1 Hz and slightly less than 2 Hz. Thus, the fundamental frequency of the peaks provided by the pump is substantially closely related to the frequency of the heartbeat, and sometimes the frequency of the peaks provided by the pump may substantially overlap with the frequency of the heartbeat, for example, differing by a few tenths of a Hz. It seems obvious that, without appropriate procedures, heart rate readings may be significantly adversely affected by the pulses provided by the pump. Some treatments may result in a decrease in the blood pressure difference between the diastolic and systolic values, thereby increasing the influence of the pump pulses.

[0006] This detrimental effect can be solved by temporarily stopping the blood pump (i.e., the treatment process) to read the pulse, but this has the disadvantage of affecting the distribution of purified blood to the patient, prolonging the treatment, requiring a specific configuration for the blood treatment device, and in any case does not allow for continuous and reliable monitoring, since the pump should be restarted after a short period of time after the reading. Continuous monitoring of the heartbeat and / or heart rate is also possible with the help of additional devices added to the system and placed in close contact with the patient's body (e.g., wearable devices). Having the additional device in contact with the patient and connected to the machine to transmit data has the following disadvantages:

[0007] - the user feels uncomfortable with the added device (wearable or non-wearable),

[0008] - Reliability issues due to close connection to the patient's body - requiring additional connectivity equipment to the machine and vice versa, which further increases the cost of developing and updating existing machines.

[0009] WO2011 / 080194 discloses an apparatus for extracorporeal blood treatment configured to monitor a fluid flow rate in a patient's cardiovascular system. The apparatus comprises an extracorporeal blood circuit and a connector for connecting the extracorporeal blood circuit to the cardiovascular system. A monitoring device obtains a time-dependent measurement signal from a venous pressure sensor in the blood circuit. The pressure sensor is arranged to detect pulses originating from the patient's heart. The system further comprises a signal processor for processing the measurement signal and obtaining a pulse profile as a temporal signal profile of the subject pulse. The fluid flow rate is calculated based on the temporal signal profile after filtering out blood pump pressure peaks / pulses.

[0010] US2018 / 078212 discloses a system and method for assessing respiratory health of a patient and indicating and characterizing respiratory stress. The device comprises a sensor that communicates with the patient to generate a biosignal that has a waveform curve in the time domain. The biosignal is processed and a waveform curve is calculated that reflects the respiratory rate of the patient. A correlation between the biosignal waveform curve and the respiratory rate waveform curve is then determined and a corresponding correlation coefficient is determined. A frequency analysis is performed on the biosignal and a respiratory metric is determined that reflects a ratio of a spectral component associated with a respiratory component of the biosignal relative to a total spectral component of the biosignal. The correlation coefficient and the respiratory metric are combined to form a respiratory stress metric for display to a user.

[0011] WO2018 / 112354 discloses a system and method for monitoring and determining patient parameters from a sensed venous waveform. The document discloses an evaluation of a plurality of frequencies associated with local maxima of a frequency domain peripheral venous pressure (PVP) signal, including a heart rate frequency (Fl) and a harmonic frequency (FH) at a harmonic of the heart rate frequency.

[0012] Despite the type of known sensing technology for detection, pump peaks in pressure or flow greatly affect the reliability of heartbeat and / or heart rate readings.

[0013] It is noted that this background section is only intended to provide some technical context. The arrangements discussed above should not be interpreted as being part of the prior art solely because they are discussed in this section. On the contrary, certain aspects described above can not be available to the public and should not be interpreted as being part of the prior art.

[0014] Therefore, the Applicant has found the need for a sensor and sensing technology aimed at solving the above-mentioned drawbacks. SUMMARY

[0015] To solve the above-mentioned drawbacks, the Applicant provides a sensor as disclosed in the present disclosure; the following aspects, which can be taken together and in combination with other parts of the description or claims, will highlight the most relevant technical features of the present disclosure.

[0016] A first aspect relates to a non-invasive heartbeat sensor (100) for determining a heartbeat and / or a heart rate in an extracorporeal segment (101) of a conduit to be connected to an extracorporeal blood treatment device, the sensor (100) comprising:

[0017] at least one source (53) for directing an optical signal towards blood flowing in the segment (101), the optical signal being directed along at least one emission axis (54);

[0018] - at least one detector (57) for receiving an optical information signal comprising a signal emitted by said source (53) at least partially after having passed through blood flowing in the segment (101), said at least one detector (57) emitting a respective output signal (200R) related to the received information signal,

[0019] - a controller (65) configured to receive the respective output signal (200R) from the at least one detector (57) and for deriving a heart beat frequency (f HR ) and / or detecting a heart rate value based on the output signal (200R).

[0020] Optionally, the information signal is altered by a flow perturbation of the blood flowing in the segment (101), said flow perturbation being at least partially generated by flow pulses originating from the beating heart.

[0021] In a second aspect according to the first aspect, wherein the information signal, in particular at least the amplitude of the information signal, is altered by or is a function of a blood volume change or a hemoglobin concentration change, which is at least due to flow pulses originating from the beating heart.

[0022] In a third aspect according to any of the preceding aspects, wherein:

[0023] - said source (53) is an optical signal source,

[0024] - said detector (57) is an optical signal detector (57),

[0025] - said information signal and said signal emitted by said source (53) are optical signals.

[0026] In a fourth aspect according to any of the preceding aspects, wherein said flow perturbation of the blood flowing in the segment (101) at a given predetermined time alters at least the amplitude of the information signal with respect to the amplitude the signal emitted by said source (53) would have at the same predetermined time, said property of the blood being a blood volume change or a hemoglobin concentration change or a parameter directly related to a blood volume change or a hemoglobin concentration change.

[0027] In a fifth aspect according to any of the preceding aspects, wherein the source (53) comprises an optical electromagnetic radiation emitter, optionally a single- wavelength or a multi-wavelength emitter, in particular a single-wavelength, optionally multi-mode and incoherent LED or a multi-wavelength LED, or a single-wavelength LASER or SLED, or a combination of a plurality of single-wavelength LASERs or SLEDs.

[0028] In a sixth aspect according to any of the preceding aspects, wherein the source (53) has at least a main lobe of emission along a predetermined emission axis, optionally wherein the predetermined emission axis is directed towards the segment (101) and the blood flowing in the segment (101).

[0029] In a seventh aspect according to any of the two preceding aspects, the sensor comprises an optical fiber, one end of which is coupled with the source (53) and the other end is placed to direct the emitted signal towards the blood at least along the predetermined emission axis.

[0030] In an eighth aspect according to any of the three preceding aspects, wherein the multi- wavelength emitter comprises a plurality of optical radiation sources having peak wavelengths in the red and infrared waveband, in particular wherein at least one of the illumination peak wavelengths of the source (53) is comprised between 0.7 pm and 1000 pm, more particularly between 1 pm and 350 pm or between 790 nm and 820 nm, for example between 800 nm and 810 nm, and / or in the red region, between 620 nm and 750 nm.

[0031] In a ninth aspect according to any of the preceding aspects, wherein the optical radiation source (53) is configured to transmit a composite optical radiation comprising at least a first component of optical radiation centered on or concentrated into a first frequency window comprising a first wavelength λ1, and a second component of optical radiation centered on or concentrated into a second frequency window comprising a second wavelength λ2, optionally with a third component of optical radiation centered on or concentrated into a third frequency window comprising a third wavelength λ3, and with a fourth component of optical radiation centered on or concentrated into a fourth frequency window comprising a fourth wavelength λ4, optionally wherein the first, second, third and fourth wavelengths are different from each other and / or wherein the first, second, third and fourth frequency windows are at least partially non-overlapping in frequency.

[0032] In a tenth aspect according to any of the preceding aspects, wherein the sensor is configured to be arranged in correspondence of a segment (101) of a conduit of an extracorporeal blood treatment apparatus, or configured to be connected to an extracorporeal blood treatment apparatus, the conduit being configured for blood flow during blood treatment with the apparatus.

[0033] In a eleventh aspect according to any of the preceding aspects, wherein the detectors are placed at different radial directions with respect to the emission axis of the source (53), or are arranged at different angles with respect to the emission axis of the source (53), to collect the reflected signals, scattered signals and / or transmitted signals according to their respective position, in particular one first detector is placed at about 180° with respect to the emission axis of the source, and / or one second detector is placed at about 90° with respect to the emission axis of the source, and / or one third detector is placed at about 45° with respect to the emission axis of the source, and / or one fourth detector is placed at about 0° with respect to the emission axis of the source.

[0034] In a twelfth aspect according to any of the preceding aspects, wherein the source (53) is configured to transmit the light radiation in a direction transverse to the main development axis of the segment (101), in particular substantially perpendicular to the main development axis of the segment (101), and wherein the detectors are configured to receive the light signals emitted by the source (53) along the direction transverse to the main development axis of the segment (101), in particular substantially perpendicular to the main development axis of the segment (101).

[0035] In a thirteenth aspect according to any of the preceding aspects, wherein the detectors receive the direct signals, reflected signals or refracted signals along respective receiving axes, the receiving axes of the detectors and the emission axis of the source (53) being contained in the same plane.

[0036] In a fourteenth aspect according to any of the preceding aspects, wherein the segment (101) of the extracorporeal blood treatment circuit is a tube portion, the detectors and the source being arranged around the tube portion at different angles around the same cross section, in particular the tube having a substantially circular cross section.

[0037] In a fifteenth aspect according to any of the preceding aspects, the sensor further comprises a housing (51), one portion of which is counter-shaped to the tube segment (101), the housing (51) being made of two or more pieces defining a through passage (52) counter-shaped to the outer shape of the tube segment to house the tube segment (101) inside the through passage (52), each detector (57) comprising a respective end portion placed at the counter-shaped portion, in the coupled condition of the housing (51) and the tube segment (101), facing the tube segment (101), in particular the source (53) comprising an end portion placed at the counter-shaped portion, in the coupled condition of the housing and the tube segment, facing the tube.

[0038] In a sixteenth aspect according to any of the preceding aspects, wherein the source (53) comprises an optical fiber (59) having one end coupled with the source (53) and the other end fixed to the housing (51), the other end of the optical fiber being placed at the shape-matching portion and facing the pipe segment (101) in the coupled condition of the housing with the pipe segment (101); wherein the at least one detector (57), in particular all the detectors (57), comprises an optical fiber having one end arranged in correspondence of the pipe segment (101), fixed to the housing, the end of the optical fiber being placed at the shape-matching portion and facing the pipe segment (101) in the coupled condition of the housing with the pipe segment (101).

[0039] In a seventeenth aspect according to any of the preceding aspects, wherein the housing (51) comprises a coupled configuration, in which the housing (51) is configured to be substantially fastened to the segment (101) through the shape-matching portion, and a non-coupled configuration, in which the segment (101) is allowed to be released; the housing (51) comprising at least a first part (51a) and a second part (51b), the first part (51a) defining a first portion of the shape-matching portion defining the through passage (52), the second part (51b) defining a second portion of the shape-matching portion defining the through passage (52), optionally wherein the first part (51a) and the second part (51b) are separable and / or hinged together to achieve the coupled configuration when connected to each other and the non-coupled configuration when at least partially disconnected from each other.

[0040] In a nineteenth aspect according to any of the preceding aspects, the sensor further comprises at least: a first detector (57; PD1) configured to receive optical radiation at a first wavelength λ1 or in a first frequency window comprising the first wavelength; and a second detector (57; PD2) configured to receive optical radiation at a second wavelength λ2 or in a second frequency window comprising the second wavelength, optionally further comprising: a third detector (57; PD3) configured to receive optical radiation at a third wavelength λ3 or in a third frequency window comprising the third wavelength; and a fourth detector (57; PD4) configured to receive optical radiation at a fourth wavelength λ4 or in a fourth frequency window comprising the fourth wavelength.

[0041] In a twentieth aspect according to any of the preceding aspects, the sensor further comprises a circuit (62) for transimpedance amplification, operatively, in particular electrically, connected to the output of the at least one detector (57), the circuit (62) for transimpedance amplification being configured to transform a current drive signal generated by the detector (57) into a voltage drive output signal.

[0042] In a twenty-first aspect according to any of the preceding aspects, the sensor further comprises at least one analog-to-digital conversion unit (64) having an input operatively, in particular electrically, connected at least at the output of the detector (57), the analog-to-digital conversion unit (64) comprising an output configured to provide a digital domain output signal to the controller (65).

[0043] In a twenty-second aspect according to any of the two preceding aspects, wherein the analog-to-digital conversion unit (64) is arranged downstream of the circuit (62) for transimpedance amplification.

[0044] In a twenty-third aspect according to any of the preceding aspects, the sensor further comprises a low-pass filtering stage 63 operatively, optionally electrically, coupled to the detector (57), optionally configured to limit an upper band of the output signal (200R) provided by the detector (57) to a frequency lower than 30 Hz, or lower than 10 Hz, or lower than 9 Hz, or lower than 8 Hz, or lower than 7 Hz, or lower than 6 Hz, or lower than 5 Hz or lower than 4 Hz.

[0045] In a twenty-fourth aspect according to any of the two preceding aspects, wherein the low-pass filtering stage (63) is arranged downstream of the circuit (62) for transimpedance amplification, optionally upstream of the analog-to-digital conversion unit (64).

[0046] In a twenty-fifth aspect according to any of the preceding aspects, wherein the controller (65) is configured to:

[0047] - electronically compute a transform of at least a reference portion (200W) of the output signal (200R) from a time domain to a frequency domain, obtaining an information signal spectrum or an output signal spectrum corresponding to the information signal spectrum,

[0048] - determine whether the at least one pump (11) is forcing circulation of fluid into the segment (101),

[0049] - in case the at least one pump (11) is forcing circulation of fluid into the segment (101), identify and optionally discard a first peak of amplitude in the information signal spectrum or in the output signal spectrum, optionally the first peak of amplitude corresponding to a first noise peak of amplitude, corresponding to a spurious flow perturbation in the segment (101) originated by the at least one pump (11) forcing circulation of fluid into the segment (101),

[0050] - performing an electronic identification of the first sought peak of amplitude in the information signal spectrum or in the output signal spectrum, in particular, after the discarding has occurred, the selection is calculated electronically by identifying a second sought peak of amplitude in the information signal spectrum or in the output signal spectrum, the second peak corresponding to a subsequent harmonic, in particular a second harmonic, of the first sought peak of amplitude,

[0051] - electronically assigning to the at least one temporary heartbeat and / or heart rate frequency (f HR ) a frequency corresponding to the first sought peak of amplitude.

[0052] In a twenty-sixth aspect according to any one of the preceding aspects, wherein the controller (65) is further configured to electronically load frequency values corresponding to a first lower frequency region (200L) and at least a second upper frequency region (200U), the second upper frequency region (200U) being located above the first lower frequency region (200L);

[0053] The electronic processing of the output signal comprises performing the following processing on the information signal spectrum or on the output signal spectrum:

[0054] - filtering out a portion of the information signal spectrum or of the output signal spectrum corresponding to the first lower frequency region (200L), or

[0055] - discarding any peak of amplitude located in the first lower frequency region (200L),

[0056] so that the electronic identification of the first noise peak of amplitude and optionally the discarding of the first noise peak of amplitude, and the electronic selection of the first sought peak of amplitude are performed in the at least second upper frequency region (200U).

[0057] In a twenty-seventh aspect according to any one of the two preceding aspects, wherein the controller (65) is configured to electronically store an upper limit frequency value of the lower frequency region (200L) and to set the upper limit frequency value of the lower frequency region (200L) to be lower than a frequency threshold of non-physiological heart pulses, in particular lower than 0.4 Hz, or lower than 0.5 Hz, or lower than 0.6 Hz, or lower than 0.7 Hz.

[0058] In a twenty-eighth aspect according to any one of the preceding aspects, wherein:

[0059] - the sensor comprises at least one electronic memory operatively accessible by the controller (65), or

[0060] - the sensor is operatively connected to a memory accessible by the controller (65).

[0061] In a twenty-ninth aspect according to any one of the two preceding aspects, the memory is configured to store at least the upper limit frequency value and / or the frequency threshold value of the lower frequency region (200L).

[0062] In a thirtieth aspect according to any one of the preceding aspects, when dependent on aspect twenty-five, wherein the controller is configured to electronically store the lowest frequency value of the upper frequency region (200U) and set the lowest frequency value of the upper frequency region (200U) to correspond to or be higher than the upper limit frequency value of the lower frequency region (200L).

[0063] In a thirty-first aspect according to any one of the preceding aspects, when dependent on aspect twenty-five, wherein the electronic processing of the output signal includes low-pass filtering the output signal at a predetermined frequency, optionally below 10 Hz, or below 9 Hz, or below 8 Hz, or below 7 Hz, or below 6 Hz, or below 5 Hz, or below 4 Hz, through a filter stage (63).

[0064] In a thirty-second aspect according to the preceding aspect, low pass filtering is performed before electronically calculating the transformation of at least the reference portion of the output signal from the time domain to the frequency domain.

[0065] In a thirty-third aspect according to any one of the preceding aspects, when dependent on aspect twenty-five, wherein the identification of the second sought peak (200P) of the amplitude is performed by searching the information signal spectrum or the output signal spectrum for a corresponding peak at a frequency (f HR2 ) is performed at the peak value of the amplitude at the frequency (f HR2 ) corresponds to the frequency of the first peak in amplitude (f HR ) twice.

[0066] In aspect 34 according to any one of the preceding aspects, when dependent on aspect 25, wherein the controller (65) is configured to perform electronic selection of a reference window for sampling the output signal when electronically processing the output signal of the at least one optical detector (57), the reference window having a predetermined length, optionally less than 1 minute long, or less than 45 seconds long, or less than 30 seconds long, or less than 20 seconds long, or less than 15 seconds long, or less than 10 seconds long, wherein a portion of the output signal constitutes a reference portion of the output signal, and wherein the electronic calculation of the transformation of at least a portion of the output signal is performed on the reference portion of the output signal and is performed after the windowing.

[0067] In a thirty-fifth aspect according to the preceding aspects, when dependent on aspect twenty-five, wherein the identification of the first noise peak of the amplitude and / or the first finding peak of the amplitude and / or the identification of the second finding peak of the amplitude is performed by applying a peak detection algorithm on at least a portion of the information signal spectrum or output signal spectrum.

[0068] In a thirty-sixth aspect according to any of the preceding aspects, when dependent on aspect twenty-five, wherein the peak detection algorithm comprises: considering a portion of the information signal spectrum or output signal spectrum, optionally the portion corresponding to the second upper frequency region (200U); and electronically computing a derivative of the spectrum to obtain a derivative spectrum, then comprising a subsequent electronic search and selection of at least one frequency, wherein the derivative spectrum changes sign, optionally wherein the derivative spectrum changes sign from positive to negative at a frequency in the course of increasing the analyzed frequency to identify a positive peak, the frequency at which the derivative spectrum changes sign from positive to negative corresponding to the peak.

[0069] In a thirty-seventh aspect according to any of the preceding aspects, when dependent on aspect twenty-five, wherein the peak detection algorithm that the controller (65) is configured to run comprises: searching for a local relative maximum amplitude point in the information signal spectrum or output signal spectrum, optionally by using moving window signal processing on the spectrum, the portion corresponding to the second upper frequency region (200U); and further selecting the frequency corresponding to the maximum amplitude point as the frequency at which the peak occurs.

[0070] In a thirty-eighth aspect according to any of the preceding aspects, wherein the peak detection algorithm comprises: defining a moving window of a predetermined amplitude within at least a portion of the information signal spectrum or output signal spectrum, optionally the portion corresponding to the second upper frequency region (200U); and electronically defining at least one, in particular a plurality, of positions for the moving window within the at least a portion of the information signal spectrum or output signal spectrum, and for the positions, optionally for each of the positions, electronically computing a maximum amplitude of the spectrum within the window, and electronically extracting and storing the frequency corresponding to the maximum amplitude.

[0071] In a thirty-ninth aspect according to any of the preceding aspects, when dependent on aspect 11, wherein the controller (65) is configured to electronically process the output signals of the plurality of first, second, third, fourth optical detectors (57), to perform an electronic averaging and / or filtering of the signals of at least a portion of the optical detectors (57), optionally all of the optical detectors (57), to obtain a combined output signal in the time domain, and wherein the transformation of at least a reference portion of the output signal from the time domain to the frequency domain is performed on the combined output signal,

[0072] wherein said output signals of the first, second, third and fourth optical detectors (57) are the result of receiving at least a portion of the information signal by the first, second, third and fourth optical detectors (57).

[0073] In a forty-first aspect according to the preceding aspects, wherein the controller (65) is configured to process the output signal of the at least one optical detector (57) with the pump-associated signal (300P) so as to render, in the output of said processing, a resulting signal which is zeroed, in particular periodically or cyclically, in correspondence of the portions of time in which the pump provides pulses in at least said segment (101).

[0074] In a forty-first aspect according to the preceding aspects, wherein the controller (65) is configured to process the output signal of the at least one optical detector (57) with the pump-associated signal (300P) so as to render, in the output of said processing, a resulting signal which is zeroed, in particular periodically or cyclically, in correspondence of the portions of time in which the pump provides pulses in at least said segment (101).

[0075] In a forty-second aspect according to any one of the preceding aspects forty and forty-one, wherein the controller (65) is further configured to electronically compute an average amplitude (Vm) of the resulting signal (301) over an analysis window of predetermined length in time, and to subtract, subsequently, said average amplitude (Vm) from at least a portion of the resulting signal (301), in particular from the portion of the resulting signal (301) which is not zeroed as a result of said multiplication, thereby generating an average signal (301A) which constitutes a reference portion of said output signal, wherein the transformation from time domain to frequency domain is performed at least on this reference portion. m

[0076] In a forty-third aspect according to any one of the preceding aspects forty to forty-two, wherein the controller (65) is configured to select a plurality of reference portions (200W) of the output signal (200R) by electronically selecting, through a sampling window, a plurality of portions of the output signal (200R) which are at least partially (optionally, completely) non-overlapping in time,

[0077] - for each of said plurality of reference portions (200W) of the output signal (200R), performing a transformation from time domain to frequency domain, obtaining a plurality of information signal spectra or a plurality of output signal spectra which correspond to or are related to a corresponding plurality of information signal spectra;​

[0078] - for each of said plurality of payload spectra or output signal spectra:

[0079] - identifying and discarding a first noise peak of the amplitudes in said information signal spectrum or output signal spectrum, said first predetermined peak of amplitudes corresponding to, or at least partially associated with, a parasitic flow disturbance in said section (101) originating from at least one pump (11) forcing fluid circulation into at least said section (101),

[0080] - after said discarding has occurred, performing an electronic identification and subsequent selection of a first finding peak of amplitudes in said information signal spectrum or output signal spectrum, said selection being electronically calculated by means of an identification of a second finding peak of amplitudes in the information signal spectrum or output signal spectrum, the second peak corresponding to a second harmonic of said first finding peak of amplitudes,

[0081] - electronically assigning to the temporary heartbeat and / or heart rate frequency (f HR1 , f HR2 , f HR3 ) a frequency corresponding to the first finding peak of amplitudes;

[0082] - calculating a definitive heartbeat and / or heart rate frequency (f HR ) from the plurality of temporary heartbeat and / or heart rate frequency values (f HR1 , f HR2 , f HR3 ) obtained for each of said spectra.

[0083] In a forty-fourth aspect according to any one of the preceding aspects, wherein according to the preceding claim, wherein the definitive heartbeat and / or heart rate frequency (f HR ) is calculated from an average of the plurality of temporary heartbeat and / or heart rate frequency values (f HR1 , f HR2 , f HR3 ) obtained for each of said spectra.

[0084] In a forty-fifth aspect according to any one of the preceding aspects, wherein said controller (65) is housed in the main body of said sensor (100).

[0085] In a forty-sixth aspect according to any one of the preceding aspects, wherein said controller (65) is configured to, in the event that said controller (65) has not acquired any heartbeat frequency (f HR ) and / or has not detected any heart rate value, and / or in the event that said controller (65) has at least temporarily acquired said heartbeat frequency (f HR) and / or no heart rate values are detected, activating an alarm signal. HR ) and / or no heart rate values are detected, activating an alarm signal.

[0086] In a 47th aspect, a method for taking heartbeats and / or heart rate in a segment (101) of a duct is disclosed, the method being performed by a non-invasive optical sensor (100); the method is characterized in that it comprises:

[0087] - transmitting a light radiation signal through the segment (101) so that at least a portion of the light radiation is transmitted through a portion of liquid present in the segment (101), in particular a portion of liquid comprising blood, performed by a light radiation source (53);

[0088] - receiving, by at least one optical detector (57) arranged substantially corresponding to the segment (101), an information signal comprising a modified version of the light radiation signal that has at least partially passed through the blood present in the segment (101) and / or a portion of the segment (101) itself, wherein the information signal is modified by, and / or is related to, or as a function of, flow perturbations of the blood flowing in the segment (101), the flow perturbations being generated at least in part by flow pulses originating from a beating heart,

[0089] - electronically processing the output signal (200R) of the at least one optical detector (57) as a result of the detection of at least a portion of the information signal by:

[0090] - electronically calculating a transformation of at least a reference portion (200W) of the output signal (200R) from the time domain to the frequency domain, obtaining an information signal spectrum or an output signal spectrum corresponding to or related to the information signal spectrum,

[0091] - determining whether at least one pump (11) is forcing the circulation of a fluid into the segment (101),

[0092] - in the case where at least one pump (11) is forcing the circulation of a fluid into the segment (101), identifying and optionally discarding a first peak of amplitude (f p1 ) in the information signal spectrum or in the output signal spectrum, optionally said first peak of amplitude (f p1) a first noise peak corresponding to an amplitude, which corresponds to or is at least partially associated with a parasitic flow disturbance in said segment (101) originating from at least one pump (11) forcing fluid circulation into at least said segment (101),

[0093] - performing, after said discarding has occurred, an electronic search or identification and subsequent selection of a first finding peak of amplitude in said information signal spectrum or output signal spectrum, said selection being electronically computed by means of an identification of a second finding peak of amplitude in said information signal spectrum or output signal spectrum, the second peak corresponding to a second harmonic of said first finding peak of amplitude,

[0094] - electronically assigning to at least a temporary heartbeat and / or heart rate frequency (f HR ) a frequency corresponding to a first finding peak of amplitude.

[0095] In another aspect 47b, a method for taking a heartbeat and / or heart rate in a segment (101) of a conduit is disclosed, said method being performed by means of a non-invasive optical sensor (100); said method being characterized in that it comprises:

[0096] - receiving, by means of at least one optical detector (57) arranged substantially in correspondence of said segment (101), an information signal comprising a modified version of a light radiation signal that has been at least partially modified by blood present in segment (101), wherein said information signal is modified by, and / or is related to, or as a function of, a flow disturbance of blood flowing in segment (101), said flow disturbance being at least partially generated by flow pulses originating from a beating heart,

[0097] - electronically processing, as a result of said at least partial detection of said information signal, an output signal (200R) of said at least one optical detector (57) by means of:

[0098] - electronically computing a transformation of at least a reference portion (200W) of output signal (200R) from time domain to frequency domain, obtaining an information signal spectrum or an output signal spectrum corresponding to or related to the information signal spectrum,

[0099] - determining whether at least one pump (11) is forcing fluid circulation into said segment (101),

[0100] - in case at least one pump (11) is forcing fluid circulation into said segment (101), identifying and optionally discarding a first peak of amplitude (f p1 ) in said information signal spectrum or output signal spectrum, optionally said first peak of amplitude (f p1) corresponding to a first noise peak of the amplitudes, the first noise peak corresponding to, or being at least partially associated with, a parasitic flow disturbance in said segment (101) originating from at least one pump (11) forcing fluid circulation into at least said segment (101),

[0101] - performing, after said discarding has occurred, an electronic search or identification of a first finding peak of the amplitudes in the information signal spectrum or output signal spectrum and a subsequent selection, said selection being electronically computed by means of an identification of a second finding peak of the amplitudes in the information signal spectrum or output signal spectrum, the second peak corresponding to a second harmonic of said first finding peak of the amplitudes,

[0102] - electronically assigning to at least the temporary heartbeat and / or heart rate frequency (f HR ) a frequency corresponding to the first finding peak of the amplitudes.

[0103] In a forty-eighth aspect according to the preceding aspects 47a or 47b, the method further comprises the step of electronically loading frequency values corresponding to a first lower frequency region (200L) and at least a second upper frequency region (200U), the second upper frequency region (200U) being located above said first lower frequency region (200L);

[0104] The electronic processing of the output signal comprises performing the following processing on the information signal spectrum or output signal spectrum:

[0105] - filtering out a portion of said information signal spectrum or output signal spectrum corresponding to the first lower frequency region (200L), or

[0106] - discarding any peak of the amplitudes located in said first lower frequency region (200L),

[0107] such that the identification and discarding of the first noise peak of the amplitudes (f p1 ) and the electronic selection of the first finding peak of the amplitudes are performed in said at least second upper frequency region (200U).

[0108] In a forty-ninth aspect according to any one of the preceding aspects 47a, 47b and forty-eight, the method comprises electronically storing an upper frequency value of said lower frequency region (200L) and setting the upper frequency value of said lower frequency region (200L) to be lower than a frequency threshold of non-physiological heart pulses, in particular lower than 0.4 Hz, or lower than 0.5 Hz, or in particular lower than 0.6 Hz, or lower than 0.7 Hz.

[0109] In a 50th aspect according to any one of the preceding aspects 47 to 49, the method further comprises electronically storing the lower frequency value of the upper frequency region (200U) and setting the lower frequency value of the upper frequency region (200U) to correspond to or be higher than the upper limit frequency value of the lower frequency region (200L).

[0110] In a 51st aspect according to any one of the preceding aspects 47 to 50, wherein the electronic processing of the output signal comprises low-pass filtering of the output signal at a predetermined frequency, optionally lower than 10 Hz, or lower than 9 Hz, or lower than 8 Hz, or lower than 7 Hz, or lower than 6 Hz, or lower than 5 Hz, or lower than 4 Hz, by a filter stage (63).

[0111] In a 52nd aspect according to the preceding aspect, wherein the low-pass filtering is performed prior to the electronic computation of the transformation of at least the reference portion of the output signal from time domain to frequency domain.

[0112] In a 53rd aspect according to any one of the preceding aspects 47 to 52, the method further comprises setting and / or arranging the non-invasive optical sensor (100) in correspondence of the segment (101) in such a way that no component of the sensor is in contact with any fluid or blood flowing into the segment (101) and in such a way that any component of the sensor (100) is introduced into the inner lumen of the segment (101).

[0113] In a 54th aspect according to any one of the preceding aspects 47 to 53, wherein the identification of the second finding peak (200P) of the amplitude is performed by searching for a peak of the amplitude in the information signal spectrum or in the output signal spectrum at a frequency (f HR2 ) corresponding to twice the frequency (f HR2 ) of the first finding peak of the amplitude. HR

[0114] In a 55th aspect according to any one of the preceding aspects 47 to 54, the method further comprises the steps of loading an electronically preset threshold value (200T) of the amplitude and subsequently applying the threshold value (200T) electronically to the information signal spectrum or to the output signal spectrum, so that the identification and discarding of the first noise peak of the amplitude and the electronic selection of the first finding peak of the amplitude are performed only among those peaks of the amplitude which exceed the threshold value (200T).

[0115] ​In a fifty-sixth aspect according to any of the two preceding aspects, wherein the identification of the second sought peak of amplitude (200P) is performed by searching in the information signal spectrum or in the output signal spectrum for amplitude peaks having an amplitude exceeding said threshold (200T) and searching for amplitude peaks being lower than said threshold (200T).

[0116] In a fifty-seventh aspect according to any of the forty-seventh to fifty-sixth preceding aspects, wherein the electronic processing of the output signal of the at least one optical detector (57) comprises an electronic selection of a reference window of output signal sampling, said reference window having a predetermined length, optionally less than 1 minute long, or less than 45 seconds long, or less than 30 seconds long, or less than 20 seconds long, or less than 15 seconds long, or less than 10 seconds long, wherein a portion of the output signal constitutes a reference portion of the output signal, and wherein the electronic computation of the transformation of at least a portion of the output signal is performed on said reference portion of the output signal and after said windowing.

[0117] In a fifty-eighth aspect according to any of the forty-seventh to fifty-seventh preceding aspects, wherein the identification of the first noise peak of amplitude and / or the first sought peak of amplitude and / or the identification of said second sought peak of amplitude is performed by applying a peak detection algorithm on at least a portion of said information signal spectrum or output signal spectrum.

[0118] In a fifty-ninth aspect according to the preceding aspect, wherein the peak detection algorithm comprises, considering a portion of the information signal spectrum or output signal spectrum, optionally said portion corresponding to the second upper frequency region (200U), and electronically computing a derivative of said spectrum to obtain a derivative spectrum, then comprising a subsequent electronic search and selection of at least one frequency, wherein said derivative spectrum changes sign, optionally wherein said derivative spectrum changes sign from positive to negative in the course of increasing the analysis frequency to identify a positive peak, the frequency at which said derivative spectrum changes sign from positive to negative corresponding to said peak.

[0119] In a sixtieth aspect according to any of the forty-seventh to fifty-ninth preceding aspects, wherein the peak detection algorithm comprises searching for a local relative maximum amplitude point in said information signal spectrum or output signal spectrum, optionally by using a moving window signal processing on said spectrum, said portion corresponding to the second upper frequency region (200U), and further selecting the frequency corresponding to said maximum amplitude point as the frequency at which the peak occurs.

[0120] In a sixty-first aspect according to any of the previous aspects forty-seven to sixty, wherein the peak detection algorithm comprises a moving window defining a predetermined amplitude within at least a portion of the information signal spectrum or of the output signal spectrum, optionally said portion corresponding to the second upper frequency region (200U), and electronically defining at least one, in particular a plurality, of positions for said moving window within said at least a portion of the information signal spectrum or of the output signal spectrum, and for said positions, optionally for each of said positions, electronically computing a maximum amplitude of the spectrum within said window, and electronically extracting and storing the frequency corresponding to said maximum amplitude.

[0121] In a sixty-second aspect according to any of the previous aspects forty-seven to sixty-one, the method comprises arranging said at least one optical detector (57) so that its main detection direction is aligned with at least the radiation axis of said light radiation source (53) and / or with the main radiation lobe axis, optionally comprising arranging the optical detector (57) in substantially contact with the outer wall of said segment (101) in a position diametrically opposite to the position of the light radiation source (53).

[0122] In a sixty-third aspect according to any of the previous aspects forty-seven to sixty-two, the method further comprises arranging at least a second optical detector (57) substantially corresponding to said segment (101) so that it is located at a different radial direction with respect to the radiation axis of the light radiation source (53) or at a different angle with respect to the main radiation lobe of the light radiation source (53) to collect reflected and / or scattered portions of said information signal.

[0123] In a sixty-fourth aspect according to any of the previous aspects forty-seven to sixty-three, wherein said different angle and / or said different radial direction has an angle of 0°, < 45° or < 90° or < 180° with respect to the radiation axis of the light radiation source (53) or with respect to the main radiation lobe of the light radiation source (53).

[0124] In a sixty-fifth aspect according to any of the previous aspects forty-seven to sixty-four, the method comprises:

[0125] - arranging a first optical detector (57) substantially corresponding to said segment (101) so that it is located substantially at 45° with respect to the radiation axis of the light radiation source (53) or with respect to the main radiation lobe of the light radiation source (53);

[0126] - arranging a second optical detector (57) substantially corresponding to said segment (101) so that it is located substantially at 45° with respect to the radiation axis of the light radiation source (53) or with respect to the main radiation lobe of the light radiation source (53);

[0127] - arranging a third optical detector (57) substantially corresponding to said segment (101) so that it is substantially located at 90° with respect to the axis of radiation of the optical radiation source (53) or with respect to the main radiation lobe of the optical radiation source (53);

[0128] - arranging a fourth optical detector (57) substantially corresponding to said segment (101) so that it is substantially located at 180° with respect to the axis of radiation of the optical radiation source (53) or with respect to the main radiation lobe of the optical radiation source (53);

[0129] - receiving, by the first, second, third and fourth optical detectors (57), at least part of the information signal;

[0130] wherein the electronic processing of the output signals of the first, second, third and fourth optical detectors (57) comprises averaging and / or filtering the signals of at least part of said detectors, optionally of all those detectors (57), to obtain a combined output signal in the time domain, and wherein a transformation of at least a reference portion of the output signal from the time domain to the frequency domain is performed on said combined output signal.

[0131] In a sixty-sixth aspect according to any one of the preceding aspects from forty-seven to sixty-five, wherein transmitting the optical radiation signal comprises transmitting an optical signal centered on at least one predetermined wavelength, optionally comprised in the infrared region, between 1.4 pm to 1000 pm and more particularly between 5 pm to 350 pm and / or in the red region between 620 nm to 750 nm.

[0132] In a sixty-seventh aspect according to any one of the preceding aspects from forty-seven to sixty-six, wherein transmitting the optical radiation signal comprises transmitting an optical signal having a plurality of components, optionally a first component, a second component, a third component, a fourth component, each component centered on a predetermined wavelength, different from the wavelengths on which the other components of said plurality of components are centered, implementing a multi-wavelength optical signal, optionally wherein said wavelengths are comprised in the infrared region between 0.7 pm to 1000 pm, more particularly between 1 pm to 350 pm or between 790 nm to 820 nm, for example between 800 nm to 810 nm, and / or in the red region between 620 nm to 750 nm.

[0133] In a sixty-eighth aspect according to any one of the preceding aspects from forty-seven to sixty-seven, wherein receiving the information signal by said first, second, third and fourth optical detectors (57) implements a spatially and wavelength-selective reception, wherein:

[0134] - a first optical detector (57) is centered on at least a first wavelength λ1 corresponding to the wavelength on which the first component of the transmitted light signal is centered;

[0135] - a second optical detector (57) is centered on at least a second wavelength λ2 corresponding to the wavelength on which the second component of the transmitted light signal is centered;

[0136] - a third optical detector (57) is centered on at least a third wavelength λ3 corresponding to the wavelength on which the third component of the transmitted light signal is centered;

[0137] - a fourth optical detector (57) is centered on at least a fourth wavelength λ4 corresponding to the wavelength on which the fourth component of the transmitted light signal is centered.

[0138] In a sixty-ninth aspect according to any one of the preceding aspects from forty-seven to sixty-eight, the method further comprises processing the output signal of the at least one optical detector (57) with a pump-association signal (300P) having a shape that is cyclic and / or repetitive in time and associated with pump cycle points, so as to obtain a resulting signal (301) whose frequency spectrum sees an enhancement of the component or peak associated with the heartbeat or heart rate with respect to the component or peak associated with the operation of the pump (11) of the device.

[0139] In a seventy aspect according to the preceding aspects, wherein said processing comprises processing the output signal of the at least one optical detector (57) with the pump-association signal (300P) so as to render, in the output of the processing, a resulting signal that is zeroed, in particular periodically or cyclically, in correspondence with the portions of time in which the pump provides pulses in at least the segment (101).

[0140] In a seventy-first aspect according to any one of the preceding aspects from sixty-eight to seventy, wherein the electronic processing of the output signal (200R) of the at least one optical detector (57) comprises the steps of:

[0141] - multiplying the output signal of the at least one optical detector (57) in the time domain with a pump-association signal (300P) having a shape that is cyclic and / or repetitive in time and associated with pump cycle points, said multiplication resulting in the generation of a resulting signal (301); said pump-association signal (300P) corresponding to a portion of time in which the pump provides pulses in at least the segment (101) being periodically or cyclically zeroed.

[0142] In a seventy-second aspect according to any of the preceding three aspects, wherein the pump-related signal (300P) is a square wave having a predetermined value corresponding to the time instants in which the pump does not provide impulses in at least the section (101), and is zeroed corresponding to the time portions in which the pump provides impulses in at least the section (101).

[0143] In a seventy-third aspect according to any of the preceding aspects sixty-eight to seventy-two, the method further comprises electronically calculating the average amplitude (Vm) of the result signal (301) over an analysis window of predetermined length in time, m and further comprises subsequently subtracting from at least a portion of the result signal (301), in particular from the portion of the result signal (301) which is not zeroed as a result of the multiplication, the average amplitude (Vm), thereby generating an average signal (301A) which constitutes a reference portion of the output signal, the transformation from time domain to frequency domain being performed at least on this reference portion.

[0144] In a seventy-fourth aspect according to any of the preceding aspects forty-seven to seventy-three, the method comprises:

[0145] - selecting a plurality of reference portions (200W) of the output signal (200R) by electronically selecting, through a sampling window, a plurality of portions of the output signal (200R) at least partially (optionally, completely) non-overlapping in time,

[0146] - for each of the plurality of reference portions (200W) of the output signal (200R), performing a transformation from time domain to frequency domain, obtaining a plurality of information signal spectra or a plurality of output signal spectra corresponding to or related to a corresponding plurality of information signal spectra;

[0147] - for each of the plurality of payload spectra or output signal spectra:

[0148] - identifying and discarding a first noise peak of amplitude in the information signal spectrum or in the output signal spectrum, the first predetermined peak of amplitude corresponding to a parasitic flow disturbance in the section (101) originating from at least one pump (11) forcing circulation of the fluid into at least the section (101), or at least partially associated with this parasitic flow disturbance,

[0149] - after the discarding has occurred, performing an electronic identification and subsequent selection of a first sought peak of amplitude in the information signal spectrum or in the output signal spectrum, the selection being electronically calculated through an identification of a second sought peak of amplitude in the information signal spectrum or in the output signal spectrum, the second peak corresponding to the second harmonic of the first sought peak of amplitude,

[0150] - electronically transmit the temporary heartbeat and / or heart rate frequency (f HR1 、f HR2 、f HR3 ) assigning a frequency corresponding to a first sought peak in amplitude;

[0151] - based on a plurality of temporary heartbeat and / or heart rate frequency values ​​(f HR1 、f HR2 、f HR3 ) calculate the final heart rate and / or heart rate frequency (f HR ).

[0152] In a seventy-fifth aspect according to the preceding aspect, wherein the final heartbeat and / or heart rate frequency (f HR ) is based on a plurality of temporary heartbeat and / or heart rate frequency values ​​(f HR1 、f HR2 、f HR3 ) calculated by the average calculation in ).

[0153] In aspect seventy-six according to any one of aspects forty-seven to seventy-five above, the information signal is not substantially altered by a change in the size and / or geometry of at least a portion of the segment (101) receiving the information signal, and / or is substantially unrelated to, or is not substantially a function of, a change in the size and / or geometry of at least a portion of the segment (101) receiving the information signal, the change in size and / or geometry being a result of the flow disturbance of the blood flowing in the segment (101).

[0154] In aspect seventy-seven according to any one of aspects forty-seven to seventy-six above, the method further comprises activating an alarm, optionally a visual alarm or an audible alarm, in case a temporary heartbeat and / or heart rate frequency cannot be obtained by the electronic search or identification and subsequent selection of the first search peak of amplitude in the information signal, or in case the first search peak of amplitude in the information signal spectrum or the output signal spectrum is not associated with a second peak corresponding to the second harmonic of the first search peak of amplitude, or in case other peaks corresponding to the first search peak of amplitude in the information signal spectrum or the output signal spectrum do not have a corresponding second peak corresponding to the second harmonic of the first search peak.

[0155] In the seventy-eighth aspect according to any one of the forty-seven to seventy-seven aspects above, wherein the second searched peak of the amplitude is arranged at a frequency substantially corresponding to twice the frequency at which the first peak is located.

[0156] In an eightieth aspect according to the previous aspects forty-seven to seventy-eight, the method further comprises:

[0157] - a step of electronically calculating a difference between the frequency (f P1 ) of the first peak of the amplitude and the heartbeat and / or heart rate frequency (f HR ), the frequency (f P1 ) of the first peak of the amplitude being at least partially associated with the parasitic flow disturbance in the segment (101) and originating from the at least one pump (11);

[0158] - a step of electronically comparing the difference, optionally the absolute value of the difference, with a predetermined difference threshold value,

[0159] - a step of generating a warning signal in the event that the difference, optionally the absolute value of the difference, is lower than the threshold value.

[0160] In an eighty-first aspect according to the previous aspects, the method further comprises a step of adapting the rotational speed or flow rate of at least the blood pump (11) of the apparatus for blood treatment as a function of the difference, optionally of the absolute value of the difference.

[0161] In an eighty-first aspect according to the previous aspects, wherein the adaptation is such that the frequency (f P1 ) of the first peak of the amplitude is moved away from the heartbeat and / or heart rate frequency (f HR ), the frequency (f P1 ) of the first peak of the amplitude being at least partially associated with the parasitic flow disturbance in the segment (101) and originating from the at least one pump (11).

[0162] Any one of the method steps can be performed by a controller 65 of the sensor. Furthermore, any one of the sensor features can be part of the sensor according to the method aspects.

[0163] In an eighty-second aspect, a software program stored on a non-transitory memory support is disclosed, comprising software code portions suitable for loading and execution on at least one data processing unit, said software code portions being configured to cause execution of the steps of the method according to one or more of the previous aspects forty-seven to eighty-one.

[0164] In an eighty-third aspect, a distributed computing environment comprising a plurality of data processing units configured to be operatively connected to each other; said distributed computing environment being configured so as to enable execution of the steps of the method according to one or more of the previous aspects forty-seven to eighty-one.

[0165] In an eighty-fourth aspect, a device for extracorporeal blood treatment is disclosed, comprising:

[0166] a) a blood pump (11) configured to control at least the flow of blood in the blood circuit (6, 7),

[0167] b) a circuit for extracorporeal treatment of blood comprising:

[0168] - a filtration unit (2) having a primary chamber (3) and a secondary chamber (4) separated by a semi-permeable membrane (5);

[0169] - a blood circuit (6, 7) comprising a blood withdrawal line (6) having a first end connected to an inlet of the primary chamber (3) and a blood return line (7) having a first end connected to an outlet of the primary chamber (3), said blood withdrawal line (6) and said blood return line (7) being designed to be connected to the cardiovascular system of a patient,

[0170] wherein a second end of the blood withdrawal line (6) is provided with an arterial connector (40) and a second end of the blood return line (7) is provided with a venous connector (41), said arterial connector (40) and said venous connector (41) being designed to be detachably connected to a vascular access of a patient; and wherein said blood circuit is configured to interface with the blood pump (11) to control the flow in the blood circuit (6, 7); and

[0171] - the secondary chamber (4) is provided with an outlet for an effluent line (13) and optionally with an inlet for a dialysis fluid line (19); and

[0172] c) a sensor according to one or more of aspects one to forty-six.

[0173] In an eighty-fifth aspect according to the preceding device aspect, wherein the blood circuit comprises the segment (101).

[0174] In an eighty-sixth aspect according to any one of the preceding device aspects, wherein the blood circuit is a disposable blood circuit.

[0175] In an eighty-seventh aspect according to any one of the preceding device aspects, wherein the disposable circuit further comprises at least one fluid line (15, 21, 25, 42; 42a) connected to the blood circuit (6, 7).

[0176] In an eighty-eighth aspect according to any one of the preceding device aspects, wherein the segment (101) is made of a material, in particular a medical grade plastic material, having a predetermined degree of transparency to light radiation, in particular to infrared and / or visible light radiation.

[0177] In an eighty-ninth aspect according to any of the preceding device aspects, wherein the sensor is arranged downstream of the blood pump (11), optionally upstream of the filtration unit (2).

[0178] In a ninetieth aspect according to any of the preceding device aspects, wherein the sensor is arranged in a position substantially close to the venous connector (41).

[0179] In a ninety-first aspect according to any of the preceding device aspects, wherein the device further comprises at least a user interface, in particular a graphical user interface, configured to allow at least viewing the heartbeat frequency (f HR ), the device being further configured to send an alarm signal, in particular a visual alarm signal and / or an acoustic alarm signal, in case the sensor (100) does not detect any heartbeat frequency (f HR ).

[0180] In a ninety-second aspect according to any of the preceding device aspects, wherein the sensor is directly constrained to the outside of a tube being part of the blood circuit (60).

[0181] In a ninety-third aspect according to any of the preceding device aspects, wherein the tube is a flexible and optically transparent tube having a circular internal and external section, in particular the tube not comprising a rigid cuvette corresponding to the sensor.

[0182] In a ninety-fourth aspect according to any of the preceding device aspects, wherein the sensor is configured to be directly constrained to any external portion of a tube having a circular internal and external section being part of the blood circuit (60).

[0183] In a ninety-fifth aspect according to any of the preceding device aspects, wherein the sensor is directly constrained to a rigid and optically transparent rigid cuvette coupled to the blood circuit to allow a blood flow passage, in particular a cuvette defining the catheter.

[0184] In a ninety-sixth aspect according to any of the preceding device aspects, wherein there are no additional sensors on the blood circuit for determining the heartbeat frequency (f HR ) and / or the heart rate value. In particular, the non-invasive heartbeat sensor of the present aspect is the exclusive and only sensor for determining the heartbeat frequency (f HR ) and / or the heart rate value.

[0185] In a ninety-seventh aspect, a control unit for a heartbeat sensor is provided, in particular for a non-invasive optical heartbeat sensor adapted to be installed in correspondence with a catheter segment (101) so as to take a heartbeat and / or a heart rate from the analysis of flow perturbations of blood flowing into said segment (101), said control unit (65) being configured so as to:

[0186] - transmit a light radiation signal through said segment (101) so that at least a portion of said light radiation is transmitted through a portion of liquid present within said segment (101), in particular a portion of liquid comprising blood, performed by a light radiation source (53);

[0187] - receive, by at least one optical detector (57) arranged substantially in correspondence with said segment (101), an information signal comprising a modified version of said light radiation signal that has at least partially passed through blood present in the segment (101) and / or a portion of the segment (101) itself, wherein said information signal is modified by, and / or is related to, or as a function of, flow perturbations of blood flowing in the segment (101), said flow perturbations being at least partially generated by flow pulses originating from a beating heart,

[0188] - the control unit (65) is further configured to process electronically, as a result of the detection of at least a portion of said information signal, an output signal (200R) of said at least one optical detector (57) by:

[0189] - electronically computing a transformation of at least a reference portion (200W) of the output signal (200R) from a time domain to a frequency domain, obtaining an information signal spectrum or an output signal spectrum corresponding to or related to the information signal spectrum,

[0190] - identifying and discarding a first peak (f p1 ) of amplitude in said information signal spectrum or output signal spectrum, optionally said first peak (f p1 ) of amplitude corresponding to a first noise peak of amplitude corresponding to or at least partially associated with a parasitic flow perturbation in said segment (101) due to at least one pump (11) forcing the circulation of fluid into at least said segment (101),

[0191] - after said discarding has occurred, performing an electronic search or identifying and then selecting a first sought peak of amplitude in said information signal spectrum or output signal spectrum, said selection being electronically computed by the identification of a second sought peak of amplitude in said information signal spectrum or output signal spectrum, said second peak corresponding to a second harmonic of said first sought peak of amplitude,

[0192] - electronically to at least the temporary heartbeat and / or heart rate frequency (f HR ) assigning a first peak-finding frequency corresponding to the amplitude.

[0193] The sensor according to any of the preceding aspects can be positioned on any tube segment of the blood circuit to detect the heartbeat frequency (f HR ) and / or the heart rate value, i.e. either on the arterial line 6 or on the venous line 7.

[0194] Moreover, the sensor can not require any dedicated test tube or coupling element, but can be positioned around any circular tube portion of the blood circuit. BRIEF DESCRIPTION OF DRAWINGS

[0195] The foregoing and other related technical aspects of the present disclosure will be described in the subsequent sections of the present disclosure with the help of the enclosed drawings, wherein:

[0196] - Figure 1A and Figure 1B shows a schematic view of an embodiment of a blood treatment apparatus to which the sensor of the present disclosure can be provided;

[0197] - Figure 2 shows the operating principle of the sensor of the present disclosure;

[0198] - Figure 3 shows a schematic view of the sensor according to the present disclosure;

[0199] - Figure 3 a shows a perspective view of the sensor according to the present disclosure in an operating configuration in which its body is open to allow the extraction or introduction of a segment of a tube or catheter of a blood circuit into a cavity in which the sensing element is arranged;

[0200] - Figure 3 b shows a perspective view of the circuit configuration of a particular embodiment of the sensor according to the present disclosure;

[0201] - Figure 4 shows a schematic block diagram of the signal processing operations performed by the sensor object of the present disclosure;

[0202] - Figure 5 shows an example graph of the output electrical signal provided by the detector component of the sensor according to the present disclosure;

[0203] - Figure 6 shows a frequency domain graph showing the combined frequency spectrum peaks of the background noise detected by the sensor of the present disclosure, the noise caused by the operation of at least one pump of the apparatus and the peaks related to the actual blood pulses provided by the heart;

[0204] -Figure 7 A flow chart is shown which illustrates the steps of a method for detecting heartbeats and / or heart rate by means of a non-invasive sensor according to the present disclosure;

[0205] - Figure 8 A combined graph is shown of the raw signal of the output signal of the detector corresponding to the sensor according to the present disclosure and the pump-associated square wave signal for processing the output signal;

[0206] - Figure 9 A combined graph is shown in which the upper part represents the resulting signal product of the multiplication between the output signal and the pump-associated square wave signal and in which the lower part represents another signal corresponding to the above-mentioned signal after having removed the average value of the non-zeroed part;

[0207] - Figure 10 A combined graph is shown in which the upper part represents the frequency domain spectrum of the pulses caused by the pump and the heart as read by the sensor according to the present disclosure, without processing of the raw output signal as schematically shown in Figure 8 and Figure 9 and in which the lower part represents the result of processing the output signal of the detector according to the procedure of Figure 8 and Figure 9 where it can be seen how the peak pulse related to the blood pulse caused by the heart then has a significantly higher amplitude than the previous one, now comparable to the amplitude of the pump;

[0208] - Figure 11 A schematic flow chart of the method disclosed in Figure 8 , Figure 9 and Figure 10 is shown; and

[0209] - Figure 12 A schematic front view of the cabinet structure of the device of Figure 1A or Figure 1B is shown. DETAILED DESCRIPTION

[0210] The present specification first discloses a non-invasive, reusable (i.e. not disposable) heartbeat sensor which operates with the use of optical radiation to detect flow variations in a fluid, including blood in an inflow conduit (in particular a conduit or tube configured to be installed in a blood circuit of an extracorporeal blood treatment device 1).

[0211] Definitions

[0212] For the purposes of the present disclosure:

[0213] - by "non-invasive" shall be meant any device, in particular a sensor, which does not come into contact with the user's body, in particular neither being configured to be introduced into the user's body nor coming into contact, in particular direct contact, with the user's fluid, in particular blood, flowing in the segment of inflow conduit, to perform the detection for which it is conceived;

[0214] - by "flow variation" shall be meant a local variation of the flow or of the density or of the volume of a fluid, in particular but in a non-limiting range, blood or a fluid containing a substantial portion of blood,

[0215] - by "light radiation" shall be meant any electromagnetic field radiation lying in the spectrum of infrared radiation, visible radiation or ultraviolet radiation, i.e. any radiation whose wavelength in vacuum is substantially comprised between 1000 pm (300 GHz, corresponding to far infrared) and 10 nm (3000 THz, corresponding to extreme ultraviolet) according to ISO standard 21348;

[0216] - by "infrared radiation" shall be meant any radiation whose wavelength in vacuum is comprised between 0.7 pm and 1000 pm, more particularly between 1 pm and 350 pm or between 790 nm and 820 nm, for example between 800 nm and 810 nm;

[0217] - by "visible radiation" shall be meant any radiation whose wavelength in vacuum is substantially comprised between 400 and 750 nm, and

[0218] - by "red radiation" shall be meant any radiation whose wavelength in vacuum is substantially comprised between 620 nm and 750 nm.

[0219] As disclosed above, the sensor according to the present disclosure is configured to be installed in a device 1 for extracorporeal blood treatment or in a segment 101 of a blood circuit suitable to be installed on said device, which device 1 can be configured to implement one or more of the following treatments: hemodialysis (HD), hemofiltration with pre-dilution (HFpre), hemofiltration with post-dilution (HFpost), hemofiltration with pre- and post-dilution (HFpre-post), hemodiafiltration with pre-dilution (HDFpre), hemodiafiltration with post-dilution (HDFpost), hemodiafiltration with pre- and post-dilution (HDFpre-post), ultrafiltration (UF).

[0220] Brief description of the device

[0221] For the sake of clarity of the presentation and context of the operation of the sensor disclosed herein, a brief description of the device 1 is provided in the following. Figure 1A and Figure 1BA non-limiting embodiment of a device 1 for extracorporeal treatment of blood is shown, which can implement the innovative aspects of the present application. In the following description and in the claims, identical components are identified by the same reference numbers. Figure 1A and Figure 1B In the following description and in the claims, identical components are identified by the same reference numbers.

[0222] The device 1 comprises at least one sensor 100, which can be configured to determine at least the heartbeat and / or the heart rate. As will emerge from the following description, the sensor 100 can be placed at any position on the hydraulic circuit, in particular on the blood circuit 60. Figure 1A A device 1 suitable for chronic treatment is shown, Figure 1B A device suitable for providing acute treatment is disclosed; both devices are configured to provide any one of the treatments such as ultrafiltration, hemodialysis and hemodiafiltration.

[0223] The device 1 comprises a treatment unit 2 (e.g. a hemofilter, an ultrafilter, a hemodiafilter, a dialyzer, a plasmapheresis filter, etc.) having a primary chamber 3 and a secondary chamber 4 separated by a semipermeable membrane 5; depending on the treatment, the membrane 5 of the treatment unit 2 can be selected to have different characteristics and properties. A blood withdrawal line 6 is connected to the inlet of the primary chamber 3, and a blood return line 7 is connected to the outlet of the primary chamber 3. The blood withdrawal line 6, the primary chamber 3 and the blood return line 7 are part of an extracorporeal blood circuit, globally identified with reference 60 in Figure 1A and Figure 1B In use, the blood withdrawal line 6 and the blood return line 7 are connected to a needle or a catheter or other access device (not shown), which is then placed in fluid communication with the vascular system of a patient, so that blood can be withdrawn through the blood withdrawal line, flow through the primary chamber and then be returned to the vascular system of the patient through the blood return line. As marked with the curved arrow F in Figure 1B The normal flow of fluid, imposed by the blood pump 11, is from the arterial connector 40 to the venous connector 41; therefore, in consideration of this flow, the expressions “downstream” and “upstream” will be mentioned. Figure 1A The blood flow rate Q binand its normal flow direction. In a non-limiting solution, the blood withdrawal line 6 and the blood return line 7 are made of a transparent plastic material, which allows, for example, to identify the fluid flow, the presence of air bubbles or air or even obstructions therein (by dedicated sensors). At least the inner portion of the blood withdrawal line and of the blood return line, in particular any portion of the disposable circuit described herein, is made of a material specifically designed for medical applications, in particular of a compatible plastic material, and which does not release substances when in contact with fluids and / or lipids in the body (e.g. lipids of drugs or nutrients). Such plastic can be, for example, PVC, in particular high-quality medical PVC. An air separator (e.g. a bubble trap 8) can be present on the blood return line; the extracorporeal blood circuit is supported by one or more holders provided in a conventional manner by the support frame 70a of the device 1. For example, as shown in Figure 12 Fig. 1, the extracorporeal blood circuit 60 can be supported by a holder 71 holding the bubble trap, a holder 72 holding the treatment unit 2 and a holder 73 positioned in correspondence of the blood pump. A safety clamp 9 controlled by the control unit 10 can be present on the blood return line downstream of the bubble trap 8. A bubble sensor 8a can be present, for example associated with the bubble trap 8 or coupled to the portion of line 7 between the bubble trap 8 and the clamp 9: if present, the bubble sensor is connected to the control unit 10 and sends a signal to the control unit for the control unit to cause the clamp 9 to close in the event that one or more air bubbles are detected above a certain safety threshold. The blood flow through the blood lines can be controlled by a blood pump 11 (e.g. a peristaltic blood pump) acting on the blood withdrawal line (as shown in Fig. 1) or on the blood return line. The operator can input a set value of the blood flow rate Qb: the control unit 10 is configured to control the blood pump based on the set blood flow rate during the treatment. Note that the control unit 10 can also be connected to a user interface 12 (e.g. a graphical user interface) which receives the input of the operator (e.g. in particular the set value of the blood flow rate) and displays the device output. For example, the graphical user interface 12 can comprise a touch screen for displaying the output and allowing the user to input, or a display screen and hard keys for inputting the user input, or a combination thereof. The spent dialysate line 13, configured to drain the effluent fluid from the secondary chamber 4, is connected at one end to the outlet of the secondary chamber 4 and at its other end to a waste, which can be a drain conduit or an effluent fluid container 14 (Fig. 1 and dashed lines in Fig. 2) which collects the fluid extracted from the secondary chamber. An effluent fluid pump 17 operates on the spent dialysate line 13 under the control of the control unit 10 to regulate the flow rate Qd Figure 2 of the effluent fluid through the spent dialysate line. The spent dialysate line 13 can be provided with a filter 18, for example a bubble trap, to remove air bubbles from the effluent fluid. The effluent fluid pump 17 can be a peristaltic pump, for example, and can be controlled by the control unit 10 to regulate the flow rate Qd out. The net ultrafiltration (i.e. the net fluid removed from the blood by the semi-permeable membrane of the treatment unit 2) can be determined by the difference in flow rate between the dialysis fluid pump 21 on the fresh dialysis fluid line 19 and the effluent fluid pump 17. Alternatively (or in combination), the apparatus can also comprise an ultrafiltration line 25 branching off from the spent dialysis fluid line 13 and provided with a respective ultrafiltration pump 27 also controlled by the control unit 10 to cause a flow rate Q F . Figure 1A and Figure 1B Embodiments of the apparatus show a pre-dilution fluid line 15 connected to the blood withdrawal line: this line 15 supplies the substitution fluid from an infusion fluid container 16 connected at one end of the pre-dilution fluid line. Although Figure 1A the container 16 is shown as a source of infusion fluid, this should not be interpreted in a limiting way: indeed, the infusion fluid can instead come from an online preparation zone. Note that as an alternative to the pre-dilution fluid line, Figure 1A the apparatus can comprise a post-dilution fluid line (not shown in Figure 1A ) connecting an infusion fluid container or an online preparation zone of infusion solution to the blood return line. Finally, as a further alternative (not shown in Figure 1A ), the apparatus can comprise both a pre-dilution fluid line and a post-infusion fluid line: in this case, each infusion fluid line can be connected to a respective infusion fluid container or can receive infusion fluid from the same infusion fluid source (e.g. the same infusion fluid container or online preparation zone). In the case where the infusion fluid is online prepared, the infusion fluid source can be an online preparation zone component of the apparatus 1 (i.e. as the online preparation zone 200 described below) or a different device, similar to the zone 200 and connected to one or more infusion lines and configured to supply fluid to the post-dilution line and / or to the pre-dilution line (see Figure 1A ). Moreover, the infusion pump 18 operates on the infusion line 15 to regulate the flow rate Q rep1 through the infusion line 15. Note that in the case of two infusion lines (pre-dilution infusion line and post-dilution infusion line), each infusion line can be provided with a respective infusion pump. Figure 1A The apparatus also comprises a fluid preparation line 19 which at one end is connected with a water inlet and at the other end is connected with the inlet of the secondary chamber 4 of the filtration unit to supply fresh treatment fluid to the secondary chamber 4. The dialysis fluid pump 21 operates on the fluid preparation line under the control of the control unit 10 to supply fluid at a flow rate Q din from a fresh treatment fluid source (e.g. a container or a zone 200 for online preparation of fresh dialysis fluid) to the secondary chamber. In Figure 1AIn the example of , line 19 links the hemodialyzer or hemodialysis filter 2 to an online preparation zone 200 configured to prepare a dialysate: zone 200 comprises a main line 201, the upstream end of which is designed to be connected to a water supply. A first secondary line 102 and a second secondary line 103 are connected to the main line 201 and are configured to supply at least the necessary amount of buffer and the necessary amount of electrolyte. The first secondary line 102, which can be looped back onto the main line 201, is configured to be fitted with a first container 104, for example, a bag or sleeve or other container containing a buffer. The line 102 is also equipped with a first metering pump 105 for metering the buffer into the fresh treatment fluid: as Figure 1A As shown, the pump can be located downstream of the first container 104. The operation of the pump 105 can be controlled by the control unit 10 based on a comparison between: 1) the set point value of the buffer concentration of the solution formed at the junction of the main line 201 and the first secondary line 102, and 2) the value of the buffer concentration of the mixture measured by the first probe 106 located in the first secondary line downstream of the first container 104 or in the main line 201 just downstream of the junction between the main line 201 and the first secondary line 102. In addition, the free end of the second secondary line 103 is intended to receive fluid from a second container 107, which contains a concentrated salt solution, for example, electrolytes such as sodium chloride, calcium chloride, magnesium chloride and potassium chloride. In a variant, the second secondary line 103 can also be looped back to the main line 201. In addition, a plurality of independent second secondary lines 103 can be envisioned in case it is desired to feed separate electrolytes or electrolyte combinations from the respective containers. Note that second secondary line 103 is equipped with a second metering pump 108 for metering electrolyte into the fresh process fluid; the operation of this second metering pump is dependent on a comparison between: 1) the conductivity setpoint value or electrolyte concentration setpoint value of the solution formed at the junction of main line 201 and second secondary line 103, and 2) the conductivity or electrolyte concentration value of this solution as measured by a second probe 109 located in the second secondary line downstream of second container 107, or in main line 201 just downstream of the junction between main line 201 and secondary line 103. Note that the specific nature of the concentrates contained in containers 104 and 107 may vary depending on the environment and the type of fresh process fluid being prepared. Furthermore, the nature and location of the first and second probes may depend on the type of buffer used, the type of electrolyte concentrate employed, and the specific configuration of the circuit formed by the main and secondary lines. Furthermore, as already mentioned, more than two secondary lines, each with corresponding concentrate containers and corresponding metering pumps, may be used in situations where multiple different types of substances need to be added to prepare the fresh process fluid. The second probe is usually a conductivity meter, which is configured to measure the conductivity σ of the dialysis fluid upstream of the filtration unit 2 in Of course, the dialysis fluid conductivity σin The device comprises another conductivity meter 112 placed on the waste dialysate line 13 to sense the conductivity σ of the dialysis fluid downstream of the filtration unit 2. out The conductivity meters 109 and 112 both provide corresponding measurement signals to the control unit 10 of the device. Flow sensors 110, 111 (volume type or mass type) can be used to measure the flow rate in each pipeline. The flow sensors are connected to the control unit 10. Figure 1A In the example of , where the infusion line 15 and the ultrafiltration line 25 lead to respective containers or bags 16, 23, a ruler can be used to detect the amount of fluid delivered or collected. Figure 1A The device includes a first scale 33 and a second scale 34, wherein the first scale 33 is operable to provide weight information W1 related to the amount of fluid collected in the ultrafiltration container 23 and the second scale 34 is operable to provide weight information W2 related to the amount of fluid supplied from the infusion container 16. Figure 1B The embodiment of FIG. 1 shows an alternative apparatus 1 designed to provide acute treatments such as hemodialysis, hemofiltration, hemodiafiltration and ultrafiltration. Figure 1B In the device shown in Figure 1A The same components as those described in the embodiment of FIG. 1 are identified by the same reference numerals and are therefore not described again. Figure 1A Different hemodiafiltration devices are used. Figure 1B The device does not present online fluid preparation, as all fluids are pre-packaged in sterile containers. Fresh dialysis fluid is contained in fresh dialysis container 43. In addition, the fluid line 19 and the effluent line 13 are of disposable type and are directly and irremovably bound to the treatment unit 2. Therefore, the dialysis pump 21 and the effluent pump 17 are peristaltic pumps (rather than Figure 1A positive displacement pump of an embodiment). Figure 1B The embodiment of the present invention presents a pre-dilution fluid line 15 connected to the blood withdrawal line 6: the line 15 supplies the replacement fluid from an infusion fluid container 16 connected at one end of the pre-dilution fluid line. In addition, the device may also include an infusion pump 18 that operates on the infusion line 15 to regulate the flow rate Q through the infusion line. rep Note that, instead of or in combination with the pre-dilution fluid line, the device may comprise a post-dilution fluid line 28 connecting the infusion fluid container 29 to the blood return line 7. Another pump 30 (e.g. a peristaltic pump) may act on the post-dilution fluid line 28 under the control of the control unit 10 and is thus also part of the means for regulating the flow through the fluid lines. In addition, Figure 1BThe disposable circuit shown in Fig. 1 can present a further infusion line 31 which at one end is connected with the blood withdrawal line 6 upstream of the blood pump 11 and at its other end with a further infusion fluid container 32 which for example can contain a drug or a local anticoagulant such as a citrate solution. This further infusion line is referred to herein as a pre-blood-pump pre-dilution infusion line 31. The means for regulating include a pbp pump 22 (for example a peristaltic pump controlled by the control unit 10) which acts on a segment of the pre-blood-pump pre-dilution infusion line 31 to regulate the pre-blood-pump infusion rate Qpbp. The pump 22 is typically part of the apparatus 1 and thus not part of the disposable. As an alternative to or in combination with the above fluid lines, Figure 1B The apparatus can include one or more auxiliary lines 42 which at one end are connected with the blood withdrawal line 6. Figure 2 A single auxiliary line is shown. Figure 2 A further pump (for example a peristaltic pump) not shown in Fig. 1 can act on the auxiliary line under control of the control circuit 10 and thus also be part of the means for regulating the flow through the fluid lines. In Figure 1A In an embodiment of the apparatus, the apparatus includes a first scale 33 which is operable to provide weight information W1 relating to the amount of fluid collected in the ultrafiltration container 23 and a second scale 34 which is operable to provide weight information W1 relating to the amount of fluid collected in the infusion fluid container 16. The scales are both connected to the control unit 10 and provide said weight information W i for the control unit to determine the actual amount of fluid in each container and the actual flow rate of fluid supplied by each container or received in each container. Figure 1B A third scale 35, a fourth scale 36 and a fifth scale 37 are also included to detect the weight of the fresh dialysis container 43, the citrate infusion container 32 and the post-infusion fluid container 29 respectively. In Figure 1A In the example of Fig. 1, in order to control the fluid balance between the amount of fluid supplied to the secondary chamber 4 and the amount of fluid withdrawn from the secondary chamber, flow sensors 110, 111 located on the fresh dialysis fluid line and the spent dialysis fluid line 13 provide signals to the control unit 10 indicative of the flow of fluid through the respective lines and one or more scales provide weight information which allows the control unit to derive the flow rate through the ultrafiltration line 25 (and through the infusion line 15 if present). The control unit is configured to control at least the pumps 17, 21 and 27 to ensure that a predetermined fluid removal from the patient is achieved over a prescribed treatment time as required by a prescription provided to the control unit (for example via the user interface 12). Note that other fluid balance systems can be used: for example, in an apparatus which includes a container which is the source of fresh treatment fluid and a container for collecting waste (seeFigure 1B ) can be used to detect the amount of fluid conveyed or collected by each container and then inform the control unit accordingly. As a further alternative, a volumetric control-based system can be used, in which the preparation line 19 and the spent dialysis fluid line 13 are connected to a balancing chamber system to ensure that at each instant the amount of fluid that flows into the line 19 is the same as the amount of fluid that exits from the line 13. From a structural point of view, one or more containers 104, 107, 16, 23 can be disposable plastic containers. The blood lines 6, 7 and the filtration unit can also be plastic disposable assemblies, which can be installed at the beginning of the treatment session and then discarded at the end of the treatment session. The pumps (e.g. peristaltic pumps or positive displacement pumps) have been described as means for regulating the flow of fluid through each line; however, it should be noted that other flow regulation means can alternatively be employed, for example such as valves or combinations of valves and pumps, etc. The scales can comprise piezoelectric sensors, or strain gauges, or spring sensors, or any other type of transducer capable of sensing the force exerted on it.

[0224] Sensor description

[0225] The sensor according to the present disclosure exploits the variation of a physical property of the light radiation to detect the flow variations in the fluid, which comprises the blood flowing into the segment 101 of the tube or conduit used for extracorporeal blood treatment. It is concluded that the segment 101 should provide some transparency to the wavelength of the light radiation involved in the measurement. In particular, the sensor 100, which is the object of the present disclosure, allows to detect the variations of the blood, in particular the concentration of red blood cells, over time, by which the heartbeats and therefore the heart rate can be identified; more in detail, when irradiated by an appropriate light radiation, the transmission of the radiation through the blood varies as a function of the concentration of the blood, in particular as a function of the concentration of red blood cells, which in turn varies according to the flow peaks generated by the heartbeats. Therefore, calculating the rhythm of the flow peaks, i.e. of the peaks (or corresponding reductions) of the radiation transmission, it is possible to detect the heartbeats and therefore the frequency of the heartbeats.

[0226] The sensor 100 according to the present disclosure is non-invasive and allows continuous monitoring of the heartbeat, which may continue without significant interruption for any desired time and for the entire length of blood treatment required by the standard or acute treatment to which the patient is subjected. Since no part of the sensor comes into contact with the user's blood during normal operation, the sensor that is the object of the present disclosure is reusable and therefore does not constitute a so-called disposable device. In this way, some processing intelligence can be arranged on board without involving the associated replacement costs that would otherwise be present in any case where the known sensors come into contact with blood. In particular, the sensor 100 is placed on a segment of the blood circuit (specifically the blood withdrawal line 6 and / or the blood return line 7). Depending on the situation, more than one sensor 100 can be used and the sensors 100 can be placed at different locations along the catheter. Without limitation, any electronically sensitive parts of the circuitry arranged within the body of the sensor should be suitably protected from external agents according to appropriate IP standards so that, if this is the case, the sensor can be washed, cleaned, sterilized or disinfected in a convenient manner when newly installed for subsequent processing without significant risk of damage and without contamination of the blood line.

[0227] Generally speaking, according to Figure 2 , the sensor 100 comprises at least one light source 55 which emits optical radiation which passes through a catheter segment 101 filled with a fluid including blood. The optical radiation thus passes through the wall of the catheter segment 101 and the fluid contained therein and then reaches an optical sensor 57 which is capable of detecting at least variations in the amplitude of the received optical radiation. The sensor transmits an output signal 200R which is then appropriately processed to extract the heart rate. Figure 3 In the specific embodiment disclosed in the drawings, the sensor 100 comprises a plastic housing 51, which is only schematically shown in the drawings. The housing 51 is designed to be tightly coupled to a blood line segment 61 of an extracorporeal blood circuit 60, where the blood or plasma parameter is to be measured. The housing 51 can be a separate body or can be attached to or be part of the support frame 70a of the device. For example, the housing 51 can be attached to the front panel of the support frame (see Figure 12 ) and is configured to accommodate at least one (only one is depicted in the example of the drawings) segment 61 of an extracorporeal blood circuit. For this purpose, the housing 51 can be directly form-matched with a portion of the blood line tubing (i.e., a circular cross-section segment of the flexible transparent plastic tubing of the blood withdrawal line 6 or the blood return line 7). The housing can be an open-and-close housing defining an internal through-channel 52 intended to accommodate the tubing of the blood circuit.

[0228] It is worth noting that the housing 51 can be made of two or more components 51a, 51b, which can be separate or joined (e.g. hinged) together to define a non-coupling configuration (see Figure 3 a) and a coupling configuration (see Figure 3 ). In the coupling configuration, the through passage 52 is shape-matched with the tube to be housed, so as to perfectly couple and house the tube. It can be noted that the first component 51a defines a first portion of the shape-matched portion of the through passage 52, while the second component 51b defines a second portion of the shape-matched portion of the through passage 52: in more detail, in the figures these components are semicircles of identical shape. The schematic shows the case in which the flexible blood tube is coupled to the sensor 100. However, alternatively, the housing 51 can be shaped to couple with a rigid test tube (e.g. for the test tubes of the sensors from Baxter In this case, the flexible tube of the blood circuit has a rigid test tube applied in a suitable manner, so that the blood flowing in the extracorporeal blood circuit 60 passes through the test tube itself; in the latter case, the through passage is shape-matched with the outer surface of the test tube, which is not necessarily circular, but instead can have a flat outer surface (polygonal cross-section).

[0229] Obviously, in the case in which the housing is to be applied to a circular flexible tube of the extracorporeal blood circuit 60, any position of the sensor along the blood withdrawal line 6 or the blood return line 7 is suitable. In the case in which the sensor 100 has a through passage shape-matched with a specific test tube, the sensor will be applied in correspondence with the test tube itself to work normally.

[0230] The housing 51 can be made of a highly absorbent material that prevents the external environmental light from reaching the receiver. This helps to reduce the risk that external sources of light radiation adversely affect the heartbeat readings, providing false peaks or reducing the light amplitude (in particular when these peaks or reductions are at frequencies close to the frequency of the physiological heartbeat).

[0231] The sensor 100 comprises at least one signal source 53 for directing a signal along an emission axis 54 towards the blood. The signal source 53 can comprise any suitable signal emitter, for example an optical (or acoustic) emitter that directs an appropriate emission signal towards the interior of the tube in which the blood flows. In an embodiment of the application, the signal source 53 comprises an electromagnetic radiation source, in particular a light source such as an LED source, a SLED or a laser source. In the following description, we refer to an optical emitter and in detail to an LED emitter 55; however, this should not be interpreted as limiting. It has been noted that the non-limiting peak wavelength of the optical radiation transmitted by the signal source 53 is set at 800-810 nm, corresponding to that point of the Hgb absorption spectrum that is not dependent on oxygenation. Again, this should not be considered as a limiting aspect; in fact, any optical radiation in the infrared or red light field can in principle be used in the present application. In a simple embodiment similar to that disclosed in Figure 2 the signal source 53 can comprise a simple multi-mode incoherent LED that transmits optical radiation having a first peak wavelength λ1 in the infrared or red region or within a predetermined wavelength (or frequency) emission window, wherein said first peak wavelength λ1 falls within the predetermined wavelength (or frequency) emission window. In addition to this, the specific implementation of the signal source 53 comprises a multi-wavelength LED emitter for light emission (i.e. MTMD6788594SMT6, Marktech Optoelectronics, NY, USA). In particular, the emitter 55 comprises 5 LEDs on the same chip having peak wavelengths λ1, λ2, λ3, λ4, λ5 in the red / infrared band. These five LEDs emit optical radiation having peak wavelengths different from each other. In this way, for the purpose of increasing the accuracy of the heartbeat detection and reducing any external influences on the heartbeat reading, a wavelength (or equivalent frequency) diversity can be obtained.

[0232] The source 53 further comprises an optical fiber 56, one end 56a of which is coupled with the signal emitter 55 and the other end 56b is fixed to the casing 51 and placed so as to direct the optical radiation along the emission axis 54 of the source 53 towards the blood. As shown in Figure 3 the coupled condition of the casing with the tube segment 61, the second end 56b of the optical fiber 56 is placed at the shape-matching portion and faces the tube.

[0233] The sensor 100 comprises a plurality of detectors 57 for receiving the signal emitted by said source after having at least partially passed through the blood; in particular, the detectors 57 collect the reflected signal, the scattered signal and / or the emitted signal depending on their respective position. Since the emitter 55 is an LED emitter, the detectors 57 can comprise photodiode receivers 58. In an embodiment, the detectors 57 are placed at different angles with respect to the emission axis 54. In more detail, Figure 3The sensor 50 comprises four different detectors 57 for receiving electromagnetic radiation from the source 53, one first photodiode receiver PD1 placed at about 180° with respect to the emission axis 54 of the signal source, one second photodiode receiver PD2 placed at about 90° with respect to the emission axis of the signal source, one third photodiode receiver PD3 placed at about 45° with respect to the emission axis of the signal source, one fourth photodiode receiver PD4 placed at about 0° with respect to the emission axis of the signal source. Of course, more (or less) than 4 receivers can be used according to specific needs, and more than one receiver can be placed at the same angle with respect to the emission axis 54 of the optical fiber. More specifically, all detectors 57 are arranged on the same plane, which in turn coincides with the plane where the source 53 is arranged. This allows to achieve a spatial diversity of the detection, which in presence of spatial diversity cooperates with the multi-wavelength emission of the optical radiation to further improve the quality of the reading of the heartbeat and make the sensor 100 more robust to external radiation influences. Each detector 57 is configured to receive radially along the normal section of the blood flow in the tube of the extracorporeal blood treatment device the signal emitted by the signal source (and suitably reflected, scattered or transmitted). The new measurement system extends the architecture of the traditional design to collect light at different geometric angles with respect to the emitter, allowing to discriminate between reflected, scattered and transmitted light. If different receivers pick up scattered light at the same time, the loss of transmitted light due to increased scattering is not erroneously detected as an increase in absorbance. To achieve the above configuration, each detector 57 comprises a respective optical fiber 59, one end of which is placed in correspondence of the segment 61, the other end being coupled to the receiver (in detail, a photodiode receiver). In more detail, the end of the optical fiber 59 corresponding to the segment 101 is fixed to the housing 51 and is placed at the shape-matching portion and, in the coupled condition of the housing with the segment 101, faces the segment 101. As mentioned, all channels for receiving the signal are placed radially along the normal section of the blood flow, except for the reflection channel (0°), which is slightly offset along the flow direction to allow the placement of the emitting optical fiber 56. Both the emitted and the collected optical radiation are coupled to and from the segment 101 using, for example, plastic optical fibers (ESKA GH4001, Mitsubishi Rayon). The photodiode receivers 58 can have a specific optical fiber coupling mechanism for the light collection channels (e.g. IFD91, Industrial Fiber Optics, Tempe, USA), corresponding to Figure 3 PD1-4 in Fig. 4.

[0234] The photodiode receiver 58 is housed on a printed circuit board 60a together with analog circuitry 62 for transimpedance amplification; the circuitry 62 for transimpedance amplification includes a current-to-voltage converter (e.g., implemented using an operational amplifier). The circuitry 62 can be used to amplify the current output of the photodiode receiver 58. Current-voltage converters are used with photodiodes that have a current response that is more linear than the voltage response (the current response typically has a linearity better than 1% over a wide range of light input). The transimpedance amplifier presents a low impedance to the photodiode and isolates it from the output voltage of the operational amplifier. There are several different configurations of transimpedance amplifiers, a common factor of which is the requirement to convert the low level current of the sensor to a voltage. The printed circuit board 60a also includes a low pass filter stage 63 and a gain stage amplification. The cut-off frequency of the low pass filter 63 is set, for example, at 30 Hz. This helps to reduce unwanted noise that can affect the signal processing performed on the output signal 200R generated by the detector. The low pass filter 63 can also be set at a lower frequency, for example, at a frequency less than 10 Hz, in particular at a frequency equal to or less than 5 Hz or 4 Hz, to further limit the upper bandwidth of the output signal 200R. Based on preliminary tests and calibrations, the gain is set to a value specific to the channel. The analog signal is then converted into a digital signal by a suitable converter 64. In more detail, the analog output is sampled at a rate of 100 Hz with a resolution of 12 bits using a NI USB-6008 DAQ card (National Instruments Italy Srl, Milano, Italy) and recorded by a custom LabView virtual instrument. The multi-LED emitter, the signal conditioning board and the DAQ card are assembled together on a 3D printed housing and placed inside a grounded metal box (see Figure 3), the grounded metal box serving for electromagnetic shielding and being provided with openings for the optical fibers 56, 59, data connections and power supply. In a particular embodiment, each detector 57 is configured to receive optical radiation in a predetermined wavelength or a predetermined frequency window. In more detail, a first detector 57 (PD1) is configured to receive optical radiation in a first wavelength λ1 or in a first frequency window comprising said first wavelength, a second detector 57 (PD2) is configured to receive optical radiation in a second wavelength λ2 or in a second frequency window comprising said second wavelength, a third detector 57 (PD3) is configured to receive optical radiation in a third wavelength λ3 or in a third frequency window comprising said third wavelength, and a fourth detector 57 (PD4) is configured to receive optical radiation in a fourth wavelength λ4 or in a fourth frequency window comprising said fourth wavelength. The several radiation wavelengths described above can be used to detect flow variations by more or less specifically analyzing the flow of hematocrit and osmolarity; since the influence of osmolarity can be detected and decoupled, a better estimate of blood volume variations can also be obtained. The use of several channels to detect radiation at different wavelengths allows to determine and remove unwanted influences and still allows to better detect the heartbeat, since the influence on the overall transmission of radiation is given by two different properties of the blood. This can lead to the fact that the variations in the amplitude of the received optical radiation in at least some channels can be more sensitive to a specific parameter, while the behavior of other channels is more like a mixture of properties (hematocrit and osmolarity). The digital signals are input to a controller 65 for use in detecting the heartbeat and heart rate through the tube segment 61 of the extracorporeal blood treatment apparatus, as will be apparent from the following detailed description.

[0235] Signal processing and method for detecting heartbeats

[0236] Applicant has understood that the (e.g. optical) response signal measured from the (e.g. optical) detector in the procedure for heartbeat detection is affected at least by the red blood cell concentration produced by the pulses provided by the heart. Moreover, said red blood cell concentration is also affected by the pulses provided by the cyclic operation of the peristaltic pump. Applicant has also found that the information signal received by the detector 57 is substantially not altered, and / or substantially uncorrelated, or substantially not a function of, the size and / or geometric shape variations of at least a portion of the information signal received by the segment 101 as a result of said flow perturbations of the blood flowing in the segment 101. This means that even if the segment 101 can expand and / or deform due to flow peaks caused by the operation of the heart or, most importantly, of any pump of the device, the reliability and accuracy of the detection of the correct heartbeat frequency is ultimately substantially not affected. In this sense, it is noted that the detection of the heartbeat frequency according to the present disclosure allows to mitigate the requirements on the material (which can be very hard or, on the contrary, very soft) and / or design of the segment 101; on the contrary, any measurement of the heartbeat by evaluating the deformation of the segment 101 to read the heartbeat frequency can require to focus on the material and size used to determine the dimensions of the segment 101.

[0237] Figure 4 A block diagram showing the main operations of the signal processing performed by the sensor 100 according to the present disclosure is shown; it can be noted that in the following the processing is described as performed by the controller 65. This should not be limiting, as at least a portion or any portion of the signal processing can be performed by a data processing unit, different from the controller 65, and which can be arranged outside the main body of the sensor 100. It can also be noted that, while today's technology allows to perform at least a portion of the signal processing described herein via software (e.g. via software loaded on a memory electronically accessible by, for example, the controller 65), this aspect should not be considered limiting either, as at least a portion of the following described procedures and steps can be carried out or performed by physical levels (i.e. hardware levels) depicted in Figure 4 Fig. 4. As depicted in Figure 4 Fig. 4, after the photodiode receiver 58, a transimpedance amplifier 62 is arranged to transform the current drive signal generated by said detector 57 into a voltage drive output signal. The output of the transimpedance amplifier 62 feeds the input of a low-pass filter 63, whose output in turn feeds the input of an analog-to-digital converter 64, which samples the signal, transforming it so that the output signal to be further processed electronically is in the digital domain.

[0238] As schematically shown in Figure 5 Fig. 4, and as shown in Figure 7corresponding to the step of receiving the optical signal through the blood and segment 101 (this step corresponds to the block 1000 of the brief flowchart reported in figure 1) Figure 5 The output signal 200R generated as output after receiving the optical signal through the blood and segment 101 (this step corresponds to the block 1000 of the brief flowchart reported in figure 1) is first sampled into a sampling reference window 200W of predetermined length. Figure 5 An example is shown in which the window is 30 seconds long, but this example should not be intended as limiting, since the length of the sampling reference window 200W can be, for example, equal to or less than 1 minute long, or equal to or less than 45 seconds long, or equal to or less than 30 seconds long, or equal to or less than 20 seconds long, or equal to or less than 15 seconds long, or equal to or less than 10 seconds long. The portion of the output signal 200R contained within the window will be referred to hereinafter as the reference portion of the output signal 200R. It is important to note that the longer the window, the greater the degree of averaging of the result of the processing. Although lengthening the window can have a positive effect on the occasional occurrence of noise spikes in the average output signal 200R, excessively long window lengths should be prevented in order to reduce the risk of a significant variation in the frequency of the center of the window, which can compromise the quality of the reading of the heart frequency and of the subsequent processing of the signal.

[0239] If the controller 65 is made by hardware processing stages, the windowing of the output signal 200R into the sampling reference window 200W of predetermined length can be performed by a time domain windowing stage 67 operating on the digital signal, the input of which is fed by the output of the analog-to-digital converter 64, in particular directly by the output of the analog-to-digital converter 64.

[0240] Figure 5 The output signal 200R not only contains information on the heartbeats achieved by the flow pulses caused by the patient's heart, but also contains unwanted noise, including the unwanted noise generated by the peristaltic blood pump 11 operating to force the flow of liquid into the blood circuit, in particular into the segment 101. In greater detail, Figure 5 is the result of the original (unfiltered) signal in the output of the detector under the following test conditions:

[0241] - the fluid flow in the segment 101 with the peristaltic blood pump 11 is set to 200 ml / min, which results in unwanted pump noise at a frequency of about 1.0 Hz for the reference device 1 used for the test results;

[0242] - the fluid flow in the segment 101 with the heart simulator is set to 70 bpm, whose nominal frequency substantially corresponds to 1.16 Hz.

[0243] Subsequently, further electronic processing of the signal is performed by the controller 65. In particular, the output signal 200R, in particular the relevant portion thereof entering the aforementioned window, is subjected to a transformation in the frequency domain, for example by applying a Fourier transform, in particular a Fast Fourier Transform (this step corresponds to block 1001 in Figure 7 It should be noted that the Fast Fourier Transform can not be the only way to calculate the transformation in the frequency domain, but it is the way chosen by the Applicant, since one of the exemplary embodiments disclosed herein acts on the output signal in the digital domain, since the output signal is transformed into the digital domain by the previously disclosed analog-digital converter.

[0244] Figure 6 An exemplary graph of the spectrum of the signal of Figure 5 Once the output signal 200R has been transformed from the time domain to the frequency domain, the exemplary graph of the spectrum is shown. If the controller 65 is made of a hardware signal processor stage, the step of transforming the windowed reference portion of the output signal 200R from the time domain to the frequency domain is performed by a Fourier transform stage 68, in particular by a stage that performs the processing according to the FFT algorithm, the input of which is fed directly by the output of the time domain windowing stage 67. The highest frequency of the spectrum under examination is set at 4 Hz; this is done, for example, by means of a low-pass filter stage 63 in the time domain, or it can be done by means of a hard cut of the Fourier transform at the aforementioned frequency; a lower highest frequency is chosen for the electronic processing of the spectrum, since the fundamental frequency and its second harmonic, when performing the heartbeat search, are considered physiologically and / or generally in the normal resting state in which the patient is during the processing, not to exceed 4 Hz. In any case, as a precaution, a higher frequency can be chosen, for example up to 30 Hz as disclosed when discussing the operation of the low-pass filter 63 as previously discussed. It is noted that below 0.3 Hz, the amplitude of the spectrum increases rapidly. Once again, the Applicant has considered that the fundamental frequency of a beating heart, at least in the resting state in which the patient is during the processing, is not lower than 0.6 Hz, or 0.5 Hz, or 0.4 Hz or even 0.3 Hz, physiologically. Therefore, the Applicant has chosen to electronically select a first lower frequency window 200L containing the portion of the spectrum that is not relevant for the current detection, and an upper frequency window 200U starting at a lower frequency just above the highest frequency of the lower frequency window 200L. In Figure 6The highest frequency of the lower frequency window 200L in the figure is 0.6 Hz. The lower frequency window 200L is removed from further signal processing; this facilitates analysis of that portion of the spectrum which is free of highly correlated unwanted noise, which has been shown to be in the lowermost portion at the bottom of the spectrum and which may be due, for example, to blood flow, breathing and / or other physiological or external "interference" within segment 101. Any relevant data about the limits of the lower frequency window 200L (e.g., the upper frequency limit of the lower frequency window 200L) and / or any relevant data about the upper frequency window 200U (e.g., its lowest and highest frequencies) may conveniently be stored in a memory 65m which is arranged within the body of the sensor 100 or is otherwise operably accessible to at least the Fourier transform stage 68. The window of interest is then the upper frequency window 200U, which is at Figure 6 In the exemplary diagram of , the lowest frequency starts at 0.6 Hz and ends at an upper frequency of 4 Hz. In these regions there is essentially any physiological fundamental heart frequency, its second harmonic, and as depicted this can be the fundamental frequency and at least the second harmonic of the peristaltic pump 11. In fact, Figure 6 The diagram of FIG. 1 shows the relevant peaks, which are marked with circled reference numerals “1”, “2”, “3”, “4” and “5”. The fundamental frequency of the pump 11 is represented by the reference frequency “f p ” mark, and its second harmonic is marked with reference frequency “f ph2 " mark; it can be seen that Figure 6 The fast Fourier transform shows the fundamental frequency f of the pump 11 p is just below 1 Hz, and its second harmonic is just below 2 Hz. Where the controller 65 comprises a hardware signal processing stage, the selection of the upper frequency window 200U, or otherwise filtering out the lower frequency window 200L, may be performed by an upper frequency window selection stage 69. It will be noted that the upper frequency window selection stage 69 effectively acts as a high-pass filter, or a band-pass filter whose lowest frequency is substantially the same as the highest frequency of the lower frequency window 200L. The input of the upper frequency window selection stage 69 is fed via the output of the Fourier transform stage 68; the output of the upper frequency window selection stage 69 is fed into a peak detection stage 70, the operation of which will be elucidated in the following description.

[0245] It will become clearer by reading the following description that the fundamental frequency of the heartbeat corresponds to peak "3" in the spectrum, and the frequencies are marked with the reference name "f HR". It is noted here that the graph also shows the second harmonic of the heartbeat frequency, whose peak is designated by reference 200P. It is noted that, up to this step, the frequency of the heartbeat is still unknown and is retrieved after some other processing steps have been performed. In fact, the controller 65 knows the fundamental frequency of the pump 11 and, therefore, its second harmonic, which nominally lies at twice the fundamental frequency. In fact, any device 1 is provided with a specific pump 11, in particular a specific group of pumps in the case where there are many pumps, which, for any pre-set flow rate [l / min], rotate at a predetermined angular speed, i.e. their rollers cycle a portion of the compression tube and expand a portion of the tube at a predetermined frequency. Therefore, it can be the case that:

[0246] - in the case where a limited table of pre-set flow rates can be set for the operation of the pump 11, a one-to-one relationship of flow rate / frequency is recorded in a table pre-stored in a memory operatively accessible by the controller 65;

[0247] - in the case where the user can set an indeterminate flow rate according to his / her own will, a sensor (for example, a Hall sensor) can be arranged on the device, in particular substantially in correspondence with the pump, so as to directly detect the operating frequency of the pump itself. Continuing, this part of the signal processing (as schematically marked in block 1006 of the flowchart of Figure 7 typically comprises retrieving the operating frequency of the pump 11 which forces the fluid flow into the relevant section 101 in which the sensor 100 is coupled, and this retrieval can be performed electronically, either by direct sensing or by loading the value from a table. It is therefore evident that, Figure 6 the peaks with reference marks "2" and "5" mentioned in the foregoing can be clearly identified and then discarded by further electronic processing. In other words, the electronic processing performed by the controller 65 comprises (block 1007 in the flowchart of Figure 7 ) searching for and excluding the fundamental frequency f p of the pump 11 and any harmonics f ph2 , f ph3 ,... f phn . If the controller 65 is made using a hardware processing level, the latter operation can be performed by a pump peak exclusion stage 71, whose input is fed by the output of the peak detection stage 70.

[0248] A particular embodiment of the processing disclosed herein involves setting a threshold 200T of the spectral amplitude before searching for any peak of the amplitude. Said threshold 200T can be fixed in time or adaptive. In the case where it is adaptive, it can be set as a function of the maximum amplitude of the signal, for example, as a percentage of the maximum amplitude of the signal. Figure 4In this, the operation is schematically represented by the input 200T of the peak detection stage 70, which is fed by the output of the upper frequency window selection stage 69. Although a careful selection of the appropriate threshold can be performed, the Applicant shows that the application of a threshold allows to reduce the computational burden of the controller 65 and to reduce the risk of false readings, provided that only the peaks whose amplitude exceeds the threshold 200T are considered as potential useful signal frequencies; this helps to reduce the risk of reading as actual heartbeats noise peaks.

[0249] According to the application of the threshold, only the peaks identified by the markers "1", "3", "4" can be potential points of interest, according to which: Figure 5 the threshold is set at a reference value 1 in the spectrum.

[0250] Then, considering any peak which exceeds (i.e. is higher than) the threshold 200T, which we here call detected peak, and considering that there is another peak exactly at twice the frequency at which the detected peak lies, the controller 65 performs a further electronic processing in the spectrum. Then, for each detected peak whose amplitude exceeds the threshold 200T (in particular, moving from the lower limit frequency to the upper limit frequency):

[0251] - if a peak 200P is found at a frequency which exactly corresponds to twice the frequency of the detected peak, this means that the detected peak corresponds to the sought heartbeat signal, and therefore to the frequency of said peak the reference f HR is assigned;

[0252] - if no peak is found at a frequency which exactly corresponds to twice the frequency of the detected peak, this means that said detected peak does not correspond to the sought heartbeat signal, and therefore not to a heartbeat; in this case, the algorithm continues considering another peak whose amplitude exceeds the threshold 200T, if present.

[0253] In the case in which the controller 65 is designed to perform these operations with a hardware processor, these operations are performed by the harmonic search stage 72; as Figure 4 depicted in the middle, the input of the harmonic search stage 72 is fed by the output of the pump peak exclusion stage 71. The harmonic search stage 72 is provided with an output configured to generate a signal representing the value of the reference frequency f HR of the heartbeat. This reference frequency can be provided on a screen, which is schematically represented by the f HR display stage 73 in the right. Figure 4

[0254] ​In a particular, but not limiting, embodiment, in the case where the peak is also considered to be below the threshold 200T level, an electronic search can be performed in the spectrum of the signal for a peak at a frequency which is double the frequency at which the peak under examination lies. This helps to reduce the risk of discarding an actual peak corresponding to the second harmonic of the heartbeat. This step corresponds to block 1008 of the flowchart of Figure 7 The heartbeat frequency f HR is then at least temporarily stored in a memory electronically accessible to the controller 65 and, in particular, is provided or provided as an electronic signal to be transmitted to a monitor or display of the device 1 in order to let the user know the heart rate Figure 7 (block 1009 of the flowchart of Fig. 1). The heart rate frequency can be transmitted by the controller 65 or by any other electronic device operatively connected thereto to a remote device (for example, a smartphone or a laptop), in particular using a wireless channel whose electromagnetic behavior is compatible (and does not interfere) with medical applications.

[0255] In the case of Figure 6 , only the peak with reference “3” is the peak which actually corresponds to another peak at a frequency which is exactly double the frequency. The peaks “1” and “4” are peaks caused by noise captured by the detector 57, which in fact do not correspond to heartbeats. The algorithm performed by the controller 65, the system is able to well distinguish between noise and real heartbeat frequencies, even if they are very close to each other and even if the noise peak exceeds the amplitude of the peak which actually corresponds to the heart rate. In the case of Figure 6 , in fact, the peak “4” differs by less than 0.1 Hz from the actual heartbeat frequency, even if its amplitude is almost twice the amplitude of the peak which corresponds to the actual heartbeat, but the peak which corresponds to the actual heartbeat is in fact detected and the peak “4” is in fact discarded.

[0256] The detection of the peaks in the spectrum of the pump is performed by means of a step of processing the output spectrum with a peak detection algorithm; in a non-limiting embodiment, the peak detection comprises: moving from a lower limit frequency to an upper limit frequency, calculating the derivative of the spectrum signal to detect and at least temporarily store the frequencies at which the sign of the derivative changes from positive to negative (this is the hallmark of a peak); said temporary storage, performed in a memory electronically accessible to the controller 65 (for example, an internal memory), is performed by means of an electronic table, whose first list indicates the values of the peak frequencies sought by the peak detection algorithm and whose second list indicates the corresponding amplitude values. Thus, a table similar to the following exemplary table can be stored in said memory.

[0257] Frequency [Hz] Amplitude f 1p ]]> A 1p ]]> f 2p ]]> A 2p ]]> … … f np ]]> A np ]]>

[0258] In another solution, the search for the peak in the output spectrum can be performed by means of a moving window algorithm. In the moving window algorithm, a predetermined width frequency window is considered for the examination and is formed, for example, from the lower frequency to the upper frequency of the reference spectrum (for example, from the lower frequency to the upper frequency of the upper frequency window 200U). It can be noted that the controller 65 can be configured to move the window in a stepwise manner. For each step of movement of the window, the local maximum amplitude of the spectrum is considered, the frequency of which is recorded in the table in a similar manner to the previous one. It can be noted that it is convenient that, in each step, the frequency of the moving window does not overlap with the frequency of the moving window of the previous step. When the controller 65 is made by means of hardware processing stages, these operations are conveniently performed by the peak detection stage 70 and / or the harmonic search stage 72. It is worth noting that the algorithm disclosed herein allows obtaining the heart rate in a real-time and substantially reliable manner, even with a low computational power processing unit, without any related delay, especially after a setup period for obtaining the first window of the signal in the time domain.

[0259] Induced modulation algorithm

[0260] The Applicant has also considered that the correct heart beat frequency f HR reliability of the reading. The following steps of signal processing, which can be conveniently performed by the controller 65, are performed before the step of transforming the output signal of the sampling reference window 200W into the frequency domain. This means that, considering the output signal 200R Figure 7 of the flowchart to be located between block 1000 and block 1001. The Applicant has found that, even in the presence of a strong noise signal, for example caused by the operation of the pump 11, the reliability of the reading of the correct heart beat frequency f HR can be further improved by processing the output signal 200R produced in the output by the block 1010 of the detector 57 Figure 11 in such a way that, when the spectral analysis is performed, the peak corresponding to the frequency of the heart beat is provided with an amplitude that is amplified with respect to the amplitude of the peak of the noise, or, correspondingly, in such a way that, when the spectral analysis is performed, the peak corresponding to the frequency of the noise sees an amplitude that is attenuated with respect to the amplitude of the peak corresponding to the frequency of the heart beat. First of all, this algorithm involves multiplying the output signal 200R produced in the output by the detector 57 Figure 8 An example of a pair of graphs is shown, in which the output signal 200R (upper graph) is multiplied by the pump associated signal 300P (lower graph). The multiplication step corresponds to Figure 11of block 1011. Generally, the pump-related signal 300P is periodically zeroed in correspondence of the time portions in which the pump provides flow pulses at least in the segment 101 in which the sensor 100 is arranged. Conveniently, in the embodiment depicted in the lower graph of Figure 8 , the pump-related signal 300P is a square wave having a predetermined duty cycle, provided with a first portion of single amplitude and a second portion of zeroing for each cycle. The first portion clearly corresponds to the time portions in which the pump does not provide flow pulses. The multiplication of the output signal 200R with the pump-related signal 300P results in the generation of a resulting signal 301 whose shape is represented in the upper graph of Figure 9 . It is clear that the resulting signal 301 is also characterized by portions that are zeroed in correspondence of the same time portions in which the pump-related signal 300P is zero. Note that the use of a square wave allows not to alter the shape in the non-zeroed portions of the output signal 200R, which helps to keep its frequency spectrum unchanged. Subsequently, as schematically represented by block 1012 of the flowchart of Figure 11 , the average amplitude V m of the resulting signal 301 is calculated for the non-zeroed portions, or more generally for a window of predetermined time length. The resulting signal 301 is then subtracted from the average amplitude V m , in particular only corresponding to the non-zeroed portions, so as to generate an average signal 301A whose shape is reported in the lower graph of Figure 9 .

[0261] Therefore, a transformation in the frequency domain is performed on the average signal 301A, for example as previously described. The further processing performed on the frequency spectrum of the output signal is eventually performed on the frequency spectrum of the average signal 301A. Figure 10 It is clearly shown how the inductive modulation affects the spectrum in terms of frequencies. While, before the inductive modulation, the amplitude peaks of the noise caused by the action of the pump 11 (peaks PI, P2, P3, P4, P5, corresponding to the fundamental, second, third, fourth and fifth harmonic, respectively) are far higher than the peaks of the heartbeat (peaks HI, H2, H3, corresponding to the fundamental, second and third harmonic, respectively) up to 4 times, after the application of the above inductive modulation process, the peaks of the amplitude of the heartbeat corresponding to the average signal 301A are enhanced. Therefore, this alleviates the requirement for a suitable threshold setting, and / or allows a more clear identification of the correct heartbeat, and allows a more precise and reliable reading. It should be noted that the execution of the above inductive modulation algorithm still allows to generate an indication of the heartbeat frequency f HR in substantially real time.

[0262] It is noted here that the moving window is cyclically repeated by the windowing process in the time domain applying a predetermined length reference window 200W for a predetermined amount of time or to provide new samples of the reference portion of the buffer output signal 200R for processing as described above. The time difference between two consecutive reference windows can be arbitrarily reduced to at most one single delay sample if allowed by the buffer stage. Figure 4 This solution of inductive modulation is also depicted in the dashed box. Since inductive modulation is not an obligatory part of the disclosed signal processing algorithm, two fictitious switches 77' are depicted between the time domain windowing stage 67 and the Fourier transform stage 68 to identify the optionality. In an embodiment, the controller 65 can comprise a square wave generator stage 74 which receives a first input from a pump cycle sensor 100s, in particular a Hall sensor coupled to the blood pump 11, and generates in output the above mentioned pump associated signal 300P. Then, a hardware multiplier 75 arranged downstream of the square wave generator stage 74 multiplies the windowed reference portion of the output signal 200R with the above mentioned pump associated signal 300P to obtain in output the above mentioned result signal 301, the shape of which is represented in the upper graph of Figure 8 The above mentioned averaging operation can be performed by means of an averaging stage 76 of the controller 65, arranged downstream of the multiplier 75 so that the output of the multiplier 75 is directly fed into the input of the averaging stage 76; then, the output of the averaging stage is fed into the input of the Fourier transform stage 68. The Applicant has finally provided a subprogram which conceives the verification and implementation of the heartbeat reading, which comprises repeating at least a portion of the previous steps a predetermined number of times, for example three times. In case the reference windowing is sufficiently short, and thanks to the real time processing allowed by the algorithm disclosed herein, we are substantially in conditions to make the following assumptions: 1) the flow rate of the pump 11 does not change throughout the above mentioned repetition, 2) the heart rate remains substantially stable. By the above mentioned repetition, a series of n (for example, 3) heartbeat frequency values f HRn are calculated electronically: f HR1 , f HR2 , f HR3 (in case of three repetitions). These n (for example, 3) values can be averaged together; the controller 65 can be configured to perform the discard of at least one of the n frequency values, for example the one which coincides with the one which is more distant from the average of the remaining frequency values. Other statistical processing can be performed on the set of n heartbeat frequency values f HRn .

[0263] The Applicant has also noticed that, during a typically rather long blood treatment, the heartbeat frequency of the patient receiving the treatment, even in resting conditions, tends to have a (positive or negative) drift, at least partly due to the continuous variation of its dynamic fluid state. This drift can cause the overlap of the heartbeat frequency with the fundamental frequency of the pump. If the heartbeat frequency f HRtoo close to the operating frequency f of the pump 11 P1 The controller 65 can also be configured to allow the activation of a warning signal. If it is observed during the blood treatment that, during this period, the heart beat frequency f HR is becoming progressively too close to the operating frequency f of the pump 11 P1 The controller 65 activates a warning user signal (for example, a visual alarm and / or an acoustic alarm) for the user and, optionally, starts recording in a dedicated buffer all the recent amplitudes of the peaks of the pump 11. This is a warning condition because if the heart frequency f HR becomes substantially coincident with the operating frequency f of the pump 11 P1 The current algorithm is no longer able to distinguish. The Applicant has further considered this event and provided a conception and configuration of the controller 65 such that, in this case, in addition to activating the alarm signal, the controller 65 sends an appropriate signal to the electric actuator of the pump 11 so that the speed (and therefore the flow rate and the operating frequency) of the pump 11 is changed so that the resulting new operating frequency is more distant from the heart beat frequency. In an embodiment, the change of speed of the pump 11 and therefore of the flow rate and of the rotation frequency is performed automatically in the iterative loop of the control performed by the controller 65; in order not to change the total amount of blood treated during the entire session, the control unit can provide for alternating variations (for example, + / - 30 ml / min) of the blood flow rate of the pump during the treatment period. Otherwise, the controller 65 can be configured to provide the operator, through the monitor of the device 1, with an indication to set a new speed of the pump 11, so that the change is performed manually.

[0264] The difference (or its absolute value) between the operating frequency f P1 of the pump 11 and the heart beat frequency f HR is electronically calculated; the result of this difference is then compared with a reference value and the control of the pump 11 is performed so that the resulting new operating frequency of the pump 11 results more distant from the heart beat frequency. Another related advantage of the detection provided by the application of the algorithm for the detection of the heart beat disclosed herein is that any sudden disappearance of the heart beat can be easily detected. The Applicant has noted that the disappearance of the heart beat (i.e., the sensor 100 no longer detects any heart beat frequency f HRsudden situation) can be the result of an unwanted disconnection of the venous port from the blood circuit 6, 7, which can lead to a serious leakage of blood, which can lead to a condition of insufficient blood volume that can even affect the life of the patient. For this purpose, an alarm signal can be generated in the event of any sudden absence of heartbeat frequency detected by the sensor 100, i.e. in the event of loss of sensor and / or inability to detect any heartbeat frequency according to the procedure disclosed above, especially while the information signal is present, i.e. while in fact the light source 53 is operable and / or the detector 57 in fact receives the information signal with the pump signal but without any other useful signal having the second harmonic within the conditions disclosed in the foregoing part of the description. Such alarm signal can be an electrical signal transmitted to a user interface (e.g. a monitor and / or a loudspeaker) of the device for blood treatment 1, or can be directly an acoustic or visible signal directly generated by the sensor 100 itself. Any component of the controller 65 can be made by means of a hardware data processing unit, including an arithmetic logic unit, suitable to perform at least part of the steps of the signal processing algorithm described herein. In particular, the controller can run a suitable program comprising portions of software code which, when executed by the controller 65, cause the execution of one or more of the steps disclosed in the present disclosure. The program can be referred to as software or firmware and can be stored in a memory, in particular a non-transitory memory operatively, in particular electronically, accessible by the controller 65; said memory can be physically arranged inside or outside the main body of the sensor 100 and in particular can be part of the device for blood treatment. The data processing unit of the controller 65 can be in the form of a general purpose processor or in the form of a dedicated processor; the controller 65 and / or components of said data processing unit can be made by means of an application specific integrated circuit or through an FPGA. In one or more embodiments, the device 1, the sensor 100, the controller 65 or the method can be implemented using one or more computer programs executing on a programmable computer (e.g. a computer comprising, for example, processing capabilities, data storage (e.g. volatile or non-volatile memory and / or storage elements), input devices and output devices). Program code and / or logic described herein can be applied to input data to perform the functions described herein and generate desired output information. The output information can be applied as input to one or more other devices and / or methods as described herein or in a known manner. Programs for implementing the methods and / or processes described herein can be provided using any programmable language or code, including a high-level procedural and / or object-oriented programming language or code suitable for communicating with a computer system.For example, any such program can be stored in any suitable device (e.g., storage medium) and whereby a suitable device can be read by a general or special purpose program for configuring and operating a computer system (e.g., including processing devices) when the appropriate device is read into the computer system so as to produce a machine for implementing the method concepts described herein. In other words, at least in one embodiment, apparatus 1, sensor 100, controller 65, or method can be realized with a computer-readable storage medium configured with a computer program, where the storage medium so configured causes a computer to operate in a specific and predefined manner to perform function described herein. Further, in at least one embodiment, apparatus 1, sensor 100, controller 65, or method can be described as being implemented by logic (e.g., object code) encoded in one or more non-transitory media that includes code for execution and, when executed by a processor, is operable to perform operations such as the methods, processes, and / or functions described herein. For example, controller 65 can be any fixed or mobile computer system (e.g., controller, microcontroller, personal computer, mini-computer, etc.). The exact configuration of controller 65 is not limiting and can be essentially any device capable of providing suitable computing and control capabilities (e.g., graphics processing, control of extracorporeal blood treatment apparatus, etc.). As described herein, a digital file can be any medium (e.g., volatile or non-volatile memory, CD-ROM, punch cards, recordable magnetic tape, etc.) containing digital bits (e.g., encoded in binary, ternary, etc.) that is readable and / or writable by controller 65 as described herein. Further, as described herein, a file in user-readable format can be any representation of data (e.g., ASCII text, binary numbers, hexadecimal numbers, decimal numbers, graphics, etc.) that can be presented in any medium (e.g., paper, display, etc.), that is readable and / or understandable by an operator. In light of the foregoing, it will be apparent to those of ordinary skill in the art that the functions described in accordance with one or more embodiments of the present disclosure can be implemented in any manner known to those of skill in the art. Thus, the computer language, computer system, or any other software / hardware used to implement the processes described herein should not limit the scope of the apparatus, sensor, processes, or programs described herein (e.g., the functions provided by such apparatus, sensor, processes, or programs). The methods and / or logic described in the present disclosure, including those attributed to the sensor and / or apparatus and / or controller, or various constituent components, can be implemented, at least in part, in hardware, software, firmware or any combination thereof. For example, various aspects of the technology can be implemented within one or more processors, including one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components, or other devices. The term "processor" or "processing circuitry" can generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry or any other equivalent circuitry.Such hardware, software, and / or firmware can be implemented within the same device or within separate devices to support the various operations and functions described in this disclosure. In addition, any of the described components can be implemented together or separately as discrete but interoperable logic devices. The description of different features in terms of being performed by, for example, a block, module, or the like, is by way of example and not limitation. That is, it is contemplated that such features can be implemented together or separately as discrete or integrated logical devices or sub-combinations of the same. Separate elements can also be implemented as a multi-functional device. It is also noted that one or more computer program products described herein can include one or more computer-readable storage media.

Claims

1. An apparatus for extracorporeal blood treatment, comprising: a) a blood pump (11) configured to control at least blood flow in a blood circuit (6, 7), b) a circuit for extracorporeal treatment of blood, comprising: a filtration unit (2) having a primary chamber (3) and a secondary chamber (4) separated by a semipermeable membrane (5); a blood circuit (6, 7) comprising a blood withdrawal line (6) having a first end portion connected to an inlet of the primary chamber (3) and a blood return line (7) having a first end portion connected to an outlet of the primary chamber (3), the blood withdrawal line (6) and the blood return line (7) being designed to be connected to a patient’s cardiovascular system, wherein a second end portion of the blood withdrawal line (6) is provided with an arterial connector (40) and a second end portion of the blood return line (7) is provided with a venous connector (41), the arterial connector (40) and the venous connector (41) being designed to be connected to a vascular access of a patient, and wherein the blood circuit is configured to interface with the blood pump (11) to control flow in the blood circuit (6, 7), and wherein the blood circuit comprises an extracorporeal segment (101); and an outflow fluid line (13) in fluid communication with an outlet of the secondary chamber (4); c) a non-invasive heartbeat sensor (100) for determining a heartbeat and / or a heart rate in the extracorporeal segment (101), characterized in that the non-invasive heartbeat sensor (100) comprises: at least one source (53) for directing a light signal towards blood flowing in the segment (101), the light signal being directed along at least one emission axis (54); detectors (57) placed at different radial directions with respect to the emission axis (54) of the source (53), or arranged at different angles with respect to the emission axis (54) of the source (53), to collect reflected, scattered and / or transmitted signals depending on the respective position of the detectors (57), and each detector (57) receives an optical information signal comprising a signal emitted by the source (53) at least partially after passing through the blood flowing in the segment (101), each of the detectors (57) emitting a respective output signal (200R) related to the received optical information signal, a controller (65) configured to receive the respective output signals (200R) from the detector (57) and to derive a heart beat frequency (f HR ) and / or to detect a heart rate value based on a predetermined number of output signals (200R).

2. The apparatus of claim 1, further comprising: a dialysis fluid line (19) in fluid communication with an inlet of the secondary chamber (4), wherein the controller is configured to process the output signals (200R) based on information signals whose amplitude is altered by flow perturbations of the blood flowing in the segment (101), the flow perturbations being generated at least in part by flow pulses originating from a beating heart.

3. The apparatus of claim 1, wherein, the controller (65) is configured to: electronically compute a transformation of at least a reference portion (200W) of one or more output signals (200R) from a time domain to a frequency domain, obtaining an information signal spectrum or an output signal spectrum corresponding to the information signal spectrum, determine whether the blood pump (11) is forcing fluid circulation into the segment (101), in the case where said blood pump (11) is forcing circulation of fluid into said segment (101), identifying and discarding a first peak of amplitude in said information signal spectrum or in said output signal spectrum, said first peak of amplitude corresponding to a first noise peak of amplitude, corresponding to a parasitic flow disturbance in said segment (101) originated by said blood pump (11) forcing circulation of fluid into said segment (101), performing an electronic identification and subsequent selection of a first finding peak of amplitude in said information signal spectrum or in said output signal spectrum, performed after said discarding has occurred, said selection being calculated by means of an identification of a second finding peak of amplitude in said information signal spectrum or in said output signal spectrum, the second peak corresponding to a second harmonic of said first finding peak of amplitude, electronically assigning to at least one of the temporary heartbeats and / or heart rate frequencies (f HR ) a first peak-finding frequency corresponding to the amplitude.

4. The apparatus of claim 3, wherein, said controller (65) is further configured to electronically load frequency values corresponding to a first lower frequency region (200L) and at least a second upper frequency region (200U), said second upper frequency region (200U) being located above said first lower frequency region (200L); wherein said controller (65) is configured to store and set an upper limit frequency value of said lower frequency region (200L) lower than a frequency threshold of non-physiological heart pulses, which is 0.7 Hz, said processing of the output signal comprises performing the following processing on said information signal spectrum or on said output signal spectrum: filtering out a portion of said information signal spectrum or of said output signal spectrum corresponding to said first lower frequency region (200L), or discarding any peak of amplitude located in said first lower frequency region (200L), so that in said at least second upper frequency region (200U) the identification and discarding of a first noise peak of amplitude and the electronic selection of a first finding peak of amplitude are performed.

5. The apparatus of claim 3, wherein, said processing of the output signal comprises low-pass filtering the output signal by means of a filter stage (63) at a predetermined frequency lower than 10 Hz, wherein the low-pass filtering is performed before the electronic calculation of the transformation of at least a reference portion of the output signal from the time domain to the frequency domain.

6. The apparatus of claim 3, wherein, By searching for the frequency (f HR2 ) to identify the second peak value (200P) of the amplitude, the frequency (f HR2 ) corresponds to the frequency of the first peak in amplitude (f HR ) twice.

7. The apparatus of claim 2, wherein, said controller (65), in electronically processing the output signal of said detector (57), is configured to perform a windowing of the output signal by performing an electronic selection of a reference window of samples of the output signal, said reference window having a predetermined length less than 1 minute long, wherein a portion of the output signal constitutes a reference portion of the output signal, and wherein the electronic calculation of the transformation of at least a portion of the output signal is performed on said reference portion of the output signal and is performed after said windowing.

8. The apparatus of claim 4, wherein, The identification of the first noise peak of the amplitude and / or the first finding peak of the amplitude and / or the identification of the second finding peak of the amplitude is performed by applying a peak detection algorithm to at least a portion of the information signal spectrum or of the output signal spectrum, wherein the peak detection algorithm comprises: considering a portion of the information signal spectrum or of the output signal spectrum, the portion corresponding to a second upper frequency region (200U); and electronically computing a derivative of the spectrum, obtaining a derivative spectrum, then comprising a subsequent electronic search and selection of at least one frequency, wherein the derivative spectrum changes sign from positive to negative in the course of increasing analysis frequencies to identify a positive peak, the frequency at which the derivative spectrum changes sign from positive to negative corresponding to the peak.

9. The apparatus of claim 8, wherein, The peak detection algorithm that the controller (65) is configured to run comprises: searching for local relative maximum amplitude points in the information signal spectrum or in the output signal spectrum, by using moving window signal processing on the spectrum, the portion corresponding to the second upper frequency region (200U); and further selecting the frequencies corresponding to the maximum amplitude points as the frequencies at which the peaks occur.

10. The apparatus of claim 8, wherein, The peak detection algorithm comprises: defining a moving window of a predetermined amplitude within at least a portion of the information signal spectrum or of the output signal spectrum, the portion corresponding to the second upper frequency region (200U); and electronically defining one or more positions for the moving window within the at least portion of the information signal spectrum or of the output signal spectrum, and for each of the positions, electronically computing the maximum amplitude of the spectrum within the window, and electronically extracting and storing the frequency corresponding to the maximum amplitude.

11. The apparatus of any of claims 1-10, wherein, The controller (65) is configured to process one or more output signals of the detector (57) with a pump-associated signal (300P), the pump-associated signal (300P) being shaped to be cyclic and repetitive in time and associated with pump cycle points, so as to obtain a corresponding result signal (301), the spectrum of which sees an enhancement of components or peaks associated with heartbeats or heart rate with respect to components or peaks associated with the operation of the blood pump (11) of the device, wherein the controller (65) is configured to multiply the output signals of the detector (57) with the pump-associated signal (300P) so as to produce in the output of the processing a result signal (301) which is zeroed in correspondence with the portions of time in which the blood pump provides pulses in at least the segment (101).

12. The apparatus of claim 11, wherein, The controller (65) is further configured to calculate an average amplitude (Vm) of the result signal (301) over a predetermined length window of time of analysis m and to perform a subsequent subtraction of the average amplitude (Vm) from at least a portion of the result signal (301) in which the result signal (301) is not nulled due to the multiplication, thereby generating an average signal (301A) which constitutes a reference portion of the output signal, the transformation from time domain to frequency domain being performed at least on the reference portion.

13. The apparatus of claim 11, wherein, The controller (65) is configured to select a plurality of reference portions (200W) of the output signal (200R) by electronically selecting, via a sampling window, a plurality of portions of at least one of the output signals (200R) which are not overlapping in time, for each of said plurality of reference portions (200W) of the output signal (200R), a transformation from the time domain to the frequency domain is performed, obtaining a plurality of information signal spectra or a plurality of output signal spectra, said plurality of output signal spectra corresponding to a corresponding plurality of information signal spectra; for each information signal spectrum of said plurality of information signal spectra or each output signal spectrum of said plurality of output signal spectra: • identifying and discarding a first noise peak of the amplitude in said information signal spectrum or output signal spectrum, said first noise peak of the amplitude corresponding to a parasitic flow disturbance in said segment (101), said parasitic flow disturbance in said segment (101) being originated from the blood pump (11) forcing the circulation of the fluid into at least said segment (101), • after said discarding has occurred, performing an electronic identification and subsequent selection of a first finding peak of the amplitude in said information signal spectrum or output signal spectrum, said selection being electronically calculated by means of an identification of a second finding peak of the amplitude in the information signal spectrum or output signal spectrum, the second peak corresponding to a second harmonic of said first finding peak of the amplitude, • electronically assigning to the temporary heart beat and / or heart rate frequency (f HR1 , f HR2 , f HR3 ) a first peak-finding frequency corresponding to the amplitude; Based on a plurality of temporary heartbeat and / or heart rate frequency values ​​(f HR1 、f HR2 、f HR3 ) calculate the final heart rate and / or heart rate frequency (f HR ), where the final heart rate and / or heart rate frequency (f HR ) is based on a plurality of temporary heartbeat and / or heart rate frequency values ​​(f HR1 、f HR2 、f HR3 ) is calculated by averaging the values ​​between .

14. The apparatus of any one of claims 1-10, wherein, said controller (65) is configured to activate an alarm signal in either of the following cases: The controller (65) has not acquired any heart rate frequency (f HR ) and / or has not detected any heart rate value, or The controller (65) has taken the heart beat frequency (f HR ) or heart rate value from the information signal at least temporarily after the heart beat frequency (f HR ) has not been taken or the heart rate value has not been detected in the presence of the information signal in the subsequent time.

15. The apparatus of any one of claims 1-10, wherein, said source (53) comprises an optical electromagnetic radiation emitter of the following form: a multi-mode and incoherent single-wavelength LED; or a single-wavelength laser or SLED.

16. The apparatus of any one of claims 1-10, wherein, said source (53) comprises an optical electromagnetic radiation emitter of the following form: a multi-wavelength LED, or a combination of a plurality of single-wavelength lasers or SLEDs.

17. The apparatus of any one of claims 1-10, wherein, said sensor further comprises: an optical fiber having one end coupled with the source (53) and the other end placed so as to direct the emission signal towards the blood at least along said emission axis; one first detector placed at 180° with respect to the emission axis of the source and / or one second detector placed at 90° with respect to the emission axis of the source and / or one third detector placed at 45° with respect to the emission axis of the source and / or one fourth detector placed at 0° with respect to the emission axis of the source; and a housing (51) having a portion shaped to match said segment (101), said housing (51) being made of two or more pieces and defining a through passage (52) shaped to match the outer shape of the segment (101) so as to house the segment (101) inside the through passage (52), each detector (57) comprising a respective end placed at the shape-matching portion and facing the segment (101) in the coupled condition of the housing (51) with the segment (101), the source (53) comprising an end placed at the shape-matching portion and facing the tube in the coupled condition of the housing with the segment (101), wherein each detector (57) comprises an optical fiber having one end arranged and fixed to the housing in correspondence of the segment (101) and having an end placed at the shape-matching portion and facing the segment (101) in the coupled condition of the housing with the segment (101).

18. The device of any one of claims 1-10, wherein, The source (53) comprises a multi-wavelength emitter having a plurality of light radiation sources having peak wavelengths in the red and infrared waveband, wherein the illumination peak wavelengths of the source (53) are comprised between 0.7 pm and 1000 pm.

19. The device of any one of claims 1-10, wherein, The source (53) is configured to transmit optical radiation comprising at least a first component of the optical radiation concentrated on a first frequency window comprising a first wavelength l1, a second component of the optical radiation concentrated on a second frequency window comprising a second wavelength l2, having a third component of the optical radiation concentrated on a third frequency window comprising a third wavelength l3, and having a fourth component of the optical radiation concentrated on a fourth frequency window comprising a fourth wavelength l4, wherein the first, second, third and fourth frequency windows at least partially do not overlap in frequency.

20. The apparatus of claim 19, wherein, The detector (57) comprises at least a first detector (57; PD1) configured to receive the optical radiation in the first frequency window comprising the first wavelength l1, a second detector (57; PD2) configured to receive the optical radiation in the second frequency window comprising the second wavelength l2, a third detector (57; PD3) configured to receive the optical radiation in the third frequency window comprising the third wavelength l3, and a fourth detector (57, PD4) configured to receive the optical radiation in the fourth frequency window comprising the fourth wavelength l4.

21. The apparatus of claim 19, wherein, The source (53) is configured to transmit the optical radiation in a direction transversal to a main extension axis of the segment (101), and wherein the detector is configured to receive the optical signal emitted by the source (53) along a direction transversal to a main extension axis of the segment (101).

22. The device of any one of claims 1-10, wherein, The segment (101) of the extracorporeal blood treatment circuit is a tube portion, the detector and the source being disposed around the tube portion at different angles around the same cross section, the tube having a circular cross section.

23. The device of any one of claims 1-10, wherein, The sensor is directly constrained to an external portion of the segment (101) having a circular internal section and an external section, wherein the segment (101) is made of a flexible material having a predetermined transparency to optical radiation.

24. A non-invasive heartbeat sensor (100) for determining a heartbeat and / or a heart rate in an extracorporeal segment (101) of a catheter to be connected to an extracorporeal blood treatment device, the sensor (100) comprising: at least one source (53) for directing an optical signal towards blood flowing in the segment (101), the optical signal being directed along at least one emission axis (54); a detector (57) placed at different radial directions with respect to the emission axis (54) of the source (53) or arranged at different angles with respect to the emission axis (54) of the source (53) to collect reflected, scattered and / or transmitted signals according to the respective position of the detector (57) and each detector (57) receives an optical information signal comprising a signal emitted by said source (53) at least partially after passing through the blood flowing in the segment (101), said detector (57) emitting a respective output signal (200R) related to the received optical information signal, a controller (65) configured to receive a respective output signal (200R) from each detector (57) and to derive a heart beat frequency (f HR ) and / or a heart rate value based on a predetermined number of output signals (200R), wherein the controller is configured to process the output signals (200R) based on an altered information signal, the amplitude of which is altered by flow disturbances of the blood flowing in the segment (101), the flow disturbances being generated at least partially by flow pulses originating from a beating heart.

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