Device and method for measuring at least one physiological parameter

Abstract

The invention relates to a measuring device (100) for measuring at least one physiological parameter, the measuring device (100) comprising a housing (101) having: a measuring chamber (104) having an inner volume filled with a gas; a sensing unit (105) allowing measurement of at least a first physiological parameter, the sensing unit (105) being arranged in contact with a gas contained in the internal volume of the measurement chamber (104); and an inlet (107) for a physiological liquid of the patient, the inlet (107) being arranged such that the physiological liquid is in contact with the gas and the gas remains between the sensing unit (105) and the physiological liquid of the patient, thereby creating an interface between the gas contained in the internal volume and the physiological liquid. The invention also relates to a method for measuring at least one physiological parameter.

Description

Technical Field

[0001] The present invention relates to a device and a method for measuring at least one physiological parameter. The present invention is particularly suitable for measuring the pressure of a physiological fluid extracted from a patient. In particular, the present invention relates to a device and a method for measuring the pressure of a physiological fluid in contact with the central nervous system. More specifically, the present invention measures the pressure of cerebrospinal fluid (CSF) extracted, for example, by lumbar puncture.

[0002] Intracranial pressure corresponds to the pressure of the CSF present within the skull that fills the central nervous system. Access to the CSF by lumbar puncture was described by Quincke in 1891. CSF pressure measured by lumbar puncture is also a measure of intracranial pressure [Lenfeldt N, Koskinen

[0003] LO,Bergenheim AT,Malm J,Eklund A.CSF pressure assessed by

[0004] Lumbar puncture agrees with intracranial pressure. Neurology. 2007; vol. 68, No 2, pp. 155-158]. The measurement of intracranial pressure by lumbar puncture marks an important advance in neurology in understanding (especially identifying) intracranial hypertension that threatens the central nervous system.

[0005] CSF pressure can be measured statically or dynamically. The static or hydrostatic method involves measuring the steady-state pressure and pulsatility of the CSF secondary to the oscillations of the heart and respiratory cycles, while the dynamic or hydrodynamic method involves applying a known stress to the intracranial fluid system, called a perfusion test, and analyzing the system's response to the stress [Czosnyka M, Pickard JD. Monitoring and interpretation of intracranial pressure. Journal of Neurology, Neurosurgery & Psychiatry, 2004, vol. 75, No 6, pp. 813-821].

[0006] The hydrostatic method makes it possible to measure the fluid pressure within the skull and identify normal pressure and increased pressure known as intracranial hypertension. This can manifest as headaches, nausea or vomiting, cognitive impairment and even coma in the most severe cases.

[0007] The causes of intracranial hypertension syndrome can be various: dilatation pathology such as tumors, intracerebral hematoma or hydrocephalus, and obstruction of the venous drainage system caused by thrombophlebitis.

[0008] There are also so-called "secondary" causes of intracranial hypertension, such as endocrinopathy (Addison's disease, Cushing's disease, hypothyroidism, hyperparathyroidism), vitamin A deficiency that alters the structure of the arachnoid villi during drug intake (hormones, antibiotics, lithium or cimetidine) and various other pathologies (sleep apnea syndrome, chronic renal failure, iron deficiency anemia).

[0009] The fluid dynamic method can be achieved by injecting physiological serum into the CSF using the access provided by a lumbar puncture. The injection of this physiological serum exerts stress on the intracranial fluid system. The response of the intracranial system after the perfusion test allows the extraction of various relevant measurements, including those of CSF flow within the skull. Increased flow resistance is an important parameter in clinical practice because it makes it possible to demonstrate objective changes in CSF circulation that indicate hydrocephalus. Background Art

[0010] In the 1930s, Professor Henri CLAUDE developed a manometer that consisted of a flexible tube connected directly to the lumbar puncture needle. The idea of ​​the CLAUDE manometer was to bring the cerebrospinal fluid into direct contact with the measuring area of ​​the manometer. CLAUDE's manometer is now banned for health reasons. In addition, CLAUDE's manometer cannot measure the pulsatility of intracranial pressure.

[0011] There is currently no simple and reliable device on the market to quantify intracranial pressure by measuring the pressure of the CSF. Therefore, in 2022, practitioners still measure cerebrospinal fluid pressure by measuring the water column, as described by QUINCE in 1891. To do this, practitioners use a seamstress's tape measure, which is manually placed along a disposable, sterile, flexible tube. In practice, the flexible tube is connected to a lumbar puncture needle. Although this basic method is sufficient to approximately measure steady-state hydrostatic intracranial pressure, it cannot accurately measure the mean and pulsatility of intracranial pressure, nor can it record signals or perform fluid dynamic exploration.

[0012] However, there are more complex solutions, which use, in particular, piezoelectric sensors. Piezoelectric sensors convert the liquid pressure into an electrical signal; the electrical signal must then be amplified and digitized in order to be processed by specific software. In fact, the sensitive cell of the piezoelectric sensor is in direct contact with the CSF in order to measure its pressure using hydrostatic or hydrodynamic methods.

[0013] In general, the CSF pressure measured by the sensitive cell of the piezoelectric sensor is the sum of two forces per unit area, the pressure transmitted by the fluid and the pressure associated with the movement of the mass of the fluid. In particular, this mass is accelerated directly or due to gravity. The piezoelectric sensor actually measures the pressure transmitted by the CSF, but also measures the acceleration of the liquid mass, which constitutes an artifact and impairs the quality of the CSF pressure signal. Therefore, the liquid pressure sensor measures all physical accelerations related to the medical environment in which the pressure measurement is performed. For example, the vibration of the medical device will generate artifacts in the signal measured by the pressure sensor, as will impacts on the patient's bed, etc. Such vibrations and other artifacts interfere with precise measurements, such as the pulsatility of intracranial pressure.

[0014] Known as The ICM+ system was developed by the University of Cambridge (UK) to enable intracranial multimodal monitoring. The software allows, among other things, the measurement of CSF pressure for static and dynamic analysis of intracranial pressure. The ICM+ system enables reliable measurement of intracranial pressure at the patient's bedside. However, this is software designed for clinical research and is not very easy to use for most practitioners at the patient's bedside. In particular, there is no software for System design specific sensors.

[0015] Document US4858619 describes a system for measuring CSF pressure changes while allowing CSF to be drained. The system allows remote measurement of CSF pressure, regardless of whether the puncture site is the lumbar spine or the skull. In the document, the pressure sensor converts the liquid pressure it measures into an electrical signal. To this end, the sensitive unit of the pressure sensor is placed in a measuring chamber, which is first evacuated of air and filled with physiological serum by purging. The CSF is then fluidically connected to the measuring chamber filled with physiological serum. On the one hand, the sensitive unit measures the acceleration of the physical acceleration artifacts that affect the pressure sensor and the mass of the physiological fluid, and on the other hand, the system does not allow the use of fluid dynamic methods to measure CSF pressure pulsatility.

[0016] Document CN105641758 describes another CSF drainage system in which the fluid is directly extracted from the patient's skull. The tube discharges the CSF extracted at the first lower end of the vertically oriented bulb tube in which a float is arranged. The bulb tube has a second upper end connected to a catheter, which is equipped with a pressure sensor. The catheter is filled with gas. The float thus constitutes a membrane, the purpose of which is to separate the CSF located below the float from the gas located above the float and in the catheter. The purpose of the system is to prevent the liquid from contacting the pressure sensor, and it is not necessary to sterilize the pressure sensor. Therefore, the system measures the pressure of the CSF by the gas contained in the catheter. When the CSF pressure increases to exceed a certain threshold, the solenoid valve allows the CSF to be discharged into the collection bag. However, the monitoring of CSF pressure changes is unreliable. Specifically, even if the gas is not in direct contact with the CSF, the CSF pressure change is measured by measuring the pressure of the gas contained in the catheter. In addition, the float that separates the gas from the CSF may interfere with the measurement by attenuating the change in CSF pressure and by the acceleration that the float may experience when the pipeline or bulb tube moves.

[0017] The object of the present invention is to overcome all or part of the above mentioned disadvantages. Summary of the invention

[0018] It is an object of the present invention to provide a reliable and cost-effective solution for measuring at least one physiological parameter (eg CSF pressure by lumbar puncture).

[0019] It is an object of the present invention to reliably measure at least one physiological parameter at the patient's bedside.

[0020] In particular, the present invention aims to provide a technical solution for reliably measuring the changes in CSF pressure over time.

[0021] The invention is particularly aimed at reliably measuring the steady-state pressure or the pulsatile pressure of the CSF.

[0022] To this end, a first aspect of the present invention relates to a measuring device for measuring at least one physiological parameter. The measuring device comprises a housing extending longitudinally between a first end and a second end opposite to the first end. The housing comprises three parts:

[0023] a measuring chamber disposed in the housing, the measuring chamber having an inner volume filled with a gas;

[0024] a sensitive unit enabling measurement of at least a first physiological parameter, said sensitive unit being arranged in contact with said gas contained in said internal volume of said measuring chamber; and

[0025] An inlet is used to draw a physiological fluid of a patient into the measurement chamber; the inlet is arranged so that the physiological fluid is in contact with the gas, and the volume of gas is interposed between the sensitive unit and the physiological fluid of the patient.

[0026] According to the invention, the measuring chamber enables two interfaces to be generated: a first interface between the gas contained in the internal volume and the physiological fluid of the patient entering through the inlet, and a second interface between the gas contained in the measuring chamber and the sensitive unit.

[0027] The measuring device according to the invention makes it possible to carry out reliable measurements of physiological parameters of liquids, such as CSF pressure. In fact, in a fluid, according to Pascal's principle, a pressure change at one point is completely transmitted to all points of the fluid. Therefore, the pressure changes of the physiological fluid are transmitted to the sensitive unit of the sensor through the gas bubbles, which corresponds to a "hydraulic transmission interface" or liquid / gas interface.

[0028] Furthermore, the device according to the invention makes it possible to reduce artifacts due to vibrations of the sensor.

[0029] In an embodiment of the first aspect of the invention, the measuring chamber may have an internal volume that is non-zero and less than or equal to 1 ml, in particular, the internal volume must be strictly less than 1 ml, preferably less than 0.7 ml. The internal volume of the measuring chamber may thus contain a certain volume of gas, so that the attenuation of the pulsatility of the pressure of the physiological fluid can be controlled. This makes the attenuation of the pulsatility acceptable in clinical practice.

[0030] In an embodiment, the gas contained in the inner volume of the measuring chamber may correspond to the atmospheric air. In particular, since the method of manufacturing the measuring device, for example by plastic injection molding, is not performed under vacuum, the measuring chamber is naturally filled with the atmospheric air.

[0031] In an embodiment of the first aspect of the invention, the measuring chamber may have an internal volume between 0.2 ml and 0.5 ml.

[0032] In an embodiment of the first aspect of the invention, the sensitive unit may be a piezoelectric unit of the pressure sensor. The liquid / gas interface also makes it possible to attenuate the physical acceleration to which the pressure sensor is subjected. This improves the reliability of the measurement results.

[0033] In an embodiment of the first aspect of the invention, the housing may include a sealing membrane, the sealing membrane being interposed between the sensitive unit and the internal volume of the measuring chamber, the sealing membrane protecting the sensitive unit. The sensitive unit of the sensor may be, for example, a piezoelectric unit of a pressure sensor. The sealing membrane makes it possible to isolate the CSF (more generally the biological tissue of the patient) from the highly toxic electronic components that the piezoelectric sensitive unit may include.

[0034] In an embodiment of the first aspect of the invention, the inner volume of the measurement chamber may be cylindrical.The cylindrical shape allows a liquid / gas interface to be formed when the physiological fluid enters the measurement chamber.

[0035] In an embodiment of the first aspect of the present invention, the measuring device may include a connector arranged at the inlet of the housing, the connector sealingly connecting the measuring chamber to a connection device for connecting to a physiological fluid of a patient. The physiological fluid connection device may be a lumbar puncture needle. Preferably, the lumbar puncture needle is directly connected to the connector of the measuring device.

[0036] In an embodiment of the first aspect of the invention, the inlet may be openable and closable to control the entry of physiological fluid into the measurement chamber.

[0037] In an embodiment of the first aspect of the present invention, the measuring means may comprise transmitting means for transmitting the measurement result of the first physiological parameter to a remote digital terminal.

[0038] In an embodiment of the first aspect of the present invention, the sensitive unit may be arranged at a first end of the housing, and the inlet is arranged at a second end of the housing.

[0039] A second aspect of the present invention relates to a measurement method for measuring at least one physiological parameter of a patient. According to the present invention, the method comprises:

[0040] a step of connecting a measuring chamber to a physiological fluid of a patient, said measuring chamber being filled with a gas and comprising a sensitive unit enabling measurement of at least one physiological parameter;

[0041] a step of generating a first interface between the gas present in the measurement chamber and the physiological fluid from the patient, the gas being interposed between the physiological fluid and the sensitive unit to form a second interface between the gas and the sensitive unit; and

[0042] The measuring step of measuring at least a first physiological parameter is performed by the sensing unit through the gas between the physiological fluid and the sensing unit.

[0043] The measurement method follows the same technical principle as the measuring device; this makes it possible to generate a liquid / gas interface at which the physiological fluid comes into contact with the gas contained in the measuring chamber. The physiological fluid then transmits the pressure of the CSF to the gas, which itself transmits this pressure to the sensitive cell of the measuring sensor.

[0044] In an embodiment of the second aspect of the present invention, the volume of gas between the sensitive unit and the patient's physiological fluid may be non-zero and less than or equal to 1 ml, in particular, the volume of the gas may be strictly less than 1 ml, preferably, the volume of the gas may be less than 0.7 ml. This volume of gas between the sensitive unit and the patient's physiological fluid makes it possible to control the attenuation of the pulsatility of the pressure of the physiological fluid. This makes the attenuation of the pulsatility acceptable in clinical practice.

[0045] In an embodiment of the second aspect of the invention, the measuring chamber can be connected to a device for sampling a physiological fluid, which can include cerebrospinal fluid of a patient. In particular, the connecting device can include a lumbar puncture needle. Preferably, the lumbar puncture needle is directly connected to the measuring chamber.

[0046] In an embodiment of the second aspect of the present invention, the first physiological parameter may correspond to a steady-state pressure or a dynamic pressure of a physiological fluid of the patient.

[0047] In an embodiment of the second aspect of the present invention, the measuring method may comprise a determination step of determining at least the second physiological parameter by measuring the first physiological parameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Other features and advantages of the present invention will become clear after reading the following description. This is merely illustrative and must be read in conjunction with the accompanying drawings, in which:

[0049] Figure 1 A longitudinal section through a measuring device according to the invention is schematically shown, which is connected to a lumbar puncture needle.

[0050] Figure 2 Schematically shows Figure 1 of measuring devices and their interaction with medical technology.

[0051] Figure 3 A measuring device according to the invention is shown schematically.

[0052] Figure 4 is a flow chart schematically illustrating a measuring method according to the present invention.

[0053] Figure 5 The experimental setup used for comparative studies of hydrostatic pressure measurements obtained by a liquid interface sensor and a liquid / air interface sensor is schematically shown.

[0054] Figure 6 shows a graphical record of the hydrostatic pressure signal measured during Experiment 1, the signal being derived from Figure 5 The device is used for liquid interface sensor and liquid / air interface sensor measurements.

[0055] Figure 7 yes Figure 6 Close-up of the record.

[0056] Figure 8 shows a graphical record of the hydrostatic pressure signal measured during Experiment 2, where the signal is represented by Figure 5 The device is used for liquid interface sensor and liquid / air interface sensor measurements.

[0057] Fig. 9 yes Figure 8 Close-up of the recording graph for cycle C8.

[0058] Fig.10 A Bland-Altman plot constructed using the data from Experiment 2 is shown.

[0059] Fig.11 A graphical record of the pressure signal measured during Experiment 3 is shown, wherein the pressure is pulsating, the signal being determined according to Figure 5 The device is used for liquid interface sensor and liquid / air interface sensor measurements.

[0060] Fig.12 yes Fig.11 Close-up of cycle C1 of the recorded curve graph.

[0061] Fig.13 yes Fig.11 Close-up of the recording graph for cycle C7.

[0062] Fig.14 Shows the use of Figure 5 4 is a graph showing the result of experiment 4 conducted with the apparatus, which shows the variation in the pulsatility of the pressure measured by the liquid / air interface sensor and the liquid interface sensor as a function of the air volume at the liquid / air interface.

[0063] Fig.15 is a schematic diagram showing the constitutive relation for the decay of the pulsatility of the pressure measured by a liquid / air interface sensor as a function of the air volume at the liquid / air interface. DETAILED DESCRIPTION

[0064] refer to Figures 1 to 3The present invention relates to a measuring device 100 for measuring at least one physiological parameter. More specifically, the measuring device 100 is configured to measure the pressure of a physiological fluid extracted from a patient's body. For example, the present invention relates to a measuring device 100 for measuring CSF pressure, which is an indirect measurement of the intracranial pressure of a patient.

[0065] like Figures 1 to 3 As shown, the measuring device 100 includes a housing 101. The housing 101 defines the housing of the measuring device 100. The housing 101 extends longitudinally between a first end 102 and a second end 103 opposite to the first end 102. The housing 101 includes a measuring chamber 104. The measuring chamber 104 extends within the housing 101. In this example, the measuring chamber 104 extends between the first end 102 and the second end 103 of the housing 101. The measuring chamber 104 is filled with a gas G by default. For example, the measuring chamber 104 can be filled with air. However, the measuring chamber 104 can also be filled with another gas.

[0066] In this example, the measuring chamber 104 has a non-zero volume of less than or equal to 1 ml. In particular, the inner volume of the measuring chamber 104 may be less than 1 ml. Preferably, the inner volume of the measuring chamber 104 is less than 0.7 ml.

[0067] According to an embodiment of the invention, the internal volume of the measuring chamber 104 may be between 0.2 ml and 0.5 ml. However, the internal volume may also be between 0.3 ml and 0.4 ml.

[0068] In this case, the inner volume of the measuring chamber 104 is cylindrical. The inner volume is bounded by the inner wall of the housing 101 .

[0069] like Figures 1 to 3 As shown, the housing 101 comprises a sensitive unit 105, so that at least one physiological parameter can be measured. The sensitive unit 105 is arranged to be in contact with the gas G contained in the internal volume of the measuring chamber 104. In this example, the sensitive unit 105 is arranged at the first end 102 of the housing 101. In particular, the sensitive unit 105 can be of piezoelectric type. The piezoelectric sensitive unit can convert the pressure measurement result into an electrical signal.

[0070] like Figures 1 to 3 As shown, the housing 101 includes a sealing film 106. The sealing film 106 is interposed between the sensitive unit 105 and the gas G contained in the internal volume of the measuring chamber 104. In this example, the sealing film 106 is arranged at the first end 102 of the housing 101. The sealing film 106 isolates the sensitive unit 105. The sealing film 106 improves the safety of the device, keeping the electronic components isolated from the internal volume of the measuring chamber 104. The sealing film can be made of a medical polymer that is impermeable to air and water, such as silicone or polyurethane.

[0071] exist Figures 1 to 3 In the example of , the housing 101 comprises an inlet 107 for the inlet of the patient's physiological fluid LP. Preferably, the housing 101 has only one inlet 107. Unlike the prior art, this is because no attempt is made to expel the gas present in the measuring chamber 104. Usually in clinical practice, contact between air and physiological fluids is avoided, and in fact, injecting small volumes of air into the blood system presents a risk of embolism with potentially serious consequences. However, injecting an equally small volume of air into the nervous system will have no effect. Therefore, the single inlet 107 makes it possible to control the formation of the liquid / gas interface within the measuring chamber 104. The inlet 107 is arranged so that the physiological fluid LP is in contact with the gas G. The gas G is then placed between the sensitive unit 105 and the patient's physiological fluid LP. For this purpose, the inlet 107 may be arranged at the end of the housing 101 opposite to the sensitive unit 105. In Figures 1 to 3 In the example of FIG. 1 , the inlet 107 is arranged at the second end 103 of the housing 101, and the sensitive unit 105 is arranged at the first end 102 of the housing 101. In this case, the inlet 107 is formed by an opening in the housing 101, and the outline of the inlet 107 is Figures 1 to 3 However, other configurations and other housing shapes are conceivable to allow the gas G to be interposed between the physiological fluid LP and the sensitive unit 105.

[0072] like Figures 1 to 3 As shown, the measuring device 100 comprises a connector 108. The connector 108 is arranged at the inlet 107 of the housing 101. In this example, the connector 108 sealably connects the measuring chamber 104 to the connection device 200 for the patient's physiological fluid LP. In this example, the connector 108 is in the form of a male tapered portion, which is configured to be connected to the female tapered end 109 of the connection device 200.

[0073] exist Figure 1 and Figure 3 In the example of FIG. 2 , the female conical end 109 of the connection device 200 is directly connected to the conical connector 108 of the housing 101. Figure 1 and Figure 3 As shown, the connection device 200 includes a lumbar puncture needle 201.

[0074] Preferably, the connection device 200 is composed of a lumbar puncture needle 201. According to this configuration, the measuring device 100 is directly connected to the lumbar puncture needle 201. This makes it easier for practitioners to use the measuring device 100.

[0075] Alternatively, the connector 108 may be connected to the tapered end 109 of the lumbar puncture needle 201 via a three-way stopcock.

[0076] According to another alternative use of the present invention (not shown), the connector 108 may be connected to tubing between the measurement device 100 and the lumbar puncture needle 201 .

[0077] A lumbar puncture involves inserting a needle through the patient's skin into the lumbar sac in order to access the CSF. Typically, a lumbar puncture is performed to collect CSF so that biochemical or biological analyses can be performed. Therefore, a lumbar puncture is often used in cases of suspected meningitis or inflammatory or neurodegenerative neurological diseases.

[0078] In addition to the window for biochemical analysis opened on the nervous system, lumbar puncture also provides a window for biomechanical analysis of the nervous system by measuring the pressure of CSF. Lumbar puncture is currently the least traumatic technology for entering cerebrospinal fluid. Specifically, in the case of the present invention, lumbar puncture constitutes a preferred way to enter CSF, and CSF constitutes a physiological fluid LP within the meaning of the present invention. Then, intracranial pressure can be measured by the pressure of CSF. However, measuring device 100 can also work with other CSF entry methods (such as intraventricular drainage).

[0079] According to an embodiment of the present invention, the inlet 107 can be openable and closable. To this end, the inlet 107 can be connected to at least a two-way stopcock via a connector 108.

[0080] like Figures 1 to 3 As shown, the measuring chamber 104 according to the present invention makes it possible to generate a first interface between the gas G contained in the internal volume of the measuring chamber 104 and the physiological fluid LP of the patient entering the measuring chamber 104 via the inlet 107. When the physiological fluid LP enters the measuring chamber 104, the gas G is interposed between the sensitive unit 105 and the physiological fluid LP of the patient, which generates a second interface between the gas G and the sensitive unit 105. The liquid / gas interface and the gas / sensitive unit 105 interface are formed by the construction of the measuring chamber 104. However, the arrangement of the sensitive unit 105 relative to the inlet 107 can also contribute to the generation of the interfaces. Figures 1 to 3 In the example shown, the liquid / gas interface has a meniscus configuration, which is partly due to the cylindrical shape of the measurement chamber 104. However, the physicochemical properties of the gas G and the physiological fluid LP also contribute to establishing a specific meniscus shape at the measurement interface.

[0081] like Figures 1 to 3 As shown, the measuring device 100 includes a transmission device 110. The transmission device 110 transmits the measurement result of the physiological parameter to a digital terminal 300 which is far away from the measuring device 100.

[0082] exist Figure 1 and Figure 2In the example of the embodiment of the invention, the transmission device 110 is arranged in an electronic compartment 111 which is arranged in the extension of the first end 102 of the housing 101. The electronic compartment 111 comprises an electronic board 112 which is connected on the one hand to the transmission device 110 and on the other hand to the sensitive unit 105. The data measured by the sensitive unit 105 are transmitted to the transmission device 110 which relays them to the remote digital terminal 300. In the case of a piezoelectric sensitive unit of the pressure sensor, the measured data are transmitted to the transmission device in the form of an electrical signal.

[0083] exist Figures 1 to 3 In the example of the transmission device 110, the transmission device 110 is wireless. For example, the transmission device 110 may include a transmitter / receiver of electromagnetic waves, such as radio waves, Bluetooth, WIFI, etc. Under certain specific conditions, the transmission device 110 may be wired.

[0084] The electronics compartment 111 may also include a battery that provides power to the electronics board 112 and the electronic components connected to the electronics board 112. The battery may be rechargeable or disposable.

[0085] exist Figure 3 In the example of , the electronics compartment 111 is spaced apart from the housing 101. In this configuration, the measuring device 100 comprises an external cable 113 which detachably connects the sensitive unit 105 to the electronic board 112. For hygienic reasons, the housing 101 is a disposable housing, and thus the electronics compartment 111 being spaced apart from the housing 101 allows the electronics compartment 111 to be used for several patients.

[0086] The digital terminal 300 may be a smartphone, a tablet, a computer or any other device making it possible to receive data and analyse the data using algorithms stored in its memory or in a remote server accessible via a telecommunication network.

[0087] like Figure 4 As shown, the present invention also relates to a measurement method 400 for measuring at least one physiological parameter of a patient.

[0088] The measuring method 400 comprises a connecting step 401 of connecting a measuring chamber to a physiological fluid of a patient. For example, the measuring chamber can be connected to the physiological fluid of a patient via a connecting device 200. The connecting device 200 can comprise a lumbar puncture needle. This allows access to the cerebrospinal fluid in order to measure intracranial pressure.

[0089] exist Figure 2 In the example shown, a three-way stopcock may also be used to connect a lumbar puncture needle 201 connected to the patient to the tubing for injection in order to perform dynamic testing.

[0090] According to the invention, during the connection step 401, the measurement chamber is by default filled with a gas G and comprises a sensitive unit making it possible to measure at least one physiological parameter. For example, the housing comprises a piezoelectric sensitive unit to measure the CSF pressure.

[0091] like Figure 4 As shown, the measurement method 400 includes a generation step 402 of generating a first interface between the gas present in the measurement chamber and the physiological fluid from the patient. Figures 1 to 3 As shown, the gas is interposed between the patient's physiological fluid and the sensitive unit in a manner that a second interface is formed between the gas and the sensitive unit. To this end, the measuring chamber can be directly fluidically connected to a connecting device 200 consisting of a lumbar puncture needle 201 .

[0092] The measurement chamber may be connected to the lumbar puncture needle 201 and tubing to perform dynamic testing.

[0093] In this example, the gas between the sensitive unit 105 and the patient's physiological fluid has a non-zero volume of less than or equal to 1 ml. The volume of the gas between the physiological fluid and the sensitive unit can also be less than 1 ml. In particular, the volume of the gas between the physiological fluid and the sensitive unit 105 can be less than 0.7 ml.

[0094] According to an embodiment of the present invention, the volume of the gas between the physiological fluid and the sensitive unit 105 may be between 0.2 ml and 0.5 ml. However, the volume of the gas between the physiological fluid and the sensitive unit 105 may also be between 0.3 ml and 0.4 ml.

[0095] Therefore, the sensing unit 105 performs the measurement via a hydro-pneumatic interface. The hydro-pneumatic interface has the advantage of attenuating physical accelerations experienced by the sensing unit 105, such as the patient's movements or vibrations caused by the medical environment (monitoring equipment, etc.), while allowing a more reliable measurement of the pressure or pulsatility of the CSF.

[0096] like Figure 4 As shown, the measurement method 400 includes a measurement step 403 of measuring at least a first physiological parameter. When the gas G contained in the measurement chamber is between the physiological fluid and the sensitive unit, the first physiological parameter is measured using the sensitive unit. For example, CSF pressure is a physiological parameter that can be measured by the measurement method 400, in which case CSF pressure can constitute the first physiological parameter. The piezoelectric sensitive unit can be used to measure the steady-state hydrostatic pressure or pulsatile pressure of the CSF.

[0097] exist Figure 4 In the example of , the measurement method 400 may include a determination step 404 of determining at least a second physiological parameter by measuring the first physiological parameter.

[0098] According to a first example, a mean value of the intracranial pressure of the patient may be determined. The mean value of the intracranial pressure constitutes a second physiological parameter.

[0099] According to a second example, the pulsatility of the patient's intracranial pressure may be determined. The value of the intracranial pulsatility constitutes a third physiological parameter.

[0100] Within the framework of the fluid dynamics approach, the method according to the invention makes it possible to determine other physiological parameters, such as the frequency of the respiratory cycle, the compliance of the brain or the resistance to the CSF flow.

[0101] like Figure 3 and Figure 4 As shown, the measurement method 400 may include a transmission step 405 of the data measured by the sensitive unit to a digital terminal 300 remote from the sensitive unit. The transmission step 405 may be performed according to a Bluetooth or WIFI type protocol, or indeed in an analog manner via a wired connection.

[0102] Upon receiving the measurement data, the digital terminal 300 may execute step 404 and process the signal in order to extract at least one physiological parameter. The intracranial pressure of the patient is a parameter that can be directly determined by measuring the CSF pressure.

[0103] According to the invention, the measuring device 100 is particularly suitable for carrying out the measuring method 400 .

[0104] The measuring device 100 and the measuring method 400 enable reliable and accurate measurement of CSF pressure in both the hydrostatic method and the hydrodynamic method. The hydrostatic method involves measuring the steady-state pressure and pulsatility of the CSF secondary to periodic cardiac and respiratory oscillations. The hydrodynamic method involves applying a known stress to the intracranial fluid system, known as a perfusion test, and analyzing the response of the system to the stress.

[0105] In order to investigate the hydrostatic component of the CSF pressure, the measuring chamber 104 is connected to a connection device 200 which is fluidically connected to the nervous system, for example by a lumbar puncture. Changes in the electrical signal measured by the sensitive unit 105 reflect changes in the CSF pressure.

[0106] To investigate the hydrodynamic component of CSF pressure, fluid stress was applied to the CSF by injecting physiological serum at a constant flow rate through an inlet port at the lumbar puncture site. This perfusion test was performed through an inlet port formed parallel to the first port, to which the connection device 200 was connected, and the measurement device 100 was in contact with the CSF fluid.

[0107] Experimental Results

[0108] In order to solve the technical problem set forth herein, the inventors conducted a comparative experimental study between the pressure measurement results obtained by a sensor having a liquid / sensitive unit interface (referred to as a "fluid sensor" 501) and the pressure measurement results obtained by a sensor having two liquid / gas / sensitive unit interfaces (referred to as a "hydraulic pneumatic sensor" 502). The work was performed in the same experimental device 500 using physiological serum S instead of the patient's physiological fluid.

[0109] Figure 5 The experimental setup 500 is schematically shown. The two sensors 501, 502 are of the piezoelectric type, sold by the company ICUMED under the trademark "Transpac TM ", for measuring invasive blood pressure. The pressure measuring device includes a measuring chamber 503, whose internal volume is 0.2 ml. In addition, the measuring device includes a fluid inlet 504 connected to a pipe 600 filled with physiological serum S. The fluid inlet 504 is equipped with a three-way stopcock 504 to control the connection or disconnection of the sensor with the physiological serum S. The measuring device used includes an end wall consisting of a sensitive unit of a piezoelectric sensor 505 opposite to the inlet 504. Near the piezoelectric sensor 505, the side wall of the measuring chamber 503 includes a clearing opening 506, the opening and closing of which is controlled by a manual valve or a stopcock. The piezoelectric sensor 505 of the measuring device has a sensitivity of plus or minus one percent and a linearity of 1%. Finally, the piezoelectric sensor is designed to measure pressure changes between -20 mmHg and 300 mmHg.

[0110] exist Figure 5 In the experimental device 500 shown, two sensors 501 and 502 are mounted on a support and kept horizontally in the same plane. In this case, the two sensors 501, 502 are connected in parallel to a pipe 600. The pipe 600 includes a three-way cock 601 at each connection point, and a connecting pipe 602 connects the pipe 600 to the sensors 501 and 502.

[0111] The sensitive element of each piezoelectric sensor 501 and 502 is independently connected to an amplifier via a cable 507 and then to a converter, after which software Recorded on computer.

[0112] exist Figure 5 In the experimental device 500 of FIG. 5 , the purge opening 506 of the hydropneumatic sensor 502 is connected to a syringe 508 containing air. The syringe 508 is graduated and makes it possible to control the volume of air in the measuring chamber 503, that is, between the sensitive cell of the piezoelectric sensor 505 and the physiological serum S.

[0113] The experimental device 500 also includes a graduated column 603 held vertically. The graduated column 603 includes a fluid connection at its lower end. The graduated column 603 allows the inventors to visualize the pressure applied to the sensors 501, 502 by measuring the water column within the graduated column 603. For this purpose, the sensors 501, 502 are positioned so that their piezoelectric sensitive units 505 are located in a horizontal plane P passing through the zero level defined on the graduated column. Figure 5 In the example of FIG. 6 , a graduated column 603 is arranged at one end of a first branch of the pipe 600 . A second branch of the pipe 600 is installed in parallel with the first branch and is supplied to the sensors 501 , 502 via a connecting cock 601 arranged at each connection point to the connecting pipe 602 .

[0114] The tubing 600 filled with physiological serum S is connected to an electric syringe pump 604. The syringe pump 604 is configured to apply a static pressure in a continuous range between -20 mmHg and 50 mmHg. These values ​​correspond to the CSF pressures that can be measured physiologically and pathologically in patients. The electric syringe pump 604 used in this experiment is Syringe pump.

[0115] The connection cock 601 allows the connection of an oscillation generator 605, if applicable to the tubing 600, in order to generate a dynamic wave pressure with a frequency of 1 Hz and an amplitude adjustable between 0.1 mmHg and 10 mmHg. These amplitude values ​​correspond to those of intracranial pressure in patients both physiologically and pathologically. The oscillation pressure generator 605 used in this experiment is type.

[0116] Note that sensors 501 and 502 naturally contain air within their measurement chambers 503 when transported.

[0117] For the fluid sensor 501, air purge is performed through the opening 506 of the measuring chamber 503 and by filling the measuring chamber 503 with physiological serum. Thus, the sensitive unit is in direct contact with the fluid in the measuring chamber. This air purge protocol is a generally recommended operating procedure for measuring fluid pressure with this type of sensor in clinical practice, especially for invasive measurement of arterial or venous blood pressure.

[0118] Once the fluid sensor 501 is purged of air, the fluid sensor 501 is connected to the physiological serum S fluid.

[0119] For the hydropneumatic sensor 502, no air purge is performed. Since the volume of the measuring chamber 503 is 0.2 ml, it will contain 0.2 ml of air. Therefore, this volume of air will be between the sensitive unit 505 and the inlet 504. The hydropneumatic sensor will then be connected to the physiological serum via the connection 602. Therefore, a controlled volume of air will be added between the piezoelectric sensor 505 and the physiological serum S. Thus, the inventors have generated a liquid / gas measurement interface in the measuring chamber according to the invention, which corresponds to the hydropneumatic principle.

[0120] The two sensors (fluid sensor 501 and hydropneumatic sensor 502 ) are fluidically connected by means of physiological serum S to a graduated column 603 , to an electric syringe pump 604 and to a dynamic pressure generator 605 .

[0121] Experiment 1

[0122] Experiment 1 involves using software Record simultaneously the pressure measurement obtained by the fluid sensor 501 and the pressure measurement obtained by the hydro-pneumatic sensor 502. As a reminder, the volume of air in the hydro-pneumatic sensor 502 is the volume of the internal volume of the measuring chamber 503, ie 0.2 ml.

[0123] Measurements of steady-state hydrostatic pressure were acquired at 100 Hz over a recording duration of 5 minutes.The hydrostatic pressure in both sensors 501 and 502 could be gradually increased by injecting physiological serum. Figure 6 Corresponds to the recording of this experiment. In this figure, the grey signal corresponds to the fluid sensor 501 and the black signal corresponds to the hydraulic-pneumatic sensor 502.

[0124] In Experiment 1, the electric syringe pump 604 was located on the table on which the experimental apparatus 500 was placed. In the baseline state, the values ​​measured by the fluid sensor 501 and by the hydraulic and pneumatic sensor 502 were the same: the two lines representing the two sensors were at Figure 6 Arrow D indicates that at time 16:53:30, the electric syringe pump 604 was turned on. When turned on, at the recorded time of 16:56:18, i.e., until the electric syringe pump 604 stopped (arrow ST), a gradual increase in pressure from 0 mmHg to about 25 mmHg was observed.

[0125] The cables of sensors 501 and 502 were connected to a computer running the "ICM+" software; thus, the inventors were able to study and compare the signal coming from the fluid sensor 501 with the signal coming from the hydro-pneumatic sensor 502. This was also the case in the subsequent experiments.

[0126] exist Figure 6In the recording of , the inventors noticed that the signals of the two sensors 501, 502 are superimposed until the electric syringe pump 604 is turned on. In the case of the superposition of the two signals, only the black signal is visible. When the electric syringe pump is turned on at D, there is on the one hand an increase in the hydrostatic pressure of both signals, following a similar curve, and on the other hand an oscillation of the gray signal recorded by the fluid sensor 501. Figure 7 yes Figure 6 , and shows that the signal from the hydro-pneumatic sensor 502 (black) also exhibits oscillations, however its amplitude is much smaller than that of the fluid sensor 501 (grey). Once the electric syringe pump 604 stops ST, the oscillations disappear; the two signals from the two sensors (fluid sensor 501 and hydro-pneumatic sensor 502) are superimposable.

[0127] This oscillation is not caused by the pulse generator 607 being turned off. This oscillation occurs once the electric syringe pump 604 is turned on, and stops once the electric syringe pump 604 is turned off. Therefore, the inventors concluded that the mechanical vibration of the electric syringe pump 604 located on the workbench is transmitted to the fluid sensor 501, while the hydraulic pneumatic sensor 502 attenuates the vibration. The density of air is 1.29 kg / m 3 , while the density of liquid (such as water) is 1000kg / m 3 . The density of water is therefore approximately 1000 times greater than the density of air. Thus, a measuring chamber of 0.2 ml of the fluid sensor has a mass of ≈0.2 g, whereas a measuring chamber of 0.2 ml of the hydropneumatic sensor has a mass of only ≈0.26 μg. During the acceleration of the fluid sensor caused by the shock waves, the mass of the water in the measuring chamber (≈0.2 g) generates mechanical stresses on the sensitive unit 505, which leads to measurement artifacts, whereas in the measuring chamber of the hydropneumatic sensor, the low mass of the air (≈0.26 μg) generates only very low mechanical stresses on the sensitive unit, thereby attenuating the shock waves.

[0128] This experiment shows that the hydro-pneumatic sensor 502 attenuates the physical acceleration transmitted to the measurement device during vibration. From a practical point of view, this translates into an improvement in the accuracy of the CSF pressure measurement results.

[0129] During this experiment 1, the two sensors were also compared from an arithmetic point of view. The mean ± standard deviation of the absolute difference between the fluid sensor and the hydro-pneumatic sensor was 0.19 ± 0.21 mmHg, and the 95% confidence interval of the absolute difference was 0.41 mmHg. That is, 95% of the differences between the fluid sensor and the hydro-pneumatic sensor were within the range of ± 0.41 mmHg.

[0130] During Experiments 2, 3, and 4, the electric syringe pump 604 was moved away from the operating table so that the physical vibrations it produced were not directly transmitted to the sensor and did not produce artifacts.

[0131] Experiment 2

[0132] Experiment 2 used apparatus 500 to investigate the effect of the volume of air in the measurement chamber on the accuracy of the static pressure measurements of the hydro-pneumatic sensor.

[0133] The pressure of the physiological serum is increased in a continuous static stage of about ten seconds, then returned to zero. The signals from the fluid sensor 501 and the hydro-pneumatic sensor 502 are recorded simultaneously at 100 Hz. Several pressure increase cycles are performed with different volumes of air in the measuring chamber of the hydro-pneumatic sensor by adding air with a syringe 508 at ambient temperature and atmospheric pressure. Figure 8 A recording lasting 23 minutes is reproduced. The first pressure increase cycle C0 is carried out without the addition of air; therefore, the volume of air in the measuring chamber is 0.2 ml. The two curves can be completely superimposed. Then 0.1 ml of air is added to the measuring chamber of the hydropneumatic sensor. The cycle C1 corresponds to the different pressure levels of the added 0.1 ml of air. The two curves can be completely superimposed. As described in Table 1, the cycles C0 to C8 are carried out with increasing volumes of air.

[0134] Table 1

[0135] cycle C0 C1 C2 C3 C4 C5 C6 C7 C8 Increased air volume (ml) 0 0.1 0.5 1 2 6 12 36 64

[0136] Looking at the curves in each cycle, it can be seen that regardless of the volume of air between the sensitive unit of the piezoelectric sensor 505 and the physiological serum S, the signals measured by the fluid sensor 501 and the hydraulic-pneumatic sensor 502 are superimposed.

[0137] Fig. 9 8 is a close-up of the graph of the period C8 of the experiment (i.e. the period of 64 ml volume of air between the sensitive unit of the piezoelectric sensor 505 and the physiological serum S). In the case of experiment 2, the volume of air of 64 ml is the maximum. In this figure, two signals can be distinguished, one from the fluid sensor 501 (grey) and the other from the hydro-pneumatic sensor 502 (black). These two signals are completely superimposed for most of the time of the recording.

[0138] Fig.10 is a Bland-Altman plot generated from the experimental data of Experiment 2. The X-axis of the plot corresponds to the average of the pressure measurements of the fluid sensor 501 and the hydro-pneumatic sensor 502, expressed in mmHg. The Y-axis of the plot corresponds to the difference between the pressure measurements of the fluid sensor 501 and the hydro-pneumatic sensor 502, expressed in mmHg. A linear regression is then performed.

[0139] The mean ± standard deviation of the absolute difference between the fluid sensor and the hydro-pneumatic sensor is 0.24 mmHg ± 0.17 mmHg, and the 95% confidence interval of the absolute difference is 0.33 mmHg. That is, 95% of the differences between the fluid sensor and the hydro-pneumatic sensor are within the range of ± 0.33 mmHg.

[0140] In Experiment 2, the pressure values ​​varied between -10 mmHg and +30 mmHg, which corresponds to the values ​​found in clinical practice. 0.33 mmHg represents at most about 1% of the pressure measurement. This variation in the measurement results is acceptable in clinical practice. It should also be noted that 1% also corresponds to the sensitivity of the sensor.

[0141] Scientific literature states that a blood pressure sensor is reliable when it provides a measurement with a percentage error of 5% compared to the patient's actual blood pressure.

[0142] Experiment 2 shows that, in comparison with the fluid sensor 501 , air volumes between 0.2 ml and 64 ml in the measuring chamber of the hydropneumatic sensor 502 allow a reliable measurement of the pressure.

[0143] Experiment 3

[0144] Experiment 3 used the apparatus 500 to investigate the effect of the air volume in the measurement chamber on the accuracy of the dynamic pressure measurements of the hydro-pneumatic sensor 502 .

[0145] To this end, the oscillation generator 605 makes it possible to generate a dynamic wave pressure with a frequency of 1 Hz and an amplitude adjustable between 0.1 mmHg and 10 mmHg. The signals from the fluid sensor 501 and the hydropneumatic sensor 502 are recorded simultaneously at 100 Hz. The recording duration is 8 minutes.

[0146] For this experiment, the static pressure is stable and the mean pressure does not vary. Only the dynamic pressure is modified with the aid of the oscillation generator 605 to observe the influence of the air volume on the pulsatility of the pressure measured by the hydropneumatic sensor 502. Several recordings are made at different pulsatility levels. For each pulsatility level, the volume of air in the measuring chamber of the hydropneumatic sensor is gradually increased by adding air using the syringe 508. Fig.11 One of the recordings is reproduced. The black line corresponds to the hydro-pneumatic sensor 502, showing the decay on each cycle of increasing air volume. In contrast, the grey line corresponding to the fluid sensor 501 remains constant from one cycle to another. As described in Table 2, cycles C1 to C7 were performed with increasing volumes of air.

[0147] Table 2

[0148] cycle C1 C2 C3 C4 C5 C6 C7 Increased air volume (ml) 0.2 0.5 1 2 5 10 20

[0149] Each time air is added to the measurement chamber, the pulsatility of the signal measured by the hydro-pneumatic sensor 502 decreases in proportion to the attenuation.

[0150] Fig.12 is a close-up of cycle C1. In this recording it is not possible to distinguish the grey signal from the fluid sensor 501 superimposed on the black signal from the hydro-pneumatic sensor 502. In case of very small air volumes, the signal attenuation is minimal.

[0151] Fig.13 is a close-up of cycle C7. At the beginning of this recording, the gray signal from fluid sensor 501 shows the pulsatility generated by wave generator 605. As soon as the hydro-pneumatic sensor is connected to 20 ml of air, the gray signal from fluid sensor 502 is immediately attenuated, and this gray signal is synchronized with the black signal from the hydro-pneumatic sensor 502, and the two sensors are connected in parallel.

[0152] Experiment 3 shows that in the case of pulsating pressure, the volume of air of the hydro-pneumatic sensor 502 modifies the dynamic measurement of pressure and thus affects the accuracy of the measurement.

[0153] Experiment 4

[0154] The purpose of Experiment 4 was to determine the volume of air in the measurement chamber of the hydro-pneumatic sensor 502 in order to provide an accurate and clinically acceptable measurement of pulsatility.

[0155] Experiment 4 consisted of performing a series of eight operations at different pulsatility levels, during which the volume of air in the hydropneumatic sensor 502 was gradually increased by adding air at ambient temperature and atmospheric pressure using a syringe 508. The experiment was performed over a period of 10 minutes, with a pulsatility of 1 Hz being generated by a generator 605, the oscillation of which was adjustable. Using the software And the acquisition is carried out at 100Hz for recording. For each air volume (period C1 to C7), the pulsatility is not calculated by the difference between the maximum and minimum values, but by measuring the exponent of the fundamental wave in the frequency range of the signal pulse, using Fourier transformation. This gives the numerical value of the pulsatility for each air volume from 0.2ml to 20ml. The graphical representation is obtained using the software XL that characterizes the pulsatility attenuation. An exponential regression analysis is performed to obtain its mathematical equation and Pearson's coefficient. Therefore, for each oscillation state, an exponential curve describing the constitutive relationship of the pulsatility attenuation as a function of the air volume can be obtained.

[0156] Fig.14Eight experiments are shown. Each point corresponds to the pulsatility value for a different volume of air of the hydro-pneumatic sensor 502. Each curve corresponds to the evolution of the pulsatility value measured during a different operation. Transferring the data to this figure allowed the inventors to draw an exponential regression curve for each operation.

[0157] From the exponential regression equation of the data from the eight runs of Experiment 4, the inventors calculated the theoretical change in the pulsatility attenuation (Δ pulsatility) caused by each increase of 0.1 ml of unit volume of air at the hydropneumatic sensor 502. The results are expressed as a percentage of the pulsatility attenuation per unit volume of air. These results make it possible to establish the mean value and standard deviation of the pulsatility attenuation of the hydropneumatic sensor 502 as a function of the volume of air in the measurement chamber. The results are given in Table 3 below.

[0158] Table 3

[0159]

[0160] As shown in Table 3, for air volumes less than 1 ml, the average pulsatility attenuation of the hydro-pneumatic sensor 502 is less than 6.55%. Therefore, taking the accuracy of blood pressure measurement results as a reference, the inventors concluded that the air volume of the hydro-pneumatic sensor must be less than 0.7 ml to ensure reliable measurement results of CSF pulsatility (<5%).

[0161] The inventors have determined a constitutive relationship that makes it possible to determine the percentage of pulsation attenuation ΔP as a function of the air volume Vair (in ml). This law is expressed according to the following equation:

[0162] Ap=0.0652 * Vair+0.0006

[0163] like Fig.15 As shown, this linear law makes it possible to define an air volume strictly less than 0.7 ml, making it possible to measure the pulsatility of the pressure of physiological fluids (such as CSF) with a hydropneumatic sensor, with a measurement variability of less than 5%.

[0164] According to these experimental results, it can therefore be determined that the volume of the measuring chamber of the measuring device is non-zero and less than 1 ml. In the case of CSF, when the liquid / gas interface is established, the physiological value that the CSF pressure may have may only cause a small change in the volume of the gas initially contained in the measuring chamber at atmospheric pressure, so that the gas initially contained in the measuring chamber at atmospheric pressure still has a non-zero volume of less than or equal to 1 ml.

[0165] In the case of the measuring method defined according to the invention, this observation applies to the volume of gas between the CSF and the sensitive cell.

[0166] These experimental results demonstrate that the pressure of biological fluids, whether steady-state or pulsatile, can be measured via a hydraulic-pneumatic interface. Thus, the present invention can be used to measure other physiological parameters, such as bladder pressure, arterial pressure, venous pressure, interstitial tissue pressure in the case of compartment syndrome, intraocular pressure, pressure in the upper respiratory tract, pressure in the digestive tract, and any other biological fluid pressure. For each of these applications, as described above, the biological fluid of interest is placed in contact with the measuring device 100 in a known manner, and the biological fluid of interest can be detected or discharged depending on its properties.

Claims

1. A measuring device (100) for measuring at least one physiological parameter, the measuring device (100) comprising a housing (101) extending longitudinally between a first end (102) and a second end (103) opposite to the first end (102), the housing (101) comprising: a measuring chamber (104) arranged in the housing (101), the measuring chamber (104) having an inner volume filled with gas; a sensitive unit (105) enabling measurement of at least a first physiological parameter, said sensitive unit (105) being arranged in contact with said gas contained in said internal volume of said measuring chamber (104); and an inlet (107) for drawing a physiological fluid of a patient into the measuring chamber (104); It is characterized in that the inlet (107) is arranged so that the physiological fluid is in contact with the gas, and the gas is between the sensitive unit (105) and the physiological fluid of the patient, and the measuring chamber (104) enables two interfaces to be generated: a first interface, which is located between the gas contained in the internal volume and the physiological fluid of the patient entering the measuring chamber (101) through the inlet (107); and a second interface, which is located between the gas contained in the measuring chamber (104) and the sensitive unit (105).

2. The measuring device (100) according to claim 1, wherein: The measuring chamber (104) has an internal volume that is non-zero and less than or equal to 1 ml, in particular, the internal volume is strictly less than 1 ml, preferably, the internal volume is less than 0.7 ml.

3. The measuring device (100) according to claim 1 or 2, wherein: The measuring chamber (104) has an internal volume between 0.2 ml and 0.5 ml.

4. The measuring device (100) according to any one of claims 1 to 3, wherein: The sensitive unit (105) is a piezoelectric unit of a pressure sensor.

5. The measuring device (100) according to any one of claims 1 to 4, wherein: The housing (101) comprises a sealing film (106) which is interposed between the sensitive unit (105) and the inner volume of the measuring chamber (104), and the sealing film (106) protects the sensitive unit (105).

6. The measuring device (100) according to any one of claims 1 to 5, wherein: The inner volume of the measurement chamber (104) is cylindrical.

7. The measuring device (100) according to any one of claims 1 to 6 comprises a connector (108) arranged at the inlet (107) of the housing (101), wherein the connector (108) sealingly connects the measuring chamber (104) to a connecting device (200) for connecting to the physiological fluid of the patient.

8. The measuring device (100) according to any one of claims 1 to 7, wherein: The inlet (107) is openable and closable.

9. The measuring device (100) according to any one of claims 1 to 8, comprising a transmitting device (110) for transmitting the measurement result of the first physiological parameter to a remote digital terminal.

10. The measuring device (100) according to any one of claims 1 to 9, wherein: The gas in the measurement chamber (104) consists of atmospheric air.

11. The measuring device (100) according to any one of claims 1 to 10, wherein: The sensitive unit (105) is arranged at the first end (102) of the housing (101), and the inlet (107) is arranged at the second end (103) of the housing (101).

12. A measurement method (400) for measuring at least one physiological parameter of a patient, characterized in that The method comprises: A connecting step (401) of connecting a measuring chamber connection device to a physiological fluid of a patient, the measuring chamber being filled with a gas and comprising a sensitive unit enabling measurement of at least one physiological parameter; a step of generating a first interface between the gas present in the measurement chamber and the physiological fluid from the patient (402), the gas being interposed between the physiological fluid and the sensitive unit to form a second interface between the gas and the sensitive unit; and A measuring step (403) of measuring at least a first physiological parameter is performed by the sensing unit through the gas between the physiological fluid and the sensing unit.

13. The measurement method (400) according to claim 12, wherein: The gas between the sensitive unit and the physiological fluid of the patient has a non-zero volume that is less than or equal to 1 ml. In particular, the volume of the gas is strictly less than 1 ml. Preferably, the volume of the gas is less than 0.7 ml.

14. The measurement method (400) according to claim 12 or 13, wherein: The measuring chamber is connected to means for connection to the physiological fluid consisting of the patient's cerebrospinal fluid.

15. The measuring method (400) according to any one of claims 12 to 14, wherein: The first physiological parameter corresponds to the pressure of the physiological fluid of the patient.

16. The measurement method (400) according to any one of claims 12 to 15, comprising a determination step (404) of determining at least a second physiological parameter by measuring the first physiological parameter.

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