Medical device for monitoring biological parameters

Abstract

Medical device (10) for monitoring biological parameters of a user, comprising - a plate (1) for measuring a mass of the user, - at least a first and a second electrode (11, 12, 21, 22) for performing impedance measurements, and - a device for measuring blood pressure and / or heart rate (23).

Description

[0001] Medical device for monitoring biological parameters

[0002] The invention relates to a medical device for monitoring biological parameters.

[0003] Daily monitoring of water and salt intake (sodium chloride, potassium, calcium, phosphorus) is essential in patients with chronic renal failure. Poor management of these intakes impairs the patient's tolerance to dialysis (particularly through the occurrence of intra-dialytic hypotension and / or cramps) and greatly increases the likelihood of the onset of side effects associated with the disease, such as hypertension and / or cardiovascular disorders.

[0004] Only a high degree of deprivation, particularly of water and salts, allows patients with chronic kidney failure to live with their disease. It is therefore essential to provide them with means to regularly monitor, especially daily, their fluid intake from their diet, thus allowing them to improve their tolerance to dialysis and reduce the risk of developing dialysis side effects.

[0005] In current practice, daily monitoring of water intake is performed empirically and approximately by simple weighing and comparison of the measured weight to a reference weight known as the patient's "ideal weight." The patient's reference weight is also called "dry weight" because it corresponds to an estimate of the weight that the patient should normally reach at the end of a dialysis session when excess water has been completely removed. The dry weight of the dialysis patient is generally determined empirically by the healthcare team as the lowest weight that can be tolerated by the patient and that does not generate adverse effects in the patient. It is a compromise, reviewed in consultation, between clinical observation of more or less observable symptoms, the history of dialysis intolerances and weight and blood pressure measurements.Thus, in most cases, dry weight is estimated by trial and error, with errors in estimating dry weight being detectable either through the development of adverse effects during dialysis sessions (in the case of underestimation of dry weight) or through the appearance of symptoms of water retention (in the case of overestimation of dry weight).

[0006] A body composition assessment would advantageously make it possible to distinguish water mass from total mass and thus determine a more reliable dry weight to refer to when managing the quantity of liquid that a patient absorbs between two dialyses, and thus determine the volume of water to be removed during a dialysis session.

[0007] In addition, daily home monitoring of indicators relating to the side effects of the disease would improve responsiveness in the management of these side effects, particularly the management of hypertension and cardiovascular disorders.

[0008] There are currently devices that allow body composition assessments to be performed, particularly at home. However, these devices are generally poorly adapted to the body composition and motor skills of a patient with chronic kidney failure, particularly because the median age of a dialysis patient is 71 years and because the disease is almost always associated with multiple comorbidities. Furthermore, existing devices do not take into account the specific needs of these patients, such as the detection and monitoring of the disease's side effects.

[0009] Furthermore, different devices measuring body composition in dialysis patients provide significantly different results depending on the device used. For this reason, it is not possible to compare measurements from different devices for the same patient. Therefore, it is not possible to monitor a patient using data from different devices.

[0010] The aim of the invention is to provide a device for monitoring biological parameters which overcomes the above drawbacks and improves the devices known from the prior art.

[0011] In particular, the object of the invention is to produce a device which is simple and reliable and which allows daily monitoring of the patient's weight and / or the quantity of liquid absorbed between two dialyses and / or daily monitoring of the side effects of chronic renal failure.

[0012] To this end, the invention relates to a medical device for monitoring biological parameters of a user comprising

[0013] - a platform for taking measurements of the user's mass,

[0014] - at least one first and one second electrode for carrying out impedance measurements, and

[0015] - a device for measuring blood pressure and / or heart rate.

[0016] In one embodiment, the blood pressure and / or heart rate measuring device is a photoplethysmographic sensor also making it possible to measure the oxygen saturation of the user's blood.

[0017] In one embodiment, the tray is equipped with the first electrode for performing impedance measurements at a foot of the user, and the second electrode is arranged so as to allow impedance measurements to be performed at a first hand of the user. In one embodiment, the medical device comprises a third electrode arranged in contact with a second hand of the user, the second and third electrodes are together capable of recording an electrocardiogram between the first hand and the second hand of the user.

[0018] In one embodiment, the medical device comprises a temperature sensor for measuring a skin temperature of the user.

[0019] In one embodiment, the medical device comprises means for adjusting a height of the second electrode relative to the plate, so as to adapt a vertical distance, measured between the second electrode and the plate, to a height of a user.

[0020] In one embodiment, the medical device comprises a first handle, on which the second electrode is fixed, arranged on a rigid arm substantially parallel to the plate, and the adjustment means is a system for adjusting the height of said rigid arm comprising the first handle relative to the plate, to allow the height of the first handle to be adjusted relative to the plate.

[0021] In one embodiment, electrodes of the medical device are capable of measuring impedance at the level of a foot or a hand of a user by injecting a current of intensity between 8 and 200 pA, or between 8 and 150 pA or between 8 and 100 pA or even around 32 pA at plus or minus 10%, and according to a frequency sweep extending from 125 Hz to 500 kHz, or even up to 800 kHz, or even extending between 4 kHz and 300 kHz.

[0022] In one embodiment, the medical device comprises an electronic processing unit. The electrodes and / or the blood pressure and / or heart rate measuring device and / or the temperature sensor are connected to the electronic processing unit by a wired or wireless communication device, such that the impedance measurements made via the electrodes are able to be transmitted to the electronic processing unit and such that the electronic processing unit is able to control the current transmitted by the electrodes to a hand or foot of a user.

[0023] In one embodiment, the medical device comprises hardware and / or software elements configured to implement the following treatments:

[0024] - measurement of a user's total mass,

[0025] - measurement of foot-hand impedance,

[0026] - measurement of a volume of intracellular water contained in a user's body,

[0027] - measurement of a volume of extracellular water contained in a user's body,

[0028] - measurement of a total volume of water contained in a user's body,

[0029] - measurement of dry weight,

[0030] - measurement of a volume of hyperhydration,

[0031] - and optionally measurement of a variation in dry weight,

[0032] - and optionally measurement of a variation in hyperhydration,

[0033] - and optionally blood pressure measurement,

[0034] - and optionally measurement of a pulse wave,

[0035] - and optionally measurement of heart rate,

[0036] - and optionally measurement of a blood oxygen saturation level,

[0037] - and optionally measurement of a hand-to-hand electrocardiogram,

[0038] - and optionally measurement of skin temperature.

[0039] In one embodiment, the measurement of an intracellular water volume, the measurement of an extracellular water volume and the measurement of a total water volume are carried out independently of one another. In one embodiment, the medical device comprises a human-machine interface allowing a display of at least one data item chosen from:

[0040] - a total mass of a user,

[0041] - a total volume of water contained in a user's body,

[0042] - a dry weight of a user,

[0043] - a variation in a user's dry weight,

[0044] - a volume of hyperhydration,

[0045] - a variation of hyperhydration,

[0046] - a user's heart rate,

[0047] - a user's blood pressure,

[0048] - a user's skin temperature,

[0049] - a bioimpedance visualization.

[0050] The attached drawings represent, by way of example, an embodiment of a monitoring device according to the invention.

[0051] Figure 1 represents a monitoring system equipped with a medical monitoring device according to the invention.

[0052] Figure 2 represents an embodiment of a medical monitoring device according to the invention.

[0053] Figure 3 schematically represents an electronic processing unit of the medical monitoring device according to the embodiment of the invention.

[0054] An example of a biological parameter monitoring system equipped with a monitoring device according to the invention is described below with reference to Figures 1 to 3.

[0055] In the remainder of the document, the term "weight" should be understood as a mass measured in kilograms. The medical monitoring system 100 mainly comprises the following elements:

[0056] - at least one medical monitoring device 10,

[0057] - a distributed network infrastructure 20, and

[0058] - at least one terminal 30 for healthcare professionals.

[0059] The distributed network infrastructure 20 comprises a network 201, a centralized memory 202 hosting a database 203 and programs for processing the data contained in the database. The centralized memory further hosts programs for managing the communication between a control unit 3 of each of the at least one medical monitoring device 10 and the user terminals 30 dedicated to healthcare professionals.

[0060] Such an embodiment, implementing a distributed architecture, makes it possible to perform the simplest calculations directly in the medical device 10, then to delegate more complex calculations to a computer server connected to the database 203.

[0061] In a minimal embodiment, the medical monitoring system 100 could consist solely of a medical device 10. The calculations would then be entirely executed locally, i.e., in the medical device 10.

[0062] In the remainder of the document, the medical monitoring device 10 is also referred to as “medical device 10” or “device 10”.

[0063] The medical device 10, particularly represented by FIG. 2, comprises:

[0064] - a tray 1 for taking measurements of the user's mass,

[0065] - at least one first and one second electrode 11, 12, 21, 22 making it possible to carry out impedance measurements according to at least two distinct frequencies, and a measurement of at least one volume of water in a user's body, and

[0066] - a device for measuring blood pressure and / or heart rate 23.

[0067] The measurement of a volume of water carried out via the first and second electrodes 11, 12, 21, 22 may be the measurement of an intracellular water volume, the measurement of an extracellular water volume and the measurement of a total water volume. These measurements are described later in the document.

[0068] The characteristics, particularly frequency characteristics, of a current injected into the electrodes to perform impedance measurements are detailed later in this document. At least two distinct current frequencies are used by the device, a first frequency allowing a measurement of a volume of extracellular water in a body, and a second frequency, higher than the first frequency, allowing a measurement of a total volume of water in the body. Advantageously, the frequency sweep of a current injected into the electrodes comprises at least two, or even three frequencies (at least one low frequency and / or one medium frequency and one high frequency), or even at least six frequencies, or even at least twelve frequencies. High frequency is understood to be a frequency greater than 50 kHz. Low frequency is understood to be a frequency less than 5 kHz. Medium frequency is understood to be a frequency between 5 and 50 kHz.

[0069] In one embodiment, the tray 1 is equipped with at least one load sensor 13 for measuring the total mass of the user. Advantageously, the tray is equipped with several load sensors 13, for example four load sensors 13, in order to optimize the accuracy of the measurement of the total mass of the user. In one embodiment, the tray 1 is equipped with the first electrode 11, 12 for carrying out impedance measurements at the level of a foot of a user. Furthermore, the second electrode 21, 22 is arranged so as to allow impedance measurements to be carried out at the level of a first hand of the user.

[0070] The first and second electrodes are thus able together to carry out impedance measurements between a foot and a hand of a user, in particular impedance measurements between an homolateral foot and hand of a user, that is to say a foot and a hand located on the same half of the user's body. Preferably, in order to limit interference from cardiac functioning on the impedance measurements, the measurements are carried out on the right half of the body.

[0071] In the remainder of this document, impedance measurements between a user's foot and hand are referred to as "foot-hand impedance measurements."

[0072] As a note, impedance measurement means any direct or indirect measurement that allows such a quantity to be obtained directly, such as measurements of voltage, voltage variations over time, current and / or current variations over time, or their derivatives.

[0073] More generally, in the remainder of the document, the term "measurement" may refer to data directly from the sensors, and / or data calculated from data collected at the sensors. The calculations may include algorithmic calculations, including calculations involving learning algorithms, for example, neural network learning calculations. Furthermore, the term "foot" is used to refer to a body part that may include a foot, including the sole of the foot, the top of the foot, and the toes, and that may extend above the ankle. Similarly, the term "hand" is used to refer to a body part that may include a hand, including the palm of the hand, the top of the hand, and the fingers, and that may extend above the wrist.

[0074] Advantageously, the platform 1 may comprise more than one electrode, for example two electrodes 11, 12 arranged so as to be simultaneously in contact with a foot of a user standing on the platform. For example, one electrode 11 may be in contact with the heel of the foot while another electrode 12 is in contact with the front of the foot. In the remainder of the document, the term “first electrode” designates one or more electrodes arranged on the platform 1. The first electrode is intended to carry out impedance measurements between a foot of the user and another area of ​​the user's body.

[0075] Additionally or alternatively, at least two electrodes 21, 22 may be arranged at a first hand of the user. For example, one electrode 21 may be in contact with the palm of the first hand and another electrode 22 may be in contact with a finger of the first hand. In the remainder of the document, the term “second electrode” designates one or more electrodes arranged in contact with a first hand of a user and intended to carry out measurements at the first hand of the user.

[0076] Thus, depending on the number of electrodes included in the medical device 10, the first and second electrodes can make it possible to carry out different types of impedance measurements between a foot and a first hand of the user, for example bipolar, tripolar or quadripolar measurements. The medical device 10 further comprises a blood pressure and / or heart rate measuring device 23.

[0077] In one embodiment, the blood pressure and / or heart rate measuring device is a photoplethysmographic sensor 23.

[0078] The photoplethysmographic sensor 23 makes it possible to carry out all or part of the following measurements: blood pressure, heart rate and oxygen saturation of the user's blood.

[0079] The photoplethysmographic sensor 23 may include a set of at least two emitting LEDs and one or two receiving photodiodes. The at least two emitting LEDs produce lights of two different wavelengths, the respective wavelengths of these LEDs being able to be situated for example between 500 and 750 nm for the first and between 850 and 1000 nm for the second.

[0080] Other embodiments of a blood pressure measuring device 23 are conceivable, for example a blood pressure cuff.

[0081] The medical device may further comprise a third electrode 41 arranged in contact with a second hand of the user. In the remainder of the document, the term “third electrode” designates one or more electrodes arranged in contact with the second hand of a user and intended to carry out measurements at the level of the second hand of the user.

[0082] Advantageously, the second and third electrodes 21, 22, 41 are then together capable of recording an electrocardiogram between the first hand and the second hand of the user. In the remainder of this document, the impedance measurements between the first and second hands of a user are called “hand-hand impedance measurements”.

[0083] In addition, the second and third electrodes 21, 22, 41 are then capable together

[0084] - to a measurement of a heart rate, and / or

[0085] - to a measurement of a pulse wave circulating between the second and third electrodes 21, 22, 41, and / or

[0086] - to a measurement of a speed of the pulse wave circulating between the second and third electrodes 21, 22, 41.

[0087] The medical device may further comprise a temperature sensor 24 making it possible to measure a user's temperature.

[0088] Advantageously, the medical device comprises a means for adjusting a height of the second electrode 21, 22 relative to the plate 1, so as to adapt a vertical distance, measured between the second electrode and the plate, to the size of the user. Thus the second electrode 21, 22 can be arranged so as to adapt to a natural position of a hand which would come into contact with the second electrode 21, 22.

[0089] The adjustment means may take various forms. For example, in a preferred embodiment, the device 10 may comprise a first handle 2 on which the second electrode 21, 22 is fixed. The adjustment means may then be a system for adjusting the height of the first handle 2 relative to the plate 1.

[0090] The medical device 10 may further comprise a second handle 4 equipped with the third electrode 41. The adjustment means may also make it possible to adjust the height of the second handle relative to the plate 1.

[0091] According to the embodiment, the medical device therefore comprises a tray for receiving the feet of a user, and two handles for respectively receiving the hands, or even the arms, of the user. Advantageously, these handles are rigid, and are arranged on two rigid arms, as will be detailed later.

[0092] The blood pressure and / or heart rate measuring device 23 and / or the temperature sensor 24 can be positioned on the first or second handle 2, 4.

[0093] The medical device 10 further comprises an electronic processing unit 3, particularly represented by FIG. 3. This unit integrates at least one computer 30, and a connector 32 allowing a connection of the computer 30 to sensors 13, 23, 24 and electrodes 11, 12, 21, 22, 41 of the medical device 10. The computer 30 can thus receive the data measured by the sensors. The electronic processing unit 3 further comprises a data recording medium or electronic memory 31. It also comprises an electrical source 34, connected to all or part of the electrodes, thus making it possible to inject electric current via the electrodes. It further comprises at least one voltage sensor 36 making it possible to collect physiological data via the measuring electrodes. This voltage sensor 36 can alternatively be located at a measuring electrode, or remotely, within the electronic processing unit 3, as shown.Finally, the electronic processing unit 3 comprises a communication device 35, which allows it to transmit electronic data to the outside, such as for example body composition measurements or blood pressure and / or to receive data from the outside such as parameter data or messages sent by a healthcare professional. The electronic memory 31 also makes it possible to store the measurements and / or the data calculated locally in the medical device 10. The measurements and / or the data calculated locally in the medical device 10 are then transmitted via the network 20 to the database 203. The measurements and / or the data calculated locally in the medical device 10 are advantageously saved for a minimum duration in the memory 31, in particular in the event of unavailability of the network 20. The minimum backup duration may be for example 15 days.

[0094] The data in the electronic memory 31 can be read by the computer 30, or even by any other computer in the electronic processing unit 3, on which a computer program is recorded for the operation of the medical device 10, in particular for the implementation of the measurements and calculations of biological parameters described in the remainder of this document.

[0095] In an embodiment represented by Figure 2, the medical device 10 comprises a support 6 connected to the tray 1 and to the first and second handles 2, 4. The support 6 comprises a vertical foot 60 fixed in its lower part to the tray 1. The vertical foot 60 is preferably perpendicular to the tray 1. It is placed so as to allow a user to climb onto the tray 1 and place one of his feet simultaneously on the two electrodes of the tray 1 1 , 12.

[0096] The support 6 also comprises a U-shaped frame composed of three parallelepiped portions 61, 62, 63 fixed together, a central portion 63 being interposed between two portions 61, 62 respectively forming the two branches of the U. In one embodiment, the portions 61, 62, 63 are rigidly fixed together and the assembly that they form extends in a substantially horizontal plane, that is to say parallel to the plane of the plate 1. Alternatively, a rotational movement of the portions forming the branches 61, 62 is possible around the central portion 63. The branch 61 comprises a first end connected to the central portion 63 and a second end connected to the first handle 2. The branch 62 comprises a first end connected to the central portion 63 and a second end connected to the second handle 4. The central portion 63 is fixed perpendicular to the vertical foot 60, in an upper zone of the vertical foot 60.In an advantageous embodiment, the attachment between the vertical foot 60 and the central portion 63 comprises a means for adjusting the height of the U-shaped frame. The height adjustment of the U-shaped frame advantageously makes it possible to adjust the height of the handles 2, 4, i.e. the vertical distance separating the handles 2, 4 from the tray 1.

[0097] According to one embodiment, the two branches 61, 62 of the medical device 10 appear as two rigid arms.

[0098] The two branches 61, 62 comprise the electrode(s) intended to cooperate with the hand of a user, via or not a handle 2.

[0099] Alternatively, the rigid frame positioned at hand height, to cooperate with a user's hands, may have a shape other than a U.

[0100] In addition, the height adjustment means may comprise a locking / unlocking device, making it possible to fix or not the two branches 61, 62 relative to the support 6, and therefore to maintain them at a chosen height. This locking / unlocking device also makes it possible to unlock this position, to allow their movement and the adjustment of their height. For this, a guide device may allow their movement, for example by at least one guide rail, in particular a movement in vertical translation. The support 6 may for example slide in a vertical translation for its adjustment, then be maintained at a chosen height by a mechanism of pins introduced into a certain respective opening of the support and of the vertical foot corresponding to a height chosen for the support.

[0101] Thus, the device ensures that the electrodes are set at the correct height to cooperate with a user's hand(s), and then ensures that this height will be kept constant during regular measurements, for example daily, for optimal consistency of the different measurements between them.

[0102] The vertical foot and / or the U-shaped frame are preferably hollow so as to be able to integrate the connections 32 of the sensors 11, 12, 13, 21, 22, 23, 24, 41 and possibly the electronic processing unit 3.

[0103] The electronic processing unit 3 can be arranged within the medical device 10 itself. Alternatively, it is presented as a unit remote from the tray 1 and from the first and second handles 2, 3 but connected to these two elements by a communication device 37, wired or wireless, as shown in FIG. 3.

[0104] In one embodiment, the electronic processing unit 3 has a distributed architecture.

[0105] In particular, in this embodiment, the management of the medical device (including the processing of data and the control of sensors and electrodes) is distributed between several microcontrollers each integrating at least one computer and a recording medium. At least two local microcontrollers are for example respectively positioned at each handle 2, 4. Each local microcontroller is thus located near the electrodes 21, 22 and 41. A central microcontroller has the role of orchestrating the progress of the measurements by coordinating the local microcontrollers and collecting the measurements carried out by the local microcontrollers. Alternatively, there may be a single local microcontroller near the electrodes, in communication with a central microcontroller.This set of local (or local) and central microcontrollers and their associated electronic memories forms a solution equivalent to the calculator 30 and the electronic memory 31 described previously.

[0106] Each local microcontroller is advantageously placed as close as possible to the sensors it controls. The local microcontrollers each integrate a multiplexer 33, an electrical source 34 and a blood pressure monitor 36, which allow them to manage each of the bioimpedance electrodes. Thus, a local electronic processing unit, similar to that described with reference to Figure 3, is positioned as close as possible to the sensors of the device. Such an arrangement makes it possible to improve the quality of the analog measurements by minimizing signal attenuation and noise.

[0107] A local microcontroller is also advantageously placed as close as possible to the photoplethysmographic sensor 23, the emitting LEDs and the receiving photodiodes for their control.

[0108] The central microcontroller further manages communication with a human-machine interface 5 dedicated to a user of the medical device 10, in particular a patient suffering from chronic renal failure. The human-machine interface 5 is part of the medical device 10.

[0109] The central microcontroller also manages communication with the network 20, for the transmission of data from the medical device 10 to the remote database 203. In one embodiment, the central microcontroller manages communication via the network 20 with a remote computer 30, or any portable object, on which there may be a human-machine interface to allow a user of the monitoring system 100, in particular a healthcare professional, to consult the data from the medical device and / or to configure the medical device 10.

[0110] The invention also relates to a computer-readable recording medium comprising instructions which, when executed by a computer, cause the computer to implement the method of calculating a water volume, as well as calculations for estimating biological parameters, such as blood pressure, vascular stiffness, heart rate and oxygen saturation.

[0111] The electronic processing unit 3 can thus control the operation of the medical device 10 by controlling bioimpedance measurements between a foot and a hand of a patient. For this, the electrical source 34 can generate an electric current via the electrodes 11, 12, 21 and 22, then measure induced electrical data, in particular via the voltage sensor 36. The voltage induced by the current flowing through is measured at at least one measuring electrode by the voltage sensor 36, and the application of Ohm's law makes it possible to determine the bioelectrical impedance of the medium crossed, that is to say the body of a patient.

[0112] Additionally, in one embodiment, the medical examination device 10 could be capable of impedance measurement in an area including the patient's cardiac region. For this, a current is generated between electrodes of the first and second hands 21, 22, 41, and measurements make it possible to deduce therefrom the bioelectrical impedance of the medium crossed, i.e. the cardiac region. In this embodiment, the third electrode would advantageously comprise several electrodes arranged in contact with the second hand.

[0113] In one mode of use, the electrical source 34 injects a low-intensity current located in a range of 8 to 200 pA, or 8 to 150 pA or 8 to 100 pA - for example around 32 pA at plus or minus 10% -, according to a chosen frequency sweep, which can extend from 125 Hz to 500 kHz, or even from 125 Hz to 800 kHz. Preferably, the frequency sweep will extend from 4 kHz to 300 kHz. This frequency sweep makes it possible to cross, by frequency zone, the different types of cell membranes and to explore the extra and intra cellular zones. Alternatively, the intensity of the current injected by the electrical source 34 could be located in a wider range of values, for example in a range of values ​​from 8 to 200 pA.

[0114] Through its electrical measurements, the medical device 10 implements bioimpedance spectroscopy - or frequency impedance - which provides a measurement of the water volume in the body.

[0115] The medical device 10 comprises hardware elements 1, 2, 3, 4, 5, 11, 12, 13, 21, 22, 23, 24, 41 and / or software configured to implement all or part of the following treatments:

[0116] - measurement of a user's total mass,

[0117] - measurement of foot-hand impedance,

[0118] - measurement of a volume of intracellular water Vi contained in the body of a user,

[0119] - measurement of a volume of extracellular water V e contained in a user's body,

[0120] - measurement of a total volume of water Vt contained in a user's body,

[0121] - measurement of dry weight,

[0122] - measurement of a volume of hyperhydration, - and optionally measurement of a variation in dry weight,

[0123] - and optionally measurement of a variation in hyperhydration,

[0124] - and optionally blood pressure measurement,

[0125] - and optionally measurement of a pulse wave,

[0126] - and optionally measurement of heart rate,

[0127] - and optionally measurement of a blood oxygen saturation level,

[0128] - and optionally measurement of a hand-to-hand electrocardiogram,

[0129] - and optionally measurement of skin temperature.

[0130] The total mass of the user, expressed in kilograms, can be determined by measurements from the at least one load sensor. In addition or alternatively, the foot-hand impedance measurement can be used to determine the total weight of the user. Preferably, the measurement of the total mass is carried out over a range of 0 to 150 kilograms, or even over a range of 0 to 200 kilograms, with an accuracy of at least 0.5 kilograms, or even at least 0.1 kilograms.

[0131] Foot-hand impedance measurements are made using electrodes 11, 12, 21 and 22, which allow an electric current to be injected between the user's foot and hand, and then induced electrical data to be measured.

[0132] Analysis of electrical data from foot-hand impedance measurements allows the calculation of a water volume in liters contained in the user's body. The water volume can include the volume of all or part of the different liquid compartments of the human body.

[0133] In a preferred embodiment, from the electrical data from the foot-hand impedance measurements, the device 10 calculates, independently of one another, three volumes of water contained in the body of a user: - a volume of intracellular water Vi contained in the body of a user,

[0134] - a volume of extracellular water V econtained in a user's body,

[0135] - a total volume of water Vt contained in a user's body.

[0136] In a preferred embodiment, measuring an intracellular water volume Vi, measuring an extracellular water volume V e and the measurement of a total water volume Vt are carried out independently of each other.

[0137] In one embodiment, the total water volume Vt contained in a patient's body is calculated according to the formula Mathl .

[0138] [Math]

[0139] OR

[0140] - K b is the patient's shape coefficient,

[0141] - p œ is the equivalent resistivity of the two extra and intra cellular compartments,

[0142] - H is the patient's height in cm,

[0143] - W is the weight in kg,

[0144] - D bis the density of the patient's body,

[0145] - R œ is the resistance extrapolated to infinite frequency by the Cole-Cole model.

[0146] The value of the equivalent resistivity p œ is obtained according to the formula Math2.

[0147] [Math2]

[0148] OR

[0149] - MNG is the non-fat mass in kilograms.

[0150] The value of the shape coefficient is obtained according to the formula Math3

[0151] OR

[0152] - L bras , L tronc and L jambe are respectively the length in centimeters of an arm, a trunk and a leg of the patient,

[0153] - C bras > C tronc etc jambe are respectively a circumference in centimeters of an arm, a trunk and a leg of the patient.

[0154] The analysis of electrical data from foot-hand impedance measurements also makes it possible to calculate the user's dry weight, a volume of hyperhydration in liters and / or a variation in dry weight, and / or a variation in hyperhydration.

[0155] The analysis of the electrical data from the foot-hand impedance measurements and the measurements provided by the mass sensors 13 also make it possible to calculate a hyperhydration volume in liters. Hyperhydration corresponds to an excess of water present in the user's body, this excess being generated by the dysfunction of the renal function. Preferably, the accuracy of the hyperhydration volume is at least 0.1 liters. The analysis of the electrical data from the foot-hand impedance measurements and the measurements provided by the mass sensors 13 also make it possible to calculate a dry weight of the user in kilograms, preferably with an accuracy of at least 0.5 kilograms, or even at least 0.1 kilograms.

[0156] Advantageously, the device 10 makes it possible to calculate a variation in hyperhydration, in particular a variation in hyperhydration between two dialyses.

[0157] In one embodiment, the foot-hand impedance measurements allow the determination of a resistance (real part of the impedance) and a reactance (imaginary part of the impedance). The determination of the resistance and reactance relative to each impedance measurement allows the impedance measurements to be used according to a method called BIVA (for the Anglicism "Bioimpedance Vector Analysis").

[0158] Analysis of data from the photoplethysmographic sensor 23 allows us to calculate

[0159] - blood pressure in mmHg or cm / Hg, and / or

[0160] - a blood oxygen saturation in percentage with an accuracy of the order of the decimal, and / or

[0161] - the user's heart rate in beats per minute.

[0162] The measurements of a hand-hand electrocardiogram are carried out via the electrodes 21, 22 and 41 which make it possible to measure the cardiac electrical activity between the two hands of the user, emitted by the sinus node of the heart which acts as an autonomous electrical source. In particular, these measurements make it possible to obtain an electrocardiogram of the user. In one embodiment, the human-machine interface 5 allows a display of at least one data item chosen from:

[0163] - a total mass of a user,

[0164] - a total volume of water Vt contained in the body of a user,

[0165] - a dry weight of a user,

[0166] - a variation in a user's dry weight,

[0167] - a volume of hyperhydration,

[0168] - a variation of hyperhydration

[0169] - a user's heart rate,

[0170] - a user's blood pressure,

[0171] - a user's skin temperature,

[0172] - a bioimpedance visualization.

[0173] In one embodiment, the medical device further comprises a means of communication, in particular wireless, with a portable device comprising a means of communication and a storage means containing anthropometric information of a user, the information comprising at least one piece of information from a date of birth, an ethnicity, a height, a gender.

[0174] For this purpose, in one embodiment, the medical device can communicate with an application installed on a mobile phone of a user. The storage means can be a memory of the phone, and the application installed on the phone retrieves the anthropometric data from the memory of the phone to communicate them to the medical device.

[0175] Alternatively, the storage medium may be an electronic card belonging to the user, the data recorded on the electronic card being able to be retrieved by the medical device directly (if the medical device is capable of reading the card) or indirectly, by an application installed on a user's telephone.

Claims

DEMANDS 1. Medical device (10) for monitoring a user's biological parameters comprising - a platform (1) for taking measurements of the user's mass, - at least one first and a second electrode (11, 12, 21, 22) allowing impedance measurements to be taken at at least two distinct frequencies, including a low or medium frequency and a high frequency, and a measurement of at least one volume of water from the user's body, and - a blood pressure and / or heart rate measuring device (23).

2. Medical device (10) according to the preceding claim, characterized in that the blood pressure and / or heart rate measurement device is a photoplethysmographic sensor (23) which also allows for measurement of the oxygen saturation of the user's blood.

3. Medical device (10) according to any one of the preceding claims, characterized in that the platform (1) is equipped with the first electrode (11, 12) enabling impedance measurements to be taken at the level of one foot of the user, in that the second electrode (21, 22) is arranged so as to enable impedance measurements to be taken at the level of a first hand of the user, and in that the impedance measurements include at least one impedance measurement between a foot and a hand of the user, in particular one impedance measurement between a foot and a hand located on the same half of the user's body, preferably the right half of the body. A medical device (10) according to the preceding claim, characterized in that it comprises a third electrode (41) disposed in contact with the user's second hand, and in that the second and third electrodes (21, 41) are together capable of recording an electrocardiogram between the user's first and second hands. A medical device (10) according to any one of the preceding claims, characterized in that it comprises a temperature sensor (24) for measuring the user's skin temperature. A medical device (10) according to any one of the preceding claims, characterized in that it comprises a means for adjusting the height of the second electrode (21, 22) relative to the platform (1), so as to adapt the vertical distance, measured between the second electrode and the platform, to the user's height.Medical device (10) according to the preceding claim, characterized in that it comprises a first handle (2), on which the second electrode (21, 22) is fixed, arranged on a rigid arm substantially parallel to the platform (1), and in that the adjustment means is a system for adjusting the height of said rigid arm comprising the first rigid handle (2) relative to the platform (1), to allow adjustment of the height of the first rigid handle (2) relative to the platform (1). Medical device (10) according to any one of the preceding claims, characterized in that electrodes (11, 12, 21, 22, 41) of the medical device (10) are suitable for impedance measurement at the level of a user's foot or hand by injecting a current. of intensity between 8 and 200 pA, or between 8 and 150 pA, or between 8 and 100 pA, or even around 32 pA plus or minus 10%, and according to a frequency sweep extending from 125 Hz to 500 kHz, or even extending from 125 Hz to 800 kHz, or even extending between 4 kHz and 300 kHz. Medical device (10) according to any one of the preceding claims, characterized in that said impedance measurements comprise at least a first measurement at a low frequency, between 125 Hz and 5 kHz, or at a medium frequency, between 5 kHz and 50 kHz, and at least a second measurement at a high frequency, between 50 kHz and 300 kHz, or even 500 kHz, or even 800 kHz, and optionally at least a third measurement at a third frequency different from the first two frequencies.Medical device (10) according to any one of the preceding claims, characterized in that it comprises an electronic processing unit (3), in that the electrodes (11, 12, 21, 22, 41) and / or the blood pressure and / or heart rate measuring device (23) and / or the temperature sensor (24) are connected to the electronic processing unit (3) by a wired or wireless communication device (37), such that the impedance measurements taken via the electrodes are capable of being transmitted to the electronic processing unit (3) and such that the electronic processing unit (3) is capable of driving the current transmitted by the electrodes to a hand or foot of a user. Medical device (10) according to any one of the preceding claims, characterized in that it comprises hardware (1, 2, 3, 4, 5, 11, 12, 13, 21, 22, 23, 24, 41) and / or software configured to achieve. based on foot-hand impedance measurements, said measurement of at least a volume of water comprising: - measurement of the volume of intracellular water (Vi) contained in a user's body, and - measurement of the volume of extracellular water (Ve) contained in a user's body, and - measurement of the total volume of water (Vt) contained in a user's body. Medical device (10) according to any one of the preceding claims, characterized in that it comprises hardware (1, 2, 3, 4, 5, 11, 12, 13, 21, 22, 23, 24, 41) and / or software configured to perform the following treatments: - measurement of a dry weight, - measurement of a volume of hyperhydration, - and optionally, measurement of a change in dry weight, - and optionally, measurement of a variation in hyperhydration, - and optionally, blood pressure measurement, - and optionally, pulse wave measurement, - and optionally, heart rate measurement, - and optionally, measurement of blood oxygen saturation levels, - and optionally, measurement of a hand-to-hand electrocardiogram, - and optionally, measurement of skin temperature. Medical device (10) according to claim 1 1, characterized in that the measurement of an intracellular water volume (Vi), the measurement of an extracellular water volume (V e ) and the measurement of a total water volume (Vt) are carried out independently of each other. Medical device (10) according to any one of claims 11 to 13, characterized in that it comprises a human-machine interface (5) allowing the display of at least one piece of data selected from: - a total user mass, - the total volume of water (Vt) contained in a user's body, - a user's dry weight, - a variation in a user's dry weight, - a volume of hyperhydration, - a variation of hyperhydration, - a user's heart rate, - a user's blood pressure, - a user's skin temperature, - a bioimpedance visualization. Medical device (10) according to any one of the preceding claims, characterized in that it comprises a means of communication, in particular wireless, with a portable device, such as an electronic card or a telephone, containing anthropometric information of a user including at least one piece of information among a date of birth, an ethnicity, a height, a gender.

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