EP1979227A1

EP1979227A1 - Method and device for self-monitoring and diagnosis when diving without an aqualung

Info

Publication number: EP1979227A1
Application number: EP07717835A
Authority: EP
Inventors: Yvan Milla; Michel Benisty
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-01-10
Filing date: 2007-01-05
Publication date: 2008-10-15
Anticipated expiration: 2027-01-05
Also published as: EP1979227B1; FR2895970A1; FR2895970B1; WO2007080303A1

Abstract

The invention relates to a method and device for self-monitoring and diagnosis when diving underwater without an aqualung. To automatically detect a risk of syncope during a dive, the method according to the invention involves analysing the speed of desaturation of the oxygen haemoglobin saturation rate (SpO2) which is established as a function of the slope of said variation near the rate in question at a given time. The means for recording and measuring the oxygen haemoglobin saturation rate (SpO2) and the heart rate is contained in a diver's glove, holding it against the relevant part of the body at a temperature sufficient to record a reliable signal pulse.

Description

DESCRIPTION

AUTOCONTROL AND DIAGNOSTIC METHOD AND DEVICE FOR APNEA DIVER

FIELD OF THE INVENTION

The present invention relates to a method and device, generally attached to the wrist, for freediving underwater diver for measuring and analyzing personal physical and environmental physiological data so as to inform him about the risks of syncope at a given moment and to bring it to the surface if necessary. BACKGROUND TECHNOLOGY

The methods and devices known in the field of diving generally implement a device, of the diving computer type, which generally comprises:

means, of the sensor type, of capturing and measuring the ambient and physiological physical data of the plunger such as the diving depth, the apnea time and the recovery time, the rate of saturation of the hemoglobin with oxygen ( SpO2) and heart rate; a clock enabling said data to be input at regular time intervals;

means, visual and / or audio types for indicating said data;

means, of the microprocessor type, for analyzing the data entered with respect to a pre-recorded model and for controlling a device that signals to the diver a risk of a diving incident and, if necessary, triggers a rescue element; means, of the memory type, of the recording of the data entered, of the results of the analysis and of the data relating to the prerecorded model.

The closest state of the art is described in GB2390903 which discusses a device and method for the safety of an apnea diver.

The known devices do not make it possible to determine the syncopal state of the diver in order to prevent it and to intervene. They only suspect a syncopal state if the subject is not reassembled in time.

Unfortunately, most syncope is on the surface and these devices do not detect it: the diver will drown on the surface and the computer will interpret this situation as a new apnea. SUMMARY OF THE INVENTION

The diving device according to the invention applies to the apnea diver in static (single apnea) or dynamic (underwater hunting) situations. He is new and original in that he is the first to detect syncope by taking into account a physiological parameter.

It is designed to be immersed in saline water or not. It is multifunctional to give information related to one or more apnea in real time such as:

- the total duration of apnea and cumulative duration of apnea expressed in seconds,

- the recovery period expressed in seconds,

the rate of saturation of hemoglobin in oxygen (SpO2) expressed as a percentage,

- the heart rate expressed in pulses per minute, as well as information related to the aquatic environment, such as the depth of the dive in meters and a memory capable of recording at least five hours (one measurement per second).

It is associated with a powerful lifejacket to keep the head out of the water in a conscious or unconscious subject. It is equipped with a syncopal accident detection system to trigger the inflation of the lifejacket if necessary.

Among the causes of mortality at sea, apnea accidents (underwater fishing or pure apnea) are the most frequent. Recent technological developments in the field of scuba diving and the corresponding regulations have considerably reduced accidents in this area. On the other hand, the mortality of accidents related to underwater hunting are still as frequent and fatal. It is in this context that this device takes all its interest. It may allow primary and secondary prevention of underwater hunting accidents:

- a primary prevention by self-monitoring of the diver by the analysis of information in real time or a posteriori by reading data on computer: for example apneas a little too pushed will indicate a too deep desaturation and make him realize that it is necessary to push a little less these;

- secondary prevention by detection of syncopal accidents by the computer by means of an analysis of the SpO2 saturation rate as a function of the rate of desaturation: in case of detection of a signal making suspect a syncopal state, a clinical test of vitality is proposed to the diver (pressing on a button of the watch): either the diver is conscious and the pressure of the button cancels the inflation of the lifejacket, either the diver is unconscious and the absence of pressure of the button at the end of a predetermined time then causes the inflation of the vest. It does not apply to the practice of scuba diving in its use of syncopal detection and the rescue process. It can only be used for indicative heart rate in said diver.

The method according to the invention is essentially characterized in that it consists, to automatically detect a risk of syncope during dive, to analyze the rate of desaturation of the oxygen saturation rate of hemoglobin (SpO2) which is established according to the slope of said variation in the vicinity of the rate considered at a given instant. The values of the saturation rate and the slope of its variation, measured on an apnea diver, are compared, at each moment, with the model, pre-recorded, which is represented by the curve "saturation rate according to the slope of its variation which delimits the non-syncopal and syncopal state areas and which has been established experimentally from a well-defined number of subjects for which the rate and slope of each of them have been measured. its variation in syncopal state limit.

The device for its implementation, which is generally attached to the wrist, essentially comprises means, sensor type, capture and measurement of ambient physical and physiological data of the plunger such as diving depth, apnea time and recovery time, saturation rate of oxygen hemoglobin (SpO2) and heart rate.

Said sensor is advantageously contained in an envelope which holds it against the part of the body concerned at a temperature sufficient to record a reliable pulsatility of the signal. Said envelope is advantageously an improved diving glove which also incorporates the wire connection which connects the digital sensor to the dive device via a sealed interface. PRESENTATION OF FIGURES

The features and advantages of the invention will appear more clearly on reading the detailed description which follows of at least one preferred embodiment thereof given by way of non-limiting example and shown in the appended figures in which: :

- Figure 1 shows the curve "saturation rate as a function of time" for a given diver;

FIG. 2 represents the curve "saturation rate as a function of the slope of its variation" which has been established from a plurality of divers for whom we have measured, for each of them, the saturation rate SpO2 and the slope of its variation in syncopal state limit and which delimits the zone of passage from a non-syncopal state or very probably not syncopal to a syncopal state or very probably syncopal. DETAILED DESCRIPTION OF THE INVENTION The self-diagnosis and rescue method for submarine snorkelers is implemented by means of a diving device essentially comprising:

means, of the sensor type, of capturing and measuring the ambient and physiological physical data of the plunger such as the diving depth, the apnea time and the recovery time, the rate of saturation of the hemoglobin with oxygen ( SpO2) and heart rate;

a clock enabling said data to be input at regular time intervals;

means, visual and / or audio types for indicating said data;

means, of the microprocessor type, for analyzing the data entered with respect to a pre-recorded model and for controlling a device that signals to the diver a risk of a diving incident and, if necessary, triggers a rescue element;

means, of the memory type, of the recording of the data entered, the results of the analysis and the data relating to the pre-recorded model (M).

Said method consists, for automatically detecting a risk of syncope during dive, of analyzing the rate of desaturation of the hemoglobin saturation rate in oxygen (SpO2) which is established as a function of the slope (P) of said variation at neighborhood of said rate at a given moment.

The values of the saturation rate SpO2 and the slope (P) of its variation, measured on an apnea diver, are compared, at each moment, with the model (M), prerecorded, which is represented by the curve "saturation rate according to the slope of its variation "which delimits the zones of non-syncopal (ZNS) and syncopal state (ZS) and which has been established experimentally from a well-defined number of subjects for which it has been measured for each of them, the SpO2 rate and the slope (P) of its syncopal state limit variation. In case of detection of a risk of syncope, there is emission of a signal, perceptible by the diver, which must be interrupted by the latter in a definite time, otherwise the rescue element will be activated by the autonomous control means.

According to an alternative embodiment of said method, the diving depth can also be taken into account, to determine the risk of syncope. The method also includes displaying, in real time, the dive device, dive depth, heart rate, saturation rate, apnea time and recovery time.

The device for carrying out the method according to the invention comprises, which is generally fixed to the wrist, essentially comprises means, of the sensor type, of capturing and measuring ambient physical and physiological data of the plunger such as the diving depth. , apnea time and recovery time, oxygen saturation (SpO2) and heart rate. Said sensor is advantageously contained in an envelope which holds it against the part of the body concerned at a temperature sufficient to record a reliable pulsatility of the signal.

Said envelope is advantageously an improved diving glove which also incorporates the wire connection which connects the digital sensor to the dive device via a sealed interface.

The rescue element is advantageously a vest provided with a CO2 capsule triggered by the clock when a syncope risk signal is issued and the diver has not invalidated said signal.

Said diving device more particularly comprises: - a 10-atmosphere sealed housing and a hemoglobin oxygen saturation (SpO2) sensor integrated into a neoprene glove: the glove and the sensor will be consumable, but reusable in a second time; absence of deterioration;

- A life jacket with CO2 capsule connected to the watch by electronic interface: said capsule will also be consumable and the vest and the watch will be reusable.

It has a waterproof connection that can accommodate both the SpO2 sensor and a computer via a PC interface.

All functions are enabled when connecting the SpO2 sensor.

Software allows you to output all data on the computer and provide a graph expressing heart rate, SpO2 rate and depth over time.

The SpO2 sensor is integrated into a neoprene glove attached to the watch via a cable that can be molded into the glove.

The glove is at the same time a little loose at the level of the fingers carrying one or two sensors to avoid any compression and enough insulation of the cold to mitigate a risk potential for peripheral vasoconstriction due to cold, with both compression and cold factors affecting signal quality.

The device is supposed to give an SpO2 value only if the pulsatility of the signal is reliable. On the other hand, the glove also makes it possible to limit the artefacts of movements.

The lifejacket is designed to lift the diver to the surface and keep his head out of the water.

A prospective study was carried out on 50 divers corresponding to 300 apneas of which 200 in static and 100 in dynamics. During this study, the following data was identified through the use of a prototype.

Of the total data, 23 syncopal or presyncopal accidents were recorded.

The objectives of this study were:

- to propose a device allowing to detect in 30 seconds the risks of syncopal accidents;

to extract graphical characteristics obtained, the means of predicting the onset of syncope and consequently of proposing detection algorithms;

- to design an industrializable device answering the problem posed. The diving device records, every second, raw data such as: the depth and total time of the apnea, the SpO2 rate and the heart rate. It calculates from these data the desaturation slope which is defined as the rate of desaturation in percentage per second. The case study showed that the desaturation slope associated with the saturation rate is the determining factor for the detection of syncope.

Indeed, at a given time and for a low SpO2 rate, the value of the slope will have an influence on the risk of syncope.

To detect a syncope according to the SpO2 rate, the computer calculates the desaturation slope, according to a mathematical model, according to the last SpO2 measurements. The desaturation slope corresponds approximately to the rate of desaturation (slope of the tangent to the SpO2 curve at time t, expressed in% / second). Each second, it analyzes a rate of SpO2 associated with a slope. At each SpO2 level corresponds a limit slope, determined by the clinical study carried out beforehand, above which a syncopal accident is highly suspect. This data will be saved in the computer database.

Each second, the SpO2 rate and its corresponding slope are analyzed: if the slope is greater than or equal to that prerecorded in the database for the same SpO2 rate, the computer will then detect a syncopal signal; otherwise he will not detect it.

To detect a syncope based on the SpO2 rate and depth, the computer analyzes the SpO2 rate as a function of depth every second. It has also been predetermined, in the database of the computer, for each depth, a SpO2 threshold below which a syncopal accident is highly suspect.

If at a given time, the diver being at a given depth, the measured SpO2 rate is lower than that recorded in the database and corresponding to the same depth, the computer will detect a syncopal signal; otherwise he will not detect anything.

To also involve the duration of the apnea, each diver will have to program his modifiable apnea limit time according to its shape and the depth at which it dives. The computer detects the beginning of the apnea when the depth is greater than a determined value and the end of the apnea when it becomes lower than said value in order to operate the stopwatch within said limits and to return it to zero at the end of apnea.

If the apnea time is greater than the programmed time, the computer will detect a syncopal signal; otherwise he will not detect it.

If a syncopal risk is detected, the vitality test procedure may be as follows:

- emitting a first sound and / or light signal for 10 seconds that the diver must stop by pressing any button on the watch; - if the diver does not intervene within ten seconds, the device then triggers the inflation of the lifejacket;

- if the diver intervenes within the 10 seconds allocated, a second sound signal is emitted after ten seconds, then a third under the same conditions, ie a total of 30 seconds of clinical control of the vitality of the diver. The detection of an alarm threshold a posteriori to control the apnea to come can be established for example in case of desaturation below a predetermined threshold by the diver (for example 85): a non-audible alarm may signal to the diver that his apneas are a little too much pushed. Several recordings at sea were made with or without glove in cold water or not, with analysis of the quality of the signal (pulsatility of the signal), and artifacts: total absence of recorded value or values not corresponding to the diver's clinical condition such as aberrant heart rate or sudden desaturation while the diver is on the surface. In hot water the use of the glove gives a good signal amplitude and the almost total absence of artifacts. The interpretation of the curves is possible and interesting for the diver and for the detection of a syncope by a possible computer In hot water the absence of use of the glove gives quickly a weak amplitude of signal and a certain number of artifacts making impossible to interpret the recorded SpO2 curves. The diver can still have a real-time idea of his heart rate, the rate of SpO2 is very unreliable. The screening according to the SpO2 rate of a possible syncope would then be random.

In cold water (up to 8 degrees) the use of the glove gives a satisfactory amplitude of signal but a little less good than in hot water. There are only few artifacts and the interpretation of the curves remains possible and interesting for the diver and for the detection of a syncope by a possible computer.

In cold water without using the glove the signal is very quickly almost completely artefacted. As a result, the use of a glove is essential for reliable recording for the diver or for possible detection of syncope. This is explained by at least two known physiological phenomena: movement artefacts and artifacts of peripheral vasoconstriction due to cold. The movement artifacts are secondary to a movement of the plunger and sensor relative to the plunger. Most new pulse oximeters help to eliminate the patient's movement artifacts. However during movement in the water the sensor will also move relative to the diver if it is not fixed correctly. This is the first role of the glove.

When the body is exposed to cold the body redistributes blood to the noble organs and reduces the vascularization of others: there is a peripheral vasoconstriction and capillary blood flow in the fingers is decreased; the pulsatility is reduced accordingly resulting in a disturbed signal. The only exposure to cold fingers causes the same reaction in the fingers without even the diver is hypothermia. The only solution is to place your finger in a warm place. This is also what a neoprene glove does. Most neoprene gloves exert significant pressure on the fingers and also cause mechanical peripheral vasoconstriction. It is therefore necessary that the finger or fingers on which the sensors are positioned are not too tight. In our experience the simple fact of dilating the finger of the glove or is positioned the sensor allowed to cancel the loss of signal amplitude. The analysis of syncope and non-syncope curves revealed that in all cases above a certain threshold of SpO2 (80 for example), syncope never occurred and that below a certain threshold (30) The subjects were almost always in syncope.

Of course, the invention is not limited to the embodiments described and shown for which the skilled person may provide other variants without departing from the scope of the invention which is determined by the content of the claims.

In particular, one may provide a version without the survival device in other words a version comprising a dive computer provided with a pulse oximeter suitable for underwater use whose sensor is integrated in a glove.

Claims

1- A method for self-checking and diagnosis for submerged diving diver using a diving device, generally attached to the wrist, essentially comprising:

a clock enabling said data to be input at regular time intervals;

means, visual and / or audio types for indicating said data; means, of the microprocessor type, for analyzing the data entered with respect to a pre-recorded model for controlling a device that signals the diver a risk of a diving incident and, if necessary, triggers a rescue element;

means, of the memory type, of recording the data entered, the results of the analysis and data relating to the pre-recorded model (M); characterized in that for automatically detecting a risk of syncope during a dive, the rate of desaturation of the oxygen saturation rate (SpO2) determined according to the slope (P) is analyzed. said variation in the vicinity of said rate at a given time.

2. Method according to claim 1, characterized in that the values of the oxygen saturation rate of the hemoglobin (SpO2) and of the slope (P) of its variation, measured on an apnea diver, are compared to each moment, to the model (M), prerecorded, which is represented by the curve "saturation rate according to the slope of its variation" which delimits the non-syncopal state (ZNS) and syncopal state (ZS) zones and which has been established experimentally from a well-defined number of subjects for whom the hemoglobin oxygen saturation rate (SpO2) and the slope (P) of its variation have been measured for each of them. in syncopal state limit.

3- A method according to claim 2, characterized in that it consists, in case of detection of a risk of syncope, to emit a signal, perceptible by the diver, which must be interrupted by the latter in a definite time Otherwise, the rescue element will be actuated by the control means.

4- Method, according to any one of claims 1 to 3, characterized in that it consists in also taking into account, to determine the risk of syncope, the diving depth. 5. Process according to any one of claims 1 to 4, characterized in that it consists in displaying, in real time, on the diving device, the diving depth, the heart rate, the saturation rate of oxygen hemoglobin (SpO2), the apnea time and the recovery time .

6- Autocontrolled and diagnostic device for submerged diving diver using a diving device, generally attached to the wrist, essentially comprising:

a clock enabling said data to be input at regular time intervals;

means, visual and / or audio types for indicating said data;

means, of the microprocessor type, for analyzing the data entered with respect to a pre-recorded model for controlling a device that signals the diver a risk of a diving incident and, if necessary, triggers a rescue element;

means, of the memory type, of recording the data entered, the results of the analysis and data relating to the pre-recorded model (M); characterized in that the means for capturing and measuring the saturation rate of oxygen hemoglobin (SpO2) and the heart rate is contained in a diving glove which holds it against the part of the body concerned at a temperature sufficient to record a reliable pulsatility of the signal.

7- Device according to claim 6, characterized in that the dive glove also incorporates the wire connection which connects the digital sensor to the dive device via a sealed interface. 8- Device according to claim 6, characterized in that the rescue element is a vest provided with a CO2 capsule triggered by the clock when a syncope risk signal is issued and the diver has not invalidate said signal.