WO1998049536A2

WO1998049536A2 - Device for determining fluctuations in end expiratory gases, method for determining fluctuations in respiratory metabolism and the use of said device

Info

Publication number: WO1998049536A2
Application number: PCT/DE1998/001172
Authority: WO
Inventors: Ludwig Wildt; Matthias Michel; Peter Licht
Original assignee: Ludwig Wildt; Matthias Michel; Peter Licht
Priority date: 1997-04-29
Filing date: 1998-04-28
Publication date: 1998-11-05
Also published as: JP2001523338A; WO1998049536A3; EP0979399A2; AU8207898A; BR9809355A; PL339915A1; DE29707771U1; CA2288281A1; TR200000279T2; DE19880567D2; HUP0004939A2; IL132603A0

Abstract

The invention relates to a device for determining the partial pressure of at least one gas in an end expiratory gas mixture, comprising a receiving unit for a volume of end expiratory gas, at least one measuring device to determine the volume of an end expiratory gas received therein and to output measuring signals, in addition to display and/or storage and evaluation unit to receive and process the signals of the at least one measuring device. The invention also relates to a method for monitoring fluctuations in respiratory metabolism of the human or animal body and to the use thereof in determining respiratory function.

Description

Device for determining end-expiratory gases, method for determining fluctuations in the breathing balance and use of the device

The invention relates to a device for determining the partial pressure of at least one gas in an end-expiratory gas mixture, a method for monitoring fluctuations in the breathing balance of the human or animal body and its use

The gas partial pressure of the various gases in end-expiratory gas mixtures depends on various bodily functions - including hormone fluctuations, diseases that disturb the respiratory system, such as asthma, cystic fibrosis, etc., as well as the energy recovery of the body (respiratory quotient) in the case of various metabolic diseases or with abusive benefits certain metabolic products are detectable in the end-expiratory gas (alcoholism, diabetes) Furthermore, it changes during heavy physical exertion and is therefore an indicator of the body's working behavior (training status)

In particular, the end-expiratory gas mixture, ie the last gas volume that is exhaled from the lungs, is a true representation of the alveolar gas partial pressure, which in turn depends on a wide variety of body functions

Previously, complex devices for measuring the current gas partial pressure, for example for anesthesia procedures, were known, in order to measure the current end-expiratory CO2 there. However, these measured values were only of interest at the moment - storage or evaluation of the stored values over a period of time was not possible Facilities complex and not suitable for private use, but tailored to operating conditions It has now surprisingly been found that gas measurements of the end-expiratory gases - in particular the end-expiratory gases and evaluation thereof for bodily functions and metabolic positions can also be used to monitor outside an operating room / intensive care unit.

The device can preferably be used for monitoring the respiratory function. These include in particular those diseases / body conditions that change the gas content of the blood. For example asthma, chronic pulmonary emphysema, oxygen therapy, training status of an athlete or to determine the performance limit, sleep apnea, also chronic; Snoring, inflammatory respiratory diseases.

Furthermore, therapies with medications that affect the respiratory center, for example barbiturates, progesterones and the like. its offspring, narcotics and analgesics whose effects are monitored. Likewise, surveillance of people in confined spaces, such as astronauts, divers, submarine operators, caisson workers, is also possible.

Among other things, this can restrict the function of the gas exchange, i.e. Occurrence of chronic or acute respiratory insufficiency, monitoring and, if necessary, discontinuation of therapy - oxygen therapy, hormone therapy or other drug therapies are determined.

The ratio of the CO2 O2 in the end-expiratory volume (pulmonary emphysema quotient) can also change the metabolic state, e.g. progress of a dietary measure or the state of training (body efficiency). B. for competitive athletes, but also for rehabilitation measures.

A particularly interesting application is the monitoring of pulmonary emphysema in the blood by measuring the pCO2. It has been since Döring: Pfluegers Archive 250 (1948), pp. 37-46 "on rhythmic fluctuations in breathing and body temperature in the menstrual cycle" and Döring, GK "On rhythmic Fluctuations in breathing and body temperature "Arch. Gynäcol. 182 (1953), pp. 746 - 758 and Döring, GK, HH Loeschke, B. Ochwadt:" Further studies on the effect of sex hormones on breathing "Pflügers Archiv 252 (1950) , Pp. 216-230 that pCO2 is subject to fluctuations in women due to the influence of progesterone, and thus also in the cycle, and it is particularly significant that a decrease in pCO2 occurs in women 3-4 days before ovulation. The end-expiratory pCO2 falls a few days shortly before ovulation - influenced by the increase in the level of progesterone in the blood and remains high during the luteal phase of the menstrual cycle and in pregnancy as a result of increased alveolar ventilation.

No attempt has yet been made to evaluate this medical phenomenon for the manufacture of measuring devices.

Devices for determining ovulation, for example so-called "cycle computers", which evaluate basal temperature measurements, or else determinations of the luteinizing hormone (LH) that can be carried out via biochemical color reactions, were always inaccurate or only provided information very close to or after the time of ovulation, which for contraception or emphysema is unusable.

In addition, the measurement of the basal body temperature is so easily influenced by "external circumstances - e.g. physical activity, feverish illnesses, medication, short sleep duration, time shifts during air travel - that the measured value is often unusable and therefore only very useful for determining the time of ovulation The known devices had the disadvantage that they were inaccurate and, moreover, evaluated body function data which can be changed so much by the patient's life circumstances that the reliability of the measurement was not given to monitor the progesterone course or pCO2 controlled by it during a risky pregnancy (e.g. asthmatics) in order to reduce the progression as early as possible sterons who endanger pregnancy, and if necessary to be able to take countermeasures.

But the measurement of other gases in the end-expiratory gas can also be interesting - especially since the values are immediately available and are not dependent on time-consuming, complicated detection reactions in laboratories.

It is therefore an object of the invention to provide a device for determining / evaluating gas partial pressures of gases in the end-expiratory gas volume.

The object is achieved according to the invention by a device which measures end-expiratory gases, with: a receiving unit for receiving end-expiratory gas, a measuring unit for determining the at least one gas of the received end-expiratory gas volume and output of measurement signals; and a processor unit for recording and further processing the signals measured over a predetermined period of time.

This processor unit first selects suitable measurement signals - ie those which are at the end of an exhalation process, since the values there are more stable and possibly also an end-expiratory value and then causes the selected measurement value to be output in memory - possibly with individual details of the measurement day, the measuring time, the individual and possibly further processing of these signals by comparison with stored values. If applicable The stored values can also be output to a printer, readable and stored on conventional portable data carriers or can be queried remotely. Processing of individually selected measured values can also be provided in the device - for example comparison with a stored measured value table and display in the event of deviations from the stored values which are greater than a predetermined threshold. It is also possible to check the change in the values over time and only output the resulting values. This unit is preferably portable, of small dimensions and possibly battery operated, so that it can be used at the various locations of the individual to be monitored.

The device can of course also be designed such that it measures several gas partial pressures simultaneously or in succession if a measurement of several gas partial pressures is desired. To do this, it is then only necessary to measure and evaluate different absorption bands of the gases at different points in a manner known per se, or to use a suitable measuring method depending on the gas - for oxygen, for example, commercially available oxygen sensors.

Advantageous further developments result from the subclaims.

It is advantageous that the physical measuring unit is an optical measuring cell, since optical measurements take place quickly and can easily be converted into electrical signals.

For the measurement of polar gases, such as CO2, it is particularly advantageous that the measuring cell is an IR measuring cell that measures an absorption band of the gas (s) to be determined in a predetermined absorption wavelength range that is not absorbed by other gases and the concentration of the gas in the gas volume is determined in a manner known per se. However, the invention is in no way limited to IR spectroscopic evidence - Raman spectroscopy, conductivity measurements, pulmonary emphysema or the like, and conventional gas sensors can also be used to determine a gas in the gas mixture.

For the evaluation of a temporal course, it can be advantageous that the measured values are stored in a memory over a predetermined period of time, which can be read out via an output unit if necessary. Typically, the device as output unit has a printer, a readable display and / or a memory chip that can be queried by computer, so that either the value can be read immediately by inspection or later the value curve can be evaluated and called up as such.

In the special case of cycle control or the determination of other hormonal fluctuations, temporal courses of the measured values can now be saved and output together with the measured data (time, atmospheric pressure etc.) - which also means that time-consuming stationary examinations can be avoided. This enables, for example, a comparison of different examinations over a longer period of time, for example cycle data. However, it also enables, for example, constant monitoring of the course of a risky pregnancy over time, without the patient having to have extensive examinations carried out at all times. In particular, the device according to the invention is also suitable for monitoring the pretreatments for in vitro fertilization and other methods of assisted reproduction.

For this purpose, the device can only measure the pCO2 in the end-expiratory gas. The pCO2 is preferably determined via the IR absorption of a predetermined end-expiratory gas volume in a measuring cell and these values are preferably either compared with individual basic data of the individual or only their relative change over a period of time is determined.

Since the amount of gas and therefore also the number of absorbable molecules in a gas volume is temperature-dependent, it makes sense for the measuring cell to be thermostatted. However, the measured value can also be computationally compensated for by means of a temperature measured value measured in the measuring cell by means of a sensor, as a result of which costly thermostats can be dispensed with - this can be particularly useful in applications with high temperature fluctuations. In addition, a measuring device for the atmospheric pressure at the time of measurement is preferably provided and the measurement result is compared with the atmospheric pressure by means of this measurement. In this way it can be avoided that falsified measurement values are obtained due to the pressure fluctuations. The device can of course also be designed, for example, in a manner known per se as a two-beam photometer.

A particularly preferred use of the device according to the invention is the prediction of the time of ovulation. For this purpose, it makes sense to provide a storage device for storing cycle data - possibly also together with other measurement data, such as temperature, which provides the corresponding outputs. The measurement data are compared with previous measurement data within a predetermined time interval and it is determined whether they differ significantly. This makes it possible to determine the ovulation time about 3 days in advance - a procedure that is much more precise for contraception or conception than, for example, the temperature determination, which is very dependent on physical activity, the time of day, etc. Subject is.

Compared to known cycle computers, which usually involve measuring the basal body temperature, which is highly susceptible to faults and therefore often inaccurate, the device according to the invention has the advantage of a fast and precise determination that is independent of events such as short sleep, physical activity, etc.

Another preferred use of the facility is pregnancy verification. The decrease in pCO2 is typical of a normal pregnancy and an increase in it is a sign of a serious disorder.

In order to obtain the end-expiratory gas, which alone gives a precise image of the alveolar conditions, a device can be connected upstream, for example, which causes the patient to exhale completely - then only evaluates the measured values measured in the last time interval of exhalation. Units that force the individual to exhale against resistance, such as when inflating a balloon or the like, are particularly suitable for this, in which case the highest measured pCO2 is the significant end-expiratory pCO2 - this can be done in a manner known per se by means of a correspondingly programmed computer unit , which records and evaluates the measurement data, are determined so that only the highest measured pCO2 per breath is stored / displayed.

The method for determining the time of ovulation or progesterone based on the end-expiratory pCO2 has: obtaining a volume of end-expiratory gas, determining the IR absorption of the CO2 band in the gas volume of end-expiratory gas and consequently determining the pCO2 therein, correcting the result for the atmospheric pressure and temperature and output of the measured value in an output unit, such as a memory, a printer, a display unit.

It can be useful to remove water vapor from the exhaled gas by absorption or condensation in front of the measuring cell in order to avoid falsification of the measuring result by fogging up the measuring cell window.

For use in other areas, e.g. to monitor respiratory function or the state of athletic training, it is necessary to measure pCO2 and pO2 and form the ratio. This ratio can either be stored as such or output or, if necessary, compared with previously determined ratios of the same individual or with standard data already in the device and a signal can be output after a certain threshold value has been exceeded.

This signal then enables the individual or his trainer (if it is a device for monitoring sporting training) to change his behavior accordingly so that the body returns to normal Area works. The signal can also be used to control therapeutic measures.

The invention will be explained in more detail below with reference to the accompanying drawing, which schematically shows an embodiment of the invention for cycle control, but to which it is in no way limited:

1 shows an embodiment of a device according to the invention in a schematic representation and

2 shows an illustration of pCO2 as a function of the course of the cycle

As can be seen from FIG. 1, in a preferred embodiment of the invention, as a cycle computer, a device according to the invention has an IR radiation source, the radiation of which is passed through a gas measuring cell. End-expiratory gas is blown into this measuring cell, which can optionally be dried in the usual way in order to avoid fogging of the measuring window. The radiation emerging from the measuring cell is blocked by an optical filter on the absorption area of the gas to be measured - here CO2 - and the radiation in the area of the desired IR absorption band of the CO2 is directed to an IR sensor. The signal from the sensor is preferably amplified in a manner known per se and then either stored and stored / further processed with further cycle data of the individual or simply output on a display. It makes sense that the device, via a processor located in it, is capable of storing a pCO2 value of an exhaled volume only when it no longer changes significantly in order to obtain an end-expiratory pCO2 value. In the embodiment with IR sensors, the temperature influence is preferably computationally compensated in the usual way by temperature measurement. However, it is also possible to temper the measuring cell itself. The measurement of the gas is also compensated for at atmospheric pressure. The device is preferably designed to be small and transportable and enables it to be carried easily by the user.

From Fig. 2 the physiological basis of the cycle computer can be seen, namely that the CO2 partial pressure is already significant about 3-4 days before the otherwise usually measured values, namely the peak of the luteinizing hormone (LH) and the estradiol (E2) as well as the basal body temperature drops and thus enables a greatly simplified and improved and, in particular, earlier determination of the expected time of ovulation compared to previously known devices ("cycle computers").

Further refinements and developments within the scope of the claims are obvious to the person skilled in the art, and the scope of protection is in no way limited to the exemplary embodiments listed here, which are only intended to serve as explanations.

Claims

Expectations

1. Device for determining the partial pressure of at least one gas in an end-expiratory gas mixture, with:

- A recording unit for recording a volume of end-expiratory gases

- At least one measuring device for determining at least one gas of the recorded end-expiratory gas volume and output of measurement signals; and

- A display and / or storage and evaluation unit for recording and processing the signals of the at least one measuring device.

2. Device according to claim 1, characterized in that at least one measuring device is an optical measuring device.

3. Device claim 2, characterized in that at least one measuring device is an IR measuring device.

4. Device according to claim 4, characterized in that the measured values are stored together with dates, individual details of the individual to be monitored.

5. Device according to one of the preceding claims, characterized in that the measurement of the partial pressure of a gas, such as pCO2, takes place in the end-expiratory gas by IR absorption of a predetermined gas volume in a specific wavelength range in a measuring device.

6. Device according to one of the preceding claims, characterized in that it has an arrangement for the absorption of water from the end-expiratory gas.

7. Device according to claim 6, characterized in that it has an IR measuring cell which measures the IR absorption of the CO2, the signal of the IR measuring cell together with time data such as date, time or name of the patient in a memory can be saved.

8. Device according to claim 8, characterized in that the stored individualized measurement data can be compared with already stored data by a program, a signal being given when a deviation occurs over a predetermined size.

9. Device according to any one of the preceding claims, characterized in that it comprises an oxygen sensor.

10. Device according to any one of the preceding claims, characterized in that the end-expiratory gas volume is the end-expiratory gas volume.

11. Device according to any one of the preceding claims, characterized in that it is a device for monitoring the respiratory function, a device for determining the time of ovulation or a device for checking the lung function.

12. Device according to one of the preceding claims, characterized in that it has its own energy supply and is portable.

13. A method for monitoring fluctuations in the respiratory balance of the human or animal body, characterized by the steps:

- Obtaining a volume of an end-expiratory gas mixture

- Measurement of the proportion of one or more of the gases contained in this volume

- Recording the value received - if necessary together with time and individual data;

- Comparison of the value (s) with a value table and

- Creation of a signal corresponding to the comparison step, which can be stored, possibly further processed and / or output.

14. The method according to claim 13, characterized in that the measured gas is CO2 or 02.

15. The method according to claim 13 or 14, characterized in that the proportion of at least one gas in the end-expiratory gas mixture is determined optically.

16. Use of the device according to one of claims 1-12 for determining the respiratory function, for checking an oxygen therapy, the training state in athletic performance.

17. Use of the device according to one of claims 1-12 for determining the time of ovulation by determining the pCO2 content in the end-expiratory gas.