WO2009006655A1

WO2009006655A1 - Device and method for noninvasive measurement of the core temperature

Info

Publication number: WO2009006655A1
Application number: PCT/AT2008/000235
Authority: WO
Inventors: Rudolf Faworka
Original assignee: Emcools - Emergency Medical Cooling Systems Ag
Priority date: 2007-07-06
Filing date: 2008-06-26
Publication date: 2009-01-15
Also published as: AT505483B1; AT505483A1

Abstract

The invention relates to a device (5) and a method for noninvasive measurement of the near-core body temperature (Tϰ), with at least one temperature sensor (13). To permit efficient and inexpensive temperature measurement, a tubular intermediate piece (6) is proposed which can be attached to a breathing tube (2) and which has at least two channels (9, 10), wherein a valve (11, 12) is arranged in each channel (9, 10) such that air flows through one channel (9) during inhalation and through one channel (10) during exhalation, and wherein at least one temperature sensor (13) for measuring the temperature of the exhaled air is arranged in the exhalation channel (10).

Description

Device and method for non-invasive measurement of core temperature

The invention relates to a device for noninvasive measurement of the near-nuclear body temperature, with at least one temperature sensor.

The invention likewise relates to a method for the non-invasive measurement of the near-nuclear body temperature.

The device and the procedure is essentially the ^■ - directed non-invasive measurement of the body temperature or kernriaheh body temperature of people, although a use in animals is also possible.

There are various devices and methods for measuring the core temperature or near-nuclear body temperature, in particular of humans. In invasive measuring methods, temperature sensors are introduced into the body via body openings and the temperature of the sensors is used to determine the core temperature. For example, it is known to arrange temperature sensors at the tip of endotracheal tubes which measure its core temperature during the ventilation of a patient.

For example, DE 299 09 141 U1 describes a hypothermia device in which the endotracheal tube used is equipped with a temperature sensor to detect the temperature of the exhaled air as a measure of the body core temperature. The disadvantage here is that the endotracheal tube must be equipped with a corresponding sensor, and thus increase its production costs. Another disadvantage is the falsification of the measured temperature values due to the flow of exhaled air, as well as their moisture.

Also EP 1 206 922 A1 describes an endotracheal tube at the tip of which temperature sensors are arranged.

Other embodiments of endotracheal tubes with temperature sensors at their tips are described in US 4 046 139 A and US 4,383,534. DE 31 08 038 C2 describes an esophagus probe, at the tip of a temperature sensor is arranged.

Other methods of measuring core temperature include sensors which are inserted into the patient's bladder using a catheter. Apart from the relatively complex and expensive special versions of the catheter, the measurement of the core temperature over the bladder is disadvantageous, since the temperature in the bladder reacts to fluctuations in the core temperature is greatly delayed in time.

The same applies to the measurement of the near-core temperature with the aid of rectally arranged sensors, since fluctuations in the core temperature can only be detected with a relatively long time delay in the rectum.

Rapid measurements of the near-core temperature are also possible with the help of infrared sensors, which detect the heat radiation at the eardrum. However, such measuring methods are particularly artifact-sensitive and difficult to perform in extreme situations. A variant of the measurement of the near-core temperature via the external auditory canal using temperature sensors is known from WO 99/19701 A1.

The measurement of the core temperature of patients is in many cases of particular importance. In particular, for the hypothermia treatment, as it has recently been recommended in particular in cardiac arrest or stroke patients, the monitoring of the core temperature to check the hypothermia measures is essential. Various devices for cooling patients with cardiac arrest or stroke have become known, which should increase the chances of survival and recovery. For example, WO 2006/000006 A1 describes a cooling device in the form of a bag, in which parts of the patient or the whole patient is inserted, and cooling with cooled air takes place.

WO 2006/037136 A2 describes a condition for cooling patients, with which a lowering of the body temperature can be achieved relatively quickly. as recommended, in particular in cardiac arrest or stroke patients. In order to prevent falling below the core temperature and the specified limits, it is expedient to monitor the core temperature.

Especially in such emergency situations, the measurement of the core temperature using conventional methods is difficult to make. The use of a respiration tube with temperature sensors arranged thereon is disadvantageous again, as it makes the respiration tube more expensive to manufacture.

The object of the present invention is therefore to provide a device and a method for non-invasive measurement of the near-nuclear body temperature with at least one temperature sensor, which is constructed as simply and inexpensively as possible, and thus can also be produced, for example, as a disposable product. The determined temperature values should reflect the core temperature as well as possible and react as quickly as possible to changes in the core temperature. Disadvantages of known temperature measuring devices and methods should be avoided or reduced.

The object of the invention is achieved in that a connectable to a breathing tube tubular intermediate piece is provided, which has at least two channels, wherein in each channel a valve is arranged so that a channel is flowed through during inspiration and a channel during the Expiration, and in that at least one temperature sensor for measuring the temperature of the expiration air is arranged in the expiration channel. The temperature measuring device according to the invention comprises a component which can be connected to a respiration tube which is used in emergency situations in any case. In this intermediate piece of the temperature measuring device, the inspiration air and the expiration air are directed by means of valves into separate channels. As the expiration air comes from within the patient's body and reflects the core temperature very well, it is an ideal medium for non-invasive detection of the core temperature. To avoid falsification of the measurement results by the patient High-humidity and flow of the exhaled air can with the aid of the temperature measuring device according to the invention, the temperature of the expiration by means of the at least one temperature sensor in the expiratory channel or outside the Expirationskanals also in the flowless state, at the beginning or during inspiration, where the Expirationskanal closed by the valve is to be captured. This temperature value reflects the actual core temperature very well. During the ventilation of a patient, about 300 to 500 ml of air per respiratory cycle are introduced into the lungs or exhaled out of the lungs. This causes a high heat exchange in the lungs, which is why the expiration air is a good indicator of the core temperature. The temperature measuring device according to the invention is plugged by means of suitable connectors or the like to conventional respiratory tubes and placed between the tube and the respirator or resuscitator. As a result, no special requirements are placed on the usual ventilators. For different sizes of ventilation tubes different sized spacers can be made or appropriate adapter elements are provided. Of course it is also possible to integrate the intermediate piece into a ventilation tube.

According to a feature of the invention, the valves are formed by membranes, in particular silicone membranes. This represents a simple and efficient realization possibility for the valves.

Alternatively, the valves may also be formed by differently shaped flaps.

Preferably, the intermediate piece is made of plastic, in particular made of sterilizable plastic.

Presupposing appropriate quantities, the intermediate piece can be produced particularly inexpensively by injection molding. In this case, appropriate thermoplastics are used.

According to a further feature of the invention, the intermediate piece is formed as a disposable product. It can be at least one Temperature sensor in the intermediate piece are also arranged so that it can be removed from the intermediate piece and reused.

For this purpose, an opening for insertion of the temperature sensor may be arranged in the intermediate piece. For transmitting the temperature values measured by the temperature sensor, a transmitting device can be provided. This transmitting device can transmit the signals by radio or by infrared light.

At least one temperature sensor may be formed by a thermistor. Thermistors are particularly suitable as a temperature sensor and are also available at very low cost.

According to a further feature of the invention, at least one temperature sensor is formed by an optical sensor. Optical sensors are less sluggish compared to thermistors.

It is advantageous if a window is arranged in the expiration channel of the intermediate piece and the optical sensor for detecting the heat radiation emanating from the window is arranged on the outside of this window. In this way, the heat radiation emanating from the expiration air can be detected by the window without inertia.

In order to ensure efficient radiation of the heat from the window to the sensor, the window is preferably colored black and the optical sensor is formed by an infrared sensor.

For better measurement results, the window can protrude into the expiration channel of the intermediate piece, so that the expiration air at least partially impinges on the window.

To ensure that the temperature values are measured in the flow-free state in the expiratory channel, a sensor for measuring the inspiratory and / or expiratory flow can be provided in the intermediate piece. Such a sensor or such sensors can also be used to monitor the ventilation. The object of the invention is achieved in terms of the method in that the temperature of the expiration air is measured in the flowless state at the beginning or during the inspiration. As already mentioned above, the expiration air reflects the core temperature particularly well. By measuring in the flowless state, distortions due to moisture and flow during expiration can be excluded.

According to a further feature of the invention, it is provided that the air flow in the region of the temperature sensor is measured simultaneously with the temperature of the expiration air, and that those values of the temperature sensor are selected as the core temperature while the flow is substantially zero. This ensures that the measured temperature values are not distorted by the air flow and the humidity of the expiration air.

According to a further feature of the invention, a plurality of temperature values can be measured with a plurality of temperature sensors, and the arithmetic average of all temperature values can be formed to determine the core temperature.

Likewise, several temperature values can be measured with several temperature sensors and the maximum of all temperature values can be formed to determine the core temperature.

According to a further feature of the invention it is provided that the temporal course of the temperature is stored. From the resulting temperature curves important information can be derived.

The present invention will be explained in more detail with reference to the accompanying drawings.

Show:

Fig. 1 is a schematic sectional view through a patient with

endotracheal tube; Fig. 2 is a schematic sectional view through an embodiment the temperature measuring device according to the invention;

3a and 3b are sectional views of an embodiment of the temperature measuring device according to the invention to illustrate the function;

4 shows a schematic sectional view through a further embodiment of the temperature measuring device according to the invention; and

Fig. 5 shows the time course of the measured temperature with the device according to the invention.

1 shows a section through a patient in the region of the trachea 1 with a respiratory tube 2 arranged therein. The respiration tube 2 is fastened by means of a balloon 3. At the outer end of the breathing tube 2 is an extension 4, to which the ventilation machine or the resuscitator (not shown) can be connected.

FIG. 2 shows a basic sectional view through an embodiment of the device 5 according to the invention for the noninvasive measurement of the core temperature. Accordingly, the temperature measuring device 5 consists of a tubular intermediate piece 6, which can be connected by means of a corresponding terminal 7 to a breathing tube 2. Via a connection 8 of the intermediate piece 6 can be connected in the usual way a respirator or a resuscitator. The intermediate piece 6 has at least two channels 9, 10, wherein in each channel 9, 10, a valve 11, 12 is arranged, which serve that via a channel 9, the air which the patient inhales, is passed, and on the another channel 10, the expiratory air is passed. Accordingly, the valves 11,

12 gegengleich arranged at the ends of the channels 9, 10. The valves 11, 12 may be formed, for example, by membranes, for example silicone membranes. The intermediate piece 6 is advantageously made of plastic. In Expirationska- channel 10 at least one temperature sensor 13 is arranged for measuring the temperature of the expiration air. At the temperature sensor

13 may be a thermistor. Of course, a plurality of temperature sensors 13 can be arranged.

FIGS. 3a and 3b illustrate the function of the temperature measurement using the device 5 according to the invention closer. FIG. 3 a shows the temperature measuring device 5 during the expiration, in which the air flows via the breathing tube 2 and the intermediate piece 6 in the direction of the arrow E into the ventilation machine 14. During the expiration, the valve 11 is closed at the end of the channel 9, so that the air flows through the channel 10, and thus via the at least one temperature sensor 13. Thus, the temperature sensor 13 assumes the temperature of the expiration air, which essentially corresponds to the core temperature of the patient. Due to the high humidity of the expiration air and the flow, however, the measured temperature would be distorted and not represent the core temperature.

For this reason, the next inspiration cycle according to FIG. 3b is waited for and the temperature measured by the temperature sensor 13 is used as the core temperature only at the beginning or during the inspiration. During inspiration, the inspiratory air flows in the direction of arrow I from the ventilator 14 via the intermediate piece 6 into the breathing tube 2 and into the lungs of the patient. In this situation, the valve 12 is closed at the end of the channel 10 in the intermediate piece 6, whereby in the channel 10 no flow prevails. In this flow-free state of the channel 10, the temperature measured by the temperature sensor 13 substantially corresponds to the core temperature.

4 shows a schematic sectional view through a further embodiment of the temperature measuring device 5 according to the invention, wherein an optical window 15 is arranged in the expiration channel 10 of the intermediate piece 6 and an optical sensor 16 for detecting the heat radiation emanating from the window 15 is arranged on the outside of the window 15. In this embodiment, the temperature sensor 13 formed by the optical sensor 16 is not disposed directly in the expiratory channel 10 of the intermediate piece 6, whereby distortions by the air flow or moisture of the expiration air can be excluded. The window 15 is preferably colored black and the optical sensor 16 is formed by an infrared sensor. In order to achieve that the window 15 clearly reflects the heat radiation of the expiration air, the window 15 can protrude into the expiration channel 10 of the intermediate piece 6. On In this way, a non-inertial measurement of the temperature of the expiration air is possible.

FIG. 5 shows by way of example a temperature profile recorded with the temperature sensor 13 in the intermediate piece 6 according to the invention. During the expiration, the temperature will be lower than the actual core temperature T _κ due to the flow and humidity of the expiratory air. At the peak of the temperature curve at the beginning of the inspiration, the temperature corresponds in good approximation to the true core temperature T _K.

The device according to the invention and the method according to the invention for the noninvasive measurement of the body temperature close to the core represents a simple and efficient possibility, which can be used in particular in emergency situations during which a patient is being ventilated.

Claims

Claims:

1. A device (5) for noninvasive measurement of the near-core body temperature (T _K ), with at least one temperature sensor (13), characterized in that a respiratory tube to a (2) connectable tubular intermediate piece (6) is provided, which at least two channels ( 9, 10), wherein in each channel (9, 10) a valve (11, 12) is arranged, so that a channel (9) during the inspiration and a channel (10) is flowed through during the Expiration, and that at least a temperature sensor (13) for measuring the temperature of the expiration air in the expiratory channel (10) is arranged.

2. Temperature measuring device (5) according to claim 1, characterized in that the valves (11, 12) are formed by membranes, in particular silicone membranes.

3. Temperature measuring device (5) according to claim 1, characterized in that the valves (11, 12) are formed by flaps.

4. Temperature measuring device (5) according to one of claims 1 to 3, characterized in that the intermediate piece (6) made of plastic, in particular made of sterilizable plastic.

5. Temperature measuring device (5) according to claim 4, characterized in that the intermediate piece (6) is produced by injection molding.

6. Temperature measuring device (5) according to one of claims 1 to

5, characterized in that the intermediate piece (6) is designed as a disposable product.

7. Temperature measuring device (5) according to one of claims 1 to

6, characterized in that in the intermediate piece (6) an opening for insertion of the temperature sensor (13) is arranged.

8. Temperature measuring device (5) according to one of claims 1 to

7, characterized in that with the at least one tursensor (13) a transmitting device for transmitting the measured temperature values is connected.

9. temperature measuring device (5) according to one of claims 1 to 8, characterized in that at least one temperature sensor (13) is formed by a thermistor.

10. Temperature measuring device (5) according to one of claims 1 to 8, characterized in that at least one temperature sensor (13) by an optical sensor (16) is formed.

11. Temperature measuring device (5) according to claim 10, characterized in that in the Expirationskanal (10) of the intermediate piece (6) has a window (15) and on the outside of this window (15) of the optical sensor (16) for detecting the window ( 15) outgoing heat radiation is arranged.

12. Temperature measuring device (5) according to claim 11, characterized in that the window (15) is colored black and the optical sensor (16) is formed by an infrared sensor.

13. Temperature measuring device (5) according to claim 11 or 12, characterized in that the window (15) protrudes into the Expirationskanal (10) of the intermediate piece (6).

14. Temperature measuring device (5) according to one of claims 1 to 13, characterized in that in the intermediate piece (6) a sensor for measuring the inspiratory and / or Expirationsströmung is provided.

15. A method for non-invasive measurement of the near-core body temperature (T _κ ), characterized in that the temperature of the expiration air is measured in the flowless state at the beginning or during the inspiration.

16. Temperature measuring method according to claim 15, characterized in that simultaneously with the temperature of the expiratory air, the air flow in the region of the temperature sensor is measured, and that those values of the temperature sensor as the core temperature be selected while the flow is substantially zero.

17. Temperature measuring method according to claim 15 or 16, characterized in that a plurality of temperature values are measured with a plurality of temperature sensors and the arithmetic average of all temperature values is determined to determine the core temperature.

18. Temperature measuring method according to claim 15 or 16, characterized in that a plurality of temperature values are measured with a plurality of temperature sensors and for determining the core temperature the maximum of all temperature values is formed.

19. Temperature measuring method according to one of claims 15 to 18, characterized in that the time course of the temperature is stored.