JPH1133119A - Breath circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to instantly detect a change of patient's body temperature, by equipping a temperature detecting member which can detect exhalation temperature in a short time onto a part of the patient. SOLUTION: A Y-shaped tube 1 is set in the vicinity of the patient side mouth of a breath tube A constituting a part of this breath circuit, and a mask 3 or an air tube connection port 2 is formed on the entrance thereof. A carbon dioxide absorption apparatus is connected to one 4 of a branch pipe and fresh gas to the other 5. It is also preferable that a gas sampling tube 7 is set in the vicinity of the connection port 2 and a warming filter made of plastic is set on the opposite side of the mask 3 with respect to the gas sampling tube 7. A temperature detecting part 25 is set in the circuit or on the end part. The temperature detecting part 25 processes the detected exhalation temperature data by a computer and displays. Thus, a change of body temperature can be instantly grasped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a respiratory circuit having a temperature sensor used for general anesthesia or artificial respiration.

[0002]

2. Description of the Related Art In general, in general anesthesia or artificial respiration, a circulating respiratory circuit such as an inhalation anesthesia machine or an artificial respirator is used to supply an anesthetic or oxygen to the lungs of a patient. During these procedures, it is necessary to determine the patient's condition by measuring the patient's body temperature.

[0003] In particular, during general anesthesia treatment involving danger, a patient may develop malignant high fever. Conventionally, an increase in the patient's body temperature is measured by an increase in the patient's rectal temperature.
Alternatively, it was detected by a color change soda lime for CO ₂ absorption by CO ₂ increase in breath by hypermetabolism of the patient.

[0004]

However, any of the conventional means for detecting a change in the body temperature of a patient has a slow reaction speed, and is capable of instantaneously detecting a sudden change in the patient's condition, particularly the occurrence of malignant high fever. Could not be detected, resulting in death or possibly the patient.

[0005] In view of the above, an object of the present invention is to provide a respiratory circuit capable of instantaneously detecting a change in a patient's body temperature.

[0006]

Therefore, a temperature detecting member for detecting expiratory temperature in a short time is provided in a part of the patient. As a temperature detecting member, a thin resistive wire for detecting the temperature of the flowing exhaled breath by a change in electric resistance, or a semiconductor thin-film resistor, or transmission of sound propagating in the exhaled breath
A transducer for receiving is used.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a Y-tube 1 is usually provided near a patient's mouth of a respiratory tract A constituting a part of a respiratory circuit for general anesthesia, and the entrance of the Y-tube is a mask 3 or a trachea. A connecting port 2 for connecting a tube (not shown) is formed. One branch pipe 4 of the Y-shaped pipe 1 is connected to a carbon dioxide absorbing device (not shown), and anesthesia is passed through the other branch pipe 5. Fresh gas mixed with gas is supplied.

A gas sampling tube 7 is provided in the vicinity of the connection port 2 of the Y-shaped tube 1 so as to sample the flowing gas. Further, a plastic moisturizing filter may be provided on the opposite side of the mounting portion of the gas sampling tube from the mask 3. A temperature detecting member 25 which is a main part of the present invention is provided in an appropriate position in the circuit or at an end of the circuit.
As shown in FIGS. 2 and 3, the temperature detecting member has a rectangular plastic or ceramic frame 23, on which a resistor fine wire 24 of about 50 μm of platinum is wound, whereby the temperature of expiration is increased. Is detected. By pressing both ends of the rectangular plastic frame 23 with flat inner walls in the breathing circuit 1, the temperature detecting member 25
2 fixed inside.

In this method, the temperature of the exhaled breath exhaled by the user is measured by measuring the electric resistance of the thin resistive wire 24. The resistor wire 24 constitutes a part of a known Wheatstone bridge circuit 30. This circuit 3
The signal from 0 is input to the amplifier 31 and amplified. Since the amplified signal is an analog signal, the analog signal is converted into a digital signal by the AD converter 32. The digital signal is calculated by a computer 33, and the calculated signal is displayed outside by an external display device 34 such as a display or a printer. By electrically processing the expiration temperature signal in this way,
It is possible to measure the temperature of expiration instantaneously and output it to the outside.

In order to increase the resistance value of the thin resistive wire, it is desirable to stretch the thin resistive wire 24 in a zigzag manner on a plastic frame as shown in FIGS. The time becomes faster, and measurement within 0.5 seconds becomes possible.

It should be noted that FIG.
As shown in FIG. That is, if a semiconductor having a narrow band gap has a remarkable change in electric resistance near a human body temperature and the temperature detecting member is formed in a film shape, the surface area is increased and the response time is increased. The thin film resistor 40 can be manufactured by depositing a polycrystalline semiconductor thin film on the surface of a thin glass plate or a mica thin plate, and the resistor can be formed into a thin film using photoetching.

Next, a description will be given of an apparatus for measuring the temperature change of the expiration by measuring the temperature change of the speed of sound by using a different principle.

In FIGS. 6 and 7, two oscillators 50 and 51 are provided on the inner wall of the respiratory circuit so as to face each other, and a pulse oscillator 52 is connected to one of the oscillators 50. A pulse-like sound wave is generated from the vibrator 50 by a pulse from the oscillator 52. This sound wave propagates through the space through which the exhaled air flows and causes the other vibrator 51 to vibrate. An amplifier 53 is connected to the vibrator 51, and the amplifier 53 amplifies a signal received by the vibrator 51. The pulse generator 52 and the amplifier 53 are connected to a time counter 54. The time counter 54, the voltage output pulses P ₁ of pulse generator 52 are input (FIG. 8
(A)), the electronic gate is opened (ON), and FIG.
(C)) The sound wave based on the voltage output pulse P ₁ is
, And when the voltage output pulse P ₂ after amplifying the output of the vibrator 51 at that time is input, the gate is closed (O
FF) (FIG. 8 (c)). A pulse train is always supplied from a reference pulse generator (not shown) provided in the time counter 54, and the pulse train is taken out only while the gate is open, and the sound speed is obtained by counting the number of pulse trains. Can be The reference pulse generator generates, for example, 10 ⁸ pulses per second. The output signal from the time counter 54 is calculated by a computer 55 to determine the sound velocity, and this signal is output from an external display 56 comprising a printer.

If the interval between the vibrator 50 and the vibrator 51 is, for example, 3.4 cm, the sound speed during expiration is about 340 m / se.
c Therefore, the pulse sound transmitted from the vibrator 50 is
Is 3.4 cm / 340 m / sec.
= 1 × 10 ⁻⁴ seconds. If the number of pulses from the reference pulse generator is 10 ⁸ per second, 1 × 10 ⁻⁴ second
0 ⁸ × 10 ^-4 = 10 ⁴ pulses.

In general, since the speed of sound propagating in a gas is proportional to the square root of the absolute temperature T of the gas, a change of 5 ° C. from 35 ° C. to 40 ° C. in a normal human body temperature change is about 0.8%. And the number of pulses are reduced. The change corresponding to the temperature change of 5 ° C. in the time T until the pulse sound wave from the oscillator 50 reaches the oscillator 51 is 10 ⁻⁴ × 0.8 × 10 ^−2.
= 8 × 10 ^-7 seconds. This is 80 pulses when counted by the wave number of the reference pulse. Therefore, even with a temperature change of 0.1 ° C., the number of pulses of 1/50, that is, about 160 pulses changes, and the change in the number of pulses can be reliably grasped, so that this temperature measurement method is extremely accurate. Since the speed of sound during expiration depends not only on the temperature but also on the concentration of carbon dioxide in the expiration and the temperature of water vapor, these fluctuations also affect the change in sound speed, but grasp changes in body temperature that are medically necessary The effect is small.

[0017]

The present invention is configured as described above.
By measuring the temperature of the exhaled air, the patient's body temperature can be measured instantaneously, a change in the patient's condition can be quickly grasped, an effect can be taken in a short time, and an unexpected accident can be prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view of a breathing circuit incorporating a temperature detector of the present invention.

FIG. 2 is a front view of a temperature detecting member installed in a breathing circuit according to the present invention.

FIG. 3 is a cross-sectional view of a breathing circuit according to the present invention.

FIG. 4 is a configuration diagram of an expiration temperature measurement system in a breathing circuit according to the present invention.

FIG. 5 is a cross-sectional view of a breathing circuit showing another embodiment of the temperature detecting member of the present invention.

FIG. 6 is a cross-sectional view of a breathing circuit showing still another embodiment of the temperature detecting member of the present invention.

FIG. 7 is a configuration diagram of an expiration temperature measurement system in the embodiment shown in FIG. 6;

FIG. 8 is an operation explanatory diagram of the expiration temperature measuring system shown in FIG. 7;

[Explanation of symbols]

 A: Respiratory tube 1: Y-shaped tube 3: Mask 25: Temperature detecting member 40: Thin film resistor 50, 51: Vibrator

Claims (5)

[Claims] 1. A respiratory circuit comprising a respiratory circuit for general anesthesia or artificial respiration, wherein a temperature detecting member for detecting a patient's expiratory temperature in a short time is provided. 2. An apparatus according to claim 1, further comprising an AD converter for converting an analog detection signal from said temperature detecting member into a digital signal, and a computer for performing arithmetic processing on said digital signal. Breathing circuit. 3. The breathing circuit according to claim 1, wherein the temperature detecting member is a temperature-sensitive resistance wire. 4. The breathing circuit according to claim 1, wherein the temperature detecting member is a semiconductor thin film resistor. 5. A pulse transmitter for applying a pulse to one of the vibrators to emit a sound wave, wherein the temperature detecting member comprises two vibrators provided at an interval during exhalation; 3. The respiratory circuit according to claim 1, further comprising a time counter for counting a pulse until a sound wave from the vibrator is detected by the other vibrator.