JPH034247Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a breathing sensor for detecting the presence or absence of breathing, the rate of breathing, and the timing of breathing.

[Conventional technology]

BACKGROUND ART Conventionally, oxygen supply systems have been proposed for patients with respiratory failure and the like that are synchronized with the patient's breathing using a breathing synchronization sensor. Compared to previous continuous oxygen supply systems, this system is extremely advantageous in terms of saving oxygen gas, making the supply device more compact, and greatly reducing patient discomfort. It can be said that there is.

Conventional respiratory sensors used in such systems include methods that measure chest impedance, breathing air pressure, breathing air temperature, and the like. Among these methods, measuring temperature changes is said to be the simplest and most accurate method, and this method involves fixing a thermistor, thermocouple, platinum resistance thermometer, etc. to the nasal cannula, which is the outlet for oxygen gas, etc. is mainly used. That is, in the case of exhalation, exhaled breath at a temperature close to body temperature is blown onto a temperature sensor installed near the nostrils, causing the temperature to rise, and in the case of inhalation, on the contrary, the temperature decreases. Generally, this temperature change is converted into a differential waveform, and appropriate threshold values are set to detect the timing of exhalation and inspiration. This signal activates a solenoid valve to synchronize the supply of oxygen gas, etc. with actual breathing.

However, if the patient has a high respiratory rate, the
The respiration rate may reach more than breaths per minute, and therefore, among the temperature sensors mentioned above, a thermocouple with the highest response speed is appropriate. On the other hand, with conventional methods of fixing thermocouples, the temperature-sensing part heats up at the tip, as shown in Figure 5 J and K, and methods such as applying a thick layer of resin or floating the tip are required to fix it. It was hot. As a result, there were structural problems such as the response speed being extremely low and the device being unable to follow rapid breathing, the tip breaking, and the device easily irritating the skin.

[Purpose of invention]

The object of the present invention is to provide a highly reliable respiration sensor that has both high precision and high-speed response without sacrificing the excellent features originally possessed by thermocouples.

[Structure of the idea]

That is, the present invention is a respiratory sensor that detects the timing of exhalation and inspiration by measuring temperature changes in the respiratory airflow with a temperature sensor installed in the nasal cannula, and the temperature sensor is a thermoelectric sensor with a wire diameter of 1 mm or less. This is a respiratory sensor characterized in that the joint part, which is exposed on the outer surface of the nasal cannula part and becomes a temperature sensing part, is provided on the front side of the tip of the thermocouple.

The thermocouple used in this invention is
According to the classification according to JISC1602-1981, noble metal thermocouples are B thermocouples, R thermocouples, S thermocouples, and base metal thermocouples are K thermocouples (formerly JIS CA
Typical examples include thermocouples (hereinafter the same applies), E thermocouples (CRC), J thermocouples (IC), T thermocouples (CC), but are not limited to these, but the strength, price, Alternatively, from the viewpoint of thermoelectromotive force, it is desirable to use a K thermocouple or a T thermocouple.

The wire diameter of the thermocouple must be 1 mm or less; if it exceeds 1 mm, the heat capacity of the thermocouple itself will increase, and the response speed will drop significantly. Therefore, considering both response speed and workability, the wire diameter
A range of 0.025 to 0.2 mm is more desirable. The thermocouple is
In order to prevent the wires from coming into contact with each other and maintain insulation from the outside, apply an insulating resin coat or cover the resin tube in advance. reliability of insulation,
Resin coating is desirable from the standpoint of safety, operability, etc. Insulating resins include epoxy resins, urethane resins, polyimide resins, polyester resins, silicone resins, polyvinyl chloride resins, and fluorine resins, but are not particularly limited to these. do not have.

Next, the structure of the nasal cannula portion in the respiratory sensor of the present invention will be explained in detail. FIGS. 1A, B, and C are diagrams showing an example of a method for fixing a thermocouple according to the present invention. As the nasal cannula 1, a molded product made of soft vinyl chloride resin is usually used, but it is not limited thereto.
Tube 6 connected to both ends of nasal cannula 1
is for supplying oxygen gas and is connected to an oxygen gas supply device. The joint part of the thermocouple 7, that is, the temperature sensitive part 4, is exposed on the outer surface of the nasal cannula 1, and the thermocouple parts 2 and 3 near both sides thereof are embedded in the nasal cannula 1. The temperature sensing portion 4 and the vicinity 2 and 3 are fixed with adhesive.

The method of fixing the temperature sensing section 4 is as shown in FIGS. 3F and 3G. Compared to the conventional thermocouple fixing method shown in FIGS. 5J and K, in the present invention, a part of the thermocouple (nearby 3) extends beyond the temperature sensing part 4 to the tip side, and this extends to the nose. Since it is embedded in the cannula 1, the temperature sensing part 4 can be easily fixed, so the amount of resin 8 coated on the temperature sensing part 4 can be reduced, and the layer of resin 8 covering the temperature sensing part 4 can be made thinner. This provides the advantage of increasing the response speed of the thermocouple.

Furthermore, as shown in Figure 2 D and E, by providing two or more thermocouple temperature-sensing parts 4 in one nasal cannula, breathing can be sensed even if one of the nostrils becomes clogged. be.

The temperature sensing part of a thermocouple is obtained by joining two types of wires mainly by resistance welding. In this case, the bonding position of the temperature sensitive part is preferably 1 mm or more, more preferably 5 mm or more away from the tip of the thermocouple. Figure 4 shows the structure of the thermocouple temperature-sensing part, which is formed by joining two types of wires that make up the thermocouple at positions closer to the tip of each wire. rear,
Furthermore, a resin coat 9 is applied to the entire body, and there is a method H in which the two wires are closely coated with the resin, and a method T in which the two wires are separated and coated with the resin separately.
Both H and I can be used, but H is preferable from the viewpoint of workability when assembling into a catheter.

[Effect of idea]

According to the present invention, conventional respiratory sensors using thermocouples have a slow response speed due to insufficient fixing methods, low thermoelectromotive force due to small temperature changes in the temperature sensing part, and malfunctions due to noise. Since the problems such as easy handling and structural defects can be solved all at once, it is possible to obtain a highly reliable respiration sensor that is extremely stable, has high precision, and high speed response.

[Brief explanation of the drawing]

Figures 1A, B and C are diagrams showing an example of the structure of the nasal cannula and the method of fixing the thermocouple in the respiratory sensor of the present invention, and Figures 2D and E are diagrams showing the structure of the nasal cannula and the method of fixing the thermocouple in the respiratory sensor of the present invention. It is a figure which shows the example which attached the thermocouple which has. FIGS. 3F and 3G are diagrams showing a method of fixing the temperature sensing part in the present invention, and FIGS. 4H and I are diagrams showing the structure of the temperature sensing part of the thermocouple. Further, FIGS. 5J and 5K are diagrams showing a conventional method of fixing a thermocouple.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A respiratory sensor that detects the timing of breathing and inspiration by measuring temperature changes in respiratory airflow with a temperature sensor installed in the nasal cannula, where the temperature sensor is A respiratory sensor comprising a thermocouple with a wire diameter of 1 mm or less, and characterized in that a joint part exposed on the outer surface of the nasal cannula part and serving as a temperature sensing part is provided on the front side of the tip of the thermocouple. (2) Utility model registration claim No. (1), characterized in that the joining part of the thermocouple is formed by joining two types of strands at a position closer to the tip of each of them.
Breathing sensor as described in section.