JPH05200116A - Auxiliary respirator - Google Patents

Abstract

PURPOSE:To provide a highly reliable auxiliary respirator which enables auxilia ry respiration accurately synchronizing spontaneous breathing. CONSTITUTION:The pressure in an air way becomes negative in relation to the start of spontaneous breathing of an organism, causing air current in an endotracheal tube 16 thus far stopped to reverse in inversion and the temperature of a thermistor 34 lowers quickly to raise a resistance value thereof. As a result, an output signal of a differentiation circuit 38 exceeds a set voltage and a trigger signal ST is outputted to an inhalation controller 26 from a comparison judgment circuit 40 to start an auxiliary respiring operation. Thus, even when a change in pressure occurs attributed to physical motions of the organism, contacts the endotracheal tube 16 and the like, the generation of the spontaneous breathing is not determined unless the air current in the endotracheal tube 16 is inverted and a change in the flow velocity occurs clearly. This enables auxiliary respiration accurately synchronizing the spontaneous breathing of the organism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary ventilator of the type which supplies air into the lungs of a living body in synchronism with the occurrence of spontaneous breathing of the living body.

[0002]

2. Description of the Related Art An endotracheal tube inserted into a trachea of a living body and an air feeding device for forcibly feeding air into the lungs of the living body through the endotracheal tube are used to generate spontaneous breathing of the living body. There is a known type of assist ventilator that performs assisted breathing by supplying air to the lungs of a living body in synchronization.

[0003]

By the way, in the above-mentioned conventional auxiliary ventilator, since the pressure sensor for detecting the pressure in the endotracheal tube is used, the intratracheal pressure detected by the pressure sensor becomes negative. The occurrence of spontaneous breathing in the living body was detected. However, in the conventional auxiliary ventilator that detects the occurrence of spontaneous breathing of the living body by using the pressure sensor as described above, when the body movement of the living body itself or a pressure change due to contact with the endotracheal tube occurs, There was a drawback that it was mistakenly recognized as the occurrence of spontaneous breathing, and the air supply was started unnecessarily.
In particular, such inconvenience is remarkable when it is necessary to detect a slight pressure change in order to perform the assisted breathing in synchronization with the occurrence of the necessary weak spontaneous breathing.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a highly reliable auxiliary ventilator capable of performing auxiliary breath reliably in synchronization with spontaneous breathing. To provide.

[0005]

Means for Solving the Problems The gist of the present invention for achieving such an object is to provide an endotracheal tube inserted into the trachea of a living body, and forcibly into the lungs of the living body through the endotracheal tube. An auxiliary ventilator of the type that performs an auxiliary breath by supplying air into the lungs of the living body in synchronism with the occurrence of spontaneous breathing of the living body, comprising: A flow velocity detecting means for detecting the flow velocity of the gas flowing through the endotracheal tube, and (b) a spontaneous breathing determining means for determining the occurrence of spontaneous breathing of the living body based on a change in the flow velocity detected by the flow velocity detecting means. And (c) an operation control unit that operates the air supply device when the spontaneous-respiration determination unit determines the spontaneous-respiration of the living body.

[0006]

By doing so, the spontaneous breathing determination means
When the occurrence of spontaneous breathing of the living body is determined based on the change in the flow velocity detected by the flow velocity detecting means, the operation control means operates the air supply device to supply air to the living body. That is, after the living body is ventilated through the endotracheal tube, if the respiration of the airflow in the endotracheal tube occurs due to the occurrence of spontaneous respiration of the living body, the flow velocity due to the reversal is detected by the flow velocity detecting means and the flow velocity The spontaneous breathing of the living body is determined based on the change of, and the air supply is started.

[0007]

[Effects of the Invention] Therefore, even if a pressure fluctuation occurs due to body movement of the living body or contact with the endotracheal tube, spontaneous respiration will occur unless the air flow in the endotracheal tube is reversed and a change in the flow velocity clearly occurs. Since it is not judged that the occurrence of
Auxiliary respiration can be performed reliably in synchronization with the spontaneous respiration of the living body.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, an air supply device 10 for forcibly supplying air to the lungs of a living body is connected to a bite block 14 via a conduit 12, and the bite block 14 is well known. The endotracheal tube 16 is connected. The endotracheal tube 16 is made of a flexible material so as to be inserted into the trachea of a living body, and is formed in various shapes and lengths according to the purpose of use.

The air supply device 10 has a structure similar to that of a conventional pressure-driven respirator, and it has a compressed gas source 18 for outputting compressed gas like an electric pump, and the compressed gas. Quantitative control valve 20 for controlling the suction gas pressure-fed from the source 18 to a preset constant flow rate
And a switching control valve 2 that can be switched between two positions, a position for supplying the inhaled gas output from the quantitative control valve 20 to the lungs of the living body and a position for discharging the gas from the lungs of the living body to the atmosphere.
2, a pressure sensor 24 for detecting the pressure of the inhalation gas sent from the switching control valve 22, and a breathing control device 26 for controlling a series of auxiliary breathing operations. The breathing control device 26 sends the suction gas from the switching control valve 22 to the endotracheal tube 16 every time a trigger signal ST described later is input, and when the pressure of the suction gas reaches a preset constant pressure. The switching control valve 22 is switched to release the gas in the lungs of the living body to the atmosphere through the endotracheal tube 16 and the switching control valve 22.

A balloon 30 for sealing between the inner wall surface of the trachea of a living body and the endotracheal tube 16 is provided on the outer peripheral surface of the distal end portion of the endotracheal tube 16. The balloon 30 is inflated by supplying pressurized gas via the balloon tube 32 during the assisting artificial respiration operation. Further, a thermistor 34 for detecting the flow velocity of the airflow in the endotracheal tube 16 is fixed to the inner peripheral surface of the distal end portion of the endotracheal tube 16.

The thermistor 34 is connected to a detection circuit 36 via a conductor 28, and constitutes a part of a bridge in the detection circuit 36 to be preheated by a bridging current. Therefore, the internal resistance of the thermistor 34 changes as the temperature changes in accordance with the flow velocity of the air flow in the endotracheal tube 16. Therefore, the output voltage of the detection circuit 36, which is the equilibrium voltage of the bridge, is the endotracheal tube. The flow velocity of the air flow in 16 is shown.

The output voltage of the detection circuit 36, which represents the flow velocity of the air flow in the endotracheal tube 16, is amplified by the amplifier 37 and then differentiated by the differentiation circuit 38 to compare the signals corresponding to the slope of the output voltage. It is supplied to the determination circuit 40. The comparison / determination circuit 40 compares the output signal of the differentiating circuit 38 with the set voltage supplied from the setter 42, and when the set voltage is exceeded, it is determined to be spontaneous breathing, and the trigger signal ST is set as the respiratory control device. To 26.

Next, the operation of the auxiliary ventilator constructed as above will be described. First, after the auxiliary breathing operation by the air supply device 10 is completed, the temperature of the thermistor 34 rises because the airflow discharged from the lungs of the living body is stopped in the endotracheal tube 16, and the resistance thereof is increased. Although the value is decreasing, as shown in FIG.
When the pressure in the respiratory tract becomes negative in connection with the start of spontaneous breathing of the living body, the air flow in the endotracheal tube 16 which has been stopped until then reverses and flows backward, so that the temperature of the thermistor 34 rapidly decreases. Its resistance value rises. Therefore, the output signal of the differentiating circuit 38 increases and exceeds the set voltage supplied from the setter 42, so that the trigger signal ST is output from the comparison / determination circuit 40 to the respiratory control device 26. In response to the supply of the trigger signal ST, the air supply device 10 compulsorily supplies air into the lungs of the living body, and when the air supply pressure reaches a preset value, The gas is discharged to wait for the next trigger signal ST. The trigger is generated by the airflow generated in the endotracheal tube 16 even during the period in which the insufflation device 10 forcibly supplies air into the lungs of the living body and during the period in which the gas in the lungs of the living body is discharged. The signal ST may occur, but if so, the respiratory controller 26 is configured to not accept the trigger signal ST until the end of one assisted breathing cycle.

Therefore, in the present embodiment, the thermistor 3
4 and the detection circuit 36 correspond to the flow velocity detecting means, the differentiating circuit 38, the setter 42 and the comparison determining circuit 40 correspond to the spontaneous breath determining means, and the respiratory control device 26 corresponds to the operation controlling means.

As described above, according to this embodiment, even if a pressure fluctuation occurs due to body movement of the living body or contact with the endotracheal tube 16, the air flow in the endotracheal tube 16 is reversed and the flow velocity is increased. Unless the change is clearly generated, it is not determined that spontaneous breathing has occurred, so that assisted breathing can be reliably performed in synchronization with the spontaneous breathing of the living body.

Further, according to this embodiment, the thermistor 34 is provided.
Is provided at the tip of the endotracheal tube 16,
The spontaneous breath detection sensitivity of the living body is suitably enhanced.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention can be applied to other aspects.

For example, in the above-described embodiment, the thermistor 34 is provided at the tip of the endotracheal tube 16, but it may be provided near the bite block 14 or in the conduit 12.

Further, in the above-described embodiment, the thermistor 34 is used to detect the air flow in the endotracheal tube 16, but a posistor having an opposite electric resistance change characteristic,
It does not matter if platinum resistance wire is used.

Further, although the air supply device 10 of the above-described embodiment is constructed in the same manner as a so-called pressure-driven respirator, it is a type that supplies a preset constant ventilation amount in one cycle. The so-called meter-type respirator may be configured in the same manner.

Further, the breathing control device 26, the differentiating circuit 38, the comparison / decision circuit 40, the setting device 42, etc. in the above-mentioned embodiment may be constituted by a so-called microcomputer.

Further, in the detection circuit 36 of the above-mentioned embodiment,
Although the flow velocity of the gas in the endotracheal tube 16 is detected based on the equilibrium voltage of the bridge related to the resistance change of the thermistor 34, the current is supplied so that the thermistor 34 is maintained at a constant temperature. It may be configured such that the flow rate of the gas is detected by the change in the current supplied.

The above is merely an embodiment of the present invention, and the present invention can be modified in various ways without departing from the spirit of the invention.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a main part configuration of an auxiliary ventilator according to an embodiment of the present invention.

FIG. 2 is a diagram showing a pressure change in the airway of a living body obtained by the operation of the embodiment of FIG.

[Explanation of symbols]

10 Air Supply Device 16 Endotracheal Tube 26 Breathing Control Device (Actuation Control Means) 34 Thermistor, 36 Detection Circuit (Flow Rate Detection Means) 38 Differentiation Circuit, 40 Comparison Judgment Circuit, 42 Setting Device (Spontaneous Breathing Judgment Means)

Claims (2)

[Claims] 1. An endotracheal tube inserted into a trachea of a living body, and an air feeding device for forcibly feeding air into the lungs of the living body through the endotracheal tube, which are used to generate spontaneous breathing of the living body. An auxiliary ventilator of a type for performing auxiliary breathing by supplying air to the lungs of the living body in a synchronized manner, the flow velocity detecting means detecting a flow velocity of a gas flowing in the endotracheal tube, and the flow velocity detecting means. Spontaneous breathing determination means for determining the occurrence of spontaneous breathing of the living body based on the change in the flow velocity detected by the means, and actuating the air supply device when the spontaneous breathing determination means determines the spontaneous breathing of the living body. An auxiliary ventilator comprising: 2. The flow velocity detecting means is provided at the tip of the endotracheal tube and senses that the resistance value changes according to the flow velocity of the gas that is heated to a predetermined temperature and flows in the endotracheal tube. The auxiliary ventilator according to claim 1, comprising a temperature resistor.