DE2543266A1 - General anaesthetic appts. with carbon dioxide control - has indicators and alarms triggered by deviations in exhalation rate - Google Patents

Abstract

The monitor and control system for general anaesthetic apparatus operates by using the measured exhaled CO2 concentration, according to a nominal value, to govern CO2 supply for inhalation. Deviations from the nominal value in either direction are indicated as well as anomalies in the expiratory CO2 concentration-time ratio. A shunt leading to the CO2 absorbers is opened or closed or in the case of semi-open or open types of anaesthetic apparatus CO2 is supplied from a pressurised gas bottle. Inspiratory CO2 supply may be indicated optically or acoustically. If the CO2 concentration in the expiratory branch of the apparatus remains constant (breathing stopped), the sensor triggers an alarm signal, as long as the system is set to spontaneous breathing.

Description

2 - Regulation on the patient under anesthesia @ In inhalation anesthesia it is common to work with too high a ventilation volume, provided the patient does not breathe spontaneously. This is especially true for uncontrolled manual ventilation. to is intended to prevent a feared hypoxemia. Normally run such anesthesia problem-free. For high-risk patients and longer periods of anesthesia However, too much CO2 is removed from the organism on expiration through hyperventilation.

If the blood buffer reserve is reduced as a result, it shifts Blood pH in the alkaline range; the arterial is particularly affected Capillary system, and the # O2 supply that is being supported by hyperventilation is to be reduced indirectly, while an inhalation anesthetic is added Lich is overdosed.

This is particularly the case with arteriosclerotic patients Complications, the cause of which cannot be identified.

The recommended hypervetilation of approx. 1O..o20 fo can be used with ventilators adjust, but is based on the physiological base value (basal metabolic rate) only, if, in rare cases, its determination has been made retrospectively.

There are also anesthesia machines in which the C02 absorber is activated by means of a Dreiwghahns + can be shunted. The CO2 admixture to the inspiratory gas mixture At best, however, an estimate remains.

Some anesthesia machines are also equipped with a CO2 compressed gas cylinder, so that a metered concentration of 002 is added to the prisch gas via a flow meter can be added. This writing is currently to be called optimal supports but rely on empirical values, provided there is no CO2 measuring device in the closed system is arranged expiratory. Even then, the manual control means an additional one Burden on the anesthetist.

It is the purpose of the invention to compensate for the malpractice of unnecessary hyperventilation and, in the case of flypoventilation, the malpractice of unnecessary hyperventilation by automatically regulated supply of CO2 into the inhalation thigh of anesthesia machines to signal ze.

A CO2 measuring device is required as a sensor, which measures the expiratory Peak or mean values are selectively recorded and then via the inspiratory limb Feeds in CO2.

Trots the variety of possible variations of anesthesia machines There are basically only two ways to achieve the desired goal: 1.) In rebreathing anesthesia systems If an outside is arranged for the CO2 absorber, the valve of which is controlled by the sensor becomes (Fig. 1).

2.) If the expiratory gas mixture is # exhaled freely, must, about the CO2 pressurized gas cylinder is regulated and fed in (Fig. 2) mixed anesthetic systems, which both basic principles make possible, should, depending on the choice of method, both Include ways.

There is a risk of hypoventilation when breathing spontaneously, if the upper limit of the CO2 concentration is set on the bowler, its Exceeding optical or acoustic signals triggers.

An early warning system in case of respiratory failure is provided via the Sensor senses the necessary discontinuity in CO2 concentration caused by the Breathing itself is conditioned. If this fails, signals are triggered.

Explanation of the figures: 1 corresponds to patient 2 "CO2 absorber 3 "Breathing bag or bellows (or respirator) 4" fresh gas supply 5 "CO2 pressurized gas cylinder 6 "CO2 measuring device with setpoint regulator 7 1 The alarm systems are not shown.

The arrows indicate directions of flow on the valves they mean directions of rotation.

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Claims (8)

Patent claims 1. Monitoring and control system for inhalation nudibranch devices, characterized in that the measured expiratory CO2 concentration, the Setpoint according to, causes an inspiratory CO2-luspeisurg and setpoint deviations are signaled in both directions as well as abnormalities in the expiratory CO2 concentration-time behavior. 2.) System according to claim. 1, characterized in that a shunt to the CO2-Absorben # is opened. 3.) System according to cont. 1, characterized by the fact that at half-open and open anesthesia machine types, the CO2 is supplied from a pressurized gas cylinder. 4.) System according to claim. 1-3, characterized in that the sensor leading extraction hoses, as well as the return CO2 supply, due to the different construction principles of anesthesia machines, arranged optionally are. 5.) System according to claim. 1-4, marked by the fact that the inspiratory CO2 feed optically or acoustically. is signaled. 6.) System according to claim. 1, 2, 4, characterized in that an already existing shunt to the CO2 absorber adjusted by means of a servo motor from the sensor will. 7.) System according to cont. 1-6, characterized. that the time behavior of the pneumatic control circuit of the inspiratory CO2 supply electronically is variably adapted. 8.) System according to cont. 1, characterized in that at constant Permanent CO2 concentration in the exhalation limb of the anesthesia machine (respiratory arrest) an alarm signal is triggered by the sensor, provided the control system is responding to spontaneous breathing is set to 0