Surgery – Respiratory method or device – Means for removing substance from respiratory gas
Patent
1987-02-11
1988-12-20
Jaworski, Francis
Surgery
Respiratory method or device
Means for removing substance from respiratory gas
A62B 710
Patent
active
047919221
DESCRIPTION:
BRIEF SUMMARY
This invention relates to apparatus for controlling the flow of gas to and from a patient in an anaesthesia system, and relates in particular to such apparatus whereby any one of several gas supply circuits may be selected without the need to change the connecting lines extending between the apparatus and the patient.
In present day anaesthetic practice there are many different systems for the supply of anaesthetic gases to and from a patient, each having particular characteristics relating to the gas flow to the patient from an anaesthesia machine and to the expiratory flow from the patient. In certain of these systems the patient may either breathe spontaneously, or, alternatively, mechanical ventilation may be provided, while other systems may only be used satisfactorily with one or the other mode of breathing. In addition, some systems cause the patient to rebreathe a portion of his expired gases, while in other systems there is little or no rebreathing and the only the fresh gas supplied by the anaesthesia machine enters the patient's lungs.
Commonly used gas supply systems which are familiar to those skilled in the art include the Mapleson A and Mapleson D systems. The former while allowing little to no rebreathing is generally suitable only for a patient who breathes spontaneously, and the latter, which does allow rebreathing, may be used with a spontaneously breathing patient or where a mechanical lung ventilator is required. Other systems which may be applicable depending on particular clinical conditions, include the so-called circle system where expired gases are passed through a carbon dioxide absorbing means before being returned to the patient.
In the conventional anaesthesia apparatus, when it is desired to switch from one gas supply system to another, it has generally been necessary to disconnect and reconnect hoses or pipes in the apparatus in accordance with the particular gas supply system required. This process is time consuming and inconvenient to the physician, and considerable care and attention must be given to ensure that the correct connections are made so that undesirable and potentially dangerous configurations are avoided.
In accordance with the invention there is provided apparatus for controlling the flow of gas to or from a patient in an anaesthesia system. The apparatus has a reservoir bag, and a selector valve means operable to connect the reservoir bag to either or both of first and second flow passages. The passages are arranged in parallel and adapted to be connected to a patient at on end remote from the selector valve means. The first passage has a first one-way valve means selectively operable to prevent the back-flow of gas from the patient into the passage. The first passage communicates with an inlet for the supply of fresh gas. A second flow passage has a second one-way valve means selectively operable to prevent the flow of gas from the passage to the patient and a selectively bypassable carbon dioxide absorbing means, there being a spill valve arranged to release gases from the second flow passage. Means are provided to control the conditions of the selector valve means and first and second one-way valve means whereby desired modes of operation of the apparatus may be selected.
The fresh gas supplied to the first flow passage via the inlet will depend on clinical conditions and may, for example, consist of a mixture of oxygen, nitrous oxide and anaesthetic vapour. As in conventional anaesthesia systems a number of different gases may be used.
In accordance with the invention, various modes of operation, corresponding to a number of different traditional gas supply systems, may be selected without the need manually to disconnect and reconnect hoses forming part of the apparatus or those extending between the apparatus and the patient. At the same time, the arrangement may be such that undesirable and potentially dangerous modes of operation are avoided. This is very important if safety standards are to be maintained.
In a first mode of operation, the selector va
REFERENCES:
patent: 3046979 (1965-10-01), Andreasen
patent: 4351329 (1982-09-01), Ellestad et al.
Lindsay-Scott David
Sugg Basil R.
Sykes Malcolm K.
Tyrrell Paul J.
Jaworski Francis
Manuel George
Penlon Limited
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