Anesthetizing and gas therapy apparatus

摘要

904,094. Respiratory appliances. STANTON, P. L. May 16, 1960 [Feb. 8, 1960], No. 17212/60. Class 81 (2). Respiratory appliance for connection with means for establishing a gas flow circuit between the lungs of a patient and a source of gas comprising inner bellows arranged within outer bellows in such a manne rthat the outer bellows when connected with the gas flow circuit will expel or receive gas upon relative increase or decrease of pressure respectively within the inner bellows. As shown, Fig. 1, a bellows 3 is connected to a hose 15 leading to a mixing chamber 6 to which anµsthetic gas or oxygen is supplied. A bellows 4 within the bellows 3 is connected by an L-shaped fitting 23 and a hose 24 with the inlet 44 of a Venturi unit 5 which also comprises a valved inlet 37 for compressed gas, e.g. air, and an outlet 42 which may be closed by a valve 45 or the operator's finger. When the inlet 37 is open and the outlet 42 closed, compressed air is drawn through the passages 40, 43 and 24 and expands the bellows 4, forcing anµsthetic gas from the space 27 between the two bellows through the hose 15, chamber 6, hose 8 and valve 16 to a mask 9. A framework 29 secured to the bellows 3 by straps 341 limits expansion and contraction of the bellows. An internal framework (not shown) at the neck of the bellows 3 prevents the bellows 4 from expanding so as to obstruct the flow of gas from the space 27. Some gas passes through the return line 12 and maintains an outlet valve 17 on the mask closed. The pressure in the patient's lungs is indicated on a gauge 21. To begin the exhalation phase, the operator opens the outlet 42 and compressed air passes to atmosphere, causing the bellows 4 to collapse and thus create subatmospheric pressure in the bellows 3. This causes the valve 16 to close and the valve 17 to open so that anaesthetic gas is withdrawn from the lungs into the space 27. Excess anµsthetic gas may be bled off through a valve 18 on the mask. The operation of the bellows 3 and 4 and the unit 5 in association with an anµsthetic gas flow circuit in which one hose is used for the inhalation and exhalation of gas is also described. The bellows are preferably of the form shown in horizontal crosssection in Fig. 5.