GB649229A - Improvements in apparatus for the control of respiration, resuscitation and anaesthesia - Google Patents

Abstract

649,229. Anaesthetic apparatus. BLEASE, J. H. Nov. 11, 1948, No. 29375. [Class 81(ii)] Apparatus for controlling respiration and anaesthesia comprises a pressure-responsive device controlling the cyclic rise and fall of pressure in an air chamber, and a second chamber, communicating with the first and containing a collapsable bag the interior of which is connected with the patient's lungs. In the apparatus described a chamber 15 is supplied with air through an inlet 14 and, as the pressure rises, at a rate determined by a leak valve 47, a diaphragm 18 is thrust outwards, against a spring 42, thereby tensioning a spring 29 and tending to turn a disc 25 which does not, however, rotate until a detent pawl 32 is withdrawn, at the end of the diaphragm's movement, by a pin 38 on a bracket 37. When so released the disc swings over and opens a valve 20 to release the pressure to atmosphere. The diaphragm now returns towards the left, its rate of movement being determined by the leak through a needle valve 41, and at the limit of this second movement, the disc is released for counterclockwise rotation by a tripping of pivoted pawl 33, and the valve 20 is closed so that the cycle is repeated. The interior of the chamber 15 communicates with a second chamber 4 containing a flexible breathing bag 46, the interior of which communicates with a face mask through a tube 2. As the pressure inside the chambers rises and falls the bag 46 is made to collapse and expand, thereby pumping its contents to and from the patient. Provision for manual control of the rate of respiration is made by closing a valve 52, to render valve 20 ineffective, and actuating a manual release valve, see Fig. 3 (not shown). Anaesthetic or other gas is introduced into the system through a branch pipe controlled by a cock 10 and the excess gas of each expiration escapes through a release valve 65. The apparatus is also fitted with a valve 55, which allows the patient to inspire directly from the atmosphere if the apparatus should fail to function, and also two screw valves 70, 72, of which the first controls the admission of air to the mask from a pipe. not shown, connected to the air pump, while the latter provides a direct communcation to the atmosphere.