Patent GB-437709-A (GB)
Title: Improvements in or relating to apparatus for artificial respiration
IPC: A61M16/00
Filed: 1935-04-02
Abstract: 437,709. Valves. SVENSKA AKTIEBOLAGET GASACCUMULATOR, Lidingo, near Stockholm. April 2, 1935, No. 10226. Convention date, April 5, 1934. [Class 135] [See also Group VI] Artificial respiration apparatus particularly for use during chest operations, comprises a gas cylinder 1 connected through a reducing valve 2, a pressure governor 3, and equalizer 4, and a conduit 5 having a throttle control 6, to a valve housing 7, containing a main supply valve 8, and, in a separate compartment 7<c> a main escape valve 9. The housing 7 is connected by a pipe 17 to a housing 18 for a valve 29 itself connected by a pipe 31 and a mouthpiece 32 with the lungs 33. The mouthpiece 32 is connected by a pipe 35 to a housing 20 for a valve 22 and thence by a pipe 19 to the compartment 7<c>. The valves 29, 22 are actuated by diaphragms 23<a>, 24<a>, adjustably spring-loaded to respond respectively to a predetermined minimum lung-pressure, slightly above atmospheric, and a predetermined maximum lung-pressure, the diaphragm compartments 23, 24 being connected by pipes 36, 34 with the pipes 35, 31 respectively. The main valves 8, 9 are interconnected by a spindle 12 passing into a compartment 10 communicating with housing 7 by a non-return valve 13. The compartment 10 contains a throw - over mechanism, comprising interconnected levers 50, 51 connected to the spindle 12 and through a spring 52 with a diaphragm 53, and communicates with atmosphere through a pipe 14 having an adjustable throttle 15. In use gas passes into housing 7 at a rate determined by the setting of throttle 6, passes through valves 8 and 29 and inflates the lungs. The rising pressure acting through pipe 34 causes valve 22 to open, valve 9 remaining closed. The maximum lung pressure when reached acts through pipes 35 and 36 to close valve 29, thus terminating inhalation; thereafter pressure building up in housing 7 opens valve 13 (which is suitably loaded), and gas flowing into compartment 10 actuates the throw-over mechanism 11 to close valve 8 and open valve 9 thus permitting air to escape from the lungs. With falling pressure, valve 29 is opened (valve 8 remaining closed), and finally valve 22 is closed, thus terminating exhalation ; pressure in compartment 10 falls at a rate regulated by throttle 15 until mechanism 11 returns valves 8 and 9 to the position shown, thus completing the cycle. In order to synchronize the apparatus with the patient's breathing after irregularities such as spasmodic inhalations or coughs, the valve 22 is connected to the diaphragm 24a through a lever 47, one end of which is connected to a valve 46 controlling an outlet 48 from the compartment 10, the valve being opened subsequent to the closing of valve 22. A spasmodic inhalation when valves 22 and 9 are open reduces the pressure in pipes 31, 34, closes valve 22, opens valve 46 and empties compartment 10 thus causing mechanism 11 to close valve 9, open valve 8 and commence an inhalation phase ; on the other hand a cough during an inhalation phase closes valve 29 and opens valve 22 by the pressure impulses transmitted through pipes 35, 36 and 31, 34, valve 46 being simultaneously closed if open ; closure of valve 29 results in change over of valves 8, 9, as described above. To enable the apparatus to be used for resuscitation, levers 42, 43 are provided, operation of which controllably increases the loading of valve 29 by a spring 44 and holds valve 22 permanently open, the action of valve 46 being unaffected ; the apparatus then works between a higher maximum, and atmospheric, pressure. The levers 42, 43 may be held in desired position by ratchet mechanism.