Patent GB-446879-A (GB)
Title: Improvements in artificial respiration apparatus
IPC: A61H31/00
Filed: 1935-10-14
Abstract: 446,879. Artificial respiration apparatus. PETERSEN, P., Lund, Sweden. Oct. 14, 1935, Nos. 28307 and 28308. Convention dates, Oct. 15, 1934. [Class 81 (ii)] [See also Group XXIX] Apparatus for producing artificial respiration comprises a band 1, Fig. 1, placed around the chest of the patient while lying face upwards, means, such as an inflatable pad 3 or a cylinder and piston, for raising the chest and arching the spine in the thoracic region, and means producing fluid pressure impulses employed alternately to tighten and relax the band and also to operate the spine-arching means during the relaxation phase. The pressure-producing means shown, comprises a cylinder 15 of compressed gas, such as oxygen containing about 7 per cent of carbon dioxide, connected by a tube 13 to a valve chamber 12 itself connected by a tube 10 to the pad 3, of rubber reinforced with fabric, and to a pump 6. The pump cylinder and the rod 7 of a piston therein are connected respectively to frames 4 having rollers 5 permitting easy movement over the patient's chest, the frames having retaining members detachably and adjustably engaging ribs 4a on the end of the band 1 and being also connected together by springs 9 lying beside the pump. Alternate phases of gas-pressure and pressure release, produced in the valve chamber 12 effect an outstroke of the piston with release of the band 1 and simultaneous expansion of the pad 3 to raise the chest and arch the spine for an inhalation phase, followed by collapse of the pad, and return of the piston by the springs 9, the band 1 being thereby tightened about the chest to produce exhalation. The valve chamber 12 contains a diaphragm 20, Fig. 3, connected, by a rod 24 with a terminal eye, to a pivoted leaf valve 18. The diaphragm 20 is adjustably pressed by a spring 29 and the casing above the diaphragm carries an outlet valve 26 and an adjustable leak 27. The leaf 18 in one position occludes the gas inlet 16 and in the other the outlet 17, and is held in the occluding positions by the poles 22, 23 of a permanent magnet. The switching over of the leaf 18 from the position shown to produce an exhalation phase is retarded to an adjustable extent by the leak 27 which prevents immediate establishment of atmospheric pressure above the diaphragm on downward movement thereof. The spring 29 and valve 26 may be replaced by a valve opening at a predetermined maximum pressure. The valve mechanism and cylinder 15, Fig. 1, may be replaced by a piston pump having delivery and suction valves loaded to open to atmosphere at a predetermined maximum and a predetermined minimum (for example, slightly less than atmospheric) pressure, the piston having a variable stroke and displacing a greater volume of air than is required such that a dwell is produced at the end of each inhalation and exhalation phase during which the piston is sucking in air from or delivering air to atmosphere. The gas discharged through 17, Fig. 3, may be delivered to an inhalation nozzle or a mask of readily expansible material which acts as a reservoir for the gas to be inhaled and from beneath the edges of which the gas escapes.