GB1436032A - Respiratory distress stimulator - Google Patents

Abstract

1436032 Respiratory stimulator HOFFMANN-LA ROCHE & CO AG 18 Feb 1974 7343/74 Heading AST A system for monitoring and treating respiratory distress conditions comprises (Figure 1, not shown) a sensor (11) supplying an electrical signal corresponding to respiratory activity to an apnea monitor (14) for detecting respiratory distress, in which event said monitor causes a pneumatic supply unit (24) to inflate a pneumatic stimulator or mattress 25 under the patient resulting in the loss of his equilibrium to startle him into a natural respiration pattern. Mattress 25 comprises two pieces 26', 26" of an elastomeric material heat sealed to a rigid tube 28 of circular or elliptical crossseotion forming part of the exterior of the mattress and supplying air to segments 27 via apertures 29. The elastomeric material may be rubber, neoprene, polyethylene vinyl or polyvinylchloride. Tube 28 need not form part of the mattress exterior and may extend on one side only of segments 27. The mattress may be rectangular, elliptical or shaped to conform to the patient's neck. The apnea monitor (14) comprises (Figure 2, not shown) an input amplifier (17) driving a Schmitt trigger (18) connected to a timer (19) for determining that apnea has persisted for a preset time, connected to a one shot unit (16). The one shot unit (16) then energises relay 31 to move wiper 32 to contact b thus energising counter 36 and two-way solenoid valve 37 to admit air to mattress 25 from reservoir 33. After one second, relay 31 is de-energised and wiper 32 reverts to contact a. Air exhausts from mattress 25 through valve 37 and power is suplied, via the nowclosed pressure switch 38 which senses the pressure in reservoir 33 to a pump 34 to repressurise the reservoir via flapper valve 35. In a modification (Fig. 4B, not shown) a normally inflated mattress is momentarily deflated to startle the patient. In a further modification (Fig. 4C, not shown) the mattress is maintained inflated by air drawn by the pump from a reservoir, a distress condition causing the mattress to be deflated and the air to fill the partly-evacuated reservoir. Two mattresses may be coupled side-by-side by an adjustablewidth spongy central member to support the head. A sequencer unit supplies power to the pump and to two solenoid valves, each connected to its own mattress, so that one mattress is inflated as the other is deflated and then vice versa for a total of four cycles to rock the patient. The sequencer unit may provide electronic or mechanical switching by cams, a multi-vibrator or a mini-processor to vary the height and times of inflation and deflation to vary the rocking motion. The central mattress member may be inflatable so that if rocking is ineffective, rising and falling is automatically attempted. Indication and audible alarms of the respiratory activity are provided.