Patent GB-1444607-A (GB)
Title: Ventilators
IPC: A61M16/00
Filed: 1973-08-30
Abstract: 1444607 Ventilators F M BIRD 30 Aug 1973 [8 Sept 1972] 40934/73 Heading A5T Ventilating apparatus comprises a manifold 37 supplied with gas from a blender 19 and connected to a flow divider 373 having a first outlet connected to a nebulizer 546 and a second outlet connected to a breathing circuit supplying gas to a patient, the flow divider being provided with valve means 374 permitting adjustment of the volume of gas flow through the second outlet thereby controlling the flow of gas to the nebuliser. The manifold 37 is also connected to a by-pass valve assembly 386 'having a flow passage therein controlled by a valve member 391 whereby additional gas can be supplied to the breathing circuit. Gas for the breathing circuit is supplied through tubes 324, 547 to the nebuliser 546 and flows via tee 548 and tube 632 to a water trap 633 and patient adapter 637 e.g. a face mask or tracheal tube. Exhaled gas passes from adapter 637 to a water trap 639 and a check valve 511 from whence it flows through a venturi assembly 503 across the top of diaphragm 566 to an outflow regulator 582 having an outlet 593 to atmosphere. Venturi assembly 503 connects to the breathing circuit through flap valves 511, 514 which open during the exhalation phase and inhalation phase respectively. If inspiratory demand pressure is below atmospheric, ambient air flows in through holes 524 to move a gate member 529 to the right thereby allowing air to pass into tee 518 and hence to the breathing circuit. If over-pressure conditions apply the breathing circuit is vented to amosphere through holes 536 and 524, gate member 529 being moved against the action of spring 537. A control cartridge 58 for the apparatus is shown in Fig. 22 and comprises a passage 402 receiving gas from a control valve 52 connected to manlfold 37, the gas passing into a chamber A via an expiratory time valve assembly 424, and into chamber B where it is trapped by valve 413. Gas also flows to chamber D, and past valve 409 to pressure chamber E: Gas also flows through an inspiratory timer valve 419 into chamber C. When chamber E is pressurised valve 417 closes so that chamber C cannot vent to atmosphere through outlet 406. The length of inspiratory phase is determined by the time taken to pressurise chamber C sufficiently to open valve 413 thereby terminating the inspiratory phase. When valve 413 opens chamber B is vented to atmosphere at 404 and therefore chamber A is vented to atmosphere. Valve 411 closes so that no gas flows through flow rate valve 422 and outlet 403. Pressure therefore drops in the passages communicating with chamber E so that gas bleeds out of chamber E to open valve 417 to vent chamber C to atmosphere through outlet 406. Valve 413 then closes. The expiratory time is determined by the time taken for gas to bleed through expiratory time valve 424 to pressurise ohambers A and B so that valve 409 will open. Means (183, Fig. 5), is provided for sounding an alarm if the inspiratory time is exceeded Means (184) is provided for locking-out flow of gases from the control cartridge after a predetermined inhalation time has elapsed. Means (Fig. 16) is provided for testing the apparatus prior to use.