A respirator system for delivering accurate portions of pressure regulated gas at a controlled flow rate consisting of a gas delivery system having two chambers with communicating liquid-filled sections separated from gas-filled sections with a valve disposed to alternately fill one chamber with gas thereby delivering a portion of gas at the outlet of the other chamber equal to the volume of the liquid displaced and at a rate determined by a flow regulator in the liquid section of the system. The respirator system also includes a control system that monitors the output of the gas-delivery system as well as monitors the respirator performance of the patient.

A continuous length of flexible polymeric tubing having a smooth fissureless inner surface throughout is provided with a region intermediate its ends which region has an inside diameter greater than the inside diameter of the remainder of said tubing and a thinner wall than that of the remainder of said tubing with a gradual transition in wall thickness and diameter therebetween. A rigid walled enclosure surrounds said region of the tubing with a slight clearance therebetween except at the ends of the enclosure which encircle the tubing beyond said region with a snug fit. A duct is joined to the enclosure near one end for feeding fluid under pressure thereto. Various arrangements of over-pressure relief prevent pinching of the tubing while affording controlled indentation thereof. The transition section of the tubing wall can cooperate with a port in the enclosure to afford said overpressure relief. Portions of the tubing wall may be thickened (i.e., strengthened) or attached to the enclosure to limit indentation.

Apparatus is disclosed for mechanically assisting circulation of blood in a patient for periods of up to a week or two until the patient's heart strengthens sufficiently to take over the full workload. The circulatory assist device includes a valveless pump with a flexible bladder, a pneumatic driver for applying pressure pulses to the bladder, and a single flexible conduit for conveying blood between the patient and the pump. In use the pump and driver are mounted external to the patient's body and the flexible conduit is connected to the pump and in end-to-side relationship with a major blood vessel on that side of the heart, either right or left, which is in need of support. The circulatory assist device is operable either synchronously with the patient's heartbeat wherein the pump bladder fills as the heart ejects, then ejects in response to a pressure pulse from the driver while the heart is at rest, or asynchronously at a fixed rate if an irregular heartbeat of the patient precludes synchronous operation. The device, which can support up to about half of the workload of the heart, is easy to implant and remove and may be used to assist blood circulation in children as well as adults.

A pump includes a housing, an enlarged block, an inlet fluid conduit, an outlet fluid conduit and a flexible diaphragm. The housing defines a chamber having an inlet and a spaced apart outlet. The enlarged block is located in the chamber and has a first region and a spaced apart second region. The inlet fluid conduit extends into the chamber, terminates at or near the first region of the enlarged block and has at least one fluid inlet aperture in the chamber. The outlet fluid conduit extends into the chamber, terminates at or near the second region of the enlarged block and has at least one fluid outlet aperture in the chamber. The flexible diaphragm is located in the chamber and is moveable between a first position in which a working fluid from the inlet fluid conduit is prevented from passing toward the outlet fluid conduit and a second position in which the working fluid from the inlet fluid conduit is allowed to pass toward the outlet fluid conduit.