Abstract: A method of and an apparatus for intra-aortic balloon monitoring and leak detection in which the balloon is inserted into the aorta of a body and the balloon is inflated and deflated with gas by a control system and in which the balloon includes an electrical conductor therein extending out of the body. An alternating current source is applied between the electrical conductor and an electrode connected to the exterior surface of the body thereby transmitting an alternating current through the body and across the balloon. The impedance between the electrical conductor and the electrode is measured which is an indication of the inflation and deflation of the balloon and the occurrence of any leak in the balloon. The control system of the balloon is automatically shut down in the event the impedance falls below a predetermined level. The frequency of the alternating current is above the range of cardiac susceptibility and the magnitude of the electrical current passing through the body is small and limited.

Abstract: A pneumatically driven balloon activated blood pump for connection either in parallel with or to one side of the heart for temporary mechanical support of an inadequately functioning heart. A tubular conduit with a sealable opening for insertion or removal of the balloon having an inlet and an outlet for connection to the circulatory system. A gas line extends from outside of the conduit through the opening and into the conduit and is connected to an inflatable balloon which is expanded and contracted by gas to form the blood propelling member. An inlet and an outlet valve are positioned on opposite sides of the balloon to provide unidirectional flow of blood through the pump. The inlet valve may be a separate occluder balloon connected to and actuated from the gas line or may be a portion of the balloon occluding the inlet side of the conduit during inflation. An outlet valve may be attached to the pump balloon.

Abstract: An electrical capacitance measurement system for monitoring at a distance the instantaneous blood volume within the body of an air or gas activated blood pump. Electrical capacitance changes within the pneumatic blood pump frequency modulates an oscillator, and the extraneous capacitances encountered are incorporated as electrical, integral components in oscillator operation. An inductor, placed within or in close proximity to the pump, and the relatively small electrical capacitance within the pump form an oscillator tank which primarily determines oscillator frequency. By thus creating a tank at the site of measurement, active and other oscillator components can be placed at a distance from the pump, and undesirable cable capacitances can conveniently be incorporated as participating feedback capacitors.

Abstract: A method and apparatus is provided which will attenuate bioelectric interference when measuring the activity in an intact nerve. An electrode probe is provided having first and second electrodes positioned on opposite sides of a thin, flexible, insulating carrier. The probe is inserted between the nerve to be measured and the underlying body tissue with one electrode contacting only the nerve and the second electrode contacting only the tissue. The nerve and the tissue thereby form in effect a Wheatstone bridge about the carrier and the symmetrical electrodes which thus provides a nulling effect on extraneous electrical potentials, while a measurement of nerve potentials appearing as a voltage difference between the electrodes provides a measurement of activity in the nerve. Additional, symmetrical pairs of electrodes may be positioned on the same carrier, and their outputs may electronically be combined for increasing the signal-to-noise ratio in the measurement.