Boc Health Care, Inc.

Spectramed, Inc.

John S Thompson

Gene A Bornzin

Wilbur R Williams

Burton E Bridge

William T Lemons

A bubble detection system for use in a fluid delivery line leading to a patient for automatic delivery of a fluid. The system monitors a parameter indicative of compressibility of the fluid being delivered and compares that monitored parameter with a known value of the same parameter using a relatively incompressible fluid. If the fluid being delivered is more compressible by a predetermined amount, the system recognizes the existence of a bubble and stops the further movement of fluid toward the patient and reduces the pressure in the fluid delivery line upstream of the bubble to prevent the bubble from progressing further toward the patient. The parameter may include pressure in the fluid delivery line, force required to deliver the fluid or motor current in the event an electric motor is used in delivering the fluid.

Bubble detection system

Heat is removed from the blood flow by heat exchange rather than cold-liquid injection; resulting temperature changes are monitored. Flow rate is found from monitored temperature and known parameters related to the amount of heat removed. Preferably heat is removed by pumping cold liquid into a sealed balloon or sheath along a catheter, which is in the blood stream. The balloon acts as a heat exchanger; its design optimizes that function. Temperature can be monitored by a thermistor or other sensor closer to the tip of the same catheter. Alternatively it appears possible to use blood-temperature measurements taken just outside the balloon, or even within the balloon, if the system is calibrated to account for the relation between the blood flow rate and the heat lost from balloon to blood. Heat removal can be either quasi steady-state or cyclical: that is, either heat is removed semicontinuously by a low-temperature-differential exposure and resulting steady-state temperatures observed semicontinuously; or heat is removed periodically in brief high-differential exposures, and temperature changes tracked in defined time periods during or after each exposure. In the latter case, a patient's heat balance can be maintained by alternately adding heat in protracted low-differential exposures.

Growing community of inventors

Oxnard, CA, United States of America

John S Thompson