System for treating blood processed in a cardiopulmonary bypass machine

Abstract

A system for reducing post-cardiopulmonary bypass encephalopathy due to microembolization of the brain of a patient with gaseous microbubbles (less than 40 microns in diameter) occurring during open-heart surgery using a cardiopulmonary bypass machine by passing a stream of blood from the patient through an ultrasonic traveling wave which propagates across the stream without reflection and sweeps the blood clean of the microbubbles without inducing blood cell trauma. The blood passes through a chamber between an input port and a filtrate exit port. An ultrasonic beam is projected so that a pressure maximum of the main lobe of the beam is centered at the filtrate exit port. The microbubbles are carried by the traveling wave to a waste exit port in the chamber downstream of the input port. To prevent establishment of resonance conditions, reflections and traveling waves the chamber may be submerged in a liquid bath and a body of acoustic absorbent material disposed at an end of the chamber opposite to the end into which the ultrasonic beam is projected.