MASSIVE AIR-EMBOLISM DURING CARDIOPULMONARY BYPASS - CAUSES, PREVENTION, AND MANAGEMENT

Abstract

Massive air embolism during cardiopulmonary bypass requires immediate response and carries strong medicolegal implications. From July, 1971, to July, 1979, there were 8 instances of massive air embolism during 3620 cardiopulmonary bypass operations. Five accidents from other institutions are included. Causes were inattention to reservoir level, reversal of pump head tubing or direction of pump head rotation, unexpected resumption of heartbeat, inadequate steps to remove air after cardiotomy, high-flow suction deep in a pulmonary artery, defective oxygenator, use of a pressurized cardiotomy reservoir and inadvertent detachment of oxygenator during bypass. Prevention includes a systematic check of pump suckers and perfusion lines before bypass, a sensing device on the oxygenator reservoir, secure fixation of the oxygenator and avoidance of traffic around pump equipment, immediate cessation of pump and inspection for abnormal noise, use of standard maneuvers to remove air from the heart, and carotid compression with resumption of heartbeat. Immediate management of massive air embolism consists of placing the patient in a deep Trendelenburg position and making a large stab wound in the ascending aorta for retrograde drainage from the cerebrovascular bed. Temporary retrograde perfusion through the superior vena cava (SVC) may be used. Subsequent steps are hypothermia with the resumption of cardiopulmonary bypass, elevation of blood pressure, steroids, ventilation with 100% O2 and deep barbiturate anesthesia. Among 13 patients, there were 4 instantaneous deaths. Cerebral injury which resolved within a 2-mo. period occurred in 3 patients. The remainder had no neurologic sequelae. Nonfatal cerebral air injury may be associated with prolonged convalescence yet complete recovery. Embolism from debris or clot offers a poorer prognosis.