Venous air embolism during neurosurgery. A comparison of various methods of detection in man

A comparison of the various methods available for the detection of air embolus has been carried out in patients undergoing posterior fossa exploration in the sitting position. A group of 17 patients (Group A) was comprehensively monitored by a central venous catheter, an infra-red carbon dioxide analyser and a Doppler ultrasonic flow transducer in addition to more traditional clinical methods. Group B (19 patients) was monitored by commonly used clinical methods consisting of continuous palpation of the radial pulse, intermittent blood pressure measurement, the use of an oesophageal stethoscope and the electrocardiograph. In Group A the detection of air embolus varied from 6% using an oesophageal stethoscope to 58% by the Doppler method. In Group B air embolus was diagnosed in 10% of patients. One patient in each group died from air embolus; one patient had a paradoxical embolus to the coronary arteries. It is concluded that comprehensive monitoring for air embolus, including the use of Doppler ultrasound, is an essential part of the management of these patients, for both diagnosis and treatment.