Cardiac catheters for diagnosis and treatment of venous air embolism

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Abstract
Patients (100) undergoing neurosurgical procedures in the seated position were monitored for venous air embolism with a Swan-Ganz pulmonary artery (PA) catheter, precordial Doppler ultrasound device and continuous end-tidal CO2 (FETCO2) analysis. Simultaneous determinations of right atrial and pulmonary capillary wedge pressures were performed during each operation. Although 80 episodes of air embolism were detected by changes in Doppler sounds, only 36 were associated with increased PA pressure and only 30 developed a decrease in FETCO2. Changes in PA pressure and FETCO2 agreed closely (r = 0.86) and only marked changes were associated with systemic arterial hypotension. Air was recovered from the right atrium and PA only in small amounts (2-20 ml) during air embolism, although it was possible to aspirate large quantities of blood. Twenty-nine patients had right atrial pressures that were higher than pulmonary capillary wedge pressures. Paradoxical air embolism from a probe-patent foramen ovale was possible in these patients. One developed signs and symptoms of systemic air embolism postoperatively. Noninvasive monitoring with the combination of a precordial Doppler device and end-tidal CO2 analysis apparently is satisfactory for rapid detection of clinically significant venous air embolism. The unique advantage of Swan-Ganz monitoring is that it permits identification of patients who may sustain paradoxical air embolism and that it differentiates the hemodynamic effects of brain-stem manipulation from those caused by air embolism.