The treatment of venous air embolism by aspiration from central venous catheters is well established. However, some anesthesiologists prefer to use a pulmonary artery catheter to monitor patients undergoing a neurosurgical procedure in the sitting position. While offering certain advantages, pulmonary artery catheters may be of limited use in the treatment of venous air embolism because the small diameter of the proximal port is poorly suited for efficient air aspiration. The authors have designed a special pulmonary artery catheter introducer sheath which can be positioned by intravascular electrocardiography to provide an efficient and effective means of air aspiration, while permitting the simultaneous use of a pulmonary artery catheter for pressure monitoring. The flow characteristics of this sheath, with and without side holes, were tested in vitro by measuring the time required to aspirate 50 ml of blood. The introducer sheath was compared to a Sorenson CVP catheter, a Bunegin-Albin Air Aspiration CVP Catheter, and the proximal port of a pulmonary artery catheter. The rank order of flow rate was: Bunegin-Albin CVP greater than introducer sheath without side holes = introducer sheath with side holes greater than Sorenson CVP greater than pulmonary artery catheter (P = 0.0001). The introducer sheath was then compared to a pulmonary artery catheter for the treatment of a 4 ml/kg venous air embolism in sitting, anesthetized dogs. The mean proportion of air retrieved by the sheath with or without side holes, 57% and 80%, respectively, was significantly greater than that retrieved by simultaneous aspiration of atrial and distal ports of the pulmonary artery catheter, 16% (P = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)