Forty-one consecutive open-chest cardiac procedures requiring sternal retractors for visualization were prospectively studied. Chest x-rays demonstrating the course of the introducer sheaths and pulmonary artery catheters (PACs) were taken before and after sternal retractor expansion. Five different introducer sheath insertion sites were monitored (right internal jugular, left internal jugular, left subclavian, right subclavian, and right supraclavicular). The incidence of permanent loss of pulmonary artery (PA) and central venous pressure (CVP) waveforms was recorded after retractor expansion. Forty-five percent of both the left and right subclavian groups suffered loss of the PA and CVP waveforms, whereas none of the other insertion site groups was affected. Therefore, it is recommended that PACs inserted for surgery requiring sternal retractors be placed via nonsubclavian routes.