Wedging the pulmonary artery catheter: changes in left atrial and pulmonary artery pressures and risk for perforation.

Objective: Clinical and experimental data indicate that when there is lung disease, wedging the pulmonary artery catheter (PAC) could cause decreases in cardiac output and systemic arterial blood pressure and an increase in mean pulmonary artery pressure (PAP). The authors studied whether wedging would alter mean left atrial pressure (LAP), and report perforations with PACs in their unit since 1975.

Design: Observational study.

Setting: University hospital operating room and intensive care unit.

Participants: Ten adult patients undergoing cardiac surgery.

Interventions: Placement of epidural catheters in the left atrium and pulmonary artery, and a PAC.

Measurements And Main Results: After weaning from cardiopulmonary bypass, mean LAP, mean PAP, and cardiac output were measured before and during wedging with the chest open and closed. Mean LAP decreased during wedging, from 13.5 +/- 2.8 (SD) mmHg to 13.0 +/- 3.0 mmHg (open chest) and from 15.8 +/- 3.2 mmHg to 15.3 +/- 3.1 mmHg (closed chest; p < 0.001), and mean PAP increased, from 18.8 +/- 3.5 mmHg to 19.7 +/- 3.5 mmHg (open chest) and from 21.3 +/- 4.3 mmHg to 21.9 +/- 4.2 mmHg (closed chest; p < 0.001). Mean PAP-mean LAP increased by 20% to 25%. Wedge pressure did not differ from mean LAP. Cardiac output and systemic arterial pressure did not change. Four perforations due to PACs occurred since 1975.

Conclusions: In adult patients undergoing cardiac surgery, wedging of a PAC resulted in a small decrease in mean LAP and a small increase in mean PAP. The wedging maneuver carries a small risk. How wedging is performed could influence the risk for perforation.