Pressure gradient across the pulmonary artery anastomosis during lung transplantation

Background. Perioperative monitoring of pulmonary artery (PA) pressures in lung transplant recipients is critical. This report characterizes an intraoperative gradient across the PA anastomosis in a series of patients undergoing bilateral sequential lung transplantation. Methods. Hemodynamic measurements were obtained in a series of 10 patients before anesthetic induction, during one-lung ventilation/perfusion of the newly transplanted first lung with the PA catheter proximal and distal to the anastomosis and after arrival in the intensive care unit. The following measurements were recorded: central venous pressure, cardiac output, PA occlusion pressure, and systemic and pulmonary arterial pressures (systolic, diastolic, mean). Results. Although a systolic pressure gradient of more than 10 mm Hg across the anastomosis was observed in all patients, there was a significant variation in systolic (13 to 59 mm Hg), diastolic (2 to 10 mm Hg), and mean (5 to 27 mm Hg) PA gradients. Mean proximal systolic PA pressure measurements (56.2 ± 20.6 mm Hg) were greater when compared to measurements obtained distal to the anastomosis (28.6 ± 10.1 mm Hg, p = 0.001) and to those obtained in the postoperative period (32.1 ± 9.7 mm Hg, p = 0.004). Conclusions. The present study demonstrates that during single-lung ventilation and perfusion, the PA pressure measured proximally may not reflect accurately the pressure distal to the vascular anastomosis.