Intraoperative monitoring for safety of bilateral total knee replacement

Cardiopulmonary hemodynamics in 79 consecutive patients who had one-stage bilateral total knee replacements were monitored prospectively with a pulmonary artery catheter. The pulmonary vascular resistance, wedge pressure, pulmonary artery pressure, and systemic vascular resistance were measured before skin incision, 5 to 10 minutes after implanting the first total knee replacement, and after the second knee replacement. The second knee replacement was cancelled in five patients because the pulmonary vascular resistance after the first knee replacement was more than double the baseline, or above 200 dyne/second/cm⁵. No patient had clinical symptoms of fat embolism during the postoperative course. Patient predictive factors, or the use of pulse oximetry readings instead of a pulmonary artery catheter, were not predictive of intraoperative elevation of pulmonary vascular resistance. For this reason, the safety of this operation for the patient requires that intraoperative measurement of hemodynamic parameters of embolism be done.