Hemodynamic effects of head-down lithotomy position in patients with coronary artery disease

The hemodynamic effect of the head-down lithotomy (HDL) position was studied in 12 anesthetized patients with documented coronary artery disease. Data were collected in patients in supine position and then 10 minutes after placement in a 10-degree HDL position. Systolic arterial pressure (SP), mean arterial pressure (AP), mean right atrial pressure (RAP), mean pulmonary artery pressure (PAP), mean pulmonary capillary wedge pressure (PCWP), cardiac output (CO), and heart rate-systolic pressure product (HRSP) increased significantly. Heart rate (HR), systemic vascular resistance (SVR), and pulmonary vascular resistance (PVR) were unchanged. In 2 patients with very low ejection fractions (EF), CO was decreased. The increase in HRSPP and PCWP suggests that all patients had increased myocardial oxygen demand. This increased demand may not be met because of impaired coronary circulation, potentially causing myocardial ischemia. This study suggests that patients with significant coronary artery disease should not be placed in the HDL position for extended periods without appropriate monitoring.