Acute cardiovascular response to passive leg raising.

Cardiac output by thoracic bioimpedance, heart rate, BP, oxygen saturation, and transcutaneous oxygen tension were measured at 1-min intervals in 45 patients before and after passive leg raising (PLR). Mean cardiac index increased only 0.09 +/- 0.02 (SEM) L/min.m2 (p less than .001), mean transcutaneous oxygen tension increased 1.6 +/- 0.6 torr (p less than .01), and mean oxygen saturation decreased 0.5 +/- 0.2% (p less than .01) after PLR. There were no significant changes in heart rate or systolic BP. Seven (16%) patients had increased cardiac index greater than 10% after PLR.