Diagnosis of central hypovolemia by using passive leg raising

Suspected central hypovolemia is a frequent clinical situation in hospitalized patients, and no simple bedside diagnostic test in spontaneously breathing patients is available. We tested the value of passive leg raising to predict hemodynamic improvement after fluid expansion in patients with suspected central hypovolemia.

Prospective study in four intensive care units at the Amiens university hospital. Thirty-four spontaneously breathing patients with suspected hypovolemia were included and were classified as responders (cardiac output increased by 12% or more after fluid expansion) or nonresponders. Patients were analyzed in the supine position during 30 degrees leg raising and after fluid expansion.

Stroke volume and cardiac output determined by echocardiographic and Doppler techniques and heart rate and blood pressure were measured at baseline, during passive leg raising and after fluid expansion. An increase of cardiac output or stroke volume by 12% or more during passive leg raising was highly predictive of central hypovolemia (AUC 0.89+/-0.06, 95% CI 0.73-0.97 for cardiac output and AUC 0.9+/-0.06, 95% CI 0.74-0.97 for stroke volume). Sensitivity and specificity values were 63% and 89% for cardiac output and 69%, 89% for stroke volume respectively. A close correlation (r=0.75; p<0.0001) was observed between cardiac output changes during leg raising and changes in cardiac output after fluid expansion.

Bedside measurement of cardiac output or stroke volume by Doppler techniques during passive leg raising was predictive of a positive hemodynamic effect of fluid expansion in spontaneously breathing patients with suspected central hypovolemia.