Is myocardial adrenergic responsiveness depressed in human septic shock?

Abstract

To assess left ventricular (LV) contractile function and adrenergic responsiveness in septic patients. We used echocardiographically defined fractional area of contraction (FAC), and LV area to end-systolic arterial pressure estimates of end-systolic elastance (E'es) and its change in response to dobutamine (5 microg/kg/min) in 10 subjects in septic shock admitted to an intensive care unit of an academic medical center. Subjects were studied on admission and again at both 5 days and 8-10 days after admission. Three of the 10 subjects died as a result of their acute process, while the others were discharged from hospital. Nine out of 10 subjects required intravenous vasopressor therapy on day 1, while only 1 of 9 subjects required vasopressor support at day 5. LV end-diastolic area (EDA) increased from day 1 to day 5 and days 8-10 (p<0.05), but neither FAC nor E'es was altered by time (EDA 15.7+/-5.8, 21.4+/-5.1, and 19.4+/-5.6 cm2; FAC 0.46+/-0.19, 0.50+/-0.20, and 0.48+/-0.15%; E'es 21.6+/-12.6, 23.2+/-8.5, and 19.2+/-6.3 mmHg/cm2, mean+/-SD, for days 1, 5 and 8-10 respectively). Although dobutamine did not alter E'es on day 1 or day 5, E'es increased in all of the 5 subjects studied on days 8-10 (p<0.05). Adrenergic hyporesponsiveness is present in septic shock and persists for at least 5 days into recovery, resolving by days 8-10 in survivors.