Is myocardial adrenergic responsiveness depressed in human septic shock?

Objective: To assess left ventricular (LV) contractile function and adrenergic responsiveness in septic patients. Methods: 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 mu g/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. Results: 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 cm(2); 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/cm(2), 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). Conclusions: Adrenergic hyporesponsiveness is present in septic shock and persists for at least 5 days into recovery, resolving by days 8-10 in survivors.