Higher vs. lower fluid volume for septic shock: clinical characteristics and outcome in unselected patients in a prospective, multicenter cohort

INTRODUCTION Patients with septic shock require fluid, but the optimum amount is unknown. Therefore we assessed patient characteristics and outcome associated with fluid volume in unselected patients with septic shock including those with three days of shock. METHODS We conducted a prospective, multicenter, observational study of all adult patients with septic shock during a 3-month study period at six general ICUs: three in university hospitals and three in regional hospitals. After day 1 and 3 of shock, patients were divided into two groups according to the overall median fluid volumes. Characteristics between these groups were compared using non-parametric and Chi-square statistics. RESULTS The 164 included patients received median 4.0 l (IQR 2.3-6.3) of fluid during the first day of septic shock. Patients receiving higher volumes (> 4.0 l) on day 1 had higher p-lactate (3.4 (2.2-5.5) vs. 2.0 (1.6-3.0) mmol l(-1), P < 0.0001) compared to those receiving lower volumes. In contrast simplified acute physiology score (SAPS) II (54 (45-64) vs. 54 (45-67), P = 0.73), sequential organ failure assessment (SOFA) score (11 (9-13) vs. 11 (9-13), P = 0.78) and 90-day mortality (48 vs. 53%, P = 0.27) did not differ between groups. The 95 patients who still had shock on day 3 had received 7.5 l (4.3 - 10.8) of fluid by the end of day 3. Patients receiving higher volumes (> 7.5 l) had higher p-lactate (2.6 (1.7-3.4) vs. 1.9 (1.6-2.4) mmol l(-1), P < 0.01) on day 3 and lower 90-day mortality (40 vs. 62%, P = 0.03) than those receiving lower volumes in spite of comparable admission SAPS II (53 (46-67) vs. 55 (49-62), P = 0.47) and SOFA scores on day 3 (10 (8-13) vs. 11 (10-14), P = 0.33). CONCLUSIONS In this cohort of unselected ICU patients with septic shock, initial fluid volume was not associated with mortality. In patients with shock for three days or more, higher fluid volumes including crystalloids, colloids and blood products were associated with reduced mortality.