Negative fluid balance predicts survival in patients with septic shock: a retrospective pilot study.

OBJECTIVE: We hypothesized that patients with septic shock who achieve negative fluid balance (< or =-500 mL) on any day in the first 3 days of management are more likely to survive than those who do not.
DESIGN: Retrospective chart review. PATIENTS: Thirty-six patients admitted with the diagnosis of septic shock.
SETTING: Twelve-bed medical ICU of a 300-bed community teaching hospital.
METHODS: Medical records of 36 patients admitted to our medical ICU over a 21-month period were examined. Patients with septic shock who required dialysis prior to hospitalization were not included. A number of demographic and physiologic variables were extracted from the medical records. Admission APACHE (acute physiology and chronic health evaluation) II and daily sequential organ failure assessment (SOFA) scores were computed from the extracted data. Variables were compared between survivors and nonsurvivors and in patients who did vs those who did not achieve negative (< or = 500 mL) fluid balance in > or = 1 day of the first 3 days of management. Survival risk ratios (RRs) were used as the measure of association between negative fluid balance and survival. RRs were adjusted for age, APACHE II scores, SOFA scores on the first and third days, and the need for mechanical ventilation, by stratified analyses.
RESULTS: Patients ranged in age from 16 to 85 years with a mean (+/- SE) age of 67.4 +/- 3.3 years. The mean admission APACHE II score was 25.4 +/- 1.4, and the day 1 SOFA score was 9.0 +/- 0.8. Twenty patients did not survive; nonsurvivors had higher mean APACHE II scores than survivors (29.8 vs 20.4, respectively) and higher first day SOFA scores than survivors (10.8 vs 6.9, respectively), and they were more likely to require vasopressors and mechanical ventilation compared to patients who survived. Whereas all 11 patients who achieved a negative balance of > 500 mL on > or = 1 of the first 3 days of treatment survived, only 5 of 25 patient who failed to achieve a negative fluid balance of > 500 mL by the third day of treatment survived (RR, 5.0; 95% CI, 2.3 to 10.9; p = 0.00001). At least 1 day of net negative fluid balance in the first 3 days of treatment strongly predicted survival across the strata of age, APACHE II scores, first- and third-day SOFA scores, the need for mechanical ventilation, and creatinine levels measured at admission.
CONCLUSION: These results suggest that at least 1 day of negative fluid balance (< or = -500 mL) achieved by the third day of treatment may be a good independent predictor of survival in patients with septic shock. These findings suggest the hypothesis "that negative fluid balance achieved in any of the first 3 days of septic shock portends a good prognosis," for a larger prospective cohort study.