Prolonged overexpansion of extracellular water in elderly patients with sepsis

Objective: To compare the sequential changes in extracellular water (ECW) expansion in elderly patients receiving intensive care for severe sepsis with those in a similar group of younger patients. Design: Inception cohort study. Setting: Critical Care Unit and University Department of Surgery in a single tertiary care center. Patients: A consecutive series of 14 patients older than 60 years (n = 8) or younger than 40 years (n = 6) with severe sepsis who completed sequential measurements of body composition during a 21-day period. Main Outcome Measure: Sequential measurements of body composition including ECW by bromide dilution, total body water by tritium dilution, and fat-free body mass by dual-energy x-ray absorptiometry were performed during 21 days after resuscitation. Excess ECW was estimated from the difference between measured ECW and ECW predicted from fat-free body mass corrected to normal hydration. Results: On the first study day, ECW was overexpanded by 9.05 +/- 1.87 L (mean +/- SEM) and 10.33 +/- 1.79 L in the young and elderly groups, respectively (P = .66). Whereas the young group excreted most of this excess ECW by day 5 (P = .008), the elderly group remained overexpanded until day 10 before mobilization of ECW occurred (P = .003). The changes over time of ECW excess were significantly different (P = .02 for group X time interaction). The elderly group required more prolonged inotropic (P = .009) and ventilatory (P = .004) support and remained in intensive care longer (P= .008) than the young group. Conclusions: The period of ECW expansion is more prolonged in elderly patients with sepsis and contributes to a poorer outcome from critical illness. This new finding is of fundamental importance to the treatment of elderly patients recovering from severe sepsis.