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.