Objectives To assess tolvaptan’s efficacy and safety in critical care patients with volume overload.

Methods Prospective observational study. Twenty-eight patients in the recovery phase from multiple organ failure and with volume overload refractory to conventional therapy treated with tolvaptan were included.

Results Patients received an initial daily dose of 3.75 (n=1), 7.5 (n=8) and 15 (n=19) mg of tolvaptan. Median treatment duration was 2 days (range: 1 to 12). All patients presented an increase in 24 hours diuresis after the first dose (median increase from baseline (IQR)=1114 (285–1943) mL), with a median net daily fluid loss of 1007 mL (456–2380) mL after 24 hours. High diuretic efficacy (daily fluid loss higher than 0.5 L with tolvaptan first dose) was detected in 18 patients (64.3%). Initial hyponatraemia was present in 16 (57.1%) patients, while overly rapid correction with tolvaptan treatment occurred in two patients without clinical consequences. Two patients presented hypophosphataemia after treatment.

Conclusion Tolvaptan is an effective therapeutic option in critically ill patients with volume overload refractory to conventional diuretics. Further studies are required to evaluate its safety profile and its effect on short-term outcomes and mortality.