Initial target enrolment was for 50 patients (25 in each group), which provided 93% power to detect a difference of 50% in urine output at 24 h between treatments, α = 0.05. The power was calculated based on the magnitude of differ- ence in urine output seen in the Acute and Chronic Therapeu- tic Impact of a Vasopressin Antagonist in Congestive Heart Failure13 (24-h mean urine output for tolvaptan was approximately 4100 ± 2100 mL vs. 2300 ± 1100 mL compared with placebo when added to standard therapy) and in the Udelson et al.15 study (24-h mean increase in urine output with tolvaptan monotherapy 2600 ± 1500 mL vs. 900 ± 850 mL with furosemide). In August 2017, because of slow enrolment (Food and Drug Administration labelling change excluding hepatic disease and reduction in hospital census), the target sample was reduced to 33 subjects, providing 80% power as- suming the same mean difference as before.