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 approxi- mately 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 he- patic 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.