Sample size estimation
The sample size was calculated using two means formula using For the first objective, which is to compare GRV between the two groups, the ratio of sample size (group A/group B) was set as 1. The sample size was calculated using the standard deviation (18.46 ml) and difference between the means (12.5 ml). Based on these two estimates, the calculated sample size for this objective was 35 subjects per group.For the second objective, which is to determine patient’s well-being for group A and B, the expected standard deviation of the paired differences