Sample size
PASS 15 Power Analysis and Sample Size Software (2017NCSS, LLC. Kaysville, Utah, USA) was used to determine the minimum number of samples. For BTV, a minimum number of 16 patients per group was required to detect a difference of at least 5.0 mm/min with a two-tailed alpha error of 0.05 and desired power of 80% (according to the data (mean, standard deviation) of a previous investigation) [