Power Calculation and Statistical Analysis
Normally distributed data are reported as mean ± standard deviation, and abnormally distributed data are reported as medians and interquartile ranges. The D’Agostino-Pearson test was applied to assess data normality. Normally distributed variables were compared using the Student The frequency of noradrenaline administration to maintain mean blood pressure above 65 mmHg or > 80% of baseline during operation was about 70% in this comparable patient population in the previous study. If the frequency of noradrenaline administration during operation was reduced by half with the administration of methylene blue, then with a significance set at 0.05 and power set at 80%, the sample size required to detect differences was 66 patients in total for two arms. Taking into account a lost-to-follow-up rate of about 10%, 70 patients were enrolled.