Statistical analysis
Sample size was calculated using the MedCalc Software version 14 (MedCalc Software bvba, Ostend, Belgium). In a pilot study on 14 patients (7 in each group), the mean norepinephrine dose in patients receiving ketofol 1:3 was 3.9 ± 5.2 mcg; and in patients receiving ketofol 1:1, norepinephrine dose was 0.7 ± 1.7 mcg. At alpha error of 0.05, we calculated that 68 patients would give 80% power to detect significant difference in the norepinephrine dose between the two groups. The number of prepared envelopes was 74 (37 envelopes per group) to compensate for possible dropouts.Statistical package for social science (SPSS) software, version 26 for Microsoft Windows (Armonk, NY: IBM Corp) was used for data analysis. Categorical data were presented as frequency (%) and were analyzed by the Chi squared test. Continuous data were checked for normality using the Shapiro-Wilk test and were presented as mean ± standard deviation or median (quartiles) as appropriate. Continuous data were analyzed using the unpaired t test or the Mann Whitney test according to normality of the data. Repeated measured data were analyzed using the analysis of variance for repeated measures with post-hoc pairwise comparisons using the Boneferroni tests. A P-value less than 0.05 was considered statistically significant.