2.5. Randomization and allocation concealment
Patients were randomly assigned to 2 groups. Random tables were generated using SPSS version 26.0 (IBM SPSS Inc., Chicago, IL). One hundred and twenty sealed envelopes were prepared by a statistician who did not participate in this study. The study was performed with neither patient nor observer awareness of the group to which each patient belonged. To ensure concealment of allocation, the numbers were kept in sealed and opaque envelopes that were opened by an anesthesiologist who was not involved in this study.