Statistical analysis
HYPOTENSIVE EPISODE
No prior study has clearly identified hypotensive episodes in older patients undergoing SAwith propofol sedation. Therefore, we determined the sample size using Poisson means. The Poisson means were derived from the retrospective review of our clinical experiences. There were 4.75 hypotensive episodes during a single surgery in older patients who underwent hip surgery under SA with propofol sedation without any continuous infusion of vasopressor, whereas there were 1.67 hypotensive episodes with the continuous infusion of norepinephrine. However, as we had only limited experience on the preventive use of norepinephrine, to ensure a sufficient number of patients, we assumed a Poisson mean of double that of 1.67, which is 3.34, for the treatment group. The calculated sample size, with α = 0.05 and power = 80% using a two-sample and two-sided equality test, was 32 patients in each group. Therefore, after considering possible dropouts, we decided to assign 35 patients into each group.The Poisson test was used to analyze the number of hypotensive episodes. Other continuous variables were analyzed using Student’s 