Comparison of effect of spinal anesthesia on heart rate and blood pressure between hypertensive patients on beta-blockers or calcium channel blockers and normotensive patients: A prospective observational cohort study

Abstract

Background: Hypertensive patients develop wide swings in blood pressure intraoperatively, especially after spinal anesthesia. Long term antihypertensive agents can modify this effect by controlling blood pressure. This study was undertaken to evaluate the haemodynamic effect in hypertensive patients on regular treatment with calcium channel blockers and beta-blockers who are undergoing elective surgery under spinal anesthesia and compared with normotensives. Methodology: 183 patients were included in the study; 61 patients were normotensives (Group A) and 61 patients were hypertensive who were regularly on calcium channel blockers (Group C) and 61 patients on beta-blockers (Group B). Both the groups continued the drug on the day of surgery. The baseline blood pressure and heart rate were recorded. After spinal anesthesia, the blood pressure and heart rate were noted at 2 min, 4 min, 6 min, 8 min, 10 min, 15 min, 20 min, 25 min, 30 min, 45 min, 60 min, 75 min, 90 min, 120 min, 150 min, and at 180 min. Statistical analysis: One way ANOVA with POSTHOC TUKEY test for comparison of the groups and CHI SQUARE test is used for categorical variables. P<0.05 was considered as statistically significant. Results: The hypotension was more in Group C compared to other groups, but is not statistically significant (P = 0.42), and requirement of vasopressor to treat hypotension is slightly more in Group C and is not statistically significant (P = 0.93). Bradycardia (heart rate<50) is seen more in Group B and were statistically significant (P<0.001). The usage atropine to treat bradycardia was more in study group and was statistically significant (P<0.002). Conclusion: Incidence of hypotension was slightly more with patients on calcium channel blockers which is slightly more than beta blocker and normotensive group. This does not warrant any discontinuation of calcium channel blocker prior to surgery, but incidence of bradycardia was seen more in patients on beta blockers who needed atropine. Anesthesiologists should anticipate and be adequately prepared for any untoward consequences.