A Comparative Study of Hemodynamic Parameters Following Subarachnoid Block in Patients With and Without Hypertension.

Background Hypotension is common in patients receiving a subarachnoid block (SAB) and can decrease vital organ perfusion, causing increased morbidity and mortality. Patients may receive intraoperative intravenous (IV) fluids and rescue medications to avoid these adverse effects and maintain adequate hemodynamic parameters. We conducted this study to compare the hemodynamic parameters and heart rate following spinal anesthesia on patients receiving antihypertensive medications (e.g., calcium channel blockers with or without beta-blockers) with those without hypertension during surgical procedures requiring SAB. Methods We conducted this two-year, single-center, prospective observational study in patients with hypertension and blood pressure within reference ranges receiving elective surgical procedures that do not require a definitive airway. All participants were from the American Society of Anesthesiologists physical status I and II. We assigned patients into three groups. Group 1 consisted of patients with hypertension receiving calcium channel blockers. Group 2 consisted of patients with hypertension receiving calcium channel blockers with beta-blockers. Patients whose blood pressure was within reference range were assigned to group 3. We collected patient ages and body weights, and we compared heart rate (HR), systolic and diastolic blood pressure (SBP; DBP), and mean arterial pressure (MAP) between the groups. We also compared the use of intraoperative rescue medications, IV fluid administration, and patient outcomes. We used Epi Info version 7.1 (Atlanta, GA: Centers for Disease Control and Prevention) public domain software for statistical analysis. Results Seventy-eight patients were included in the study (41 men, 37 women); group 1, HR, SBP, DBP, and MAP significantly declined over time in all groups, but there were no significant differences when comparing parameters between groups. Hypotension occurred in significantly more patients in group 1 (p=0.02) than groups 2 and 3. Bradycardia was experienced by significantly more patients in group 2 (p<0.05) than group 1 and group 3. Twenty-four patients in group 3, 17 patients in group 1, and 14 patients in group 2 required IV fluid in the first 20 minutes of the procedure, and the differences between the groups were not significant. Likewise, 15 patients in group 3, 14 in group 1, and 10 in group 2 required ephedrine, but the differences were not significant. Conclusions We compared intraoperative hemodynamic parameters following spinal anesthesia on patients receiving antihypertensive medications with patients without hypertension following SAB. Our results showed no meaningful differences in hemodynamic parameters between patients receiving antihypertensive drugs (calcium channel blockers without or in combination with beta-blockers) and those not receiving antihypertensive drugs after SAB. Therefore, calcium channel blockers alone or in combination with beta-blockers can be used to control patient blood pressure prior to surgery.