Effect of Surgical Position and Preoperative Antihypertensive Medication on the Incidence of Intraoperative Hypotension in Patients Undergoing Spine Surgery

Background: Antihypertensive medications taken before surgery are associated with increased intraoperative hypotension, and patient positioning can further influence hemodynamics during surgery. However, the combined effects of antihypertensive medication use and patient positioning on intraoperative hypotension during spine surgery have not been clearly established. Objectives: This study aimed to investigate the incidence of hypotension in patients undergoing spine surgery according to surgical position, antihypertensive drug use, and patient characteristics through a retrospective analysis of medical records. Methods: This retrospective study analyzed 4,973 patients who had undergone spine surgery. Demographic data, medical history, antihypertensive medication use before surgery, and anesthetic information, including blood pressure during surgery, were collected from electronic medical records (EMRs). The incidence of hypotension according to surgical positioning (supine vs. prone) and antihypertensive medication use was investigated. Results: The incidence of intraoperative hypotension was higher in patients positioned prone (supine: 19.06% vs. prone: 24.91%) and among those taking more antihypertensive medications (no medication: 19.49%; one medication: 25.18%; two or more medications: 32.97%). Logistic regression indicated that patients with a history of hypertension undergoing surgery in the prone position had a significantly greater risk of hypotension [odds ratio (OR) = 1.407] and severe hypotension (OR = 1.940) compared with those with no history of hypertension undergoing surgery in the supine position. Older age, longer anesthesia duration, cervical surgical site, and the use of multiple antihypertensive agents were associated with an increased risk of intraoperative hypotension. In particular, taking two or more antihypertensive drugs (OR = 1.601) and undergoing surgery in the prone position (OR = 1.505) were independent predictors of hypotension and severe hypotension during spine surgery. Conclusions: Preoperative use of two or more antihypertensive medications increases the risk of intraoperative hypotension, and spine surgery in the prone position increases the risk of severe hypotension.