SUPINE VS. TRENDELENBURG POSITIONING EFFECTS ON BLOOD PRESSURE, CARDIAC OUTPUT, AND VASOPRESSOR REQUIREMENT DURING SPINAL ANESTHESIA

Abstract

Background: Spinal anesthesia commonly induces hypotension due to sympathetic blockade, leading to decreased cardiac output and increased vasopressor requirement. Patient positioning plays a crucial role in modulating these hemodynamic changes. The comparative effects of the supine versus Trendelenburg position on blood pressure, cardiac output, and vasopressor use remain an important clinical consideration.

Objective: To compare the effects of supine and Trendelenburg positioning on blood pressure, cardiac output, and vasopressor requirements during spinal anesthesia.

Methodology: A 6-month cross-sectional comparative study was conducted at Hayatabad Medical Complex, Peshawar, including 172 adult surgical patients selected through probability sampling. Sample size was calculated using Cochran’s formula. Patients were allocated into two groups: Supine (n=86) and Trendelenburg (n=86). Hemodynamic parameters, including systolic and diastolic blood pressure, mean arterial pressure, heart rate, and cardiac output, were measured at baseline and at regular intervals post-spinal anesthesia. Vasopressor requirement and total dose administered were recorded. Data were analyzed using SPSS 26, with mean ± SD for quantitative variables and chi-square tests for categorical comparisons. A p-value ≤ 0.05 was considered statistically significant.

Results: The Trendelenburg group showed significantly better maintenance of systolic and diastolic blood pressure compared to the supine group (p < 0.05). Cardiac output was consistently higher in the Trendelenburg position across all measurement intervals. Vasopressor requirement was lower in the Trendelenburg group (23.2%) compared to the supine group (44.1%), with a significantly reduced total vasopressor dose (p < 0.01). Age and gender distributions were comparable between groups.