Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 0 0 2026 01 01 1371 1371 Naeimeh Naeimi Bafghi Clinical Research Center, Shahid Bahonar Hospital, Kerman University of Medical Sciences, Kerman, Iran. Shirin Salajegheh Clinical Research Center, Shafa Hospital, Kerman University of Medical Sciences, Kerman, Iran. Neda Naeimi Bafghi Clinical Research Center, Shahid Bahonar Hospital, Kerman University of Medical Sciences, Kerman, Iran. Shahryar Hakimpour Clinical Research Center, Shahid Bahonar Hospital, Kerman University of Medical Sciences, Kerman, Iran. Vida Mirzaie Department of Anatomical Science, Afzalipour School of Medicine, Kerman University of Medical Sciences, Kerman, Iran. 2025 08 06 2025 08 13 Background: With advancements in medical technology, surgery has become a primary therapeutic option for numerous diseases. A successful surgical procedure requires proper anesthesia and accurate monitoring of vital signs, particularly blood pressure and arterial oxygen saturation. In the lateral decubitus position (LDP), hydrostatic forces may cause differences in blood pressure between the dependent and non-dependent limbs. This study aims to investigate non-invasive blood pressure (NiBP) and arterial oxygen saturation positional differences between dependent and non-dependent limbs. Methods: 17 males and 22 females undergoing nephrectomy with convenience sampling, aged 18–70 years, with ASA physical status I or II were selected. Patients with peripheral vascular disease, cardiac disorders (e.g., atrial fibrillation, coarctation), inability to measure BP in one arm, significant preoperative BP asymmetry, uncontrolled hypertension, and refusal to participate were excluded. Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP), Mean Arterial Pressure (MAP), and Arterial Oxygen Saturation (SpO₂) were pre-specified and were consistently measured using non-invasive monitors. Results: A significant difference was observed in systolic, diastolic, and mean arterial pressures between the two arms following the lateral positioning (p < 0.001). However, oxygen saturation levels did not differ before and after positioning. Conclusion: The findings indicate a significant variation in blood pressure between dependent and non-dependent limbs in LDP, but no change in oxygen saturation. This emphasizes the importance of choosing the correct arm for accurate blood pressure measurement and hemodynamic management. https://aacc.tums.ac.ir/index.php/aacc/article/view/1371