Effects of anesthesia techniques on tissue oxygenation and recovery in lower abdominal surgery

EFFECTS OF ANESTHESIA TECHNIQUES ON TISSUE OXYGENATION AND POSTOPERATIVE RECOVERY IN LOWER ABDOMINAL SURGERY SUMMARY Surgical stress and perioperative pain increase adrenergic activation, leading to peripheral vasoconstriction, reduced perfusion, and tissue hypoxia. Tissue oxygen pressure (StO₂) is critical for wound healing and postoperative recovery. Different anesthesia techniques can influence microcirculation and tissue oxygenation. Near-infrared spectroscopy (NIRS) allows noninvasive and continuous monitoring of regional tissue oxygenation. This study aimed to investigate the effects of different anesthesia techniques applied in lower abdominal surgeries on tissue oxygenation and postoperative recovery, and to evaluate the predictive ability of NIRS monitoring of thenar and plantar regions in assessing peripheral tissue oxygenation and postoperative recovery. This prospective, observational, single-center study was conducted at Trakya University Faculty of Medicine between March 2023 and March 2025. The study was approved by the Ethics Committee (TUTF-GOBAEK 2023-25) and registered at ClinicalTrials.gov (NCT07102108). A total of 180 patients aged 18–85 years, ASA I–III, undergoing open lower abdominal surgery in the supine position were included. Patients were divided into four groups according to the anesthesia technique: General Anesthesia (Group G), General + Epidural (Group GE), Spinal (Group S), and Epidural (Group E), each consisting of 45 patients. Patients with liver, heart, kidney, or lung failure, peripheral vascular disease, obesity (BMI > 40.5), neurological deficits, or communication difficulties were excluded. Peripheral tissue oxygen saturation (StO₂) was measured from the plantar and thenar regions using the Masimo MOC-9 (O3-RO®) device. Demographic data, vital signs, incision length, VAS scores, Quality of Recovery-40 (QoR-40) scores, and postoperative outcomes were recorded. Regional anesthesia techniques—particularly spinal and epidural anesthesia—were hypothesized to enhance microvascular perfusion by reducing sympathetic tone, thereby improving tissue oxygenation, accelerating postoperative recovery, reducing complication rates, and shortening hospital stay. Understanding the effects of different anesthesia methods on tissue oxygenation may contribute to developing anesthetic strategies that optimize microcirculation and improve postoperative outcomes. Especially, continuous and noninvasive NIRS monitoring of thenar StO₂ may serve as a valuable tool for assessing peripheral tissue perfusion and recovery quality in patients undergoing abdominal surgery. Keywords: StO₂, Thenar, Plantar Anesthesia, Spinal anesthesia, Epidural anesthesia, NIRS, Tissue oxygenation, Postoperative recovery, QoR-40, Lower abdominal surgery.