Total Intravenous Anesthesia (TIVA), Combined Intravenous-Volatile Anesthesia (CIVA), and Balanced Anesthesia (BAL) on Perioperative Oxidative Stress in Video-Assisted Thoracoscopic Surgery (VATS)

Scientific Rationale and Validity of the Medical Research Hypoxic pulmonary vasoconstriction (HPV) is a homeostatic mechanism unique to the pulmonary vascular system. In response to alveolar hypoxia, intrapulmonary arteries constrict and redirect blood flow toward better-oxygenated lung segments, thereby optimizing ventilation/perfusion matching and systemic oxygenation . Additionally, HPV acts as a physiological protective mechanism by reducing the shunt of deoxygenated blood and improving the degree of hypoxemia. This physiological modulation is influenced by various factors including medications, temperature, acid-base status, airway pressure, patient positioning, and cardiac output . Numerous animal and isolated lung studies have demonstrated that HPV is modulated by volatile anesthetics . However, human studies have reported inconsistent results regarding the effects of various anesthetics on systemic oxygenation during one-lung ventilation.

One-lung ventilation is frequently employed during thoracic surgical procedures such as thoracotomy and thoracoscopy to provide an adequate surgical view. Patients undergoing one-lung ventilation are at risk of hypoxemia due to impaired oxygenation, as well as postoperative lung injury attributable to oxidative damage occurring during reventilation of the non-dependent lung.

During one-lung ventilation, the non-ventilated lung becomes not only atelectatic but also hypoperfused as a result of HPV. Once two-lung ventilation is re-established, the reintroduction of oxygen into the airways triggers reactive pulmonary vasodilation and reperfusion of the lung tissue, which may result in the generation of excessive oxidative radicals. Although the lung is relatively resistant to hypoxia owing to dual blood supply and consumption of oxygen stored in alveolar spaces, re-expansion injury observed after pneumothorax treatment and reperfusion injury following lung transplantation serve as examples of potential oxidative damage .

Research Questions How do TIVA, CIVA, and BAL anesthetic techniques affect oxidative stress responses in patients undergoing one-lung ventilation? Which anesthetic management approach (CIVA, TIVA, BAL) provides better preservation of oxygenation? Will there be a significant difference in postoperative nausea and vomiting (PONV) incidence among the groups? Study Design, Methods, and Procedures Participants Written informed consent will be obtained from all participants. Sixty patients aged 18-65 years, classified as American Society of Anesthesiologists (ASA) Physical Status I-II, scheduled for elective video-assisted thoracoscopic surgery (VATS) at Atatürk University Medical Faculty Hospital between December 1, 2025 and May 1, 2026, and requiring one-lung ventilation for more than 60 minutes will be included. Patients will be informed about the study prior to enrollment. Individuals who decline participation, have known allergies to the study drugs, have a recent history of vitamin supplementation, or who have significant cardiovascular, renal, or hepatic disease will be excluded. The study will be conducted in three groups.

Randomization Patients will be randomly assigned into three equal groups (TIVA, CIVA, and BAL) using the Microsoft Excel RAND function. All other investigators and outcome assessors will remain blinded to group allocation.