Effects of Low-Flow and Standard-Flow Sevoflurane Anesthesia on Inflammatory Markers in Bariatric Surgery

This retrospective observational cohort study investigated the effects of low-flow and standard-flow sevoflurane anesthesia on perioperative inflammatory markers and hemodynamic stability in patients with obesity undergoing laparoscopic sleeve gastrectomy. The study included 155 adult patients operated between January 2022 and January 2025 at Adana City Training and Research Hospital, Adana, Turkey.

Patients were divided into two groups according to the fresh-gas flow rate used during anesthesia:

Low-flow group: sevoflurane with a total fresh-gas flow rate of 1 L/min,

Standard-flow group: sevoflurane with a total fresh-gas flow rate of 4 L/min.

All patients received general anesthesia as part of routine clinical care. No randomization or intervention was performed by the investigators. Demographic characteristics, anesthesia records, intraoperative hemodynamic parameters (mean arterial pressure, heart rate), and perioperative laboratory results were obtained retrospectively from hospital electronic records.

Preoperative and postoperative (24-hour) values of inflammatory markers-including C-reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR), and red cell distribution width (RDW)-were compared within and between groups. The primary endpoint was the change in these inflammatory biomarkers between pre- and postoperative measurements. The secondary endpoint was the comparison of intraoperative hemodynamic stability (MAP and HR variability, incidence of hypotension or bradycardia) between the two groups.

This study aims to provide evidence regarding whether low-flow sevoflurane anesthesia (1 L/min) offers comparable or superior inflammatory and hemodynamic profiles compared with standard-flow anesthesia (4 L/min) in morbidly obese patients. The findings may help optimize anesthetic techniques for bariatric surgery by balancing patient safety, hemodynamic stability, and environmental considerations.

Inclusion criteria

• Adult patients aged 18-60 years
• Underwent laparoscopic sleeve gastrectomy under general anesthesia
• Received low-flow or standard-flow sevoflurane anesthesia
• ASA physical status I-III
• Complete perioperative records available

Exclusion criteria

• Conversion to open surgery
• Incomplete or missing data
• Significant comorbidities (e.g., severe cardiac, hepatic, or renal dysfunction)
• Perioperative complications unrelated to anesthesia
• Age <18 or >60 years