Modulation of the Inflammatory Response in Bariatric Surgery

This is a prospective, randomized, double-blind, comparative observational study designed to assess the perioperative inflammatory response in patients undergoing bariatric surgery under three anesthetic techniques: opioid-free anesthesia (OFA), opioid-based intravenous anesthesia (OBA-IV), and opioid-based inhalational anesthesia (OBA-Inh).

A total of 90 patients scheduled for elective laparoscopic bariatric surgery will be enrolled and randomized using computer-generated allocation into three equal groups (n=30 each). Allocation concealment will be maintained using sealed opaque envelopes. Blinding will involve both the patients and outcome assessors; anesthesiologists administering the interventions will not be blinded due to the nature of the techniques.

The study's primary focus is to evaluate the perioperative modulation of inflammation through quantification of biomarkers including interleukin-6 (IL-6), C-reactive protein (CRP), serum cortisol, leukocyte count (WBC), erythrocyte sedimentation rate (ESR) and lactate. Heart rate variability (HRV) will be continuously monitored as a surrogate marker for autonomic modulation of the inflammatory response.

Biomarkers will be sampled at three time points: preoperative baseline (T0), at the end of surgery (T1), and 24 hours postoperatively (T2). HRV data will be collected from induction to the end of surgical intervention using a non invasive monitoring system with time- and frequency-domain analysis.

Secondary outcomes include intraoperative and postoperative analgesic consumption, pain intensity assessed by visual analog scale (VAS), sedation scores using the Ramsay Agitation-Sedation Scale (RASS), incidence of opioid-related side effects (nausea, vomiting, respiratory depression), patient satisfaction (via validated questionnaire), and length of hospital stay.

Sample size was calculated based on preliminary data detecting a clinically significant difference in IL-6 levels, assuming an alpha of 0.05 and power of 0.8. Data will be analyzed using ANOVA or Kruskal-Wallis test for continuous variables, chi-square for categorical variables, and multivariate regression models to adjust for potential confounders.

This study aims to identify anesthetic strategies that minimize systemic inflammation and autonomic dysregulation in the bariatric surgical population, with potential applications in broader surgical settings.

Inclusion criteria

• Patients scheduled for bariatric surgery.
• Age 18-65 years.
• BMI ≥ 30 kg/m².
• ASA physical status II-III.

Exclusion criteria

• Pregnancy or breastfeeding.
• Chronic opioid use before surgery.
• Severe renal or hepatic failure.
• Uncontrolled psychiatric disorders.
• Significant intraoperative complications requiring protocol deviation.