Perioperative hypothermia is a frequent and preventable complication that may cause adverse outcomes such as increased blood loss, impaired coagulation, and delayed recovery. Various active warming techniques are used to maintain normothermia during anesthesia; however, their comparative effects on systemic inflammatory responses remain unclear.

This randomized controlled clinical trial aims to evaluate the effects of different intraoperative warming methods on hematologic inflammatory indices - including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII) - in patients undergoing elective laparoscopic cholecystectomy under general anesthesia.

A total of eligible adult patients will be randomly assigned into four groups according to the intraoperative warming method applied:

Control Group: No active warming applied.

Forced-Air Warming (FAW) Group: Warming blanket system used throughout surgery.

Fluid Warming (FW) Group: Intravenous fluids warmed to maintain normothermia.

Combined Warming (FAW + FW) Group: Both forced-air and fluid warming applied simultaneously.

Core body temperature and perioperative data will be recorded. Venous blood samples will be obtained preoperatively and 24 hours postoperatively to calculate inflammatory indices.

The primary objective is to determine whether active intraoperative warming techniques modulate postoperative inflammatory markers compared to no warming. Secondary outcomes include intraoperative temperature trends, recovery times, and the incidence of hypothermia-related complications.

The results are expected to identify the most effective warming strategy to minimize inflammation and optimize postoperative recovery in laparoscopic procedures.

Unintended perioperative hypothermia (core temperature <36°C) commonly occurs during laparoscopic surgeries due to anesthesia-induced thermoregulatory impairment, pneumoperitoneum, and cold ambient conditions. Even mild decreases in body temperature can impair coagulation, delay drug metabolism, and alter immune function. Maintaining normothermia is therefore critical for improving surgical outcomes.

While both forced-air warming systems and fluid warming devices are routinely used, limited data exist comparing their individual and combined effects on postoperative inflammatory responses. Hematologic inflammatory indices such as NLR, PLR, and SII provide cost-effective and reproducible markers that reflect systemic inflammation and immune balance.

This prospective, randomized, controlled, parallel-group study will be conducted at Atatürk University Faculty of Medicine, Department of Anesthesiology and Reanimation.

Eligible participants are adult patients (aged 18-65 years, ASA I-II) scheduled for elective laparoscopic cholecystectomy under general anesthesia. Patients with infection, chronic inflammatory disease, hematologic disorder, or those converted to open surgery will be excluded.

Participants will be randomly assigned to one of four groups:

Group C (Control): No active warming; standard passive insulation only.

Group FAW (Forced-Air Warming): Forced-air warming blanket applied from induction until the end of surgery.

Group FW (Fluid Warming): Intravenous fluids administered through a warming device.

Group CF (Combined Warming): Both forced-air warming and fluid warming used together.

Standardized anesthesia induction and maintenance protocols will be followed for all patients. Core temperature will be continuously monitored via nasopharyngeal probe. Temperature, hemodynamic parameters, and perioperative variables will be recorded at fixed intervals.

Blood samples will be obtained at two time points - preoperatively and at 24 hours postoperatively - for complete blood count analysis. The inflammatory indices (NLR, PLR, SII) will be calculated and compared among groups.

Primary Outcome:

Postoperative change in hematologic inflammatory indices [(neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII)].

Secondary Outcomes:

Intraoperative temperature maintenance, recovery characteristics, and hypothermia-related adverse events.

Statistical analyses will be performed using SPSS. Continuous variables will be expressed as mean ± SD or median (IQR) and analyzed using ANOVA or Kruskal-Wallis test, as appropriate. Categorical data will be compared using Chi-square or Fisher's exact test. A p-value <0.05 will be considered statistically significant.

This study seeks to clarify whether intraoperative thermal management strategies influence the systemic inflammatory response, potentially guiding clinicians toward the most effective warming method to enhance recovery and minimize postoperative complications.

Inclusion Criteria:

• Patients scheduled for elective laparoscopic cholecystectomy.
• ASA (American Society of Anesthesiologists) physical status I-III.
• Age between 18 and 65 years.
• Willingness and ability to provide written informed consent.

Exclusion Criteria:

• ASA IV-V patients.
• Emergency surgery requirement.
• Preoperative fever (>38.0 °C) or hypothermia (<36.0 °C).
• Operation duration <60 minutes or >180 minutes.
• Endocrine/metabolic disorders affecting body temperature (e.g., moderate-severe thyroid dysfunction, pheochromocytoma, severe dysautonomia, malnutrition).
• Active infection/sepsis or systemic infection within past 2 weeks.
• Chronic immunosuppressive therapy (e.g., ≥10 mg/day prednisolone equivalent ≥2 weeks or biological agents in the past month).
• Hematologic disorders (e.g., leukemia, aplastic anemia, myeloproliferative disorders) or abnormal blood counts (platelet <100 ×10⁹/L, leukocyte <3 ×10⁹/L).
• Active malignancy or ongoing chemotherapy/radiotherapy in last 3 months.
• Severe organ failure (Child-Pugh C liver, eGFR <30 mL/min/1.73 m² or dialysis, NYHA III-IV heart failure, GOLD III-IV COPD).
• Coagulopathy or uncontrolled antithrombotic therapy.
• Pregnancy or lactation.
• Conversion from laparoscopic to open surgery.
• Non-adherence to assigned warming protocol.
• Inability to place esophageal temperature probe or unreliable temperature monitoring.
• Intraoperative hemodynamic instability requiring prolonged vasopressor support or blood transfusion.
• Missing or incomplete preoperative or postoperative CBC preventing calculation of inflammatory indices.
• Withdrawal of consent or loss to follow-up.

De-identified participant data (demographics, perioperative temperature, hematologic inflammatory indices) will be made available upon reasonable request to qualified researchers after publication of the primary study results.

Data and supporting documents will be available starting 6 months after publication of the primary study results, for a period of 5 years.

Qualified researchers affiliated with recognized academic or clinical institutions may request access to the de-identified dataset and supporting documents via email to the corresponding author. Requests will be reviewed for scientific validity and compliance with ethical standards, and data will be shared under a data use agreement.