Postoperative nausea and vomiting (PONV) are among the most common complications following general anesthesia (GA), significantly affecting patient comfort and recovery. Although various risk factors for PONV have been identified-such as female sex, non-smoking status, and history of motion sickness-these predictors are not always sufficient to determine individual risk accurately.

Heart rate variability (HRV) reflects autonomic nervous system (ANS) balance and has been proposed as a potential physiological biomarker for predicting PONV. Reduced HRV is associated with increased vagal imbalance, which may contribute to gastrointestinal (GI) dysregulation and PONV.

This prospective observational study aims to investigate the predictive value of HRV in estimating the incidence and severity of PONV in female patients undergoing elective laparoscopic cholecystectomy (LC). A total of 110 participants will be enrolled, and preoperative and early postoperative HRV measurements will be obtained using a validated chest-strap heart rate monitor (Polar H10). HRV parameters, including the standard deviation of normal-to-normal intervals (SDNN), the root mean square of successive differences (RMSSD), and the low-frequency/high-frequency (LF/HF) ratio, will be analyzed via the Elite HRV application. Standardized anesthesia, analgesia, and antiemetic protocols will be used for all participants. PONV severity will be assessed over the first 24 hours postoperatively using a 4-point scale.

The primary objective is to evaluate whether preoperative HRV can predict PONV occurrence. Secondary outcomes include correlations between HRV parameters and PONV severity.

Inclusion Criteria:

• Female patients aged 18 to 65 years
• Scheduled for elective laparoscopic cholecystectomy
• American Society of Anesthesiologists (ASA) physical status I
• Body mass index (BMI) < 35 kg/m²
• Non-smokers
• Able and willing to provide written informed consent

Exclusion Criteria:

• History of cardiovascular, neurological, or gastrointestinal disease
• Use of medications affecting HRV (e.g., antihypertensives, diuretics, atropine, antidepressants, antipsychotics, steroids)
• Presence of systemic diseases that may affect PONV risk
• Inability to comply with study procedures

Adult female patients aged 18-65 years, scheduled for elective laparoscopic cholecystectomy under general anesthesia at a tertiary care hospital.

Individual participant data will not be shared due to institutional policies and data privacy concerns.