Several studies have demonstrated that inhalational anesthetic agents such as desflurane and sevoflurane may cause varying degrees of postoperative sore throat, hoarseness, and cough in orotracheally intubated patients. However, data evaluating these outcomes under low-flow anesthesia conditions remain limited and insufficient.

This single-center, prospective, randomized controlled study will be conducted in patients aged 18-65 years, classified as American Society of Anesthesiologists (ASA) physical status I-II, who are scheduled to undergo elective laparoscopic cholecystectomy under general anesthesia and who provide written informed consent to participate in the study.

The primary objective of the study is to compare the effects of low-flow desflurane and low-flow sevoflurane anesthesia on the incidence and severity of postoperative sore throat.

The secondary outcomes include the evaluation of postoperative hoarseness and cough, the incidence of postoperative nausea and vomiting (PONV), and the total consumption of inhalational anesthetic agents.

Postoperative sore throat (POST) is a common complaint occurring after extubation, with a reported incidence of 14-62%, and is primarily caused by mucosal irritation or injury related to orotracheal intubation and airway manipulation. Cough and hoarseness are also frequently observed complications following tracheal intubation and may negatively affect patient comfort; the incidence of these symptoms has been reported in the literature to range widely from 7% to 90%. Female sex, inappropriate endotracheal tube size, high cuff pressure, airway management devices, and the anesthetic and neuromuscular blocking agents used are among the factors associated with POST.

Low-flow anesthesia offers several advantages, including reduced heat and humidity loss, preservation of mucociliary activity, and decreased environmental pollution and cost. However, it requires close monitoring due to potential risks such as hypoxemia, hypercapnia, and hemodynamic or anesthetic depth alterations related to insufficient or excessive anesthetic delivery. Although some studies have suggested that desflurane, due to its irritant properties, may have more adverse effects on sore throat and cough compared with sevoflurane, the number of studies comparing these two agents under low-flow anesthesia conditions remains limited.

In this study, cuff pressure was standardized within the range of 20-30 cmH₂O and endotracheal tube sizes were determined according to sex in order to minimize potential confounding effects related to tube size and cuff pressure.

The study will be conducted at Kayseri City Hospital to compare low-flow sevoflurane and low-flow desflurane anesthesia in patients aged 18-65 years, classified as ASA physical status I-II, who are scheduled for elective laparoscopic cholecystectomy under general anesthesia.

All patients will receive standard monitoring including electrocardiography (ECG), non-invasive blood pressure, peripheral oxygen saturation (SpO₂), and capnography. Depth of anesthesia will be monitored using the Bispectral Index (BIS), and neuromuscular blockade will be assessed with Train-of-Four (TOF) monitoring. Prior to induction, an anesthesia machine leak test will be performed and the CO₂ absorbent will be checked. A 20G intravenous line will be established and fluid infusion initiated. Induction will be achieved with fentanyl, lidocaine, propofol, and rocuronium. Orotracheal intubation will be performed using a Macintosh laryngoscope; cuffed endotracheal tubes with an internal diameter of 7.0-7.5 mm for females and 7.5-8.0 mm for males will be used. Cuff pressure will be maintained between 20-30 cmH₂O using a manometer.

During maintenance, remifentanil infusion will be administered. The concentration of the inhalational anesthetic agent and opioid dosage will be titrated to maintain a BIS value between 40-60 and mean arterial pressure within ±20% of baseline values. In both groups, a fresh gas flow of 4 L/min will be applied for the first 10 minutes, after which the flow will be reduced to 1 L/min to maintain low-flow anesthesia. Sevoflurane or desflurane concentrations will be adjusted according to age-related minimum alveolar concentration (MAC) values. Expiratory fraction of oxygen will be maintained above 50%, and 5 cmH₂O positive end-expiratory pressure (PEEP) will be applied. Pneumoperitoneum will be maintained at 10-14 mmHg, and patients will be positioned in reverse Trendelenburg position.

For postoperative analgesia, paracetamol and tramadol will be administered, and granisetron and dexamethasone will be given for postoperative nausea and vomiting (PONV) prophylaxis. Metoclopramide will be used as rescue antiemetic if necessary. Before extubation, oropharyngeal secretions will be carefully aspirated. Neuromuscular blockade will be reversed with neostigmine and atropine, and extubation will be performed once the TOF ratio exceeds 90% with adequate spontaneous respiration.

The primary outcome will be the presence and severity of postoperative sore throat assessed at 0, 2, 4, and 24 hours after extubation using a 4-point scale (0-3).

Secondary outcomes will include the presence and severity of postoperative hoarseness and cough at the same time intervals, the incidence and severity of postoperative nausea and vomiting, the requirement for rescue antiemetic, intraoperative consumption of inhalational anesthetic agents, duration of surgery and anesthesia, and patient satisfaction at 24 hours postoperatively.

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) physical status I-II
• Aged between 18 and 65 years
• Patients who provide written informed consent to participate in the study

Exclusion Criteria:

• Patients with a recent history of upper respiratory tract infection
• Patients with a recent history of sore throat
• Patients with chronic cough
• Patients with a history of previous neck or tracheal surgery
• Patients with predictors of difficult intubation
• Patients with a history of difficult intubation
• Obese patients (BMI > 35 kg/m²)
• Patients with chronic respiratory diseases (asthma, COPD)
• Pregnancy
• Use of dexamethasone
• Patients with hepatic impairment
• Patients with allergy to paracetamol, tramadol, granisetron, dexamethasone, or metoclopramide
• Patients with known allergy to halogenated anesthetic agents
• Patients with a history of malignant hyperthermia
• Patients with mental disorders or those unable to provide reliable assessment