Effect of Adding Remifentanil to Thiopental Anaesthesia Induction on Classic Laryngeal Mask Airway Insertion Success: A Randomized Double-Blind Clinical Trial

This study received approval from the Okmeydani Education and Research Pharmaceutical Research Local Ethics Committee (decision number 110), and informed consent was obtained from all patients. Conducted from October 2013 to December 2013, the study included 100 ASA class I-II patients, aged 18-65 years, undergoing elective surgery without muscle relaxants, with operations lasting no more than 2 hours, and requiring LMA insertion. Patients with conditions such as neck or upper respiratory tract pathologies, high aspiration risk, morbid obesity, or difficult airway indicators (e.g., Mallampati class 3-4, limited neck mobility), along with those with histories of pulmonary disease, allergies to study medications, or substance dependence, were excluded. Standard monitoring included ECG (lead II), non-invasive blood pressure (SAP, DAP, MAP), SpO2, respiratory rate, end-tidal CO2, and inspired oxygen concentration. Anaesthesia depth was measured using a bispectral index (BIS-Vista™, Aspect Medical Systems, Newton, MA, USA). Patients received preoxygenation with 6 L/min oxygen, followed by IV midazolam (0.03 mg/kg). Patients were randomly assigned to four groups (n=25 per group) receiving 0.5, 1, 2, or 3 µg/kg remifentanil via coded syringes prepared by an independent anaesthesiologist. Remifentanil was infused over 60 seconds with an infusion pump (Braun Infusomat®). Thirty seconds after starting remifentanil, thiopental (5 mg/kg) was administered over 30 seconds. LMA was inserted 90 seconds after thiopental administration, provided BIS values were below 40 and adequate jaw relaxation was achieved. The conditions for LMA insertion were assessed using a 6-variable scale evaluating chin opening, ease of insertion, swallowing, coughing, laryngospasm, and patient movement. Outcomes were categorized as excellent, satisfactory, or poor. Hemodynamic parameters (SAP, DAP, MAP, HR, BIS, SpO2) were recorded at baseline, 1 minute before LMA insertion, and at 1, 2, 3, 4, and 5 minutes after insertion. Postoperative assessments included the presence of blood after LMA removal and evaluations for throat pain and dysphagia upon discharge from the recovery unit. Throat pain was scored from 0 (no complaints) to 3 (severe pain). Dysphagia was assessed as difficulty swallowing provoked by drinking.