Effect of Laryngeal Mask Cuff Shape on Pharyngeal Stress

Laryngeal masks are widely used supraglottic airway devices, but their cuffs differ considerably in shape and design. The cuff exerts pressure on the pharyngeal structures, which may provoke a physiological stress response and contribute to postoperative pharyngeal complaints. This prospective, randomized, two-centre trial compares three commercially available laryngeal masks with different cuff designs (SaCoVLM, LMA Supreme and Ambu AuraGain) in 162 adult patients undergoing elective surgery under general anaesthesia. Anaesthesia induction is standardized and guided by State Entropy, and cuff pressure is standardized to 40-50 cmH2O in all groups. The primary outcome is the change in mean arterial pressure after laryngeal mask insertion. Secondary outcomes include heart rate, nociception and depth-of-anaesthesia indices (Surgical Pleth Index, Response Entropy - State Entropy difference), insertion characteristics, oropharyngeal leak pressure and postoperative pharyngolaryngeal complaints up to 24 hours. The hypothesis is that cuff shape modifies the stress exerted on the pharynx and thereby influences the patient's stress response.

Inclusion Criteria: * Age 18-80 years * ASA physical status I-II * Scheduled for elective surgery under general anaesthesia with a laryngeal mask airway indicated * No history or predictors of difficult airway * Signed informed consent Exclusion Criteria: * Refusal to sign informed consent * ASA physical status III or higher * Emergency surgery * Laparoscopic surgery * Surgery in the prone position * Head and neck surgery * Increased risk of pulmonary aspiration (e.g. gastro-oesophageal reflux disease, body mass index \> 35 kg/m2) * Pre-existing sore throat, hoarseness or upper respiratory tract infection within the preceding 2 weeks