Ventilation Safety in Beach Chair Shoulder Surgery: SafeLM Versus I-gel

Shoulder surgery is frequently performed in the beach chair position (BCP), which may alter upper airway anatomy and increase the risk of airway-related complications. Changes in head and neck alignment, limited access to the airway due to surgical draping, and fluid extravasation during arthroscopy may negatively affect ventilation.

Supraglottic airway devices (SADs) are widely used in general anesthesia due to their ease of insertion and reduced invasiveness compared to endotracheal intubation. The i-gel® is a commonly used second-generation SAD with a non-inflatable cuff, while SafeLM™ is a video-guided laryngeal mask airway that allows real-time visualization of the glottic structures.

This prospective, randomized controlled study aims to compare SafeLM™ and i-gel® in patients undergoing shoulder surgery in the beach chair position. Patients aged 18-80 years with ASA physical status I-III will be randomly assigned to either the SafeLM™ or i-gel® group.

All patients will receive standardized anesthesia management, including induction with propofol and fentanyl and maintenance with sevoflurane. No neuromuscular blocking agents will be used. Following successful placement of the airway device, correct positioning will be confirmed by clinical and capnographic parameters.

The primary outcome of the study is the comparison of oropharyngeal leak pressure (OLP) within the first 10 minutes after transition to the beach chair position. OLP will be measured using a standardized technique with the adjustable pressure-limiting valve set to a maximum of 40 cmH2O.

Secondary outcomes include the incidence of ventilation impairment, need for airway interventions (such as jaw thrust, head repositioning, device adjustment or replacement), desaturation and hypercapnia episodes, first-attempt success rate, insertion time, and postoperative complications including sore throat, dysphonia, and postoperative nausea and vomiting.

In the SafeLM™ group, glottic visualization will be assessed using a standardized scoring system, and changes in glottic view associated with positional changes will be recorded.

This study aims to provide evidence on whether a video-guided supraglottic airway device offers advantages over a conventional device in maintaining airway stability and ventilation safety in the beach chair position.

Inclusion criteria

• Patients aged 18-80 years
• American Society of Anesthesiologists (ASA) physical status I-III
• Scheduled for elective shoulder surgery
• Body mass index (BMI) between 18-40 kg/m^2
• Adequate preoperative fasting (approximately 8 hours)
• Ability and willingness to provide written informed consent

Exclusion criteria

• Age <18 or >80 years
• Refusal to participate
• ASA physical status >= IV
• BMI >40 kg/m^2
• Failure of supraglottic airway device placement after three attempts
• Revision surgery
• Multiple trauma
• Maxillofacial fracture
• Active malignancy receiving radiotherapy or chemotherapy
• Active infection or ongoing antibiotic therapy (except prophylaxis)
• Chronic steroid or immunosuppressive therapy
• Full stomach
• Gastroesophageal reflux disease
• History of gastric surgery
• Gastroparesis
• Known egg allergy