Laryngeal mask bite blocks - rolled gauze versus Guedel airway

Background: Biting on the silicone tube and pilot balloon of the laryngeal mask airway (LMA) may obstruct or damage them with the teeth and a bite block is recommended. The recommended bite block is a wad of gauze swabs rolled into a cylindrical shape and placed alongside the LMA. It is considered that this avoids irritating the posterior pharyngeal wall and damage to teeth whilst supporting the LMA tube when taped to it. The Guedel airway is commonly used as a bite block with the tra-cheal tube and many anaesthetists also use it with the LMA. The aim of the following study was to compare rolled gauze swabs with a Guedel airway as a bite block for the LMA.
Methods: We compared the Guedel airway with rolled gauze swabs as a bite block for the laryngeal mask airway (LMA) in 120 ventilated patients in whom cuff pressures were limited to 5.87 kPa (60 cm H₂₀) and anaesthesia management was standardised.
Results: In the Guedel airway group, there was a higher incidence of ventilatory problems (0 vs 4, P < 0.05), bleeding (0 vs 8, P < 0.01), hoarseness (0 vs 4, P 0.05) and sore throat (2 vs 12, P < 0.01).
Conclusion: 1. The Guedel airway is an unsuitable bite block for the LMA. 2. Cuff pressure limitation is compatible with adequate ventilation. 3. The combination of LMA and Guedel airway probably prevents either from sitting in the correct anatomical position.