Optimal End-Tidal (ET) Sevoflurane and Desflurane Concentration for Extubation of Supreme Laryngeal Mask Airway (LMA) in Adults

Optimal End-Tidal Concentration of Sevoflurane and Desflurane for Removal of Supreme Laryngeal Mask Airway in Anaesthetized Adults

The purpose of this study is to determine the optimal volatile anaesthetic (sevoflurane and desflurane) to remove a Supreme LMA in adults in which there is minimal airway response.

Null hypothesis: there is no significant difference between the optimal end tidal concentration of sevoflurane and desflurane for Supreme LMA removal.

The manufactures' instructions for removal of the LMA recommend waiting until protective reflexes have returned. However, the appropriate timing for removal remains controversial. A more frequent incidence of airway hyperreactivity and complications has been reported by some studies when the LMA was removed in the awake state versus the anesthetized state. Techniques that reduce the time from LMA removal to the return of protective airway reflexes would minimize the risk of aspiration, contamination, or airway obstruction.

With increasingly common use of Supreme LMA in anaesthetic practice, a safe and suitable depth for removal of the Supreme LMA requires research.

Thus the determination of the optimal end-tidal concentration of commonly used volatile agents ie. Sevoflurane and Desflurane for Supreme LMA removal requires research, both for patient safety and minimising anaesthetic costs in dealing with airway complications.

Inclusion Criteria:

1. ASA 1-2 patients
2. Age 18 - 49 years old
3. Elective surgery of short duration ( < 2 hours ) which require local anaesthetic infiltration

Exclusion Criteria:

1. Upper respiratory tract symptoms in the previous 10 days
2. Risk of gastric oesophageal reflux or regurgitation
3. Known or predicted difficult airway
4. Poor dentition with high risk of damage
5. BMI > 30 kg/m2
6. Refusing to participate