A Study Comparing the Laryngeal Mask Airway Supreme With the Laryngeal Mask Airway Protector In the Ambulatory Surgery Unit

• Outpatients planned for elective minor surgery, routinely done with LMA, will be asked to participate in the study.
• The patient is preoxygenated for 3 min. Anaesthesia is induced with 0.15 mcg/kg sufentanil and 1 - 4 mg/kg propofol. Routine monitoring is used together with BIS-monitoring. No neuromuscular relaxing agent is used. Patients lungs will be ventilated with a face mask for 3 min and then the LMA will be inserted while the neck of the patient is flexed, the head extended. LMA cuff is completely deflated. The LMA is inserted using a single-handed rotational technique. Failed insertion is defined as: failed passage in the pharynx, malposition (air leak) and ineffective ventilation (expired tidal volume<25% of administered volume). The time between picking up the LMA and successful placement is recorded. When failed on the first attempt the LMA will be inserted with a digital guided technique. A Third attempt will be a gum-elastic-bougie guided technique.
• Oropharyngeal leak pressure is determined at 0-40ml cuff volume in 10 ml increments. The expiratory valve of the circle system is closed at a fixed gas flow of 3 l/min and noting the airway pressure at equilibrium (max allowed 40 cmH2O)
• Fiber optic position: 4=only vocal cords visible, 3=vocal cords + posterior epiglottis, 2=vocal cords + anterior epiglottis, 1=vocal cords not seen. Fiber optic position will only be evaluated if available at the moment of the study.
• Cuff pressure is set at 65 cmH2O using a manometer and patients lungs are ventilated at a tidal volume of 10 ml/kg, at a respiratory rate of 12/min. Presence of air leak is detected by listening over the mouth, gastric air leak (stethoscope over epigastrium, larynx, drain tube air leaks (lubricant over proximal end) or end-tidal CO2 > 45 mmHg. Respiratory settings are changed at the discretion of the anesthesiologist after successful placement.
• Correct gastric tube placement is assessed by suction of fluid. Cardiorespiratory data are collected: bradycardia >100/min, tachycardia >, hypotension, hypoxaemia
• Upon removal of the LMA at the end of the procedure the device will be checked for blood staining.
• At discharge from day surgery unit patients will be asked for presence of sore throat.

Inclusion criteria

• Patients who are planned for elective minor surgery in the ambulatory surgery unit, who are ASA I or II or III, aged 19-71 years, whose operation is routinely done with a Laryngeal Mask Airway in the supine position.

Exclusion criteria

• Patients are excluded if they are <19 or >71 years, have an anticipated difficult airway, a body mass index > 35kg.m-2 or are at risk of aspiration.