Muscle Relaxants on Efficacy of LMA Insertion

• rocuronium (Drug), also known as Rocuronium bromide: After standard anesthetic monitoring (non-invasive blood pressure monitor, pulse oximetry, 3-lead echocardiography), patients are inhaled with sevoflurane. When the patients asleep, 0.3 mg/kg rocuronium is administered. After 2 min, flexible laryngeal mask airway (fLMA) is inserted using standard method. The fLMA is inflated with air to 40 cmH2O using manometry. The oropharyngeal leak pressure (OLP) was determined by the method described by Lopez-Gil and colleagues.
• saline (Drug), also known as 0.9% normal saline: After standard anesthetic monitoring (non-invasive blood pressure monitor, pulse oximetry, 3-lead echocardiography), patients are inhaled with sevoflurane. When the patients asleep, 0.3 mg/kg saline is administered. After 2 min, flexible laryngeal mask airway (fLMA) is inserted using standard method. The fLMA is inflated with air to 40 cmH2O using manometry. The oropharyngeal leak pressure (OLP) was determined by the method described by Lopez-Gil and colleagues

Primary outcomes

• Oropharyngeal leak pressure (OLP) [During 1 min after successful LMA intubation]: It was determined by the method describe by Lopez-Gil and colleagues. Briefly, it was measured by closing the expiratory valve of the circle system at a fixed gas flow of 3l/min, recording the airway pressure at which audible leak sound was heard.

Secondary outcomes

• Intubation time [During 5-10 min after inhalation of sevoflurane]: from the time of mouth opening until the time at square-wave capnography was detected
• Ease of intubation/mask bagging [During 5-10 min after inhalation of sevoflurane]: After successful LMA insertion, investigator recorded subjective difficulty during whole period of LMA manipulation by Likert scale: 1, easy 2, moderate, and 3: difficult.
• Fiberoptic view of LMA [During 5min after successful LMA insertion]: The fibreoptic view was assessed by fibreoptic bronchoscopy through the LMA and graded.
• Mean blood pressure [During 5-10 min after inhalation of sevoflurane]: mean blood pressure (mmHg) is recorded before and after the insertion of LMA.
• Heart rate [During 5-10 min after inhalation of sevoflurane]: Heart rate is (beat per minutes) recorded before and after the insertion of LMA.
• Watcha scale every 10 min from time to PACU admission to discharge [During 60 minutes after PACU admission]: On arrival and every 10 min after PACU admission, patients were checked Watcha scale as following 4-point scale 1. calm 2. crying, but can be consoled 3. Crying, cannot be consoled 4. Agitated and thrashing around
• FLACC score on initial, 10, 20, and 30 min [During 60 minutes after PACU admission]: Face, legs, activity, cry, and consolability (FLACC) score is checked every 10min after PACU admission
• Eye opening time [During 1 hour after operation]: defined as the interval from the cessation of anesthetics to eye opening
• Extubation time [During 1 hour after operation]: time from discontinuation of anesthetics to extubation
• Peak inspiratory pressure before and after the surgery [During 4 hour after anesthetic inhalation]: check the peak inspiratory pressure (cmH2O) before and at the end of surgery
• Tidal volume ratio before and after the surgery [During 4 hour after anesthetic inhalation]: check the expiratory tidal volume/setting tidal volume ratio before and at the end of surgery
• Respiratory adverse events [During 1 hour after operation]: check the adverse events during emergence and PACU stay such as coughing, laryngospasm, bronchospasm, postoperative stridor and mild desaturation; SpO2 <95%.
• Postoperative complications [During 1 hour after operation]: check the adverse events including respiratory adverse events, gastric insufflation, excessive secretion, postoperative nausea and vomiting, sore throat, and tinged blood on LMA surface.

Sex: All, ages: 2 Years to 7 Years

Inclusion Criteria:

* Children aged between 2 and 7 years of American Society of Anesthesiologists physical status (ASA PS) I or II who are planned to receive ophthalmic surgery under general anesthesia

Exclusion Criteria:

* Refusal of consent
* Present URI or other respiratory symptoms
* Oro or facial anomaly
* Poor dental condition
* who cannot open their mouth or limited mouth opening
* when the tracheal intubation is definitely needed

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• Results publication: Byun SH, Kim SJ, Kim E. Comparison of the clinical performance of the flexible laryngeal mask airway in pediatric patients under general anesthesia with or without a muscle relaxant: study protocol for a randomized controlled trial. Trials. 2019 Jan 9;20(1):31. doi: 10.1186/s13063-018-3141-2. PMID 30626406

• Eugene Kim, MD, PhD, Study chair, Assistant professor