Comparison of ETT and LMA on Respiratory Mechanics during the Induction of General Anesthesia in Children

Son, Soo Chang; Ko, Young Kwon; Lee, Seung Jin

Abstract

BACKGROUND: Laryngeal mask airway (LMA) has recently been introduced as an alternative for the endotracheal tube. The respiratory mechanics and respiratory parameters during positive pressure ventilation (PPV) via the laryngeal mask airway (LMA) are not well known in children. So, we compared the effects of the endotracheal tube and the laryngeal mask airway on respiratory mechanics during the induction of general anesthesia in children.
METHODS
We studied sixty ASA physical status I and II healthy children undergoing general anesthesia. Anesthesia was induced with sleep dose ketamine 1.0 mg/kg i.v., supplemented with propofol 2 mg/kg, Rocuronium 1.0 mg/kg i.v and maintained with 50% nitrous oxide and 2.0 Vol% sevoflurane. After inserting the laryngeal mask airway, its cuff was inflated using a balloon cuff gauge until the intracuff pressure reached approximately 60 cmH2O. Adequacy of ventilation was assessed by observing the end tidal carbon dioxide wave form, chest wall movement, and by stethoscope auscultation. Data were collected with lung mechanics recorders (Ventcheck, Novametrix Medical System, U.S.) at 5 and 10 minutes after intubation or LMA insertion. The data included Peak Inspiratory Pressure (PIP), Mean Airway Pressure (MAP), Peak End Expiratory Pressure (PEEP), Inspired Tidal Volume (VTins), Expired Tidal Volume (VTexp), Airway resistance (Raw), and Compliance (Cdyn).
RESULTS
No significant difference was observed between the airway pressures, tidal volumes and gas leak fractions of the ETT and LMA groups. In terms of airway resistance and compliance, significant differences were observed between the two groups at 5 and 10 minutes.
CONCLUSIONS
We conclude that the laryngeal mask airway is superior to endotracheal intubation in terms of airway resistance and compliance. The laryngeal mask airway offer an alternative for the children needing to avoid intubation under general anesthesia.