Appropriate laryngeal mask airway size for overweight and underweight children.

The aim of this study was to compare conventional laryngeal mask airway sizing by weight with sizing by age in over- or underweight children. We studied 26 overweight (body mass index > 85th centile) and 26 underweight (body mass index < 15th centile) children. After general anaesthesia was induced, laryngeal mask airways sized by the patient's weight and by an ideal weight (estimated from the patient's age according to standardised tables) were inserted consecutively. In overweight children, oropharyngeal leak pressure was significantly greater when the laryngeal mask was sized by the patient's actual weight. On the other hand in underweight children, it was significantly greater when sized by the ideal weight. In conclusion, laryngeal mask airway sizing according to the manufacturer's weight-based recommendation is to be preferred in overweight children, but laryngeal mask airway size by an ideal weight estimated from the patient's age is a better choice in underweight children.