Oxygen enrichment during emergence with the laryngeal mask--the 'T-bag' versus the T-piece.

We have compared the performance of a new oxygen enrichment device, the 'T-bag', with a T-piece during emergence from spontaneous breathing anaesthesia with the laryngeal mask airway. Thirty patients were randomly allocated to each group. Inspired and end-tidal gases were sampled from the proximal end of the laryngeal mask airway. Cardiorespiratory variables were recorded immediately prior to discontinuation of anaesthesia, 2 min later and then at 5-min intervals until removal of the laryngeal mask airway. The mean inspired oxygen concentration was greater than 70% and the inspired carbon dioxide was less than 2 mmHg in both groups throughout emergence. There were no episodes of hypoxia (oxygen saturation < 92%). Both devices performed well, but the 'T-bag' offered advantages in terms of respiratory monitoring and ventilatory capability.