The laryngeal mask for laser surgery to the pharynx

Susceptibility of the pilot balloon of the disposable laryngeal mask airway to puncture during laser therapy

The tube of the laryngeal mask airway is frequently protected by foil during ablative laser procedures. The pilot balloon, however, is often left exposed. The effect of firing seven different cutaneous lasers at the pilot balloon of a disposable laryngeal mask airway was examined to assess its susceptibility to accidental laser strikes. The time taken for each laser to penetrate the pilot balloon was calculated from an average of five laser strikes. The carbon dioxide and erbium YAG lasers punctured the pilot balloon in a mean (SD) of 0.07 (0.02) s and 0.7 (0.1) s, respectively, with the neodymium YAG laser the next quickest to puncture at 3.3 (1.0) s. All other lasers punctured the pilot balloon in less than 15 s. These data suggest that protection of the pilot balloon of the LMA is necessary when using carbon dioxide and erbium YAG lasers.

Supplementary oxygen and the laryngeal mask airway--evaluation of a heat-and-moisture exchanger

Heat-and-moisture exchangers (HMEs) are routinely used in anaesthesia for the humidification and warming of inspired gases. The use of the Laryngeal Mask Airway (LMA) is widespread, and many anaesthetists choose to leave it in situ until the patient regains consciousness. In this study, we have investigated the effectiveness of an HME as a means of administering supplemental oxygen via LMA in the immediate postoperative period. Oxygen was administered at varying flow rates via the gas sampling port of the HME and the oxygen delivery recorded, using end-tidal oxygraphy as a measure of alveolar PO2. At an oxygen flow rate of 4 l.min-1, the HME provided a mean end-tidal oxygen concentration of 36.2% (+/- 6.2), which compares favourably to other previously described devices. The HME thus represents a convenient, effective and economical means of oxygen supplementation via the LMA.