GAS LEAKAGE AND THE LARYNGEAL MASK AIRWAY - A COMPARISON WITH THE TRACHEAL TUBE AND FACEMASK DURING SPONTANEOUS VENTILATION USING A CIRCLE BREATHING SYSTEM

The ability of the laryngeal mask airway, tracheal tube and facemask t o provide a leak free seal in a clinical setting was assessed by measu ring the minimal fresh gas flows needed in a closed circle system duri ng spontaneous ventilation on 60 subjects. The fresh gasflow was reduc ed until no spillage occurred from rite pop-off valve. This fresh gas flow was taken to represent the sum of gas uptake by the subject and g as leakage fi on? the circuit. The median fresh gas flow after 20 minu tes was 350 ml.min(-1) in the laryngeal mask airway group, 350 ml.min( -1) in the tracheal tube group and 450 ml.min(-1) in the facemask grou p. The fresh gas flow required for facemask group was significantly hi gher than that for the laryngeal mask airway ol tracheal tribe groups (p < 0.01). There was no significant difference between the flesh gas flows required for the tracheal tube and laryngeal mask airway groups. We conclude that the laryngeal mask airway provides as good a gas tig ht seal as a tracheal tribe in this context and would be of benefit in I educing anaesthetic gas pollution.