The use of laryngeal mask airway (LMA), size 3 or 4, and endotracheal tube (ETT) 8.0 mm was studied comparatively to determine the adequacy of respiratory function during positive pressure ventilation (PPV) by applying a series of given peak inspiratory pressures (PIPs) of 10.0, 12.5, 15.0, 17.5, 20.0 and 30.0 cm H2O. Eleven anesthetised patients underwent a double comparative trial. First they were ventilated via the LMA and afterwards via the ETT. Tidal volume (VT), dynamic compliance, end-tidal carbon dioxide and peripheral oxygen saturation were recorded in a supine position, before skin incision. Higher values of VT (1.7 mk.kg-1) were expired via the LMA compared with ETT when a given PIP of less than 20 cmH2O was applied. LMA as opposed to ETT secured normocapnia during PPV with low PIPs.
Female Humans