[A clinical investigation of the laryngeal mask airway]

The size 2, 3 and 4 laryngeal masks (LM) were used in 50 patients having various types of clinical anesthesia. We measured the airway pressure at which gas leak occurred during the use of the LM. We compared the time taken to obtain clear airway, when patients were receiving 4.5 or 6 l.min-1 fresh flow by anesthetic machines. We compared the changes of SpO2, heart rate (HR) and arterial pressure (AP) at the time of insertion of the LM during the tracheal intubation. The LM could be successfully inserted in all the patients. Even if the head position was changed, there was no significant change in the leak pressure on each LM size. In both children and adult, the time interval taken to obtain clear airway by the LM was two-thirds of the time necessary during the tracheal intubation. While the LM or the endotracheal tube was inserted, delta SpO2 and delta HR in children, and delta AP in adult were much smaller in the LM group than in the endotracheal tube group. We conclude that the LM is very useful in the clinical anesthesia, and the LM gives less influence to cardiopulmonary system compared with tracheal intubation while offering clear airway.