Insertion of the laryngeal mask airway--a prospective study of four techniques.

The standard insertion technique (ST 0) for laryngeal mask airway insertion was compared to three alternative techniques in 120 patients. The alternative techniques included insertion using the standard approach, but with the cuff either semi-inflated (ST 0.5) or fully inflated (ST 1.0), and a non-standard approach using a back-to-front technique (like a Guedel airway) and with the cuff fully deflated (T 180). Successful insertion was judged by fibreoptic positioning (P < 0.02) and that confirmed that the ST 0 and T 180 were superior to ST 0.5 and ST 1.0 in terms of fibreoptic positioning (P < 0.02) and that insertion with the cuff deflated (ST 0 and T 180) resulted in fewer insertion failures than with the cuff inflated (ST 0.5 and ST 1.0) (P < 0.05). Insertion with the LMA back-to-front with the cuff deflated produced similar fibreoptic and functional results to the standard technique. In 23%, however, there was some residual rotation of 25-90% to the coronal plane.