Topical lidocaine improves conditions for laryngeal mask airway insertion

We hypothesized that optimal laryngeal mask airway (LMA) insertion conditions might be achieved with topical lidocaine and a smaller dose of propofol. In this study, insertion conditions after topical lidocaine 40 mg followed by propofol 2 mg.kg(-1) were compared with propofol 2 mg.kg(-1) or propofol 3 mg.kg(-1) alone.

Ninety patients were recruited for this randomized prospective double-blind study. One group received four sprays of topical lidocaine (40 mg) over the posterior pharyngeal wall followed by propofol 2 mg.kg(-1) (Group 2PL; n = 30). The other two groups received four sprays of 0.9% normal saline followed by propofol 2 mg.kg(-1) (Group 2P; n = 30) or by propofol 3 mg.kg(-1) (Group 3P; n = 30). The frequency of optimal insertion conditions (successful insertion at the first attempt without adverse responses) and side effects were recorded.

The frequency of optimal insertion conditions was greater in Group 2PL (20/30, 67%) and Group 3P (22/30, 73%) than in Group 2P (11/20, 37%) (P = 0.009). In Group 3P, the mean blood pressure was lower than in the other groups prior to LMA-Classic insertion (P = 0.003) but was similar after insertion. The incidence of apnea was greater in Group 3P patients (17/30, 57%) than in Group 2P (2/30, 7%) or Group 2PL patients (1/30, 3%) (P < 0.001).

Topical lidocaine 40 mg followed by propofol 2 mg.kg(-1) can provide optimal insertion conditions of the LMA-Classic comparable to those of propofol 3 mg.kg(-1), with fewer hemodynamic changes and a lower incidence of apnea.