Effects of Inhaled Lidocaine on Airway Function in Asthmatic Subjects

Abstract

The effect of inhaled lidocaine was measured on pulmonary function in 8 asthmatic subjects. Plethysmographic specific airways conductance (SGaw) and the 1 s forced expired volume (FEV1) were measured before and after the inhalation of 2 cm3 of lidocaine (4%). Responses were also measured after patients were pretreated with aerosolized isoproterenol, aerosolized atropine or i.m. atropine. In response to lidocaine alone, a 23.4 .+-. (SE) 4.8% fall in FEV1 and a 64.1 .+-. (SE) 3.8% fall in SGaw (P < 0.001) was observed. These effects were reversed with aerosolized atropine or isoproterenol. After pretreatment with aerosolized atropine or isoproterenol, the bronchoconstrictor effect of lidocaine was prevented or markedly reduced. The protective effects of i.m. atropine varied in different subjects, but in general aerosolized bronchodilators afforded better protection against the bronchoconstrictor effect of lidocaine. Although lidocaine was theoretically capable of blocking neurogenic reflexes in the lung, this topical anesthetic agent may produce untoward reflex-mediated bronchoconstriction in patients with asthma and hyperirritable airways.