Intern Université de Montréal St-Hyacinthe, QC, Canada
Abstract: Background – Inhaled lidocaine reduces bronchial hyperreactivity in humans and cats, and improves clinical scores and airway inflammation in asthmatic horses after a two-week treatment. Its short-term effect on bronchoconstriction in severe equine asthma (SEA) is unknown. Hypothesis – Nebulized lidocaine induces transient bronchodilation. Animals – Nine horses with SEA from the Equine Asthma Research Laboratory. Methods – In a randomized, cross-over study, nebulized 10% lidocaine (2 mg/kg), 0.9% saline, and salbutamol (1.6 µg/kg, metered-dose inhaler) were administered during exacerbation. Lung function was recorded before and 5, 10, 30, and 60 minutes after administration. Data were analyzed using mixed-effects models with Dunnett’s corrections. Results – Compared to baseline measurements, lidocaine nebulization improved pleural pressure at 10 and 30 minutes (from 33.6 (mean) ±31.0 (SD) to 21.8 ±16.6 and 18.6 ±18.5 cmH2O, p< 0.03) and pulmonary elastance at 30 minutes (from 3.4 ±3.9 to 1.6 ±1.9 cm H2O/L, p< 0.03), but did not affect resistance. Salbutamol improved lung function at 5, 10, and 30 minutes (pleural pressure: from 37.3 ±30.8 to 15.9 ±11.7, 12.3 ±4.4 and 12.8 ±4.4 cmH2O; resistance: from 2.3 ±1.1, to 1.0 ±0.3, 0.8 ±0.2 and 0.9 ±0.2 cmH2O/L/s; elastance: from 3.1 ±2.8 to 1.1 ±0.7, 0.9 ±0.5 and 1.1 ±0.5 cmH2O/L, p< 0.03). Saline had no significant effect. Conclusion and Clinical Importance – Nebulized lidocaine induces transient bronchodilation, although to a lesser extent than salbutamol. The rapidity of the bronchodilation suggests that it is not solely due to the anti-inflammatory properties reported with its prolonged use.
