In asthmatics requiring endotracheal intubation airway stimulation can induce severe reflex-mediated bronchoconstriction. This reflex is neurally mediated in part by the vagal nerves. Is there any evidence for the use of lidocaine pretreatment to prevent reflex bronchoconstriction?
TL;DR: Based on the studies below, pretreatment with lidocaine prior to intubating asthmatics is not recommended. The evidence may even suggest avoiding nonemergent use of lidocaine (eg renal colic) in patients with asthma.
The Evidence:
1. Two studies by Groeben have showed that IV and inhaled lidocaine attenuate histamine induced bronchospasm in asthmatics. HOWEVER the authors note that there was a high incidence of initial bronchoconstriction in the inhaled lidocaine group. This is believed to be due to irritant effect.
2. Chang investigated the effect of IV lidocaine on baseline airway tone in asthmatic patients. This study did not pharmacologically induce bronchospasm in their subjects. Chang found that IV lidocaine INCREASED airway tone and caused airway narrowing. Still, the authors hypothesized that IV lidocaine can reduce bronchospasm due to intubation.
3. Maslow performed a prospective, randomized, double-blind, placebo controlled trial to test the ability of intravenous lidocaine and inhaled albuterol to attenuate airway reactivity after tracheal intubation in asthmatic patients undergoing general anesthesia. They found that inhaled albuterol blunted airway response to tracheal intubation in asthmatic patients, whereas intravenous lidocaine did not.
4. However, there is some evidence that IV lidocaine given after endotracheal intubation mitigates bronchoconstriction in patients with asthma. Even so, these patients require close monitoring as initial bronchospasm is still a concern
