Acute respiratory failure secondary to polymyxin-B inhalation.

A patient with asthma was given aerosol treatment with a solution containing 25 mg of polymyxin-B, and 0.7 ml of isoetherine diluted in 2 ml of isotonic saline. After a few inhalations, he had a severe, near-fatal asthmatic reaction requiring resuscitation, intubation, and mechanical ventilation. The reaction was attributed to the polymyxin-B and occurred despite the patient's receiving maintenance prednisone, 80 mg per day, and the concomitant administration of isoetherine. Possible mechanisms include: (1) bronchial irritant effect or reflex bronchoconstriction, (2) type I (IgE mediated) allergic reaction, or (3) direct histamine release induced by polymyxin, a basic polypeptide known to cause histamine release.