Fentanyl-induced cough--pathophysiology and prevention.

Many reports have demonstrated that intravenous administration of a bolus of fentanyl at induction of anesthesia can cause coughing with varying degrees. This cough can be benign, but sometimes it causes undesirable side effects including an increase in intraabdominal, intracranial or intraocular pressure. Many studies demonstrated that the incidence and severity of fentanyl-induced cough could be related to age, ethnicity, history of smoking, as well as to the rate, route, dose and concentration of fentanyl administered. This cough was described by several mechanisms including an inhibition of central sympathetic system leading to vagal predominance, reflex bronchonstriction after the stimulation of tracheobronchial tree receptors, or histamine release. The efficacy of several measures to avoid fentanyl-induced cough have been demonstrated, and several anesthetics adjuncts can be given prior to fentanyl administration aiming at decreasing this unwanted side effect.