Airway reflexes, autonomic function, and cardiovascular responses

In this article, we review the cardiovascular responses to the inhalation o f irritants and pollutants. Many sensory receptors in the respiratory syste m, from nose to alveoli, respond to these irritants and set up powerful ref lex changes, including those in the cardiovascular system. Systemic hypoten sion or hypertension, pulmonary hypertension, bradycardia, tachycardia, and dysrhythmias have all been described previously. Most of the experiments h ave been acute and have been performed on anesthetized experimental animals . Experiments on humans suggest we have similar sensory systems and reflex responses. However, we must use caution when applying the animal results to humans. Most animal experiments, unlike those with humans, have been perfo rmed using general anesthesia, with irritants administered in high concentr ations, and often to a restricted part of the respiratory tract. Species di fferences in the response to irritants are well established. We must be eve n more careful when applying the results of acute experiments in animals to the pathophysiologic changes observed in prolonged exposure to environment al pollution in humans.