Physiologic consequences of tracheal intubation.

Many principles that originate in the operating room and in fluid mechanics modeling are relevant to endotracheal intubation in the pulmonary and critical care setting. These factors should be appreciated by pulmonologists and intensivists, as they may contribute to improved safety during the process of airway access. The usual reflex responses to stimulation of oropharyngeal and upper airway receptors include glottic closure, hypertension, tachycardia, and reflex bronchoconstriction. These reflexes can be modified by technical or pharmacologic reduction of sensory receptor stimulation or by parenteral agents, which diminish efferent responses, including anesthetics, vasoactive drugs, and adrenergic blockers. Topical anesthesia and parenteral sedatives may be the preferred agents when overall risk and benefit are considered. Intubation also has consequences related to a reduction in airway caliber, to changes in respiratory mechanics, and to the creation of turbulent airflow in the endotracheal tube.