Anatomy and physiology of tracheostomy.

The trachea is easily accessible at the bedside. As such it provides ready access for emergency airway cannulation (eg, in the setting of acute upper airway obstruction) and for chronic airway access after laryngeal surgery. More commonly, tracheostomy tubes are placed to allow removal of a translaryngeal endotracheal tube. Tracheostomy tubes have an important effect on respiratory physiology. The most recent and methodological robust studies indicate that these tubes reduce resistive and elastic work of breathing, when compared to endotracheal tubes. This is a result of tracheostomy tubes lessening inspiratory and expiratory airways resistance and intrinsic positive end-expiratory pressure. Whether these physiologic benefits are of clinical importance in enhancing weaning success remains to be elucidated.