Better understanding of ventilator-induced lung injury, gas exchange, and tolerance to respiratory acidosis has provided a knowledge base upon which less hazardous ventilatory approaches can be fashioned. Several innovative, but unproven, approaches have been designed to accomplish acceptable ventilation without incurring excessive airway cycling pressures. Tracheal gas insufflation represents a minimally invasive adjunct to ventilatory support, which is potentially applicable to a broad spectrum of clinical problems characterized by poorly tolerated carbon dioxide retention and excessive ventilatory pressure. Tracheal gas insufflation reduces the anatomic deadspace by expiratory flushing of the proximal airway with fresh gas injected near the carinal level, thereby improving carbon dioxide clearance when small tidal volumes are used. A considerable body of experimental work in animals, as well as more limited clinical data, indicate the clinical potential of tracheal gas insufflation in an intensive care setting.