Use of the endotracheal tube as a pharyngeal airway

An animal study was conducted to determine whether an endotracheal tube placed above the vocal cords in the pharynx can be used for ventilation. Four dogs undergoing general anesthesia were ventilated through an endotracheal tube placed in the oropharynx with the remainder of the airway occluded. Ventilation was performed for 3 of every 5 minutes during a total period of 25 minutes. Arterial Pco2 was compared in sequential samples alternating apnea and pharyngeal ventilation. Ventilation via the pharyngeal tube significantly reduced the arterial Pco2 from 48.8 mm Hg (SD 16) during apnea to 30.1 mm Hg (SD 10.9). Repeated measures ANOVA F = 8.2, P< .001. All Pco2 levels during ventilation were in or below the normal range of 34 to 46. Provided that the mouth and nose can be sealed, an endotracheal tube placed in the pharynx above the cords allows for adequate ventilation.