Small endotracheal tubes: ventilator and intratracheal pressures during controlled ventilation.

The use of small endotracheal tubes reduces the trauma of intubation. Ventilator and tracheal pressures were measured during controlled ventilation with various tube dimensions and ventilation volumes. Ventilation with large volumes using small tracheal tubes results in high ventilator pressures. However, tracheal pressures are only marginally greater than those obtained with larger tubes. Small endotracheal tubes and high ventilation volumes result in a positive tracheal pressure at the end of expiration. The measured end-expiratory pressures are within the limits which might be used therapeutically (in PEEP). The force required to reshape endotracheal tubes of varvious dimensions to an "anatomical" shape was related to the tube dimensions; the beneficial effects of performed, "anatomically shaped" endotracheal tubes can be achieved by using small tubes of standard design.