Airflow Resistances of Endotracheal Tubes

An increase in airway resistance secondary to the retention of pulmonary secretions is commonly observed in acute respiratory failure and represents one of the cardinal indications for endotracheal intubation. Placement of an endotracheal tube promotes tracheal toilet by providing a patent airway through which copious or viscid secretions may be suctioned. On the other hand, it must be remembered that an endotracheal tube constitutes a flow-resistive element against which the ventilatory apparatus must work. Usually, this added work is of minor clinical consequence because the energy is furnished by a mechanical ventilator instead of the patient. In such a context, the facilitation of bronchial hygiene constitutes the highest priority. Once the patient is stabilized and the withdrawal of mechanical ventilatory support (weaning) is contemplated, however, the net benefit of tube maintenance may become marginal or illusory. A recent communication in JAMA 1 has effectively emphasized the fact that the endotracheal