Hypoxic Drive

The patient described in the vignette is hypoventilating because of an excessive inspired concentration of oxygen. Patients who have some forms of chronic pulmonary disease (eg, bronchopulmonary dysplasia [BPD]), often have some degree of carbon dioxide retention and depend on their hypoxemic respiratory drive to maintain adequate ventilation. Thus, they may hypoventilate if too high a concentration of oxygen is administered to them, although in practice, this is a rare occurrence.

The rapid onset of respiratory failure reported for the child in the vignette makes either pneumonia or congestive heart failure highly unlikely. Further, respiratory muscle fatigue would be unusual in a child whose respiratory rate was normal and who showed no signs of respiratory distress during the initial physical examination. An upper airway obstruction usually is recognized immediately as the patient makes efforts to re-establish an airway.

To minimize the risk of hypoventilation in the child who has chronic lung disease, some experts recommend providing oxygen in concentrations sufficient to maintain oximetry readings in the low to mid-90s. Oxygen toxicity is not a concern in patients who already are hypoxic and in acute respiratory failure. These patients should receive assisted ventilation along with high levels of oxygen as necessary to maintain adequate oxygenation. The inspired oxygen concentration can be weaned as the patient stabilizes.

Stokes DC. Respiratory failure. Pediatr Rev. 1997;18:361-366
Toder DS, McBride JT. Home care of children dependent on respiratory technology. Pediatr Rev. 1997;18:273-280