Episodic airway obstruction in premature infants.

Seventy-six premature infants with clinical apnea, bradycardia, or cyanosis were studied with polygraph recordings of heart rate, nasal thermistor detection of airflow, and impedance pneumography. Pathologic apnea was defined by cessation of breathing for greater than 20 s or less than 20 s with bradycardia (heart rate, less than 100 beats per minute). Apnea was classified as central, obstructive, or mixed. Four hundred thirty-three apnea episodes were demonstrated: 238 (55.0%) were central, 53 (12.2%) showed obstructive apnea, and 142 (32.8%) were mixed. Fifty-two infants (68.5%) demonstrated some degree of obstructive apnea, while 24 infants (31.5%) had central apnea only. Bradycardia did not occur in any patient unless preceded by apnea. In premature infants, a significant percentage of apnea was associated with airway obstruction.