1714 UPPER AIRWAY OBSTRUCTION IN THE SUDDEN INFANT DEATH SYNDROME (SIDS)

Abstract

Acute airway obstruction in the pharynx or larynx causing asphyxia is a proposed cause of SIDS and “near miss” SIDS. Documentation of these events in such cases is rare. We studied 2 infants at high risk for SIDS in whom absent respiratory efforts alternating with obstructed respiratory efforts (i.e., mixed apnea) produced episodes of asphyxia. Infant A (28wk gestation) had apnea and bradycardia spells through the first month of life. In polygraphic studies at 5days of age (heart rate, abdominal excursion, nasal and oral airflow, TcPO2), we identified 9 mixed apnea spells causing hypoxemia (TcPO2 as low as 29Torr) and bradycardia (as low as 33bpm). This infant died at home of SIDS (autopsy diagnosis) at 14wks of age. Infant B, a thriving 32wk gestation infant, had a family history of SIDS (half sibling) but no history of apnea or bradycardia until 4wks when he required resuscitation for sudden cardio-respiratory arrest (i.e., “near miss SIDS”). Spells of apnea, cyanosis and bradycardia recurred for 4wks in this otherwise healthy infant. We monitored 4 episodes of mixed apnea, each causing hypoxemia (TcPO2 as low as 36Torr) and bradycardia (as low as 70bpm). In infant B we found the site of obstruction to be above the larynx by using a pharyngeal catheter which detected transmission of thoracic pressure during obstructed breaths. Documentation of mixed apnea causing asphyxial spells in these at risk and subsequent SIDS infants supports the concept that mixed apnea with pharyngeal obstruction could be a cause of the fatal SIDS event. (NIH grant#HD 10993)