APNEA CAUSED BY REGURGITATION IN INFANTS

Abstract

Regurgitation (R) of gastric contents is presumed to cause apnea in some infants. The mechanism of such apnea is unclear and polygraphic documentation is lacking. We recorded nasal airflow (flowmeter), abdominal movements, oral CO2 and EKG in 13 infants. Group A (9 preterm infants, age 2-4 wk and 1 term, age 1 wk) had a history of idiopathic prolonged apnea and ordinary post-feeding R episodes (spitting up); Group B (3 term infants, age 3 mo) had R only. R episodes were recorded in all infants (43 episodes in Group A and 10 in Group B). In 37 of 53 R episodes pharyngeal pressure and pH were recorded to aid in detection of R. In Group A most R episodes (92%) were immediately followed by either a short apnea (S-apnea = absent airflow ≥3 sec) or prolonged apnea (P-apnea = absent airflow for ≥20 sec or absent flow with heart rate ≤100 or cyanosis). Although most of the 100 P-apneas recorded in Group A were unrelated to R episodes, 8 P-apneas (occurring in 4 preterm infants) coincided with R (a statistically significant association in 3 infants: p<.01, p<.05, p<.05). All Group A infants had S or P-apnea, or both, during R. There were no S or P-apneas during R in Group B. Most P-apnea (83%) and S-apnea (78%) consisted of obstructive inspiratory efforts or breathing pauses combined with obstruction. We conclude: 1) regurgitation has little effect on breathing in healthy term infants but often causes S-apnea and, occasionally, P-apnea in infants with a past history of apnea; and 2) the mechanism of this apnea involves both airway obstruction and respiratory depression. Funding: NIH HD 10993.