Relationship of the ventilatory response to hypoxia with neonatal apnea in preterm infants.
OBJECTIVE
Correlate the ventilatory response of preterm infants to hypoxic exposure with incidence of neonatal apnea. Study design Seventeen stable convalescing premature infants underwent bedside cardiorespiratory monitoring of respiration using respiratory inductance plethysmography, heart rate, and oxygen saturation (SaO(2)) for a 12-hour period. These studies were scored for number of apneas > or =15 and > or =20 seconds. Infants then underwent a 3-minute hypoxic exposure. Minute ventilation (V(E)) was calculated for 30-second epochs from the time inspired oxygen reached 15%. Linear regression analysis was used to correlate the change in V(E) normalized for decrease in SaO(2) (DeltaV(E)/DeltaSaO(2)) during the first and third minutes of hypoxic exposure with the number of apneic episodes during the 12-hour study.


RESULTS
The majority of infants exhibited an anticipated biphasic ventilatory response to hypoxia. There was a significant positive correlation between DeltaV(E)/DeltaSaO(2) during the first and third minutes of hypoxic exposure and number of apneic episodes > or =15 and > or =20 seconds during the preceding 12 hours.


CONCLUSIONS
Preterm infants with a greater number of apneic episodes exhibit an increased ventilatory response to hypoxic exposure, suggesting that apnea of prematurity may be associated with enhanced peripheral chemoreceptor activity.
Nock
Mary L
ML
Department of Pediatrics, Division of Neonatology, Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, Ohio 44106, USA. mnock9@hotmail.com
Difiore
Juliann M
JM
Arko
Marina K
MK
Martin
Richard J
RJ
D001049:Apnea / Q000503:physiopathology*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D007231:Infant, Newborn; D007234:Infant, Premature; D016014:Linear Models; D008297:Male; D010991:Plethysmography; D012119:Respiration