Preemies' Risk for SIDS Jumps with Prone Sleep

A well designed research study reinforces the importance of "back to sleep", showing that oxygen saturations in newborn infants tend to be lower in the prone position.  Dr. Susarla

Preemies' Risk for SIDS Jumps with Prone Sleep

BALTIMORE -- Preterm infants who sleep in the prone position may be at additional risk for sudden infant death syndrome (SIDS) due to decreased cerebral oxygenation, researchers reported here.

Measures of cerebral tissue oxygenation in preterm infants showed prone position sleeping was associated with significantly 7% reduced tissue oxygenation during quiet sleep at weeks 2 to 4, and months 2 to 3 (P<0.05), according to Karinna Fyfe, PhD, of the Ritchie Center of Monash University in Melbourne, Australia, and colleagues.

The preterm infants also had 3% significantly lower cerebral oxygenation during quiet (P<0.01) and active sleep (P<0.05) when sleeping in the prone position at 5 to 6 months, Fyfe said during an oral presentation at the Associated Professional Sleep Societies meeting.

The authors noted that preterm infants are at 9.6% increased risk for SIDS, which may be associated with cardiovascular instability and failure of arousal from sleep. Preterm births are also associated with lower blood pressure, abnormal blood pressure control, higher heart rate, and reduced heart rate control in infants.

The prone sleeping position has been associated with reduced blood pressure and cerebral oxygenation in full-term infants, which increases risk for SIDS.

The authors studied cerebral oxygenation and continuous blood pressure in a population of 25 otherwise healthy preterm infants who had 27 to 36 weeks gestation. Special attention was paid to months 2 and 3, as they are considered the highest risk period for SIDS, Fyfe noted.

Participants received daytime polysomnography at ages 2 to 4 weeks, 2 to 3 months, and 5 to 6 months at corrected developmental age, during which the researchers measured continuous blood pressure, heart rate, oxygen saturation, body temperature, and cerebral tissue oxygenation index.

Vital signs were measured in 2-minute intervals and were validated through continuous, noninvasive, measures.

The authors collected data on infants while in the prone and supine sleeping positions, as well as during active and quiet sleep, and all comparisons were done between prone and supine sleeping positions.

Prone sleep was significantly associated with lower oxygenation during active and quiet sleep in preterm infants at ages 2 to 4 weeks and 2 to 3 months. Oxygenation was lower, but not significantly so, at months 5 and 6 in the prone position while sleeping.

Blood pressure and peripheral oxygen saturation did not differ significantly between sleep positions.

Heart rate was significantly elevated in prone versus supine sleeping position at weeks 2 to 4 during quiet sleep (P<0.05), although this association was not seen at months 2 to 3, 5 to 6, or during active sleep.

Preemies also had a significantly higher skin temperature across all ages in the prone position versus supine position (P<0.05 for all).

Fyfe suggested the effects on oxygenation and body temperature were associated with neck blood vessels while in the prone position, as well as immature cerebral autoregulation, based on post-mortem and Doppler flow studies.

"Reduced cerebral oxygenation in the prone position may leave preterm infants vulnerable to critically low cerebral oxygenation during a cardiorespiratory event during sleep," Fyfe said, adding that these changes based on sleep position "may underpin the risks of SIDS amongst preterm infants."

She also noted that oxygenation outcomes were worse in preterm infants than full-term infants in a comparison of data from a separate study.

Session moderator Ann Halbower, MD, of Children's Hospital Colorado in Aurora noted that follow-up research should look at carbon dioxide levels of infants in a prone sleeping position.Read article here.