Car seat test for preterm infants: comparison with polysomnography.

OBJECTIVES

To monitor preterm infants in a cot and a car seat and compare an observed car seat trial with polysomnography (PSG).

DESIGN

Non-randomised controlled trial.

SETTING

Regional neonatal unit.

PATIENTS: Preterm infants before discharge.

INTERVENTIONS: Nap PSG respiratory and sleep variables were measured including gastro-oesophageal pH. Nurse observations included respiratory distress, apnoea measured by apnoea alarm, oxygen saturation and heart rate. Infants were studied supine in a cot and then in a car seat. Nursing observations were compared with PSG during the car seat trial only. Criteria for failure of the PSG and observed tests were predefined.

MAIN OUTCOME MEASURES: Difference in respiratory instability between cot and car seat. Concurrence regarding failure of the car seat trial between nurse-observed data and PSG.

RESULTS

20 infants (median gestation 33 weeks (range 28-35 weeks; median postmenstrual age (PMA) at study 36.5 weeks (range 35-38 weeks)) were studied. There were sufficient car seat data on 18 infants for comparison. There were fewer central apnoeas and arousals in the cot than the car seat (p = 0.047 and p = 0.024, respectively). Airway obstruction was not more common in the car seat. Younger PMA at time of study predicted failure in both car seat (p = 0.022) and cot (p = 0.022). The nurse-observed test had low sensitivity for predicting PSG failure but more accurately predicted airway obstruction on PSG.

CONCLUSIONS

Immature infants exhibit respiratory instability in cots and car seats. A car seat test does not accurately detect all adverse events during sleep in the seat.