Effects of child seats on the cardiorespiratory function of newborns.

Background: This study aims to determine the effect of differently positioned infant car seats on cardio-respiratory parameters in healthy full-term newborns.

Methods: We examined 15 healthy term newborns for respiratory compromise due to normal restraint in a recommended infant car seat. There are currently two types of car seats available in Japan: a chair-shaped car seat and a bed-shaped car seat. Using a sleep apnea recorder, we simultaneously monitored heart rate, percutaneous oxygen saturation, chest impedance and nasal airflow in infants placed in each of the car seats and also placed in the supine position on a nursery cot. Episodes of oxygen desaturation below 95% and longer than 10 s (mild desaturation) and below 90% longer and than 10 s (moderate desaturation) were evaluated over 30 min observation period.

Results: The amount of time infants spent in a sleep state was significantly longer in the car seats than it was on the cot (P = 0.0015 for bed-shaped, P = 0.0012 for chair-shaped) and there was no difference in this measure between the two types of car safety seats. Mean of oxygen saturation with the chair-shaped car seat (95.8%) was significantly lower than that with the bed-shaped car seat (98.8%) (P = 0.0008). Newborn infants laid on the cot showed no episodes of desaturation. Newborn infants placed in the chair-shaped car seat had significantly more episodes of mild desaturation (mean, 7.33 times in nine of 15 infants), whereas in the bed-shaped seat observed only once each in two infants (P = 0.008). Moderate desaturation was observed in four of 15 infants in the chair-shaped car seat, whereas not observed in the bed-shaped car seat (P = 0.068).

Conclusion: The results suggest that prior to discharge the degree of oxygen desaturation that occurs when an infant is placed in a chair-style car seat should be checked.