Oxygen Desaturation in Term Infants in Car Safety Seats

The need for a period of observation of infants born prematurely to monitor for oxygen desaturation, apnea, or bradycardia when positioned semireclined in car safety seats has been well established.^1–3 Whether otherwise healthy term infants are at risk for similar episodes while positioned in car safety seats, however, has not been fully determined and warrants additional investigation. A recent study, published in this journal in which 50 term infants were monitored documented that when properly positioned semireclined in rear-facing car safety seats, the mean oxygen saturation levels declined significantly from 97% to 94% after 60 minutes.⁴ Also, 8% of these term infants had oxygen saturation values of <90% for longer than 20 minutes. A previous report of a series of selected term infants with preexisting health conditions believed to place them at risk for potential oxygen desaturation documented that 28.6% of those infants demonstrated oxygen saturations <90% when tested in their car safety seat for 90 minutes.⁵ In addition, the same report speculated that prolonged oxygen saturations under 96% while in a car seat may be associated with clinical consequences. One infant was described, after an apparent life-threatening event, to have oxygen saturations during a car safety seat test in the 90% to 95% range for 90 minutes. When that patient was retested in the supine position, saturations of 96% and above were noted for a full 90 minutes. A relationship between this infant’s predisposition to oxygen desaturation in the car safety seat and the apparent life-threatening event has been suggested but is unproven.

The same authors have also documented the death of a premature infant while positioned in a car safety seat.³ In addition, we are aware of several anecdotal reports of deaths attributed to sudden infant death syndrome of both term and preterm infants that have occurred while positioned semireclined in car safety seats. In other patient groups, specifically children with congenital heart disease, it is thought that chronic oxygen desaturation may have long-term consequences on cognitive function.⁶ Whether these findings are pertinent to infants experiencing oxygendesaturation associated with car safety seat positioning is unknown. We strongly recommend additional investigation of these potential relationships.

It is certain that the use of car safety seats is essential for prevention of injuries to children in motor vehicle crashes.⁷ Physicians must continue to encourage their proper use. Effectiveness of correctly used child safety seats in preventing death and serious injury to infants is clearly documented,⁸ but there is also a need for more research on the optimum design of child restraints and the effect of positioning on the respiratory physiology of young infants.

At the present time, the use of car beds for infants who experience documented apnea, oxygen desaturation, or bradycardia is a necessary alternative to the use of rear-facing car safety seats for safe transportation. The relative safety provided by these car beds compared with rear-facing car safety seats, however, has not been determined. Development of methods to evaluate the relative protection provided by these types of child restraints and the design of seats that properly accommodate small infants should also be encouraged.

Current information suggests that:

1. In addition to infants born prematurely, near term and term healthy newborns may experience oxygen desaturation when properly positioned upright in car safety seats. Until additional research on the potential significance of oxygen desaturation in car safety seats is available, consideration should be given to limiting the time spent in car safety seats to that necessary for transportation and ensuring children are not left unattended while in a car safety seat.

2. Positioning young infants in devices such as swings, infant carriers, backpacks, or slings may have similar physiologic effects in susceptible infants to positioning semireclined in car safety seats, and consideration should also be given to limiting the use of these devices as well.

We emphasize that these recent observations and the considerations proposed above are consistent with current American Academy of Pediatrics policy guidelines for safe transportation of children in motor vehicles. They are intended to provide a practical perspective on the recent report of Merchant et al⁴ as well as draw attention to important areas in need of additional research.

• Copyright © 2002 by the American Academy of Pediatrics