To the Editor.—
Recently, I had the opportunity to review my hospital’s policy on safe transportation of newborns from the hospital. The recommendation of the American Academy of Pediatrics for routine testing of infants <37 weeks’ gestation for car safety-seat intolerance1,2 lacks supporting evidence-based data. No studies of validated protocols or interventions are presented. Recommendations based on sensible suggestions to use car seats properly are not objectionable. However, many questions are unanswered. What if car-seat design is the source of the problem? Evidence-based studies are needed.
Interpreting the results of a “car-seat” test is daunting. No protocol has been validated to predict the infant at risk. Poets3,4 addressed the importance of carefully controlled studies monitoring oxygen saturation to evaluate the incidence of hypoxia in the newborn. Oxygen saturation may fall into the 80% range in infants who are well.4,5 Clearly, some infants become hypoxic while sitting in a car seat. The infant’s gestational age, size, posture, muscle tone, and position seem to contribute to car-seat intolerance.6–8 Because the infant’s head is proportionally large relative to the rest of the body, the straight back of the car seat may flex the neck excessively, increasing the risk of hypoxia. Tonkin et al9 found that a simple intervention reduced neck flexion and decreased the incidence of hypoxia.
How long should an infant be evaluated while sitting in a car seat? One and a half hours are recommended,6 which represents a significant burden to the nursing staff. Large controlled studies do not exist to justify a prolonged evaluation. If the concern relates to the infant’s risk of central hypoxia or sudden infant death syndrome, then the infant should be evaluated differently.
What is the best intervention? The car bed may be problematic. Infants in a supine position have more frequent episodes of periodic breathing and hypoxia.4 Also, car beds are expensive and may not be readily available. If one is found it may be too big to fit in the family’s vehicle. If the problem lies in the design of car safety seats, we should focus on improving the evaluation and certification of these products.
Do other devices used to hold infants (such as swings, snugglies, bouncy seats, etc) cause problems? Stening et al10 studied infants held in sling-type carriers and in prams. Term infants did well, but premature infants had episodes of oxygen desaturation related to their position in the sling.
The American Academy of Pediatrics guidelines are a good starting point.1,2,11 However, car-seat testing should not be recommended until validated protocols and evidence-based data are available. Other devices that hold infants also may cause problems and should be studied. Infant positioning and improving the devices used to hold infants may produce the greatest benefit.
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- Copyright © 2004 by the American Academy of Pediatrics
