Preterm infants are at increased risk of cardiorespiratory compromise due to pulmonary and neurologic immaturity, which is exacerbated by positional changes such as sitting upright in a car seat. The AAP recommends a period of observation in a car seat prior to discharge for all neonates born <37 weeks' gestation, or the Infant Car Seat Challenge (ICSC), to monitor for apnea, bradycardia, desaturations. There are ~500,000 infants that qualify annually. This is a resource intensive test with little information on failure rates and risk factors for failure. We sought to determine the incidence of failure of the ICSC and identify significant clinical/demographic predictors in order to potentially minimize resource utilization by allowing more selective testing.
Retrospective medical record review of all neonates born <37 weeks' GA during a two year period between January 1, 2009 and December 31, 2010 that qualified for ICSC based on prematurity. We looked at ICSC result as well as potential demographic and clinical risk factors and then performed bivariate and multivariate logistic analysis to evaluate for significant predictors of failure.
Of the 1118 qualifying infants, we obtained records on 953 (85%). 12 died, 12 had no results, so we had records on 929 (83%). Of these, 44 failed (4.7% failure rate). Bivariate analysis showed no significant differences based on race, gender, mode of delivery, singleton vs. multiple gestation, or use of steroids, diuretics, or reflux medications. Those that failed had a significantly higher birth gestational age with median 36-1/7 weeks’ vs. 34-6/7 in those that passed (p=.002), higher birth weight at 2200grams vs. 2501grams in those that passed (p=.009), and lower chronologic age (p=.0004). Those that passed were significantly more likely to have required some form of respiratory support (p=.04), and to have been on caffeine (p=.046). On logistic analysis, chronologic age at testing (failure OR=.977, 95% CI .955-.99) and use of anti-reflux medications (failure OR=.123, 95% CI .02-.68) were significant predictors of failure when controlling for gender, race, and birth weight.
Many expect that neonates born at younger gestations, smaller weights, with longer periods of critical illness would be more likely to fail the ICSC, and that the late preterm neonates (34-37 weeks’) would be more likely to pass and may not need to be tested. Our data indicates that those that fail tend to be the late preterm neonates, require fewer medical interventions, and are chronologically younger at the time of the test. A significant predictor of failure was younger chronologic age at the test. This indicates that it is important to continue ICSCs for these higher risk late preterm neonates. Use of anti-reflux medications was also significant (lower OR of failure) which needs to be further evaluated.