Based on a review of research related to the infant car seat challenge (ICSC), the Canadian Paediatric Society (CaPS, Canada’s version of the American Academy of Pediatrics, or AAP) has issued a revised position statement. It now says that insufficient evidence exists to recommend routine use of the ICSC as part of discharge procedures for preterm infants.
The ICSC is a screening test that has been widely used to assess preterm and other at-risk infants for apnea and reduced oxygen levels and heart rate when in the semi-upright position of a RF CR. (In the U.S., the terms “car seat tolerance test” and “angle tolerance test” are also commonly used.) Since 1991, the AAP has recommended that preterm infants (less than 37 weeks gestational age) routinely undergo ICSC screening prior to hospital discharge. The recent Canadian position statement, based on a review of available studies led by Dr. Michael Narvey, essentially changes the Canadian stance on routine ICSC from no recommendation to a recommendation against the practice. (It does not have any effect on U.S. recommendations of the AAP.)
For the position statement, Narvey first examined whether research supports the underlying basis for screening, which is that the semi-upright position of a rear-facing CR may be inappropriate for some preterm newborns because they have a much higher likelihood of oxygen desaturation (reduced oxygen in the blood), bradycardia (low heart rate), and apnea (periods of breathing cessation). While three studies were cited that indicate that there is an increased risk, these contrasted somewhat with a 1989 study of 50 infants that found some respiratory improvement while semi-reclined. (Nonetheless, polygraph data from this study confirmed some infants experienced apnea, bradycardia, and oxygen desaturation episodes in this position.) Because all four studies were not in complete agreement, Narvey concluded, “This leaves the etiology [cause] of cardiorespiratory instability in the semi-upright position unknown.”
The research also sought to examine whether evidence links adverse outcomes to placement in car seats. While the report was very clear that no infant, whether term or preterm, should be left in CRs when not in transit, it found very few incidences of babies who have died in CRs in noncrash situations. Of those few cases of infant deaths, nearly all were left in a CR as a sitting device for nontravel purposes, and even in those cases, other medical conditions were possible contributors, and only one infant had been born preterm.
Another potential adverse outcome is the delay of cognitive development among infants who spend periods of time with insufficient oxygen (hypoxemia), the negative effects of which can manifest throughout childhood. Little research has been conducted to examine this concern, and Narvey found none that was specific to hypoxemia caused by being seated in a CR. However, considering available, non-CR studies on the link between hypoxemia and neurodevelopmental outcomes (nearly all of which involved infants with problems such as congenital heart disease or sleep-disordered breathing), Narvey found “insufficient evidence to support an association with future adverse neurodevelopment.”
To complete the analysis, Narvey considered studies on how an infant’s gestational age correlates to the likelihood to fail the ICSC and whether that outcome is reliable. Although an uncited study was acknowledged to have found that the likelihood of apnea and oxygen desaturation when seated in a car seat was greater the lower the gestational age, a more recent, larger study of 1,173 infants published in 2013 found that late preterm infants (34 to <37 weeks gestational age) were more at risk than ones born at either a younger or older gestational age. The 2013 study found that the infants who passed the screening were more likely to have been born with a younger gestational age, to have been treated previously with caffeine, and to have received respiratory support.
A study of 49 preterm infants who had been screened twice (between 12 and 36 hours apart) was used to assess reliability of the ICSC. In 86 percent of the cases, the results were congruent (either both results were pass or both were fail), while in 8 percent of the cases, an infant who passed the first screening failed in the follow-up. In another study, 60 preterm infants were tested three times, with 24 to 48 hours between tests. In this test, 11 percent of those that passed a first test failed one of the subsequent tests.
“Assessment of cardiorespiratory stability using the infant car seat challenge before discharge in preterm infants (<37 weeks’ gestational age).” Citations for the individual studies reviewed by CaPS are listed in that document.
“Transportation of Preterm and Low Birth Weight Infants at Hospital Discharge.” American Academy of Pediatrics.