Physiological monitoring studies have shown that some preterm infants who are otherwise ready for hospital discharge experience episodes of oxygen desaturation, apnoea, or bradycardia when seated in standard car safety seats. The American Academy of Pediatrics recommends that all preterm infants are assessed for cardiorespiratory stability in their car seat before discharge: the "car seat challenge". This screening test has been incorporated into discharge assessments in most neonatal units in North America and is being increasingly used in the United Kingdom and elsewhere. The evidence base for the use of the car seat challenge in discharge assessment, the possible implications for infants, their families, and health services of adopting the practice, and the issues that may be resolved with further research are discussed.

Current information suggests that: 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. 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.

Objectives. To test prospectively the hypothesis that an infant car seat modification to allow the infant’s head to rest in a neutral position on the trunk would prevent narrowing of the upper airway and thus reduce oxygen desaturation in preterm infants who are restrained in car seats. Methods. Seventeen preterm infants who were approved for discharge were evaluated in a car seat for newborns, with and without a foam insert that provided a slot for the back of the infants’ head. Respiration timed inspiratory radiographs for assessment of upper airway dimensions were taken during quiet sleep in each position. Infants were monitored in each position for 30 minutes with continuous polygraphic recording of respiratory, cardiac, and nasal airflow activity and pulse oximetry. Results. Placement of the insert in the car seat was associated with a larger upper airway space (mean ± standard deviation, 5.2 ± 1.3 vs 3.6 ± 1.4 mm). This radiologic improvement was associated with a significant reduction in the frequency of episodes of oxygen desaturation to <85% (1.5 ± 2.1 vs 3.5 ± 3.5 episodes/infant), of bradycardia <90 bpm (0.1 ± 0.3 vs 1 ± 1.7), and of arousal (median [25th, 75th], 2.5 [1.3, 4.0] vs 5.0 [4.0, 7.0]). Conclusions. The cause of oxygen desaturation in preterm infants who are restrained in car seats is multifactorial. The present data strongly support the hypothesis that flexion of the head on the body is a significant contributor to these episodes and that the mechanism is posterocephalic displacement of the mandible, leading to narrowing of the upper airway. Critically, this pilot study demonstrates that the frequency of episodes of desaturation in a standard newborn car seat can be substantially reduced by placement of a simple foam insert that allows the infant to maintain the head in a neutral position on the trunk during sleep.

Aims: To determine the combined effects of sudden infant death syndrome (SIDS) risk factors in the sleeping environment for infants who were "small at birth" (pre-term (<37 weeks), low birth weight (<2500 g), or both). Methods: A three year population based, case-control study in five former health regions in England (population 17.7 million) with 325 cases and 1300 controls. Parental interviews were carried out after each death and reference sleep of age matched controls. Results: Of the SIDS infants, 26% were "small at birth" compared to 8% of the controls. The most common sleeping position was supine, for both controls (69%) and those SIDS infants (48%) born at term or 2500 g, but for "small at birth" SIDS infants the commonest sleeping position was side (48%). The combined effect of the risk associated with being "small at birth" and factors in the infant sleeping environment remained multiplicative despite controlling for possible confounding in the multivariate model. This effect was more than multiplicative for those infants placed to sleep on their side or who shared the bed with parents who habitually smoked, while for those "small at birth" SIDS who slept in a room separate from the parents, the large combined effect showed evidence of a significant interaction. No excess risk was identified from bed sharing with non-smoking parents for infants born at term or birth weight 2500 g. Conclusion: The combined effects of SIDS risk factors in the sleeping environment and being pre-term or low birth weight generate high risks for these infants. Their longer postnatal stay allows an opportunity to target parents and staff with risk reduction messages.

Pediatric Pulmonary Unit, MassGeneral Hospital for Children, Harvard Medical School, 55 Fruit St, Boston, Massachusetts 02114, USA. tkinane@partners.org OBJECTIVE: The objective of this study was to compare the respiratory physiologic features of healthy term infants placed in either a car bed or a car safety seat. METHODS: Within the first 1 week of life, 67 healthy term infants were recruited and assigned randomly to be monitored in either a car bed (33 infants) or a car safety seat (34 infants). Physiologic data, including oxygen saturation and frequency and type of apnea, were obtained and analyzed in a blinded manner. RESULTS: The groups spent similar amounts of time in the devices (car bed: 71.6 minutes; car seat: 74.2 minutes). The mean oxygen saturation values were not different between the groups (car bed: 97.1%; car seat: 97.3%). The percentages of time with oxygen saturation of < 95% were also similar for the 2 groups (car bed: 11.8[corrected]%; car seat: 18.3[corrected]%). In both groups, a number of infants spent high percentages of study time with oxygen saturation of < 95%. The 6 infants with the most time at this level were all in the car safety seat group (54%-63% of study time). Values for the 6 infants in the car bed group with the most time at this level were lower (20%-42%). This difference in the duration of oxygen saturation of < 95% was not statistically significant. The mean end-tidal carbon dioxide levels and the numbers of episodes of apnea were similar for the 2 groups. CONCLUSIONS: The respiratory physiologic features of infants in the 2 car safety devices were observed to be similar. Of note, substantial periods of time with oxygen saturation of < 95% were surprisingly common in both groups. PMID: 16882803 [PubMed - indexed for MEDLINE]

Department of Pediatrics, University of Texas, Southwestern Medical Center, Dallas, Texas, USA. walid.salhab@UTsouthwestern.edu OBJECTIVE: To compare the incidence of apnea, bradycardia, or desaturation in a car seat with that in a car bed for preterm very low birth weight (< or = 1500 g) infants. STUDY DESIGN: Infants were studied for 120 minutes in a car seat and in a car bed. Apnea (> 20 seconds), bradycardia (heart rate < 80/min for > 5 seconds), desaturation (SpO2 < 88% for > 10 seconds), and absent nasal flow were monitored. RESULTS: We assessed 151 infants (median birth weight, 1120 g [range, 437 to 3105]; median birth gestational age, 29 weeks [24 to 34]) in both devices. Twenty-three infants (15%) had > or = 1 event in the car seat compared with 29 (19%) in the car bed (P = .4). Time to first event was similar in the car seat and car bed (mean, 54 to 55 minutes). In logistic regression analyses, bronchopulmonary dysplasia was a significant predictor for a car seat event and a lower gestational age at birth was a risk factor for a car bed event. CONCLUSIONS: We found no evidence that an event is less likely in a car bed than in a car seat. Whichever device is used, very low birth weight infants require observation during travel. PMID: 17307533 [PubMed - in process]

Objective. Premature infants who are discharged from intensive care nurseries are known to be at increased risk for apnea, bradycardia, and oxygen desaturation while in the upright position. These small infants also do not fit securely in standard infant car seats. Because of these problems, the American Academy of Pediatrics recommends a period of observation in a car seat for all infants who are born at <37 weeks' gestation. It is not clear whether this recommendation should apply to the minimally preterm infants (born at 35-36 weeks' gestation) who are healthy at birth and are hospitalized in the normal newborn nursery. The objective of this study was to evaluate the respiratory stability and safety requirements of healthy, minimally preterm infants in car seats compared with term infants. Methods. Fifty healthy, nonmonitored, preterm infants (mean gestational age: 35.8 ± 0.6 weeks) and 50 term infants (mean gestational age: 39.5 ± 1.4 weeks) were recruited from a level I newborn nursery in a community hospital. Appropriateness of car seat fit was documented for each infant. Heart rate, respiratory rate, and pulse oximetry were evaluated while infants were supine and in their car seats. Apneic and bradycardic events were recorded in addition to a continuous recording of oxygen saturation values. Results. Twenty-four percent of preterm and 4% of term newborn infants did not fit securely into suitable car seats despite the use of blanket rolls. Mean oxygen saturation values declined significantly in both preterm and term infants from 97% in the supine position (range: 92%-100%) to 94% after 60 minutes in their car seats (range: 87%-100%). Seven infants (3 preterm and 4 term) had oxygen saturation values of <90% for longer than 20 minutes in their car seats. Twelve percent of the preterm infants (95% confidence interval: 4.5%-24.3%) but no term infants had apneic or bradycardic events in their car seats. Conclusions. Our data support the current American Academy of Pediatrics recommendations that all infants who are born at <37 weeks' gestation, including those who are admitted to level I community hospitals, be observed for respiratory instability and secure fit in their car seats before hospital discharge. Because lowering of oxygen saturation values was seen uniformly in all newborn infants, car seats should be used only for travel, and travel should be minimized during the first months of life. Key words: car seat, newborn, prematurity, apnea, bradycardia, oxygen desaturation.

Department of Pediatrics, Division of Neonatal Medicine, Robert Wood Johnson Medical School / University of Medicine and Dentistry of New Jersey, New Brunswick, New Jersey, USA. ojadiva@umdnj.edu BACKGROUND: Little is known about the factors that predispose to the occurrence and severity of cardio-respiratory symptoms during the placement of a prematurely born infant in a car seat. The impact of gestational age, weight at discharge and infant's pre-existing cardio-respiratory status (in the supine position) on cardio-respiratory function during pre-discharge testing in a car seat (semi-upright position) has not been investigated. METHODS: The cardio-respiratory function of 42 preterm neonates with gestational age 24 to 35 weeks and discharge weight 1790 to 2570 grams were monitored for 45 minutes before, during, and after placement in a car seat. The occurrence of periodic breathing, apnea, bradycardia, or decreased oxygen saturation (SaO2) was analyzed. RESULTS: Prior to the car seat testing, 15 (35.7%) infants displayed one or more abnormalities of cardio-respiratory function. During the car seat testing, 25 (59.6%) infants had periodic breathing, 33 (78.2%) had oxygen saturation <90%, 14 (33.3%) had bradycardia less than 80 beats per minute, and 35 (83.3%) had a combination of these symptoms. Infants, both with and without pre-existing cardio-respiratory abnormalities, had an almost equal probability (80% vs. 83.3%) for the development of cardio-respiratory symptoms during placement in the car seat. Weight at discharge ([less than or equal to] 2,000 grams) but not the gestational age (<28 weeks or [greater than or equal to] 28<37 weeks), was associated with either increased episodes of oxygen desaturation or the combination of cardio-respiratory symptoms that were seen during the placement of these infants in the car seat. Repositioning from the car seat to the supine position showed normalization of cardio-respiratory function in the majority (83%) of the tested infants. None of the tested clinical factors were associated with the severity of the cardio-respiratory symptoms. CONCLUSION: Pre-discharge testing of the cardio-respiratory function of preterm infants during placement in a car seat is important for the prevention of cardio-respiratory symptoms during their transportation. However, the high risk for developing cardio-respiratory symptoms will require the consideration of an alternative mode of safe home transportation for preterm infants; especially those with a discharge weight less than 2,000 grams.