Assessment of babies for car seat safety before hospital discharge

Fetus and Newborn Committee, Canadian Paediatric Society (CPS)

Paediatr Child Health 2000;5(1):53-6
Reference No. FN00-02

Reaffirmed February 2011

Index of position statements from the Fetus and Newborn Committee

Contents:

• What is the magnitude of the cardiorespiratory risks for babies in car seats?
• Who should be tested?
• What parameters should be monitored?
• What criteria should be used to determine 'failure'?
• What if the baby fails?
• References

Car seats have been strongly advocated to reduce mortality and morbidity associated with automobile accidents in infants and children (1-5). Car seats should always be used, including the initial automobile ride (6). Commercially available infant seats offer the optimum protection for healthy babies born at term. Special care beds offer a high level of protection for infants with special needs. An infant with special needs should never be transported in a vehicle in the parent’s arms, a cot or other device.

Education is important to ensure car seats are used appropriately for all infants (3,4,7-9). Babies born before term may present particular challenges, and the American Academy of Pediatrics (AAP) has recommended that babies born at less than 37 weeks’ gestation have a period of observation in a car seat before discharge to monitor for possible apnea, bradycardia or oxygen desaturation (1).

Hypoxemia related to positioning and apneic episodes are common in infants born before term in whom apnea may persist up to and beyond term gestation (10,11). Predischarge respiratory recordings in very low birth weight infants may reveal significant apnea in many babies otherwise ready for discharge (12). The use of car seats is recommended for all babies during automobile travel, but this manoeuvre may expose such infants to other potential risks.

What is the magnitude of the cardiorespiratory risks for babies in car seats?

Evidence indicates that babies born before term are at increased risk of adverse cardiorespiratory effects when placed in a semi-upright position, such as that typical with usual infant car seats (13-19). Infants may also be exposed to a variety of dangerous situations while sleeping in cots, chairs or beds (20). The magnitude of potential problems seems greatest in preterm infants who may ‘fail’ testing in car seats 11% to 60% of the time. There is little knowledge of the potential long term effects for preterm babies who may have been discharged without prior observation or monitoring in car seats. A MEDLINE search from 1980 to 1998 using key words of ‘neonate’, ‘newborn’, ‘car’ and ‘seat’ failed to reveal any studies indicating death or disability associated with the use of car seats, although deaths in babies who were ‘wedged’ in other sitting positions were reported (2). In Alberta, the percentage of babies dying while in a car seat, snow sled, carriage stroller or swing increased from 2.9% of total sudden infant death syndrome (SIDS) deaths in 1977 to 1981 to 8.2% in 1992 to 1996 (21), primarily because of a reduction in SIDS deaths in other situations. It is not known what percentage of deaths were specifically related to car seat use and how many of these babies were born prematurely. SIDS rates have not declined in very low birth weight babies as they have in larger babies (22).

Although some hospitals routinely assess selected babies before discharge, this does not occur in the majority of Canadian centres (19). Because little epidemiological evidence exists, health care professionals may rely on relevant studies completed in hospitals, with the expectation that the outcome measures of detected episodes of hypoxemia, apnea and/or bradycardia may have serious long term adverse effects on at least some of these babies. However, health care professionals should also be aware that apparent cardiorespiratory abnormalities in infants born prematurely are common at the time of hospital discharge, and there are no monitoring criteria that predict an increased risk of SIDS (23).

Who should be tested?

The criteria of less than 37 weeks’ gestation at delivery recommended by the AAP appears to be based on the initial selection criteria by Willett et al (14,15), who reported a failure rate of 30% to 60% in preterm babies undergoing cardiorespiratory monitoring in car seats before discharge. In 1996, Young et al (19) reported that 24% of the infants who failed in the study were tested at a mean adjusted age of 39 weeks. In this study, 20 of the 22 babies who failed initially passed at 40 weeks’ adjusted age while the other two passed at 42 weeks. In a similar study by Bass et al (16) in 1993, 18.4% of infants showed desaturation associated with apnea or bradycardia while in car seats. Seven of 33 (21%) neonates at 36 weeks’ adjusted age failed their predetermined criteria. Finding cardiorespiratory abnormalities in babies born at 35 to 36 weeks’ gestation has significant implications not only for neonatal intensive care units (NICUs), but also for normal newborn nurseries that care for these otherwise healthy babies. Based on 1992 data, this would indicate that 6% to 7% of all babies born in Canada should be considered ‘at risk’ (24).

In addition to preterm infants, Bass and Mehta (25) reported oxygen desaturation in selected term infants in car seats. These were babies who had genetic abnormalities or for whom there were concerns about apnea or desaturation based on information from parents or health care professionals. Eight of 28 monitored infants (28.6%) had a period of oxygen desaturation of less than 90% while in car seats.

Babies born at less than 37 weeks’ gestation are at risk of oxygen desaturation while in car seats, even when they have exceeded that adjusted age. The risk of oxygen desaturation while in car seats may be similar to other babies who have cardiorespiratory abnormalities noted in the neonatal period. The significance of periodic episodes of oxygen desaturation to overall health of the baby remains unknown.

What parameters should be monitored?

Although recommendations for observation and monitoring were made in the AAP statement, details of what parameters should be monitored and criteria for failure were not provided (1). In the study by Young et al (19), babies were monitored for end tidal carbon dioxide, heart rate, respiratory rate and hemoglobin saturation with oxygen using continuous pulse oximetry over 90 mins in each of a crib and car seat. Data were collected continuously using a recorder or computer acquisition system. Studies by Willett et al (14,15) and Bass et al (16) were similar, although it is not clear that the measurement of nasal air flow (to help diagnose obstructive apnea) was included.

Data acquisition systems similar to those used in these research studies may not be readily available to study the  large number of babies in many Canadian hospitals (26). However, such extensive cardiorespiratory monitoring may not be required. All 29 infants who failed in the study by Young et al (19) experienced desaturation (less than 88%); detection of apnea was an additional finding. In the study by Bass et al (16), of 87 infants with 16 failing testing, 15 experienced variable degrees of oxygen desaturation. Of 20 babies reported by Willett et al (14), none had bradycardia or apnea without desaturation. Based on polygraphic information in a second study, pulse oximetry alone was used to retest babies before discharge. It may be advisable, especially with some oxygen saturation monitors, to use cardiorespiratory monitoring simultaneously to help ensure that the saturation monitor is appropriately indicating the baby’s oxygen saturation. Oxygen saturation monitoring appears likely to detect 99% of babies who might demonstrate other respiratory abnormalities with more extensive polygraphic monitoring.

What criteria should be used to determine 'failure'?

Even for babies born before term who may have recurring apnea associated with desaturation in the NICU, the long term implications are unclear and there is little knowledge of the threshold for adverse effects (27). Willett et al (14), testing babies for 90 mins, noted that in a group of 10 normal term babies in car seats, 4.8% of the baby’s time was spent with an oxygen saturation less than 90% and 1.4% of time with an oxygen saturation less than 85%. In a subsequent study in preterm infants selected because of clinical concern, babies spent 1.0% time with oxygen saturation of less than 85%, and had a mean of 11 events in 90 mins with an oxygen saturation of less than 80% (15). Bass et al (16) also studied preterm babies in car seats for 90 mins and reported episodes of an oxygen saturation less than 90% in 16 of 87 babies (18.4%), although the duration of such episodes was not specified. Young et al (19) used prospectively determined ‘failure’ criteria based on previous studies at the same institution. However, it has not been shown that their criteria of two or more episodes of an oxygen saturation less than 88% for more than 10 s during a 90 min recording are predictive of significant increased risk later.

What if the baby fails?

It should be noted that 18 of the 29 babies, who failed in the study by Young et al (19), were reported to have desaturation corrected immediately by decreasing the angle of recline of the car seats to 30° from the recommended 45° (reducing the total failure rate to less than 9%). Smith and Turner (18) reported a similar benefit with placing the car seat in a relatively more recumbent position. However, this may not allow the car seats to provide the safety required if a vehicle accident occurs. Of the 29 babies who failed in the car seat in studies by Young et al (19), eight also failed testing in the crib. These babies may require additional consideration of their readiness for discharge. For babies whose desaturation is confined to sitting in their car seat, the recent availability of recumbent car beds and car seats in Canada is a reasonable solution to facilitate safe discharge home from hospital if there is no significant desaturation when babies are tested in the recumbent position.

Young et al (19) report that some babies who failed car seat testing were treated with theophylline and/or oxygen, with hospital discharge delayed from one to 20 days. Although theophylline and oxygen are commonly used to treat preterm babies in the NICU, and may be effective in some babies who might not otherwise be ready for discharge, no specific recommendations for this treatment, the length of treatment and subsequent monitoring on either a continuous or intermittent basis can be made at this time. Young et al (19) report that one baby readmitted following an apparent life-threatening event was subsequently discharged on a home monitor. This should not be interpreted as indicating that babies with abnormalities on testing while in infant car seats should be sent home on monitors, although this may be recommended occasionally for selected preterm infants with symptomatic apnea beyond 37 weeks’ gestation (28).

Unfortunately there is little information on the health care benefits or economic impact of recommendations for testing infants in car seats before hospital discharge. However, the Canadian Paediatric Society concludes the following.

• All parents should have instruction and supervision in the placement of their baby in a car seat by qualified health care personnel. Instruction should include special emphasis on the proper support and positioning of babies who are born before term, have a low birth weight, or have significant cardiorespiratory or neurological problems. Restraining devices should be installed in accordance with current standards. Parents should be cautioned never to leave their baby unattended in the car seat.
• There can be no specific recommendation concerning babies who should undergo monitoring before hospital discharge. However, with current information, it appears to be increasingly common that babies in NICU who are born at less than 37 weeks’ gestation or more mature babies with respiratory or neurological abnormalities (eg, hypotonia) are tested with oxygen saturation monitoring while in their car seats before their discharge home.
• There is no clear definition of significant cardiorespiratory abnormalities. Significant cardiorespiratory abnormalities have empirically been considered as two or more episodes of oxygen desaturation (less than 88%) for 10 s or more during a 90 min monitoring period. Babies who meet these criteria, but are otherwise healthy, may be sent home in a recumbent car restraint if repeat testing in the recumbent position is satisfactory. Babies who continue with significant oxygen desaturation may require continued hospitalization, further investigation and management.
• Parents and other caregivers (including health care personnel) should be cautioned that adverse cardiorespiratory events in babies before and following discharge from hospital may not be restricted to the positioning of the baby in the car seat. Similar consideration needs to be given to proper positioning and observation of the baby during holding, and caution should be exercised in the use of baby slings, snugglies and other infant seats for babies born preterm until they are at least one month adjusted age, and for other babies with cardiorespiratory or neurological abnormalities until they can sit independently.
• The costs and benefits of monitoring selected babies in car seats before discharge from hospital and associated changes in care should be the subject of ongoing surveillance and research.

References

1. Committee on Injury and Poison Prevention and Committee on Fetus and Newborn, American Academy of Pediatrics. Safe transportation of premature and low birth weight infants. Pediatrics 1996;97:758-60.

2. Committee on Injury and Poison Prevention and Committee on Fetus and Newborn, American Academy of Pediatrics. Safe transportation of premature infants. Pediatrics 1991;87:120-2.

3. Canadian Paediatric Society. Well Beings: A Guide to Promote The Physical Health, Safety and Emotional Well-Being of Children in Child Care Centres and Family Day Care Homes. Ottawa: Canadian Paediatric Society, 1996:468-71.

4. Selecting and using the most appropriate car safety seats for growing children: guidelines for counseling parents. American Academy of Pediatrics. Committee on Injury and Poison Prevention. Pediatrics 1996;97:761-3.

5. Nichols JL. Effectiveness and Efficiency of Safety Belt and Child Restraint Usage Programs: The Safety Potential Of Safety Belts, Child Restraints and Programs to Promote Their Use. Washington: US Department of Transportation National Highway Traffic Safety Administration, 1982:15.

6. American Academy of Pediatrics Committee on Accident and Poison Prevention: Safe transportation of newborns discharged from the hospital. Pediatrics 1990;86:486-7.

7. Margolis LH, Wagenaar AC, Molnar LJ. Use and misuse of automobile child restraint devices. Am J Dis Child 1992;3:361-6.

8. Graham CJ, Kiltredge D, Stuemky JH. Injuries associated with child seat safety misuse. Pediatr Emerg Care 1992;8:351-3.

9. Selecting and using the most appropriate car safety seats for growing children: guidelines for counseling parents. American Academy of Pediatrics. Committee on Injury and Poison Prevention. Pediatrics 1996 May;97(5):761-3

10. McEvoy C, Mendoza ME, Bowling S, Hewlett V, Sardesai S, Durand M. Prone positioning decreases episodes of hypoxemia in extremely low birth weight infants (1000 grams or less) with chronic lung disease. J Pediatr 1997;130:305-9.

11. Eichenwald EC, Aina A, Stark AR. Apnea frequently persists beyond term gestation in infants delivered at 24 to 28 weeks. Pediatrics 1997;100:354-9.

12. Barrington KJ, Finer N, Li D. Predischarge respiratory recordings in very low birth weight newborn infants. J Pediatr 1996;129:934-40.

13. Bull MJ, Stroup KB. Premature infants in car seats. Pediatrics 1985;75:336-9.

14. Willett LD, Leuschen MP, Nelson LS, Nelson RM Jr. Risk of hypoventilation in premature infants in car seats. J Pediatr 1986;109:245-8.

15. Willett LD, Leuschen MP, Nelson LS, Nelson RM Jr. Ventilatory changes in convalescent infants positioned in car seats. J Pediatr 1989;115:451-5.

16. Bass JL, Mehta KA, Camara J. Monitoring premature infants in car seats: Implementing the American Academy of Pediatrics policy in a community hospital. Pediatrics 1993;91:1137-41.

17. Hamelin K, Overly B. Premature infants and car seat safety. Can Nurse 1996;92(4):31-4.

18. Smith PS, Turner BS. The physiologic effects of positioning premature infants in car seats. Neonatal Netw 1990;9:11-5.

19. Young B, Shapira S, Finer NN. Predischarge car seat safety study for premature infants. Paediatr Child Health 1996;1:202-5.

20. Byard RW, Beal S, Bourne AJ. Potentially dangerous sleeping environments and accidental asphyxia in infancy and early childhood. Arch Dis Child 1994;71:497-500.

21. Wang DM. Secular trends of SIDS mortality and associated risk factors during 1977-1995 in Alberta, Canada. University of Calgary, 1998. [Thesis]

22. Bigger HR, Silvestri JM, Shott S, Weese-Mayer DE. Influence of increased survival in very low birth weight, low birth weight, and normal birth weight infants on the incidence of sudden infant death syndrome in the United States: 1985-1991. J Pediatr 1998;133:73-8.

23. Statistics Canada. Births 1992 [catalogue 84-210 annual]. Ottawa: Marketing Division, Statistics Canada, 1995:2.

24. Hodgman JE. Apnea of prematurity and risk for SIDS. Pediatrics 1998;102:969-71.

25. Bass JL, Mehta KA. Oxygen desaturation of selected term infants in car seats. Pediatrics 1995;96:288-90.

26. McMillan DD. How should premature infants be assessed for car seat safety before discharge? Paediatr Child Health 1996;1:197-9.

27. Martin RJ, Fanaroff AA. Neonatal apnea, bradycardia, or desaturation: Does it matter? J Pediatr 1998;132:758-9.

28. The infant home monitoring dilemma. Fetus and Newborn Committee, Canadian Paediatric Society. CMAJ 1992;147:1661-4.

Fetus and Newborn Committee

Members: Drs Deborah Davis, Department of Pediatrics, Children’s Hospital of Eastern Ontario, and Department of Obstetrics/Gynecology/Newborn Care, Ottawa Hospital, Ottawa, Ontario; Daniel Faucher, Department of Pediatrics, Royal Victoria Hospital, Montréal, Québec; Arne Ohlsson, Department of Pediatrics, Mount Sinai Hospital, Toronto, Ontario (chair 1999-2001); Gary Pekeles, The Montreal Children’s Hospital, Montréal, Québec (director responsible 1999-2000); Douglas McMillan, Department of Pediatrics, Calgary Regional Health Authority, Calgary, Alberta (chair 1993-1999 and principal author); John van Aerde, Department of Pediatrics, Stollery Children’s Health Centre, Edmonton, Alberta; Michael Vincer, Department of Pediatrics, IWK-Grace Health Centre, Halifax, Nova Scotia; Robin Walker, Children’s Hospital of Eastern Ontario, Ottawa, Ontario (1992-1998); John Watts, Children’s Hospital at Hamilton Health Sciences Corporation, Hamilton, Ontario (director responsible 1993-1999)
Liaisons: Ms Debbie Fraser-Askin, St Boniface Hospital, Winnipeg Manitoba (Neonatal nurses 1994-1999); Drs Michael Klein, BC’s Women’s Hospital, Vancouver, British Columbia (College of Family Physicians of Canada); Line Leduc, Hôpital Sainte-Justine, Montréal, Québec (Maternal-Fetal Medicine Committee, Society of Obstetricians and Gynaecologists of Canada);  James Lemons, Riley Children’s Hospital, Indiana University Medical Center, Indianapolis, Indiana (Committee on Fetus and Newborn, American Academy of Pediatrics); Cheryl Levitt, Hamilton Health Sciences Corporation, McMaster University Medical Centre, Hamilton, Ontario (College of Family Physicians of Canada, 1997-1999); Catherine McCourt, Laboratory Centre for Disease Control, Bureau of Reproductive & Child Health, Health Canada, Ottawa, Ontario (Health Canada); Saroj Saigal, Children’s Hospital at Hamilton Health Sciences Corporation, Hamilton, Ontario (Neonatal-Perinatal Medicine Section, Canadian Paediatric Society); Reginald Sauve, Department of Pediatrics, University of Calgary, Calgary, Alberta (Neonatal-Perinatal Medicine Section, Canadian Paediatric Society 1996-1997); Ms Amanda Symington, Hamilton Health Sciences Corporation, McMaster Unversity Medical Centre, Hamilton, Ontario (Neonatal nurses)
Principal author: Dr Douglas McMillan, Department of Pediatrics, Calgary Regional Health Authority, Calgary, Alberta (chair 1993-1999)

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