Safe transportation of preterm and low birth weight infants requires special considerations. Both physiologic immaturity and low birth weight must be taken into account to properly position such infants. This clinical report provides guidelines for pediatricians and other caregivers who counsel parents of preterm and low birth weight infants about car safety seats.
INTRODUCTION
Improved survival rates and earlier discharge of preterm (<37 weeks' gestation at birth) and low birth weight (<2500 g at birth) infants have increased the number of small infants who are being transported in private vehicles. Car safety seats that are used correctly are 71% effective in preventing fatalities attributable to passenger car crashes in infants.1 To ensure that preterm and low birth weight infants are transported safely, the proper selection and use of car safety seats or car beds are necessary.
Federal Motor Vehicle Safety Standard (FMVSS) 213, which establishes design and dynamic performance requirements for child-restraint systems, applies to children weighing up to 65 lb. However, the standard has no minimum weight limit and does not address the relative hypotonia and risk of airway obstruction in preterm or low birth weight infants. Most rear-facing car safety seats are designated by the manufacturer for use by infants weighing more than 4 or 5 lb, with some designated for use from birth regardless of weight.
Infant dummies as small as 3.3 lb have been shown to be satisfactorily restrained in standard rear-facing car safety seats during crash tests.2,3 Test dummies, however, cannot replicate the airway and tone variables that occur in preterm infants, and there is no information on restraint of infants who weigh less than 3.3 lb (1.5 kg).
Rear-facing car safety seats provide the best protection in a frontal crash, because the forces are transferred from the back of the restraint to the infant's back, the strongest part of an infant's body. The restraint also supports the infant's head. Severe tensile forces on the neck in flexion are also prevented by use of rear-facing car safety seats.4
The long-term experience and documented protective value of car safety seats make them the preferred choice for travel for all infants who can maintain cardiorespiratory stability in the semireclined position.4 A car bed that meets FMVSS 213 may be indicated for infants who manifest apnea, bradycardia, or low oxygen saturation when positioned semireclined in a car safety seat.2,5 Of note, some preterm and term infants positioned in car beds and car safety seats seem to have similar rates of apnea, bradycardia, and oxygen desaturation.6,7
A car bed is designed to accommodate an infant in a fully reclined position and is oriented in the vehicle seat perpendicular to the direction of travel. An infant is secured in the car bed with an internal harness, and the car bed is secured to the vehicle with the vehicle's seat belt. Car beds, like car safety seats, have specific weight requirements designated by the manufacturer and, like car safety seats, should be used according to manufacturer recommendations.
The size of the infant, especially for those born preterm, is an important consideration when selecting a car safety seat or car bed.2,8 Weight, length, neurologic maturation, and associated medical conditions (especially bronchopulmonary dysplasia) all influence the potential risk of respiratory compromise for infants in seating devices.6,9
Preterm infants are subject to an increased risk of oxygen desaturation, apnea, and/or bradycardia,10 especially when placed in a semireclined position in car safety seats.5,11–13 Furthermore, frequent cardiorespiratory events and intermittent hypoxia may adversely affect later neurodevelopment, psychosocial behavior, and academic achievement.14,15 In 1 study, mental development in preterm infants with 5 or more cardiorespiratory events during 210 hours or more of cardiorespiratory monitoring was associated with a lower mental development index on the Bayley Scales of Infant Development (95.8 vs 100.4; P = .04)14 ; physical developmental indices were not different (94.4 vs 91.7; P = .37). It is unclear whether the association of cardiorespiratory events and lower mental development reflects an underlying abnormality or a negative consequence of the events. It is rational, if practical, to attempt to reduce the frequency and severity of cardiorespiratory events experienced by preterm infants seated in car safety seats to minimize potential neurodevelopmental sequelae. Therefore, car safety seat monitoring in the infant's own car safety seat before discharge from the hospital should be considered for all infants less than 37 weeks' gestation at birth to determine if physiologic maturity and stable cardiorespiratory function are present, as recommended in the American Academy of Pediatrics publication Guidelines for Perinatal Care.16 Because information is limited about the severity and frequency of adverse outcomes in preterm infants who experience cardiorespiratory events, including those events that occur while in car safety seats, additional research is needed.17
Many infants are discharged from the hospital with cardiac/apnea monitors, supplemental oxygen, and, occasionally, portable ventilators, suction machines, batteries, and other equipment. These objects are heavy and could cause injury if they were to hit the child or another vehicle occupant in the event of a sudden stop or crash. Although there is no commercially available securement system for portable medical equipment, restraint is recommended.18
No data are available to establish a specific age or neurodevelopmental status at which an infant with respiratory compromise who was discharged from the hospital in a car bed can safely transition to a semireclined car safety seat. Before discontinuing use of a car bed, the physician can consider arranging for a follow-up study to determine when the infant can travel semireclined without apnea, bradycardia, or oxygen desaturation. The time to perform the test may vary depending on the rate of growth and neurologic maturation of the infant and the infant's respiratory status and should be determined by the treating physician.
Car safety seats are used frequently for positioning infants for purposes other than travel. Potential detrimental effects of excessive use of infant seating devices, including exacerbation of gastroesophageal reflux and potentiation of plagiocephaly, have been documented.19,20 Use of car safety seats for purposes other than travel also may increase the risk of adverse cardiorespiratory and other adverse medical events.
CLINICAL IMPLICATIONS
Several important considerations for transportation of preterm and low birth weight infants at risk for recurrent oxygen desaturation, apnea, or bradycardia include the following.
The increased frequency of oxygen desaturation and episodes of apnea or bradycardia while sitting in car safety seats suggests that preterm infants should have a period of observation in a car safety seat, preferably their own, before hospital discharge. This period of observation should be performed with the infant carefully positioned for optimal restraint and the car safety seat placed at an angle that is approved for use in the vehicle. A period of observation for a minimum of 90 to 120 minutes or the duration of travel, whichever is longer, is suggested.5,6,11,21
Hospital staff who are trained in positioning infants properly in the car safety seat and in detecting apnea, bradycardia, and oxygen desaturation should conduct the car safety seat observation.
Hospitals should develop protocols to include car safety seat observation before discharge for infants born at less than 37 weeks' gestation.22 Some hospital protocols include car safety seat observations for infants at risk of obstructive apnea, bradycardia, or oxygen desaturation other than those born at less than 37 weeks' gestation. Examples include infants with hypotonia (eg, Down syndrome or congenital neuromuscular disorders), infants with micrognathia (Pierre Robin sequence), and infants who have undergone congenital heart surgery.9
Families should be taught by trained hospital staff how to position the infant properly in the car safety seat.
The duration of time the infant is seated in a car safety seat should be minimized. Parents should be advised that car safety seats should be used only for travel.
A conventional car safety seat that allows for proper positioning of the preterm infant should be selected if a semiupright position can be maintained safely by the infant. Better observation of the infant may be possible when the child is in a rear-facing car safety seat adjacent to an adult rather than in a car bed. In addition, the protection provided by a rear-facing car safety seat is better documented than the protection provided by car beds.4
If events documented on cardiorespiratory monitoring in a car safety seat are deemed significant by the treating physician or the hospital policy, interventions to reduce the frequency of desaturation and episodes of apnea and bradycardia are recommended (eg, use of car bed; supplemental oxygen; continued hospitalization or further medical assessment). If a car bed is considered, a similar period of cardiorespiratory monitoring while the infant is in the car bed should be performed before discharge.
Infants with documented oxygen desaturation, apnea, or bradycardia in a semiupright position should travel in a supine or prone position in an FMVSS 213–approved car bed after an observation period that is free of such events as described in point 1 above. This may need to be revised as new evidence becomes available from future research. Specific information regarding currently available car beds can be obtained from several resources.23
Before transitioning from a car bed, a period of observation of an infant for apnea, bradycardia, and oxygen desaturation in the infant's own semireclined car safety seat should be considered. The study can be performed as a home oxypneumocardiogram, as an outpatient polysomnogram, or as an observed outpatient clinical evaluation performed similarly to that described in point 1 above.
Infants at risk of respiratory compromise in car safety seats may be at similar risk with use of other upright equipment, including infant swings, infant seats, backpacks, slings, and infant carriers. Consideration should also be given to limiting the use of these devices until the child's respiratory status in a semireclined position is stable.24
Infants for whom home cardiac and apnea monitors are prescribed should use this monitoring equipment during travel and have portable, self-contained power available for at least twice the duration of the expected transport time.
Commercially available securement systems for portable medical equipment such as monitors are not available; therefore, this equipment should be wedged on the floor or under the vehicle seat to minimize the risk of it becoming a dangerous projectile in the event of a crash or sudden stop.2,8
Proper positioning of preterm and low birth weight infants in car safety seats is important for minimizing the risk of respiratory compromise. Specific national guidance for selecting car safety seats and positioning preterm and low birth weight infants includes the following.
Infants should ride facing the rear as long as possible and to the highest weight and length allowed by the manufacturer of the seat for greatest protection.25 -27 By the time infants weigh 20 lb or reach the top length allowed by the manufacturer of the seat, they should ride facing the rear in infant seats or convertible car safety seats approved for rear-facing use at higher weights and lengths. Most convertible car safety seats are approved for rear-facing use up to 30 to 35 lb and 36 in. Parents of infants born preterm may benefit from specific counseling about this concept.
Infant-only car safety seats with 3-point or 5-point harness systems or convertible car safety seats with 5-point harness systems provide optimum comfort, fit, and positioning for the preterm or low birth weight infant. A small infant should not be placed in a car safety seat with a shield, abdominal pad, or arm rest because of potential breathing difficulty behind the shield or injury to an infant's face and neck during a sudden stop or crash.2,21
Car safety seats with the shortest distances from the crotch strap to the seat back should be selected to reduce the potential for the infant to slip forward feet-first under the harness (ie, “submarining”). Some car safety seats have crotch-to-seat back distances as short as 5.5 in, which may accommodate some preterm or low birth weight infants well. A small rolled diaper or blanket between the crotch strap and the infant may be added to reduce the risk of submarining (Fig 1) in smaller infants. A car safety seat with multiple harness-strap slots provides more choice and may be more suitable for small but rapidly growing infants. Ideally, car safety seats with harness straps that can be positioned at or below the shoulders should be selected.21
The infant should be properly positioned in the car safety seat, with buttocks and back flat against the back of the car safety seat. The harness must be snug, and the car safety seat's retainer clip should be positioned at the midpoint of the infant's chest, not on the abdomen or in front of the neck (Fig 1).
Some car safety seats come with head-support systems as standard equipment. Many head-support systems, however, are sold as aftermarket products and may decrease the safety provided by the seat and harness system, because they introduce slack into harness straps. Only products that come with the seat or are sold by the manufacturer for use with their specific seat should be used. Most very small infants require positioning support in addition to the head support that comes with the seat. Blanket rolls may be placed on both sides of the infant to provide lateral support for the head and trunk (Fig 1).
The rear-facing car safety seat should be reclined approximately 45° or as directed by the instructions provided with the car safety seat. If the vehicle seat slopes and the seat is too upright, the infant's head may fall forward. A lightweight, noncompressible object, such as a tightly rolled blanket or pool “noodle,” may be placed under the car safety seat to achieve the appropriate angle. Some car safety seats have built-in angle indicators and angle adjusters to assist with achieving the proper angle (Fig 2).
A rear-facing car safety seat should never be placed in the front passenger seat of any vehicle equipped with a passenger-side front air bag because of risk of death or serious injury from the impact of the air bag. In some vehicles without rear seating positions, the air bag can be deactivated when the front seat is used for a child passenger. The back seat is the safest place for all children to travel.28,29
Infants riding in the rear seat may be more difficult to observe, and whenever possible, parents should arrange for an adult to be seated in the rear seat adjacent to the infant. In the event of a monitor alarm, if a second caregiver is not available, the driver may need to come safely to a stop and assess the infant.
An infant should never be left unattended in a car safety seat inside or out of the car.
RESEARCH IMPLICATIONS
Studies are needed to gather more information on the severity and frequency of adverse outcomes in preterm infants who experience cardiorespiratory events, including those events that occur while in car safety seats.
Studies need to be conducted to determine the risk factors associated with cardiorespiratory events among preterm and low birth weight infants and criteria that indicate neurodevelopmental and physiologic maturity required for an infant to be positioned upright without respiratory compromise.
Studies should be designed to assess the correlation of car safety seat monitoring performed in the hospital, while stationary in the car, and while traveling.
Methods should be developed to better determine the relative protection provided by rear-facing car safety seats and car beds.
Design of car safety seats should be encouraged to specifically meet the positioning and transportation needs of preterm and low birth weight infants.
Methods should be developed to better secure heavy medical equipment, such as monitors and oxygen, in vehicles.
The efficacy of various protocols for car safety seat monitoring and car safety seats for different patient populations of at-risk infants needs to be determined.
SUMMARY
Proper selection and use of car safety seats or car beds are important for ensuring that preterm and low birth weight infants are transported as safely as possible.
The increased frequency of oxygen desaturation or episodes of apnea or bradycardia experienced by preterm and low birth weight infants positioned semireclined in car safety seats may expose them to increased risk of cardiorespiratory events and adverse neurodevelopmental outcomes.
It is suggested that preterm infants should have a period of observation of 90 to 120 minutes (or longer, if time for travel home will exceed this amount) in a car safety seat before hospital discharge. Educating parents about the proper positioning of preterm and low birth weight infants in car safety seats is important for minimizing the risk of respiratory compromise. Providing observation and avoiding extended periods in car safety seats for vulnerable infants and using car seats only for travel should also minimize risk of adverse events.
COMMITTEE ON INJURY, VIOLENCE AND POISON PREVENTION, 2006–2007
Gary A. Smith, MD, DrPH, Chairperson
Carl R. Baum, MD
M. Denise Dowd, MD, MPH
Dennis R. Durbin, MD, MSCE
Kyran P. Quinlan, MD, MPH
Robert D. Sege, MD, PhD
Michael S. Turner, MD
Jeffrey C. Weiss, MD
Joseph L. Wright, MD, MPH
LIAISONS
Julie Gilchrist, MD
Centers for Disease Control and Prevention
Lynne Haverkos, MD, MPH
Eunice Kennedy Shriver National Institute of Child Health and Human Development
Jonathan D. Midgett, PhD
Consumer Product Safety Commission
Lori Roche
Health Resources and Services Administration
Alexander “Sandy” Sinclair
National Highway Traffic Safety Administration
Lynne J. Warda, MD
Canadian Paediatric Society
STAFF
Bonnie Kozial
COMMITTEE ON FETUS AND NEWBORN, 2006–2007
Ann R. Stark, MD, Chairperson
David H. Adamkin, MD
Daniel G. Batton, MD
Edward F. Bell, MD
Vinod K. Bhutani, MD
Susan E. Denson, MD
Gilbert I. Martin, MD
Kristi L. Watterberg, MD
LIAISONS
Keith J. Barrington, MD
Canadian Paediatric Society
Gary D.V. Hankins, MD
American College of Obstetrics and Gynecology
Tonse N.K. Raju, MD
National Institutes of Health
Kay M. Tomashek, MD
Centers for Disease Control and Prevention
Carol Wallman, MSN, RNC, NNP
National Association of Neonatal Nurses and Association of Women's Health, Obstetric and Neonatal Nurses
STAFF
Jim Couto, MA
Car safety seat with a small cloth between crotch strap and infant, retainer clip positioned at the midpoint of the infant's chest, and blanket rolls on both sides of the infant.
Car safety seat with a small cloth between crotch strap and infant, retainer clip positioned at the midpoint of the infant's chest, and blanket rolls on both sides of the infant.
All policy statements from the American Academy of Pediatrics automatically expire 5 years after publication unless reaffirmed, revised, or retired at or before that time.
The guidance in this report does not indicate an exclusive course of treatment or serve as a standard of medical care. Variations, taking into account individual circumstances, may be appropriate.
This document is copyrighted and is property of the American Academy of Pediatrics and its Board of Directors. All authors have filed conflict-of-interest statements with the American Academy of Pediatrics. Any conflicts have been resolved through a process approved by the Board of Directors. The American Academy of Pediatrics has neither solicited nor accepted any commercial involvement in the development of the content of this publication.
Comments
Evidence for Car Safety Seat Testing
We thank Dr. Greenberg for his comments. He raises several important issues about the duration of car seat monitoring and use of car beds. Dr. Greenberg points out that the incidence of cardiopulmonary events experienced by preterm infants studied in car seats and car beds was similar. [Salhab] Furthermore, the longer an infant is in a car seat or car bed, there is a higher risk of such events. Not all preterm infants had cardiopulmonary events in both car seats and car beds; some infants only had events in one device, but not the other. This suggests that car restraint selection should be individualized.
One solution to reduce the number of cardiopulmonary events in car restraint devices, as Dr. Greenberg suggests, is to educate families about the problem and limit the duration of exposure to car restraint devices to 30 minutes. Unfortunately, some infants experience events before 30 minutes of car restraint use. We agree that it would be ideal to limit travel for at risk children as much as possible until they are more physiologically stable and that they be observed by a second adult in the back seat whenever possible; however, such requirements are not feasible for some families.
Importantly, car seat testing has been recommended to identify those at risk infants who develop cardiopulmonary events while positioned in a car restraint device. Car restraint studies have shown that some infants have events as long as 90-120 minutes after being positioned. (Salhab) Thus, 90-120 minutes was recommended for car seat testing. Because data is limited about time of events after 90 minutes of car seat use, additional study is needed and encouraged.
If infants in car restraint devices have cardiopulmonary events, we believe that investigations and/or interventions to reduce the frequency of events is warranted. In the clinical report, it is suggested that use of a car bed; supplemental oxygen; continued hospitalization or further medical assessment be considered for infants experiencing cardiopulmonary events. The extent of the investigation or interventions must be individualized for the specific infant depending on the cause for such events (such as airway obstruction, aspiration, insufficient cardiopulmonary reserve) and response to interventions. As Dr. Greenberg suggests, an infant who has events in a car seat may also have events in a car bed. For infants placed in a car bed, as described in the clinical report, a period of cardiopulmonary monitoring before travel is also suggested. If such infants have no events, additional investigation may not be necessary. However, and depending on the cause for the events, additional study or treatment (such as oxypneumocardiogram, investigations to detect gastroesophageal reflux, supplemental oxygen) may be warranted.
Prolonged use of car safety seats is discouraged. It is also important that infants in car safety seats be observed while seated in such devices as much as practically possible. We agree with Dr. Greenberg that these concepts are best taught to parents and families by knowledgeable and expert hospital staff during the discharge education process.
William A. Engle, MD, FAAP
Marilyn J. Bull, MD, FAAP
Salhab WA, Khattak A, Tyson JE, et al. Car Seat or Car Bed for Very Low Birth Weight Infants at Discharge Home. J. Pediatr. 2007;150(3):224- 228
Conflict of Interest:
None declared
Lack of Evidence for Car Safety Seat Testing
The value of the infant car seat to reduce the risk of death or injury attributable to motor vehicle accidents is well documented. It is also clear that infants, especially those born prior to 37 weeks gestation have a heightened risk of proximal airway obstruction, apnea, cyanotic episodes and bradycardia. The American Academy of Pediatrics continues to support the notion of car safety seat monitoring prior to hospital discharge to demonstrate physiologic maturity and stable cardiorespiratory function (1). However, no specific recommendations regarding the nature of such monitoring are provided. As the authors of the Guideline point out, additional research is needed to determine how health care providers might interpret the data from a car safety seat monitoring session. This places those responsible for ensuring the safe discharge of a neonate from the intensive care nursery in a tenuous position. We are encouraged to test for stability, but have no useful way to define stability. This predicament has predictably led to a proliferation of car safety seat monitoring protocols in our regional hospitals, some lasting for many hours. Pass/fail criteria are arbitrary at best. Those who fail are simply retested until they pass. Those who persistently fail are recommended for a car bed. However, recent published data demonstrates that such patients do not fare any better with these devices
Salhab et al (2) reported increasing frequency of desaturation episodes beyond approximately 50 minutes when infants were appropriately positioned in a car safety seat or car bed. We believe that the Academy’s recommendation to conduct “a period of observation for 90-120 minutes or the duration of travel, whichever is longer” is unwarranted and lacks a sound physiologic basis. There is simply no evidence that extended periods of car safety seat monitoring prior to discharge reduce risk of unanticipated cardiopulmonary compromise. Such testing may in fact, inadvertently convey a false sense of security for parents (3). Patient care staff time devoted to testing is much better spent orienting parents and caregivers to proper car safety seat positioning, installation, and observation of the infant.
Based upon clinical experience and data presented by Salhab et al, it is unlikely that any preterm infant ready for discharge from an NICU is sufficiently mature to safely remain in a car safety seat for more than 30 -40 minutes. We do agree that parents must receive careful orientation and instruction including information regarding how to minimize head flexion. Further, infants in car safety seats should be placed in the back seat under the direct observation of an adult caregiver. When car travel beyond 30 minutes duration is unavoidable, regular stops to reposition the infant and minimize head flexion must be included, even if inconvenient. While automobile travel is a fact of modern life, we cannot avoid the reality that newborn human infants, especially those born before 37 weeks gestation have not experienced sufficient evolutionary time for adaptation.
1. Bull MJ, Engle WA, the Committee on Injury Violence, and Poison Prevention and the Committee on Fetus and Newborn. Safe Transportation of Preterm and Low Birth Weight Infants at Hospital Discharge. Pediatrics 2009;123:1424-1429. 2. Salhab WA, Khattak A, Tyson JE, et al. Car Seat or Car Bed for Very Low Birth Weight Infants at Discharge Home. J. Pediatr. 2007;150(3):224-228 3. Greenberg JM. The Challenge of Car Seats. J. Pediatr. 2007;150(3):215- 6.
Conflict of Interest:
None declared
Cardiopulmonary Monitoring in Car Safety Seats
The letter written by Dr. Strauss outlines the need for additional research about the impact of cardiopulmonary events in low birth weight or small infants positioned in car safety seats. We appreciate the suggestion, and fully support the need for additional information to refine the clinical management of these infants.
This clinical report is based on expert opinion and a number of clinical series demonstrating an increased rate of cardiopulmonary events in low birth weight infants while seated in car seats. These events are analogous to the events that are observed when monitoring such infants during neonatal intensive care. For significant events occurring in the intensive care setting, low birth weight infants may require interventions such as tactile stimulation, or, in some cases, resuscitation with supplemental oxygen, medications or a manual resuscitator. Such events, especially if unexpected or new, will result in additional investigation to determine a cause (i.e. polysomnogram, evaluation for sepsis or gastroesophageal reflux, echocardiography, etc.).
Because low birth weight infants who are nearing discharge from the hospital are often relatively hypotonic compared to term infants and have a predisposition for apnea and cardiopulmonary complications of prematurity, it is reasonable to assess whether these infants have such events when placed in a new position that could cause airway obstruction or other physiologic stress, such as that in a car seat. If events occur in a car seat, like events in the intensive care setting, investigation about the cause and interventions may similarly be a reasonable course of action.
We believe it is incumbent on clinicians to ensure that infants in car seats are as physiologically and clinically stable as are infants in their crib. We thank Dr. Strauss for his comments and urge investigators to further address the value of cardiopulmonary monitoring of low birth weight infants in car seats.
Conflict of Interest:
None declared
Overreaching
The statement on the safe transportation of preterm infants continues to reinforce the myth of utility of pre-hospital discharge "car seat testing". There is no valid study to date that demonstrates that either normal or abnormal findings on a pneumogram or other testing of cardio-respiratory events (observation) has any relevence to what happens to a preterm infant when placed in a car seat for the ride home. Unless a study is performed that records continuous events while the infant is in the actual car seat positioned in the car for different time intervals - nothing can be stated about the supposition that one has anything to do with the other. Rather than inappropriately raising caretaker anxiety about the discharge or delaying the discharge for having an "abnormal test", time and effort would be better spent on making sure a preterm infant is ready for a safe discharge (no recent cardiorespiratory events, preparation of the parents about safe positioning and support for the infant's airway and the common sense notion about avoiding unnecessary travel, etc). Car seat testing is a notion that has found its way into the neonatal literature (one of a suggested list of late preterm infant discharge criteria) without evidence to support it. We can do better than this.
Conflict of Interest:
None declared