Apparently life threatening events in infant car safety seatsBMJ 2006; 333 doi: https://doi.org/10.1136/bmj.39021.657083.47 (Published 07 December 2006) Cite this as: BMJ 2006;333:1205
All rapid responses
Tonkin et al. describe the cases of nine infants having apparently life
threatening episodes while restrained in car safety seats . The cause
of these events seems
to be related to the design of the car safety seats: The seats do not
provide space for the infant's large occiput, leading to forward flexion
of the neck and airway obstruction.
A car seat insert increasing the gap for the occiput has been designed by
the same group three years ago  but is not commercially available in
the United Kingdom.
A far easier `low-tech' solution is to put a folded towel behind the
This simple method is commonly used in paediatric anaesthesia and in
tal emergency care to keep the airway open and to avoid neck flexion in
infants immobilised on a spine board .
This is not stating the obvious: A group from Tel Aviv went to great
prevent lateral head movement in infant car seats and unsurprisingly found
difference in the frequency of hypoxia .
A folded towel or similar padding will not change the restraining function
seat in an accident, certainly not more than a winter jacket without hood.
Towels are readily available to all parents, all we need to do is to
show them how to do it. A demonstration of a few minutes could save a baby
from airway obstruction and can be integrated easily in the `car seat
test' . Midwives, health visitors, and general practitioners may be in
the best position to teach parents how to use an infant car safety seat
 Tonkin SL, Vogel SA, Bennett L, Gunn AJ. Apparently life
threatening events in infant car safety seats. Br Med J. 2006 9th
December;333(7580):1205 -- 1206. First author given as Tonkin in bmj.com,
Tondon in printed clinical research edition.
 Tonkin SL, McIntosh CG, Hadden W, Dakin C, Rowley S, Gunn AJ.
Car Seat Insert to Prevent Upper Airway Narrowing in Preterm Infants: A
Pilot Study. Pediatrics. 2003;112(4):907 -- 913.
 Gausche-Hill M, Brownstein D, Diekmann RA, editors. Pediatric
for Prehospital Professionals: PEPP Resource Manual. Sudbury: Jones &
 Dollberg S, Yacov G, Mimouni F, Ashbel G. Effect of Head Support
Oxygen Saturation in Preterm Infants Restrained in a Car Seat. Amer J
Perinatol. 2002;19:115 -- 118.
 American Academy of Pediatrics, Committee on Injury and Poison
Prevention. Safe transportation of newborns at hospital discharge.
1999;104:986 -- 987.
Competing interests: No competing interests
We appreciate the comments by Dr Syed, and would like to clarify
We do not know the smoking status of other family members in this
series. Nicotine is known to delay or attenuate responses to hypoxia –
but of course this does not explain the underlying reasons why the infants
needed to arouse in the first place.
Some of the babies in our series were first born, but others had
varying positions in the families. Our sample was too small to relate any
response to birth order.
Re scene recreation. This was carried out by the care giver in
response to a request to ‘show me how baby was when you found him/her and
were worried‘. The evaluation was part of a routine medical service
provided for medical referrals for surveillance with apnoea alarms for
apparent life threatening events. Infants were fully monitored and were
not at risk. The caregivers fully understood beforehand the goal of
understanding what had happened, and all said afterwards that they felt
much better now that they understood that for their baby the problem was
the specific situation, and thus could avoid it happening again.
As we state in the article, precautionary apnoea monitoring was also
provided for all infants and no further events occurred.
Re the age of the babies suffering the ALTE’s. Note that the one 6
months old baby was born prematurely, whereas all of the full term babies
were very young. Thus the developmental range is not as wide as it first
We believe that it is highly unlikely that there is any real ‘safe’
period for leaving babies asleep in a position of head flexion onto the
chest in car safety seats, especially when those seats are placed on the
floor out of the car when they are often more upright, promoting greater
‘head flop’ forwards. Even in cars we recommend infant observation by the
care giver – a mirror can be rigged to watch an infant in the back seat.
Thus, our general advice at present to parents is that baby should be
taken out of the seat immediately when not in the car, and placed to sleep
flat, in a normal cradle or bassinet.
Re infant occiput. We have previously reviewed the relevant anatomy
(Tonkin 2002). For all newborn infants of all ethnic groups the spine is
straight and the head is large (between 1/3 and ¼ of the total length) The
neck is very short. The head sits on the spine like a toffee apple on a
stick with about ¼ of the head depth being behind the spinal line. There
are individual differences in the occipital protuberance but it is always
present in some degree. In many small babies when this occipital bulge is
forced to be in line with the spine, the head flexes forwards –the chin is
pressed onto the chest, and that in turn pushes the loosely articulated
jaw backwards carrying the tongue inside it posteriorly to obstruct the
upper airway. We have confirmed that this is an important effect in
premature babies in car seats (Tonkin 2003) using simultaneously
radiographs and polygraphs. In that setting we reported that this problem
could be alleviated with the use of a foam plastic insert in the seat to
allow the head to remain upright in sleep.
We very strongly agree that the correct use of car safety seats has
saved infant lives and will continue to do so, but at the same time they
may have some potential risk. The cases that we report here strongly
suggest that this risk is mainly when they are used as a household bed,
for which they were not designed or intended, instead of for their
Tonkin SL, Gunn TR, Bennet L, Vogel SA, Gunn AJ. A review of the anatomy
of the upper airway in early infancy and its possible relevance to SIDS.
Early Hum Dev. 2002;66:107-121
Tonkin SL, McIntosh CG, Hadden W, Dakin C, Rowley S, Gunn AJ. Simple
car seat insert to prevent upper airway narrowing in preterm infants : a
pilot study Pediatrics 2003; 112: 907-13
Competing interests: No competing interests
We read recent BMJ article and we certainly agree that infant safety
seats (ISS) are designed with the goal to reduce the number of infant
passengers killed or injured in motor vehicle crashes. When used for
their intended purpose, ISS’ hold great potential to decrease the risk of
infant death or injury.
It is of concern that ISS misuse may be occurring among caregivers
using ISS’ outside motor vehicles thereby putting their infant at risk of
injury. The objective of the current study was to describe incidence and
factors associated with injuries from ISS misuse among infants aged 0 – 1
years presenting to the British Columbia (BC) Children’s Hospital
Emergency Department over 6 years (1997 – 2002).
The results of our recent study in BC children hospital support
previous literature suggesting that ISS misuse may expose infants to falls
and superficial head injuries (1, 2). Superficial head injuries from ISS
misuse are of particular concern because infant skulls are malleable and
susceptible to fracture and intracranial injury (3).
Narratives accompanying the injury data indicated that 3 patterns of
injury associated with ISS misuse are injuries resulting from falls from:
1) placement of the ISS on an elevated surface; 2) falling out of the ISS
while being carried and 3) ISS overturn on hard floors. Due to the
patterns demonstrated in falls related injuries, it is possible that
caregivers are not anticipating how readily or how quickly the ISS would
roll or tip over when placed on an elevated surface.
ISS manufacturers should be advised to expand their instructions to
include advice on ISS misuse. ISS manuals would benefit by having the
following messages: 1) never place ISS on an elevated surface and 2)
always use the ISS harness in all settings and 3) do not use a ISS outside
of the motor vehicle setting. Warnings in word form should be augmented
with pictorial representations that articulate the main messages (2).
Pictorial diagrams improve the usability and appear to improve label
compliance, especially when a label is positioned in an appropriate
location (4). In addition to changes to instruction manuals and labels, a
previous study suggested there is a need for innovation in the design of
ISS, so that they are more functional and stable (2). To increase
stability, ISS design features could be improved to reduce the risk to
children, and to allow for multi-purpose use both inside and outside a
Frequently parents lack the knowledge of effective safety measures to
prevent injuries to children, and consequently misuse protective safety
devices (5). Caregivers could benefit from education on proper ISS use by
messages placed in a variety of accessible settings. Potential settings
include primary care offices, community-based organizations, child care
settings, emergency departments, maternity wards and commercial outlets
and point of sale locations. Primary care could increase their involvement
in education efforts as per the American Academy of Pediatrics who
recognize injury prevention education for caregivers should be priority
area for counseling during routine health maintenance visits for young
children (6). A recent review by Gittelman and Durbin (2005) (7) has
suggested that an emergency department visit for an injury represents a
"teachable moment" for the patient and their family, which may make the
injured more receptive to educational information.
(1). Pollack-Nelson C., Fall and suffocation injuries associated with
in-home use of car seats and baby carriers. Pediatr Emerg Care. 2000;
(2). Wickham T, Abrahamson E., Head injuries in infants: the risks of
bouncy chairs and car seats. Arch Dis Child.2002; 86(3):168-9.
(3). Lallier, M., Bouchard, S., St-Vil, D., Dupont, J., Tucci, M.,
Falls from heights among children: A retrospective review. Journal of
Pediatric Surgery 1993; 34 (7) 1060-1063
(4). Rudin-Brown C.M., Greenley M.P., Barone A., Armstrong J., Salway
A.F., Norris B.J., The design of child restraint system (CRS) labels and
warnings affects overall CRS usability. Traffic Inj Prev. 2004; 5(1):8-17.
(5). Duhaime A.C., Alario A. J., Lewander W.J., Head injury in very
young children: mechanisms, injury types, and ophthalmologic findings in
100 hospitalized patients younger than 2 years of age. Pediatrics. 1992;
(6). Eichelberger M.R., Gotschall C.S., Feely H.B., Harstad P.,
Bowman L.M., Parental attitudes and knowledge of child safety. Am J Dis
Child. 1990; 144:714 –720
(7). Gittelman, M.A., Durbin, D., Injury prevention: Is pediatric
Emergency Department the appropriate place? Pediatric Emergency Care 2005;
27 (7) 460-467
Competing interests: No competing interests
I read with great interest the article by TONKIN et al (1) from New
Zealand in BMJ. They have provided interesting information. Although it
was widely known that the pre-term infants (less than 37 week gestation)
or who require intensive care admission at birth should preferably avoid
travel in car safety seats for first month (2)and may suffer from
desaturation, this is perhaps the first case series showing actual
evidence of leading to apnea in normal term infants in a car safety seat (Which was not seen in study by Merchant et al (2)). This is obviously a
matter of concern for parents and doctors alike.
I myself being a parent of a 4 Month old baby and working in Trauma
& Orthopaedics have special interest in safety of car seats ( in case
of accident in specific & the safety for their occupant in general )
especially those seats which are rear-facing and semi-reclined. I would
like to raise following points which need clarification
It would be beneficial to know if the smoking status of father or
other family members was noted? Was there any correlation between the age
of presentation and the smoking status of other family members i.e. the
children of smoking family presented at a younger age or towards the
Were these the first child of every family or were there multiple
Authors have mentioned that the scene was recreated and 'position
kept for long enough for care giver to recognize signs for concern'. This
appears to be a brave undertaking! I would like to know whether parents
had any reservation for this reconstruction to be carried out, especially
taking into account the clinical risk management issue for any serious
harm occurring. Was it easy to get an ethical committee approval for this
Authors have mentioned that infants were very young, when head
control was not well developed. This may not be the case for the 6 Months
old baby referred to in the age range of cases.
Authors suggested that the parents were given advice including NOT
leaving infants for excessive periods in car seat. I would like to know
what this excessive time period is; 30 minutes or two Hours? Does that
mean that if babies are sleeping and one is traveling one should get them
out after this time period on a regular basis? I am also surprised that
the reference quoted for this is AAOP 2005 publication in Pediatrics (3).
I believe when this study was carried out in 1999-2000 this advice would
not have been available!!
Authors have mentioned 'Prominent Occiput' as a probable cause. I
think I may have overlooked this in the article as I was unable to find
any reference to the occiput size of this cohort or any cranial
It is vital to know whether the cohort under consideration was
Caucasian or a mix population group including Polynesian, Afro-Carribean.
This is important as the Occiput shape and size would be different for
Is it possible that 'Prominent Occiput' may be the only common factor
among this cohort? Has this been excluded? If it is the only group then as
a profession we can offer targeted advice rather than alarming all the
Authors state that the permission to publish was obtained from only
seven patients but they refer to the mean ages of the nine patients!
As a profession it is our duty to ensure that this important
information must be taken in context and avoid its exploitation by media
for their quest for sensational news. One must remember that each year car
seats save thousands of precious lives.
Finally this article illustrates that the findings of this
interesting case series took about 06 years to be able to be disseminated
across the medical profession , unless authors did not prepare it, which
is highly unlikely considering the significance of this information!
1. Shirley L Tonkin, Sally A Vogel, Laura Bennet, , Alistair Jan
Gunn, Apparently life threatening events in infant car safety seats BMJ
2006;333:1205-1206 (9 December), doi:10.1136/bmj.39021.657083.47
2. Merchant JR, Worwa C, Porter S, Coleman JM, deRegnier RA.
Respiratory instability of term and near-term healthy newborn infants in
car safety seats. Pediatrics 2001;108:647-52
3. American Academy of Pediatrics Task Force on Sudden Infant Death
Syndrome. The changing concept of sudden infant death syndrome: diagnostic
coding shifts, controversies regarding the sleeping environment, and new
variables to consider in reducing risk. Pediatrics 2005;116:1245-55.
Competing interests: No competing interests