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Kids in cars


The mercury on the outside thermometer is inching past 40oC for the third day in a row, and for once, you are grateful to be in the cool, air-conditioned emergency department.  The emergency phone snaps you back into alertness. The paramedics are bringing in a toddler who has been liberated from the back of a parked car.

Bottom Line

Despite widespread public information campaigns, children are still left alone in cars every heatwave.

Just 15 minutes unattended is enough to raise the temperature of the car to lethal levels.

Heat illness varies on a continuum from heat stress and cramps to heat exhaustion and then heatstroke.

Heatstroke is a medical emergency and is characterized by neurological deterioration, anhydrosis and a core temperature above 40oC

How big a problem is it?

During the recent heatwave in Melbourne, when the temperature topped 40 degrees for four days straight, Ambulance Victoria received 60 calls for children trapped in cars. Fortunately, there were no fatalities. During the 1995-2002 period in the United States, there were 171 entirely preventable deaths.

Studies have suggested that on a hot day, the temperature in a locked vehicle can rise as high as 51-67oC within 15 minutes. 75% of this rise occurs within the first five minutes of the door closing, so even short periods of leaving a child unattended can be dangerous. There is some evidence that leaving the window cracked can make a difference, but all the data suggests that it has to be open at least 20 cm to make an appreciable difference.

Why are children at particular risk?

Even though kids have a larger body surface area-to-mass ratio than adults, they have much less effective thermoregulation. They have a higher metabolic rate, so they are really little furnaces.  Unfortunately, they are less well able to regulate their cardiac output in response to heat stress and produce less sweat per apocrine gland compared to adults. Perhaps more importantly, unlike most adults, they cannot get out if they are left in the car seat on their own.

What’s the difference between heat stress, heat exhaustion, and heatstroke?

Words are important. What the lay public means when they say heatstroke is very different from what the medical professional means.

Heat stress is what we all feel when the mercury rises – we’re grumpy, irritable, sweaty and often listless but not unwell. The core temperature is unaffected.

Heat exhaustion occurs as a result of salt and/or water depletion. It may be compounded by nausea, vomiting and excessive sweating. The core temperature may or may not be up.

Heatstroke is a medical emergency and is typically classified as either exertional (think running a marathon on a hot day)  or non-exertional (sitting in a hot car).  As the core temperature rises above 40oC the patient often becomes more lethargic and delirious. Seizures, then coma, eventually ensue.

How do children lose their excess heat?

Heat is lost via radiation, conduction, evaporation, and convection with these latter two being most amenable to change.

As with all potentially toxic exposures (to heat in this instance), removal from the source is vital. The child should be managed in a cool environment if possible, and attention paid to their ABCs.

  • Airway – they may require intubation if clinically indicated
  • Breathing – if they need to be intubated, then mechanical ventilation will need to be initiated
  • Circulation – children suffering from heatstroke are often profoundly dehydrated with challenging IV access. Don’t hesitate to break out your favourite intraosseous device. As peripheral cooling is instituted, more blood is returned to the central circulation, increasing the risk of pulmonary oedema.
  • Disability – seizures should be treated with benzodiazepines initially. Still, you should check the UEC urgently and assess the sodium for hypo- or hypernatraemia, depending on whether salt and water depletion or pure water depletion predominates.
  • Exposure – having discovered a high core temperature it is time to do something about it. Techniques can range from removing clothes, ice packs in the axillae and groins, cool fans, and cold IV fluids to the Macgyver – creating a cooling tent. This can be done by soaking a sheet in cold water and draping it, suspended, over the patient with a fan to push air through it. The aim is to maximize heat loss via convection, conduction, and evaporation.

They’ve got a temperature; shouldn’t you give them some paracetamol/Tylenol/acetaminophen?

There is no evidence that antipyretics lower the temperature in cases of heat-related illness.

Disposition for the sick patient is straightforward.  They need admission to the HDU/ICU. But what should you do for the well-appearing child?

There is no consensus as to how long a patient should be observed, but common sense would dictate that if their temperature has normalized and they are rehydrated, then they are fit enough to go home.

Should you involve social services?

That is the million-dollar question. Certainly, in Australia, Section 231 of the Children and Young Persons (Care and Protection) Act 1998 clearly states:-

A person who leaves any child or young person in the person’s care in a motor vehicle without proper supervision for such a period or in such circumstances that :

(a) the child or young person becomes or is likely to become emotionally distressed, or
(b) the child’s or young persons health becomes or is likely to become permanently or temporarily impaired is guilty of an offence.

Hasn’t the distraught parent been through enough?  This excellent piece from the Washington Post, entitled Fatal Distraction, eloquently puts parents’ struggle into words.


Little Nelly is brought in, nearly naked and crying. Her rectal temperature is 38oC, and she tolerates a delicious icy pole. Her mother is beside herself. You discuss the case with the local social services, who agree to follow up.

Selected References

McLaren C, Null J, Quinn J. Heat stress from enclosed vehicles: moderate ambient temperatures cause significant temperature rise in enclosed vehicles. Pediatrics. 2005 Jul;116(1):e109-12. PubMed PMID: 15995010

King K, Negus K, Vance JC. Heat stress in motor vehicles: a problem in infancy. Pediatrics. 1981 Oct;68(4):579-82. PubMed PMID: 7322691.

Grubenhoff, Joseph A., Kelley du Ford, and Genie E. Roosevelt. “Heat-related illness.” Clinical Pediatric Emergency Medicine 8.1 (2007): 59-64.

Guard, A., and Susan Scavo Gallagher. “Heat related deaths to young children in parked cars: an analysis of 171 fatalities in the United States, 1995–2002.”Injury Prevention 11.1 (2005): 33-37. accessed 21st January 2014

Bouchama, Abderrezak, and James P. Knochel. “Heat stroke.” New England Journal of Medicine 346.25 (2002): 1978-1988.

Wexler, Randell K. “Evaluation and treatment of heat-related illnesses.”American family physician 65.11 (2002): 2307-2313.



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