Number of children dying in hot cars remains a problem

Dr. Melissa Sparrow
Dr. Melissa Sparrow (Courtesy of Mimi Azrael, Baltimore Sun)

No parent would ever intentionally leave a child in a steaming car on a hot summer day. But it happens every year to astounded parents. Dr. Melissa Sparrow, clinical director of pediatric inpatient and emergency services at Greater Baltimore Medical Center, talks about what can happen when babies are left in hot cars and how to prevent it.

How common a problem is kids getting left in hot cars?

Kids getting left in cars is fairly common, but the incidence of death from being left in a hot car is the number we can clearly articulate. (In some states it is a crime to leave a child unattended in a car and in some states it's not, so the numbers are difficult to estimate.) In the United States, in the last few years, between 30 to 50 children per year have died from "vehicular hyperthermia."

The reason the media is currently focusing on this subject is because this summer, given the high heat index, the rates of heat-related injuries and deaths of children left unattended in cars have spiked. [Eight children left in hot cars died Aug. 1-7, in what officials say is the "worst week on record for these tragedies."] The majority of children who are left in hot cars are left unintentionally, meaning that because the child is quiet or silent, and not visible — as with babies in their rear-facing car seats — he or she has been forgotten by the caregiver.

How long does a child have to be left in a car before he or she suffers health problems?

It depends on the age of the child, what he or she is wearing, and how hot the ambient temperature is. Also factored in would be whether or not the car is parked in direct sunlight and the color of the car's upholstery. The darker the color, the more heat absorbed. It's important to know that even at mild temperature like 70 degrees Fahrenheit, the heat can become amplified in a parked car in a matter of minutes. The fundamental message to parents and caregivers is: Even a minute is too long to leave a child unattended in a car.

Why do children's bodies heat up faster than adults'?

The younger you are, the greater the ratio of body surface area to body. In other words, babies have a whole lot of skin covering their little bodies, and with skin comes exposure. Their skin is thinner than adult skin and very vascular, so it both loses heat rapidly and absorbs heat rapidly. One of the ways the body tries to cope with excessive heat is through "insensible losses" from these surface areas, and the more a person sweats (i.e., insensible loss) without replenishment of fluid, the more dehydrated he/she gets. With dehydration, electrolyte abnormalities set in. Besides being more exposed to ambient temperatures because of their skin-to-body ratio, children's "thermoregulatory" systems, which are in their brains, are less mature. Babies and children also do not have the cognitive ability to take measures to cool or warm themselves.

Heatstroke is the leading cause of car-related deaths in children after accidents. What happens to a child who suffers heatstroke?

Heatstroke, as it is somewhat arbitrarily named, is the end stage of a continuum of responses the body has to excessive heat. The continuum includes heat syncope, heat exhaustion, heat cramps. By the time you are at heatstroke, you have significant mental status changes that can include confusion, agitation, hallucinations, actual ischemic stroke and coma. At a physiologic level, the heat is cytotoxic and directly damages the body's cells. The proteins that make up the cells become denatured. (Just as when you cook something, the proteins in what you are cooking change structure.) Brain cells are especially sensitive to this cytoxic damage, which is why the brain stops working well at the onset of heatstroke. In response to diffuse cellular damage, the body unleashes a systemic inflammatory response that ends up hurting body organs rather than protecting them. Blood starts to clot where it's not supposed to. It leaks out of vessels where it's not supposed to. The physiology of the body and its breakdown begins to parallel fulminant sepsis.

What other health problem can children suffer if left in a hot car too long?

Dehydration, psychological trauma, as well as the other parts of the "continuum" of physiologic responses to excessive heat already mentioned.

Does cracking the windows open prevent overheating in children?

Cracking a window doesn't make much of a difference. The sun's radiant heat passing through the car windows and being absorbed by objects in the car causes the rapidly rising temperature. A small opening in the window isn't going to decrease that absorption. Just think about your oven with the door cracked open a little bit. It still gets hot enough to bake a ham.

What can parents do to remind themselves their child is in the car?

National advocacy groups have put forward many good ideas on how to "never forget." One idea is to put a purse or briefcase or whatever one carries all the time also in the back seat when a baby or small child is seated there. Another is to have a stuffed animal that is always placed on the front seat when the baby is in the back.

An earlier headline misstated that the number of deaths of children dying in hot cars were increasing. The Sun regrets the error. andrea.walker@baltsun.com


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