• noaa heat index chart

    Summer is here with a vengeance and parts of the Midwest and Southern U.S. are experiencing record high temperatures in major heat waves. Officials predict a high-risk situation for 200 million citizens as places as far north as Buffalo, NY hit 90 degrees Fahrenheit for a week straight, while Pheonix, Arizona will have multiple days in the 110s. The air temperature in Death Valley, California may reach as high as 125 degrees.  

    Even in places where the air temperature isn’t as high, the “heat index” is surpassing the 90s, 100s, and the 110s. The heat index is a measure of the effects of air temperature combined with high humidity.  Above 60% relative humidity, loss of heat by perspiration is impaired and exposure to full sun increases the reported heat index by as much as 10-15 degrees F. All this increases the chances of heat-related illness such as heat stroke and heat exhaustion.

    In the next few weeks, we can expect the power grid to be challenged by tens of millions of air conditioning units set on “high”. Major health issues may arise if the electricity goes out and people have to fight the heat with hand fans, like they did in the “good old days”.

    HEAT ISLANDS

    graph of temperatures from urban to rural

    Things are even worse in the city. Buildings and roads replace open land and vegetation. Concrete and asphalt surfaces in the sun become much hotter than air temperature, resulting in a “heat island” effect in large populated areas. Rural areas are more moist and cool, leading to less heat-related emergencies.

    Another factor may increase the risk of heat-related emergencies. Homes without air conditioning will not only become sweatboxes, but many people cooped up in closed environments are a recipe to increase the number of COVID-19 cases (so much for the summer giving us a break from the pandemic).

    HEAT WAVES ARE NATURAL DISASTERS

    man,it’s hot!

    You might not consider a heat wave to be a natural disaster, but it most certainly is. Heat waves can cause mass casualties, as it did in Europe when tens of thousands died of exposure (not in the Middle Ages, but in 2003). India, Pakistan, and other underdeveloped tropical countries experience thousands of heat-related deaths yearly.

    HOW HEAT KILLS

    So how exactly does heat kill a person? Your body core regulates its temperature for optimal organ function. When core body temperature rises excessively (known as “hyperthermia”), inflammation occurs, cells die, and toxins leak. Fatalities can occur very quickly without rapid intervention. Even with modern technology, hyperthermia carries a 10% death rate, mostly in the elderly and infirm. Those who are physically fit, however, are not immune.

    HEAT EXHAUSTION AND HEAT STROKE

    The ill effects due to overheating are called “heat exhaustion” if mild to moderate; if severe, these effects are referred to as “heat stroke”. Heat exhaustion usually does not result in permanent damage, but heat stroke does; indeed, it can permanently disable or even kill its victim.  It’s a medical emergency that must be diagnosed and treated promptly.

    Simply having muscle cramps or a fainting spell doesn’t necessarily signify an imminent heat-related medical emergency. You will see “heat cramps” often in children that have been running around on a hot day.  Getting them out of the sun, massaging the affected muscles, and providing hydration will usually resolve the problem.

    Heat exhaustion’s signs and symptoms include:

    • Confusion
    • Rapid pulse
    • Profuse sweating
    • Flushing
    • Nausea and vomiting
    • Headache
    • Temperature elevation up to 105 degrees F

    If no action is taken to cool the victim, they could easily progress to heat stroke. In addition to all the possible signs and symptoms of heat exhaustion, heat stroke will manifest as loss of consciousness, seizures or even bleeding (seen in the urine or vomit).  Breathing becomes rapid and shallow. Shock and organ malfunction may ensue, possibly leading to death.

    heat exhaustion (left) vs heat stroke (right)

    In heat stroke, the skin is likely to be red and hot to the touch, but dry; sweating might be absent.  Once the body core hits 105 degrees or more (it varies from person to person), thermoregulation breaks down and the body’s ability to use sweating as a natural temperature regulator fails. In heat stroke, the body core can rise as high as 110 degrees Fahrenheit or more.

    (Aside: The highest body temperature ever recorded was 115 degrees: On July 10, 1980, 52-year-old heatstroke victim Willie Jones of Atlanta was admitted to the hospital with a temperature of 115 degrees Fahrenheit. He spent 24 days in the hospital and recovered.)

    In some circumstances, the victim’s skin may actually seem cool. Despite feeling “clammy” to the touch, it’s important to realize that it is the body core temperature that’s elevated. You could be misled unless you take readings with a thermometer to reveal the patient’s true status.

    Avoid giving fluids unless the victim is awake and fully oriented

    When overheated patients are no longer able to cool themselves, it is up to their rescuers to do the job. If hyperthermia is suspected, the victim should immediately:

    • Be removed from the heat source (for example, out of the sun).
    • Have their clothing removed.
    • Be drenched in cool water (with ice, if available)
    • Have their legs elevated above the level of their heart (the shock position)
    • Be fanned or otherwise ventilated to help with heat evaporation
    • Have moist cold compresses placed in the neck, armpit and groin areas

    Why the neck, armpit and groin? Major blood vessels pass close to the skin in these areas, and cold packs will more efficiently cool the body core. Recent studies by the military suggest that cold packs to feet and hands are also helpful.

    Oral rehydration is useful to replace fluids lost, but only if the patient is awake and alert. If your patient has altered mental status, he or she might “swallow” the fluid into their airways; this is known as “aspiration” and causes damage to the lungs.

    Heat stroke is preventable in many cases. The Arizona department of health recommends the following:

    • Drink at least 2 liters (about a half-gallon) of water per day if you are mostly indoors and 1 to 2 additional liters for every hour of outdoor time. Drink before you feel thirsty, and avoid alcohol and caffeine.
    • Wear lightweight, light-colored clothing and use a sun hat or an umbrella to deflect the sun’s rays. Use sunscreen if available.
    • Eat smaller, more frequent meals instead of large ones.
    • Avoid strenuous activity.
    • Stay indoors as much as possible.
    • Take regular breaks if you exert yourself on warm days.

    In a heat wave, it’s important to check on the elderly, the very young, and the infirm regularly and often. These people have more difficulty seeking help, and you might just save a life if you’re vigilant. You can bet there’ll be more than one heat wave this summer, so know the warning signs and how to help those with hyperthermia.

    Joe Alton MD

    Joe Alton MD

    Learn more about heat-related illness and 150 other medical topics by checking out a copy of The award-winning Survival Medicine Handbook‘s Third Edition. Plus, look over our entire line of medical kits and supplies at store.doomandbloom.net.

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