As we enter the full furnace blast that is Summer in most parts of the country, we turn to medical issues influenced by environmental factors. If you aren’t prepared to deal with your environment, it is truly an enemy to be reckoned with.

Hyperthermia

In the aftermath of storms or in the wilderness, you may find yourself without shelter to protect you from the elements. In the heat of summer, a common condition you’ll encounter might be heat stroke, otherwise known as “hyperthermia“. Even in cold weather, significant physical exertion in an over-clothed and under-hydrated individual could lead to significant heat-related injury. The elderly and the very young are particularly prone to issues relating to overheating, and must be watched closely if exposed to the sun. Many animals may also succumb to hyperthermia.

The ill effects due to overheating are called “heat exhaustion” if mild to moderate; if severe, these effects are referred to as “heat stroke”. This is a continuous process in which symptoms start piling one upon another. Heat exhaustion usually does not result in permanent damage, but heat stroke does; indeed, it can permanently disable or even kill its victim. It is a medical emergency that must be diagnosed and treated promptly to avoid long-term effects.

Heat Stroke and the Heat Index

The risk of heat stroke correlates strongly to the “heat index”, a measurement of the effects of air temperature combined with high humidity. Above 60% relative humidity, loss of heat by perspiration is impaired, increasing the chances of heat-related illness. Exposure to full sun increases the reported heat index by as much as 10-15 degrees F. As such, it is important to factor in shade as a survival commodity just as it is to consider food and water sources. Other things to consider include what times of day it is most appropriate to put your people to work outdoors; providing shade and a pint of water an hour will go a long way to prevent heat-related events.

Simply having muscle cramps or a fainting spell does not necessarily signify a major heat-related medical event. 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.

To make the diagnosis of heat exhaustion, a significant rise in the body’s core temperature is required. As many heat-related symptoms may mimic other conditions, a thermometer of some sort should be a component of your medical supplies.

In addition to muscle cramps, dizziness, and/or fainting, heat exhaustion is characterized by:

· Confusion
· Rapid pulse
· Flushing
· Nausea and Vomiting
· Headache
· Temperature elevation up to 105 degrees F

If no action is taken to cool the victim, heat stroke may ensue. Heat stroke, in addition to all the possible signs and symptoms of heat exhaustion, will manifest as loss of consciousness, seizures or even bleeding (seen in the urine or vomit). Breathing becomes rapid and shallow.

If not dealt with quickly, shock and organ malfunction may ensue, leading to your patient’s demise. The skin is likely to be hot to the touch, but dry; sweating might be absent. The body makes efforts to cool itself down until it hits a temperature of 106 degrees or so. At that point, 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 to 110 degrees Fahrenheit or more.

You’ll notice that the skin becomes red, not because it is burned, but because the blood vessels are dilating in an effort to dissipate some of the heat.

In some circumstances, the patient’s skin may actually seem cool. It is important to realize that it is the body CORE temperature that is elevated. A person in shock may feel “cold and clammy” to the touch. You could be misled by this finding, but sim

ply taking a reading with your thermometer will reveal the patient’s true status.

Only give fluids if awake and alert

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 with cool water (or 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
If water/ice are in good supply, use as much as needed to cool the patient

Why the neck, armpit and groin? Major blood vessels pass close to the skin in these areas, and you will more efficiently cool the body core. In the wilderness, immersion in a cold stream may be all you have in terms of a cooling strategy. This is a worthwhile option as long as you are closely monitoring your patient.

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 causes damage to the lungs and puts you in worse shape than when you started. Close monitoring of mental status is important in the evaluation of any heat (or cold) related event.

You might think that acetaminophen or ibuprofen could help to lower temperatures, but this is actually not the case. These medications are meant to lower fevers caused by an infection, and they don’t work as well if the fever was not caused by one.

Wear clothing appropriate for the weather. Tightly swaddling an infant with blankets, simply because that is “what’s done” with a baby, is a recipe for disaster in hot weather. Have everyone wear a head covering. A bandanna soaked in water, for example, would be effective against the heat. Much of the sweating we do comes from our face and head, so towel off frequently to aid in heat evaporation.

If you can avoid dehydration, you will likely avoid heat exhaustion or heat stroke. Work or exercise in hot weather (especially by someone in poor physical condition) will easily cause a person to lose body water content.

A loss of just 1% of your total water initiates the thirst mechanism. You’ll need a pint of water an hour to stay hydrated. If thirst is not quenched, as little as 2% water loss begin to affect work efficiency, mood, and other parameters. At 6%, you’re as delirious and uncoordinated as if you’ve been crawling for miles through Death Valley. At 10% and more, organ malfunction begins to occur and your patient could easily die.

Carefully planning your outdoor work in the summer heat and keeping up with fluids will be a major step in keeping healthy and avoiding heat-related illness. Monitor the workload (and the workers) and you’ll stay out of trouble.

Dr. Bones