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Safety Nugget Week of March 27 - New Definition of Heat Stroke< Back to Blog

Mar 27, 2017
By: G. Yepsen
Categories: Safety


We are coming up to the hotter months of the year.  Heat exhaustion and heat stroke become more of an issue.


Recently, the National Institute for Occupational Safety and Health (NIOSH) updated its Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments for the first time since 1986. The most significant change is in the definition of “heatstroke.”


The accepted definition of “heatstroke” includes confusion, unconsciousness, and/or convulsions, accompanied by a lack of sweating. Workers were warned that if they stopped sweating, heatstroke was imminent. This type of heatstroke, now called “classic heatstroke,” isn’t the type that most commonly strikes workers.


NIOSH says that “exertional heatstroke” is more common in workers—and profuse sweating is one of its symptoms. So workers who have been taught that sweating is a positive sign are actually at increased risk.


Exertional heatstroke is caused by the combination of heat exposure and heavy physical exertion and can lead to a condition called rhabdomyolysis. Symptoms of rhabdomyolysis include muscle pain and cramping, swelling, weakness, and decreased range of motion. Fatigue, abdominal pain, back pain, nausea or vomiting, and confusion may also occur. However, many cases occur with very mild symptoms that are mistaken for heat stress. This creates a potentially dangerous situation because these workers don’t receive the intensive medical intervention they require.


Another potential complication of rhabdomyolysis is compartment syndrome, or swelling in a specific type of muscle, usually in the lower extremities, that blocks blood flow. Compartment syndrome is often delayed—it may take several hours to develop—and can lead to permanent loss of function in the affected limb.


Symptoms of compartment syndrome include the “5 Ps”: pain, pallor, pulselessness, paresthesias (sensation of tingling, numbness, or burning, usually felt in the hands, feet, arms, or legs), and paralysis. Pain is the most common and tends to be extremely severe. Workers who experience these symptoms must go to a hospital immediately. Quick surgical intervention is required to treat compartment syndrome.


Both types of heatstroke are accompanied by extremely high body temperature, and both types are a medical emergency that require immediate medical attention. First aid includes cooling the worker as quickly as possible by any means available, including an ice bath, circulating air around the worker, and placing cold packs on the head, neck, armpits, and groin. For exertional heatstroke, oral hydration is vital.


So, stay hydrated and stay safe!


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