Thermal Regulation, Protective Apparel and Heat Stress – The Exogenous Factor

Whether it’s today’s chemical, biological agent scare or tomorrow’s first responder call, firefighters are among the chosen few who continually play Russian Roulette with their health each time they don their hazardous material suit or turnout gear and head into disaster. Each year governing committees amend standards to improve protective equipment. Yet, in spite of these good intentions, protective fabrics place an immeasurable health risk on the human body. As enigmatic as the term “heat stress” is, so is a “cure-all” solution.

Firefighters, EMTs and other first responders are well versed on the facts and remedies of the minor heat illness occurrencesโ€ฆ heat rash, heat cramps, tetany (painful muscle spasms caused by faulty calcium metabolism or diminished parathyroid function), heat syncope (fainting) and heat exhaustion. But, it’s the obscure damage that one serious heat related incident as heat stroke can cause that is shrouded in obscurity. In a 1995 Occupational Medicine article, the Cancer Registry of Norway reported a correlation between the incidence of kidney cancer and both exposure and cumulative exposure to working in hot environments and volatiles some 20 to 35 years before observation. The main findings of this study revealed heat Removal and Understanding Stress and kidney cancer in the group with at least three years of total employment. A quote from this study stated, “increased risk of kidney cancer has been reported from previous studies of workers in aluminum smelters and other hot environments such as foundries and coke ovens”.

Studies published in the American Journal of Medicine suggest that Acute Respiratory Distress Syndrome (ARDS) and a variety of other critical conditions associated with ARDS are also linked to heat stroke. Recently, the Center for Disease Control revealed astounding facts about Chronic Fatigue Syndrome (CFS) that resembles the chronic effects of an individual who survives heat stroke, but it doesn’t end there. Medical research hints a correlation between continual exposure of heat to the body that forces the individual to near exhaustion usually results in mild to serious physiologic and neurologic aftereffects. Typically described as exhaustion and poor stamina, the underlying factor in both a severe heat illness and CFS is their pathology involving our body’s cellular energy “storehouse”.

Research cannot well define the dysfunction of our body’s immune system when it is broached by a disruption caused by severe heat. It does, however, intimate that as our body experiences this severe disruption, our natural killer cells that fight viruses can be suppressed or deficient, compromising our immune system. Commonalities discovered between CFS and sequelae (the medical term for recurrent complications frequently noticed in individuals who recover from a severe heat illness) are:
-overall muscle discomfort, flaccid muscles, headaches and weakness
-sleep disturbances or hypersomnolence (requiring excessive sleep hours and naps)
-spatial disorientation, light headedness and dyslogia (speech impairment, reasoning, memory loss
and/or the ability to concentrate)
-chills and night sweats (a thermoregulatory problem)
-skin sensitivity and sensitivity to heat and cold
-irregular heart beat and recurrent chest and/or abdominal pain
-lowered tolerance to alcohol, irritable bowel and/or diarrhea
-weight fluctuation and menstrual cycle disruption

Our bodies are truly a complex chemical, electrical and biological organism. In the early stages of a severe heat illness, at the cellular level, tremendous hyperactivity and abnormalities are taking place. Excessive heat exposure radically denatures proteins, lipoproteins and phospholipids; it liquifies membranes and provokes electrolyte abnormalities that ultimately leads to cardiovascular collapse, multi-organ failure and finally death. Lipids (one of the principal structural materials of living cells) are transported by the lipoproteins throughout the blood, so disruption of our cells is most definitely not a good thing. As we destroy the lipo-proteins that sheath the myelin in the neurotransmitters (nerve fibers), we impair our communication central processing system. Potassium is essential for muscular contraction and function of the heart, skeletal and smooth internal organ muscles, as well as the osmotic pressure and ionic electrical balance. As heat stress persists, potassium levels peak and wane as muscle damage occurs. As these minerals work together to facilitate one another, abnormal levels of calcium, potassium, magnesium and phosphates could become significant enough to cause hypertension (persistent high blood pressure), cardiac arrhythmias or tachycardia (irregular or elevated heart rate) or be the precursor to mild stroke and require immediate treatment.

As our electrolytes become imbalanced, the onset of vomiting and diarrhea can occur. If excess sweating has occurred, the level of sodium usually measures high unless plenty of water without sodium replenishment was previously ingested. Sodium helps maintain osmotic pressure of extracellular fluid, gastrointestinal absorption of certain sugars and proteins, cell permeability and muscle function. Liver damage is a consistent finding and hypoglycemia (low blood sugar) is very common and may be incited by liver failure.


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