Whether it's today's chemical, biological agent scare
or tomorrow's first responder call, firefighters are
the chosen few who continually play Russian roulette
with their health each time they don their hazardous
material suit or turnout gear. 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 and EMTs are well versed on the facts
and remedies of the minor heat illness occurrences…
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 like 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 hot environments and volatiles
some 20 to 35 years before observation. The main findings
of this study revealed heat 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 resemble the chronic effects of
an individual who survives heat stroke. Medical research
hints a correlation between continual exposure of heat
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 broached by a disruption caused
by severe heat. It does, however, intimate that as our
body experiences 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 liquefies membranes and provokes electrolyte abnormalities
that ultimately lead 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 not a good thing. As we destroy the
lipoproteins that sheath the myelin in the neurotransmitters
(nerve fibers), we destroy 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.
Hemodynamic reports (the study of the forces involved
in blood circulation) reveal in severe dehydration cases,
abnormal coagulation occurs altering amino acids and
causes cerebral edema (excess fluid in the brain cells
or tissues). Prolonged intravascular coagulation or
loss of blood to the lungs incites damage to the lung
tissues and may predispose people to develop pulmonary
problems like ARDS. Once this occurs, individuals require
more positive inhalation pressure via mechanical ventilation.
Serious heat damage is often associated with endotoxemia
(the presence of endotoxins in the blood and tissues)
that form an integral part of the cell wall of certain
bacteria and are released when the cell destructs. Blood
hemorrhaging in the skin (red bumps) can occur followed
by blood in the urine. As dehydration increases, the
viscosity of the blood changes (from oxygen rich, easily
perfused fluid to a sludge-like substance). Vascular
tone and capacity, in turn, alter blood pressure and
cardiac output. If left untreated, the heart becomes
tired and quits.
Neurologic complications vary from mental disorientation
to delirium, unconsciousness, convulsions or a comatose
state (displaying similar symptoms to that of sustaining
a serious head injury). Those individuals may require
tomography scans to determine the level of Central Nervous
System (CNS) damage. Nerve damage can be as subtle to
recovering victims as partial or permanent anhidrosis
(cessation of sweating). From thereon, their ability
to maintain thermal equilibrium may be compromised,
especially when faced with heat stress conditions. Irreparable
damage to the body's heat-dissipating bodily mechanisms
may be noted along with muscle coordination may be weak
and affected in some or all quadrants of the body. One's
equilibrium and hand-eye coordination may be off. In
some cases, lack of nerve conductivity in the lower
limbs may be noted.
Neurologic disorders during heat related illnesses
are further complicated by release of adrenaline (epinephrine
- the most potent stimulant of our sympathetic nervous
system). Adrenaline stress is extremely prevalent in
high-risk occupations where tension, fear, anger, excitement
and life threatening situations occur. Release of adrenaline
changes the physiological responses and causes a magnitude
of complex reactions including, but not limited to increased
blood pressure, heart rate and force of blood vessel
contraction, relaxation of bronchiolar and intestinal
smooth muscles and other metabolic effects. According
to John LoZito, Neurologist, a release of some adrenaline
is good, but needless adrenaline incites hyperactivity
akin to dropping a fuel drum on a bonfire further increasing
susceptibility for more serious maladies: stroke, cardiac
stress, etc.
Extreme dehydration causes retention of carcinogens
and an imbalance of myoglobin (oxygen carrying proteins)
in prominent organs like the bladder and colon. Loss
of fluid prevents diluting and flushing of the toxins,
predisposes one for constipation and urinary tract infections,
as well as bladder and colon cancer. Kidney stones may
form more readily as calcium, uric acid and other substances
become concentrated and form crystals due to fluid loss.
Heat damage incites sudden rhabdomolysis and intramuscular
necrosis (destroying skeletal muscles and decay of muscle
tissue also known as muscle wasting). Researchers have
long purported good fluid intake neutralizes the cavity
causing acids, flushes away sugar and inhibits the micro-organisms
that cause gum disease and other oral hygiene problems.
For individuals afflicted with asthma, drying of the
nose, throat and lung tissues presumably incite more
asthma attacks than with hydrated tissues or humid weather.
Dehydration, measuring as little as one percent of one's
body weight in non-heat stress conditions can be the
cause for headaches, fatigue, muscle cramps and the
"blah" feeling. A net water loss of as little
as four percent of one's body weight can cause blood
pressure to plummet quickly. These and a host of other
disorders make simple nausea and headaches just a walk
in the park.
The typical information from organizations like the
National Institute of Health, OSHA, NIOSH, CDC, Worksafe
Australia and others do not reflect the pathophysiology
of how heat stress affects our body at the cellular
level. Medical science has just begun to unravel the
baneful mysteries of bodily reaction to heat, unfortunately
many times after the fact.
This
is the first part in a series of educational articles
analyzing the in-depth effects of heat stress, including
noteworthy considerations for firefighters and other
emergency responders, by Kathryn Doherty. Kathryn is
a graduate from the University of Oklahoma. She has
conducted heat stress awareness seminars, consulted
with companies and published numerous articles on this
subject. Kathryn can be reached by email at: The50DegreeCo@aol.com
