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PBL Case 11 (HEATSTROKE (PATHOPHYSIOLOGY (Excessive accumulation of…
PBL Case 11
HEATSTROKE
Dictionary Definition:
"raised body temp., absence of sweating, and eventual loss of consciousness due to failure or exhaustion of the temperature regulating mechanism of the body"
"It is potentially fatal unless treated immediately: the body should be cooled by applying damp cloths and body fluids restored by giving drinks or IV injections of salted water
HEAT EXHAUSTION
Dictionary Definition:
"fatigue and collapse due to the low BP and blood volume that result from loss of body fluids and salts after prolonged or unaccustomed exposure to heat"
" it is treated by giving drinks or intravenous injections of hot water"
If heat exhaustion isn't spotted and treated early on, there's a risk it could lead to heatstroke
SYMPTOMS
tiredness and weakness
feeling faint or dizzy
decrease in BP
headache
muscle cramps
feeling and being sick
heavy sweating
intense thirst
fast pulse
less and darker urine
Main cause is dehydration
Heatstroke is less common, but more serious. It can put a strain on the brain, heart, lungs, liver and kidneys, and can be life threatening
SYMPTOMS
Same as heat exhaustion
confusion
disorientation
seizures
loss of consciousness
TREATMENT
lie down in a cool place (the shade)
remove any unnecessary clothing (to expose as much of their skin as possible)
cool their skin (use whatever's available e.g. cool, wet sponge, cold packs around neck & armpits, etc.)
fan their skin while it's moist (helps water evaporate, which will help their skin cool down)
get them to drink fluids (ideally water, fruit juice or rehydration drink)
Most people should start to recover within 30 minutes
RISK FACTORS
elderly
babies and young children
Sufferer's of long term health conditions (e.g. diabetes or heart or lung condition)
already ill and dehydrated
people doing strenuous exercise for long periods
More likely to experience problems if:
you're dehydrated
there's little breeze or ventilation
wearing tight, restrictive clothing
Medications that increase risk:
diuretics
antihistamines
beta-blockers
antipsychotics
recreational drugs (e.g. amphetamines and ecstasy)
PATHOPHYSIOLOGY
Hyperpyrexia can cause cytotoxicity which results in the
degradation and aggregation of extensive intracellular proteins
, influencing the change of membrane stability and fluidity, damaging the transmembrane transport of protein and the function of surface receptor , and inducing different cytoskeletal changes
Heatstroke resembles sepsis in many aspects, and endotoxemia and cytokines may be implicated in its pathogenesis
Concentration of IL6 has been positively correlated with the severity of heatstroke
Excessive accumulation of cytotoxic free radicals (e.g. peroxide & superoxide) and oxidative damage may occur in the brain tissues during the genesis and development of heatstroke
Circulatory shock and cerebral ischemia resultant from heatstroke correlated closely with the free radicals, the peroxidation of lipids, and low activity of antioxidase in the brain
Excessive heat denatures proteins, destabilises phospholipds and lipoproteins, and liquefies membrane lipids, leading to cardiovascular collapse, multi organ failure, and, ultimately, death
on a cellular level, an array of inflammatory cytokines, interleukins and heat shock proteins (HSPs) are produced
In particular, HSP-70 allows the cell to endure the stress of its environment. It the stress continues, the cell will succumb to the stress and die (apoptosis)
On a microvascular level, heat stroke involves inflammation, translocation of lipopolysaccharides from the gut , and activates the coagulation cascade
Heat illness is viewed as a continuum of illnesses relating to the body's inability to cope with heat. *Heatstroke is the most severe form of heat related illness and is defined as a body temp. higher than 41.1C associated with neurological dysfunction
TYPES
EXTERTIONAL HEATSTROKE
Generally occurs in young individuals who engage in strenuous physical activity for a prolonged period of time in a hot environment
NONEXERTIONAL HEATSTROKE
More commonly affects sedentary elderly individuals, persons who are chronically ill, and very very young persons
Occurs during environmental heat waves and is more common in areas that do not typically experience periods of prolonged hot weather
DEHYDRATION
Dictionary Definition:
"Loss or deficiency of water in body tissues. The condition may result from inadequate water intake and/or from excessive removal of water from the body (e.g. sweating, vomiting, or diarrhoea)"
"symptoms include great thirst, nausea, and exhaustion. The condition is treated by drinking plenty of water; severe cases require oral rehydration therapy or IV administration of water and salts"
SYMPTOMS
Dehydration can be
mild, moderate or severe
, depending on how much of your body weight is lost through fluids
Thirst
dark-coloured urine
dizziness or light headedness
headache
tiredness
dry mouth, lips, and eyes
passing small amounts of urine infrequently
loss of strength and stamina
If dehydration is chronic, it can
affect kidney function and increase the risk of kidney stones
and
lead to muscle damage and constipation
SEVERE DEHYDRATION
If dehydrated is left untreated, it can become severe
symptoms:
lethargy
confusion
dizziness when you stand up that doesn't go away after a few seconds
not passing urine for 8 hours
weak pulse
rapid pulse
seizures
low level of consciousness
TREATMENT
Drink lots of fluids (e.g. water, diluted squash or diluted fruit juice)
A sweet drink can help to replace lost sugar, and a salty snack can help to replace lost salt
Oral Rehydration Solutions
Contains a mixture of potassium and sodium salts, as well as glucose or starch
Thirst quenching efficacy is increased by administering chilled hypotonic fluid with lemon or other fruit acid added (for stimulation of salivation)
CAUSES
Sweating
Alcohol
Diabetes
It is possible to become over hydrated while exercising (this is known as hypernatremia)
PATHOPHYSIOLOGY
Due to water retention and drinking following simulation of ADH secretion and thirst, osmoregulation is overruled by volume conservatory mechanisms, which lead to hyponatreamia
Those who are unable to drink will develop a progressive water deficit - with or without salt depletion - recognisable by hypernatreamia
Decreased effective arterial blood volume and hypernatreamia affect cerebral function in a way that perception of external stimuli as well as perception of pain will be impaired
Alert dehydrated patients are disturbed mainly by thirst and dryness of the mouth
Both symptoms are perceived more intensely by young than by elderly people
Dryness of the mouth can increase thirst on its own
Distress by thirst and oral dryness increases as a function of the level and rapidity of developing hypernatremia
TYPES
WAter loss dehydration (hyperosmolar, due either to increased sodium or glucose)
Salt and water loss dehydration (hyponatremia)
ALCOHOL
DEHYDRATION
Drinking excess alcohol can cause vomiting, which depletes the body of fluids
In general, the less a person weighs, the less alcohol it takes to cause dehydration or vomiting
The NAtional HEalth and Medical Research Council recommends that men and women drink no more than 4 standard drinks on any single occasion - drinking more is considered excessive, and can increase the risk of alcohol related injury
Alcohol decreases body's production of ADH - this causes the body to lee more fluid than usual through increased urination
PATHOPHYSIOLOGY
Direct Effects of Alcohol:
dehydration
electrolyte imbalance
gastrointestinal disturbances
low blood sugar
sleep and biological rhythm disturbances
DEHYDRATION AND ELECTROLYTE IMBALANCE
Causes the body to increase urinary output
Promotes urine production by inhibiting the release of ADH
In return, reduced levels of ADH prevent the kidneys from reabsorbing water and thereby increase urine production
Additional mechanisms must be at work to increase urine production as ADH levels increase ? as BAC levels decrease
Has been shown to act as a peripheral vasodilator
This increases fluid loss through evaporation which further exacerbates the dehydration that is potentially already present
There is further interference of central thermoregulatory mechanisms consequently resulting in core body temperature
DRUGS
ECSTASY
Adverse effects include:
hyperthermia
liver toxicity
neuropsychiatric effects
severe dehydration leading to excessive fluid intake and water intoxication
ALCOHOL AND ECSTASY
Risk of overheating and severe dehydration when combined
Alcohol is involved in most ecstasy related deaths, many of which are from
heatstroke
after people have danced for long periods of time in hot clubs without replacing the fluids they've lost by drinking water
Greater strain on liver and kidneys when combined
AMPHETAMINES
like ecstasy
