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"

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"

"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

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

If heat exhaustion isn't spotted and treated early on, there's a risk it could lead to heatstroke

SYMPTOMS

  • Same as heat exhaustion
  • confusion
  • disorientation
  • seizures
  • loss of consciousness

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

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

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

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

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

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

On a microvascular level, heat stroke involves inflammation, translocation of lipopolysaccharides from the gut , and activates the coagulation cascade

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)

dropped image link

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

Main cause is dehydration

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

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

Thirst quenching efficacy is increased by administering chilled hypotonic fluid with lemon or other fruit acid added (for stimulation of salivation)

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

DRUGS

In general, the less a person weighs, the less alcohol it takes to cause dehydration or vomiting

Alcohol decreases body's production of ADH - this causes the body to lee more fluid than usual through increased urination

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

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

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