Transcript PowerPoint-presentation

Heatstroke
Sun Stroke
Acute Management and Prevention
Dr. Aidah Abu El Soud Alkaissi
BSc Law, RN, BSc, MSc, PhD
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Heatstroke
Sun Stroke
• Caused by overexposure to sun and extremely
high temperatures
• occurs when the brain fails to control its own
"thermostat".
• It’s a life-threatening condition which can cause a
casualty to become unconscious within minutes.
• As well as an unusually high temperature, a
casualty may show signs of restlessness,
headaches and hot, flushed skin.
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Heatstroke
Sun Stroke
• The underlying cause of heat stroke is
connected to the sometimes sudden inability
to dissipate (To drive away) body heat
through perspiration, especially after
strenuous physical activity
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Heatstroke
Sun Stroke
• This accounts for the excessive rise in body temperature.
• It is the high fever which can cause permanent damage to internal
organs, and can result in death if not treated immediately.
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Recovery depends on heat duration and intensity.
• The goal of emergency treatment is to maintain circulation and lower
body temperature as quickly as possible.
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Definition
• core temperature > 41° C OR
- core temp > 40.5 ° C with anhidrosis
(absence or severe deficiency of sweating),
altered mental status or both
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Classification
• exertional: typically seen in healthy young adults
who overexert themselves in high ambient
(Surrounding) temperatures or in a hot environment
to which they are not acclimatized (To adapt).
• Patients sweat normally.
- non-exertional (classic): usually affects elderly and
debilitated patients with chronic underlying disease.
Result of impaired thermoregulation combined with
high ambient temperatures. Often due to impaired
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sweating
Pathophysiology
• Substantial fluid shift from central compartment
to periphery. Reversible on cooling
- cardiac output increased +++ (3 l/min per ° C
increase in rectal temperature). May fail in
patients with limited cardiac reserve
- mediators such as endotoxin and cytokines are
implicated in the pathogenesis of organ damage
in heat stroke
- intractable Disseminated Intravascular
Coagulation (DIC) is usual mode of death in
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fatal cases
Predisposing factors
• Increased heat production
• - hyperthyroidism
- exercise
- sepsis
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• Impaired heat loss -Impaired sweating
• Drugs
- anticholinergics, anti-Parkinsonian drugs, antihistamines, butyrophenones, phenothiazines,
tricyclics
• Abnormal sweat glands
- sweat gland injury following acute heat stroke,
barbiturate poisoning
- cystic fibrosis
- healed thermal burn
• salt and water depletion
- diuretic induced
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• Hypokalemia
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Impaired voluntary mechanisms
coma
physical disability
mental illness
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• Impaired delivery of blood to peripheral
circulation
• cardiovascular disease
• hypokalemia (decreased muscle blood flow)
• dehydration
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• Others
• - elderly
- high ambient temperature and humidity,
poor ventilation
- lack of acclimatization
- obesity
- fatigue
- DM
- malnutrition
- alcoholism
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Clinical features
• often little in the way of warning prodrome (An
early symptom indicating the onset of an attack
or a diseas) prior to development of nonexertional heat stroke (classic heat stroke).
• As thermoregulatory mechanisms fail body
temperature rises rapidly and patient can
deteriorate rapidly from apparent baseline health
to coma or an obtunded state
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Clinical features
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3 cardinal signs are:
CNS dysfunction
hyperpyrexia (core temperature >40° C)
hot dry skin. Pink or ashen depending on
circulatory state. However may be clammy and
sweat
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CNS
• Direct thermal toxicity causes cell death,
cerebral oedema and local haemorrhage
- irritability or irrational behaviour may precede
the development of either form of heatstroke
- confusion, aggressive behaviour, delirium,
convulsions and pupillary abnormalities may
progress rapidly to coma
- ± decorticate posturing, faecal incontinence,
flaccidity or hemiplegia (however focal signs are
unusual)
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• cerebellar signs, including ataxia and dysarthria
(Speech that is characteristically slurred, slow,
and difficult to produce (difficult to understand).
may be permanent in a few patients. Cerebellum
particularly sensitive to heat
- hypothalamic damage may exacerbate heat
stroke by further impairing sweating and heat
loss
- LP may show increased protein, xanthochromia
(is the yellow discoloration indicating the
presence of bilirubin in the cerebrospinal fluid
(CSF) and slight increase in lymphocytes
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CVS
• - tachycardia
- hypotension or normotension with wide pulse
pressure
- hyperdynamic haemodynamic profile
- myocardial pump failure. Myocardial damage
and frank infarction frequent even in patients with
normal coronaries due to the effect of heat on
myocytes and coronary hypoperfusion secondary
to hypovolaemia
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ECG of a patient with a core temperature of 40°C
dysrhythmias
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Same patient after cooling
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RS
• - extreme tachypnoea with RR up to 60/min
- crackles and cyanosis late signs of pulmonary
oedema
- direct thermal injury to pulmonary vascular
endothelium may lead to cor pulmonale or
Acute respiratory distress syndrome
(ARDS)
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Metabolic
• Dehydration leading to raised urea and
creatinine, and haemoconcentration
- sweating leading to low levels of Na, Mg, K,
early in the illness. Hypokalaemia decreases
sweat secretion and therefore exacerbates the
condition
- rhabdomyolysis resulting in hyperkalaemia,
hypocalcaemia and renal failure
- metabolic acidosis and respiratory alkalosis
common.
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Rhabdomyolysis
• A condition in which skeletal muscle cells
break down, releasing myoglobin (the oxygencarrying pigment in muscle) together with
enzymes and electrolytes from inside the
muscle cells. The risks with rhabdomyolysis
include muscle breakdown and kidney failure
since myoglobin is toxic to the kidneys.
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• Hyperthermia alone can cause primary
hyperventilation and respiratory alkalosis,
while hypoperfusion, tissue hypoxia, and
anaerobic metabolism may lead to lactic
acidosis with respiratory compensation.
Former less common.
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Renal
• Some renal damage occurs in nearly all patients
as a direct result of heat
• potentiated by dehydration and
Rhabdomyolysis
• acute renal failure 5-6 times more common in
patients with exertional heat stroke in whom it
occurs in 30-35%
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Splanchnic
• Ischaemic intestinal ulceration common. May
lead to haemorrhage
• Hepatic damage common. In 5-10% hepatic
necrosis may be severe enough to cause death
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Haematological
• Anaemia and bleeding. Result from: direct
inactivation of platelets and clotting factors by
heat
• liver failure
• unexplained decrease in platelets and
megakaryocytes (The source of blood platelets)
• platelet aggregation due to heat
• DIC. Due to activation of clotting cascade by
damaged vascular endothelium. Latter may be
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damaged as a direct result of heat
Investigations
• temperature
- electrolytes, urea, creatinine, calcium
- LFTs
- CPK
- ABG: note that Paco2 and Pao2 will be falsely
low and pH falsely elevated if results are not
corrected for temperature
- ECG and ECG monitoring
- urine output
- FBC, clotting, fibrinogen, FDP, D-dimer.
Anaemia frequent. Platelets low/normal.
Lymphocytosis
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- test urine for myoglobin
Symptoms of Heatstroke or
Sunstroke
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Headache, nausea, dizziness
Red, dry, very hot skin (sweating has ceased)
Pulse-strong & rapid
Small pupils
Very high fever
May become extremely disoriented
Unconsciousness and possible convulsions
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If exposure to heat continues, the body temperature
rises and heatstroke may develop, causing symptoms
such as:
1.Cessation of sweating
2. Body temperature of 105 degree Fahrenheit
or higher
3. Rapid and shallow breathing
4. Rapid heartbeat
5. Elevated or lowered blood pressure
6. Confusion and disorientation
7. Seizure
8. Fainting, which may be the first sign in older
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adults
• Left untreated, heat stroke may progress to
coma. Death may result due to kidney
failure, acute heart failure, or direct heat
induced damage to the brain.
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First Aid for Heatstroke
or Sunstroke
• HEATSROKE IS LIFE THREATENING!
• Remove victim to cooler location, out of the sun
• Loosen or remove clothing and immerse victim in very cool
water if possible
• If immersion isn't possible, cool victim with water, or wrap in
wet sheets and fan for quick evaporation
• Use cold compresses-especially to the head & neck area, also to
armpits and groin
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First Aid for Heatstroke or
Sunstroke
• Seek medical attention immediately--continue first aid to lower
temp. until medical help takes over
• Do NOT give any medication to lower fever--it will not be effective
and may cause further harm
• Do NOT use an alcohol rub
• It is not advisable to give the victim anything by mouth (even water)
until the condition has been stabilized.
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Once in the hospital, an examination is done, and blood tests
are carried out to assess the level of salts in the blood.
• Treatment of heat stroke is usually carried out
in a critical care unit.
• The body temperature is lowered by sponging
the body with tepid water or loosely wrapping
the person in a wet sheet and placing him or
her near a fan.
• Intravenous fluids are given.
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• Once the body temperature has been reduced
to 100 degree F(38 degree), these cooling
procedures are stopped to prevent hypothermia
(below) from developing.
• Monitoring is still carried out continuously to
make sure that the body temperature returns to
normal level and that the vital organs are
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functioning normally
• In some severe cases, mechanical
ventilation may be required to help
breathing.
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• when temperature approaches 39° active cooling
should be terminated as the body temperature
will continue to fall 1-2° C
- chlorpromazine 10-50 mg IV 6hrly may be
useful in preventing shivering
- use of dantrolene controversial. Probably
should not be used routinely at present.
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Dantrolene
• A skeletal muscle relaxant, used as the
sodium salt in the treatment of chronic
spasticity and the treatment and prophylaxis
of malignant hyperthermia (Malignant
hyperthermia is an inherited disease that
causes a rapid rise in body temperature
(fever) and severe muscle contractions
when the affected person receives general
anesthesia
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Some medicines can put the patient
in danger of heatstroke.
• Allergy medicines
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(antihistamines)
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• Cough and cold medicines
(anticholinergics)
• Blood pressure and heart
medicines
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Alpha andrenergics such as
midodrine (one brand:
ProAmatine) or pseudoephedrine
(one brand: Sudafed)
Beta blockers
Calcium channel blockers
Diet pills (amphetamines)
Irritable bladder and
irritable bowel medicines
(anticholinergics)
Laxatives
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Some medicines can putthe patient
in danger of heatstroke.
• Mental health medicines
Benzodiazepines such as
clonazepam (one brand:
Klonopin), diazepam (one
brand: Valium),
chlordiazepoxide (one
brand: Librium)
Neuroleptics
Tricyclic antidepressants
• Seizure medicines
(anticonvulsants)
• Thyroid pills
• Water pills
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Supportive
• IV volume replacement. Note that many of these
patients only require 1-1.2 l of replacement fluid
- if inotrope required dobutmine probably drug of
choice
- urgent treatment of hyperkalaemia
- do not treat hypocalcaemia per se; only give
calcium if ECG changes of severe hyperkalemia
occur as calcium may exacerbate rhabdomyolysis
- small dose of mannitol may benefit patients with
rhabdomyolysis
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Preventing heat-related
illness
• Dress for the heat — Wear lightweight, light-coloured clothing.
Light colours will reflect away some of the sun’s energy. It is also a
good idea to wear hats or to use an umbrella.
• Drink water — Carry water or juice with you and drink continuously
even if you do not feel thirsty. Avoid alcohol and caffeine, which
dehydrate the body.
• Avoid foods that are high in protein, which increase metabolic heat.
• Stay indoors when possible.
• Take regular breaks when engaged in physical activity on warm
days.
• Take time out to find a cool place.
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