Heatstroke Sun Stroke Acute Management and Prevention

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HeatstrokeSun StrokeAcute Management and
Prevention

• Dr. Aidah Abu El Soud Alkaissi
• BSc Law, RN, BSc, MSc, PhD

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HeatstrokeSun Stroke

• Caused by overexposure to sun and extremely high
  temperatures
• occurs when the brain fails to control its own
  "thermostat".
• Its 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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HeatstrokeSun 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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HeatstrokeSun 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.
• 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 gt 41 C OR- core temp gt 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 sweating

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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 fatal
  cases

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Predisposing factors

• Increased heat production
• - hyperthyroidism- exercise- sepsis

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• Impaired heat loss -Impaired sweating
• Drugs- anticholinergics, anti-Parkinsonian
  drugs, anti-histamines, 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
• 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
  non-exertional 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

• 3 cardinal signs are
• CNS dysfunction
• hyperpyrexia (core temperature gt40 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 40C
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 oxygen-carrying
  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
  damaged as a direct result of heat

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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-
  test urine for myoglobin

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Symptoms of Heatstroke or Sunstroke

• 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 sweating2.      Body temperature
  of 105 degree Fahrenheit or higher3.      Rapid
  and shallow breathing4.      Rapid
  heartbeat5.      Elevated or lowered blood
  pressure6.      Confusion and disorientation7.  
      Seizure8.      Fainting, which may be the
  first sign in older adults

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• 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
  functioning normally

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• 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 (antihistamines)
• Cough and cold medicines (anticholinergics)
• Blood pressure and heart medicinesAlpha
  andrenergics such as midodrine (one brand
  ProAmatine) or pseudoephedrine (one brand
  Sudafed)Beta blockersCalcium 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 medicinesBenzodiazepines such as
  clonazepam (one brand Klonopin), diazepam (one
  brand Valium), chlordiazepoxide (one brand
  Librium) NeurolepticsTricyclic 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 suns 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.