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CLINICAL MANAGEMENT OF
HEAT RELATED ILLNESS, MOH
MALAYSIA
DR LEE OI WAHKETUA PENOLONG PENGARAH
KANAN (PERUBATAN)
INTRODUCTION
• Heat related illness is a medical emergency .• Mortality -70% in cases of heat stroke• If appropriate treatment is started without delay, survival
rates may approach 100%.• Factors contributing to heat stroke: extrinsic factors-extreme temperature, physical effort &
environmental conditionPhysiologic limitation-children, elderly, chronic illness eg
DM , heart disease, renal failure.
DEFINITION OF HEAT RELATED ILLNESS
Heat related illness is a group of disorder ranging from minor (heat oedema, pricklly heat, heat syncope, heat cramps and heat exhaustion) to major (heat stroke).
HEAT OEDEMA
• Mild swelling of feet, ankle and hands• Appears in few days of exposure in hot environment• Oedema usually does not progress to pretibial region• Treatment conservatively eg elevate leg & compressive
stocking• Resolves spontaneously
PRICKLY HEAT
• Pruritic maculopapular, erythematous rash over covered areas of body
• If prolonged or repeated heat exposure may lead to chronic dermatitis
• Treatment with antihistamine & chlorhexidine (cream or lotion based)
HEAT CRAMPS
• Painful, involuntary , spasmodic contractions of skeletal muscle
• Usually occurs at the calves, thighs and shoulders• Occurs in individuals sweating profusely and only
drinking water or hypotonic solution• Rx- fluid & salt replacement(IV or oral) - rest in cool environment
HEAT TETANY
• Paraesthesia of the extremities and circumoral or carpopedal spasm
• Due to hyperventilation• Rx- remove patient from hot environment & calm patient
HEAT SYNCOPE
• Postural hypotension• Usually in elderly• Rx- RULE OUT OTHER CAUSES FIRST - Rest and IV drip
HEAT EXHAUSTION
• Presented as headache, nausea, vomiting , malaise , dizziness and muscle cramps.
• TEMPERATURE < 40◦C OR NORMAL• May progress to heat stroke if fails to improve with
treatment• Rx - volume replacement - if no response after 30 min , need to aggresively cool the patient to core temperature < 39◦C
HEAT STROKE
• Defined as a core temperature > 40.5◦C accompanied by CNS dysfunction
• Types of heat stroke – classical heat stroke (CHS) - exertional heat stroke (EHS) - confinement hyperpyrexia
CLASSICAL HEAT STROKE (CHS)
• Occurs slowly within few hours to days ; leading to volume and electrolyte loss
• Population at risk - elderly - children - pharmacological treatment• Occurs during severe heat wave (environmental ◦T >
39.2◦ C)
EXERTIONAL HEAT STROKE (EHS)
• Occurs in healthy young individuals after severe exertion• May occur in normal or humid or hot environment• Commoner in Malaysia
CONFINEMENT HYPERPYREXIA
• Subtype of non-exertional hyperpyrexia• 3 circumstances:- child left inside car human traficking- enclosed vehicle workers exposed to heat in enclosed space
DIAGNOSIS OF HEAT STROKE
• History of heat exposure and1. Core body temperature greater than 40◦C2. Signs of CNS dysfunction - confusion - delirium - ataxia - seizures - coma3. Other late findings - anhidrosis - coagulopathy - multiple organ failure
DIFFERENTIAL DIAGNOSIS OF HEAT STROKE
• CNS injury• Hyperthyroid storm• Infection / septicemia• Neuroleptic malignant syndrome• Pheochromocytoma• Anticholinergic poisoning• Drug ingestion• Heat exhaustion
WORKUP FOR HEATSTROKE
1. ABG - hypoxemia - metabolic acidosis2. RBS – to exclude hypoglycemia / hyperglycemia3. Electrolytes – hypo or hypernatremia - hypo or hyperkalemia - hypocalcemia4. LFT – elevated ALT 5. Coagulation studies – derangement6. FBC - ↓ platelet , ↑ TWDC , ↑ PCV7. Renal function test – pictures of acute kidney injury8. Muscle enzymes - ↑ creatinine kinase9. Urine analysis – protein , cast , myoglobin
WORKUP FOR HEATSTROKE
10.ECG - arrhytmia 11. CXR – to detect atelectasis , pneumonia , pulmonary
infarction etc12.CT scan – TRO ICB if patients did not show
improvement in neurological signs
PRINCIPLE OF MANAGEMENT ON SITE
1. Detect the clinical sybdrome of heat exhaustion / heat stroke
2. To initiate effective cooling measures immediately3. Transfer to nearest appropriate hospital for definitive
treatment
MANAGEMENT AT ED
Aim of management:1. To prevent further metabolic derangement
(rhabdomyolysis , coagulopathy , liver and acute kidney injury)
2. To institute effective cooling measures
MANAGEMENT AT EDInitial management of the heat stroke patients is as following: • Focused clinical assessment regarding cardiovascular,
respiratory and neurological function. • Exclude other differential diagnoses. • Ensure patent airway, keep patient nil by mouth. • Provide oxygen supplementation. • Ensure adequate respiratory effort. • Insert intravenous cannula and initiate fluid management• Check body core temperature• Institute active cooling measures• Seizure control• Patient monitoring• Co-management with ICU if necessary
IV FLUID MANAGEMENT
• Fluid resuscitation guided based on hemodynamic status, comorbid and ensure urine output (UO) more than 0.5 ml/kg/hr in adult.
• When HR, BP, and UO do not provide adequate hemodynamic information, fluid administration should be guided by other non-invasive and invasive hemodynamic parameters
ACTIVE COOLING MEASURES
• Removal of body clothing • Ice packs at groins, neck and axilla, spray cool water • Use mist fan / air conditioned room / Stand fans. • Ongoing tepid sponging / cooling blankets. • Consider lavage with cold saline via nasogastric tube or 3
way urinary catheter. • DO NOT administer Paracetamol or Aspirin or other
NSAIDS. • Target to reduce temperature by 0.2°C per minute up to
approximately 38°C.
SEIZURE CONTROL
• Administer benzodiazepine in titrated doses for agitated patient and prepare for securing the airway definitively.
• Barbiturates may be used for patients having seizures and resistance to benzodiazepines.
PARAMETER FOR PATIENT MONITORING
• Core body temperature.
• Blood pressure / pulse rate / pulse oximetry.
• 12 lead ECG and continuous ECG monitoring.
• Hourly urine output (for patient with continuous bladder drainage).
• ½ hourly Glasgow Coma Scale (GCS).
• 4 hourly capillary blood sugar.
• Nasogastric tube drainage (for intubated patient)
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