CLINICAL MANAGEMENT OF HEAT RELATED ILLNESS, MOH MALAYSIA DR LEE OI WAH KETUA PENOLONG PENGARAH KANAN (PERUBATAN)
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)