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)