Current Management Of Heat Stroke

Heat disorders are commonly seen in the middle Myanmar such as Magway, Minbu, Myingyan, Pakokku, Monywa, and west bank of Irrawaddy River, where most of the industrial complexes and factories are situated. Sporadic cases are usually seen in the hotter parts of the season but the unusual clustering of cases may be witnessed during the month of May in conjunction with the presence of abnormal heat waves. Among the heat related disorders, heat stoke is a life threatening medical emergency and effective, systematic and timely management is necessary to prevent mortality and morbidity.

Diagnostic criteria

1. High fever > 106 F / 41 C (oral/ rectal)
2. Hot and dry skin with absence of sweating
3. Cerebral symptoms (confusion, delirium, convulsion, coma)

Predisposing factors are

1. Unacclimatized people
2. Infancy and old age
3. Unsuitable clothing
4. Poor ventilation especially in enclosed space
5. Acute febrile illnesses, e.g. malaria, pneumonias( by inhibition of sweating during the fever)
6. Concomitant degenerative cardiovascular diseases
7. Increased production of heat due to body metabolic processes (e.g. hyperthyroidism, excessive muscular activity) in conditions of high temperature and humidity
8. Congenital absence of sweat glands (cystic fibrosis)
9. Obesity
10. Use of medications impairing sweating , salt and water balance direction and anticholinergic drugs ( e.g. atropine)
11. Excessive consumption of alcohol (by increasing the metabolic production of heat by peripheral vasodilatation with subsequent dehydration)
12. Dehydration (In cases of heat exhaustion; when dehydration is left untreated, leads to cessation of sweating)
13. Use of dermatological oily preparations (by inhibiting sweating

There are two types of heat stroke

1. Classical or nonexertional heat stroke
a. prolonged exposure to heat
b. common in very young and elderly
c. with chronic mental disorders
d. with cardiopulmonary diseases
e. with medications impairing sweating , salt and water balance direction

2. Exertional heat stroke
a. Manual workers
b. Long distance runners and football players
c. Military personnel
d. Cocaine and amphetamine abuse

“Awareness of possibility of heat stroke in all patients with above triad of symptoms during hot season is very important”

The core temp ranges from 40-470C (104-117 0F). Brain dysfunction is usually severe but may be subtle, manifesting only as inappropriate behaviour or impaired judgment → delirium to frank coma. Seizures may occur especially during cooling.
All patients have tachycardia and hyperventilation. PaCO2 is < 20mmHg.
25% of patients have hypotension.
Other features- respiratory alkalosis, lactic acidosis, hypophostaemia, hypokalemia, rarely hypoglycaemia, hypocalcaemia, hyperproteinameia,
Exertional heat stroke- rhabdomyolysis, hyperphosphataemia, hypocalcaemia, hyperkalaemia

Complications

MODS (multiorgan-dysfunction syndrome)

• Encephalopathy
• Rhabdomyolysis
• Acute renal failure
• Acute respiratory distress syndrome
• Myocardial injury
• Hepatocellular injury
• Intestinal ischemia or infarction
• Pancreatic injury and
  Haemorrhagic complications _ DIC with pronounced thrombocytopenia

Management

It is an acute medical emergency- admission to hospital without delay

1. Nursed in air conditioned room (or) kept in well ventilated room ,directly under ceiling fan or close to standing fan
2. Stabilize the patient. If unconscious – Patent Airway, Adequate Breathing and
   Circulation (A B C)
   – Position an unconscious patient on his or her side and clear the airway.
   – Administer O2 at 4 L/minute.
   – Start IV fluids (crystalloids) promptly. N/S or 5% D/W
3. Tepid sponging / wrapped loosely in a cool wet sheet. Evaporation is hastened by continuous fanning. Cold Towel or Ice packs should be placed in axilla, groin and neck
   over areas of large arteries.
4. Body temperature should be monitored closely reduced to 100 F / 37 C within one hour.
5. Basic essential investigations: Urine RE, CP,MP, U&E, RBS,LFT, ECG,CXR (CK, AST, LDH, Ca2+, PO4, Mg2+- if suspect rhabdomyolysis and coagulation screen and ABG only if indicated)
6. I/M chlorpromazine (CPZ) 25-50 mg has triple action: sedation, decrease temperature and Blood pressure
7. Correction of fluid& electrolytes based on U&E
8. Avoid- injecting analgesin, and immersion in ice- water
9. Treat associated febrile illness even on clinical ground (malaria, pneumonia)
10. Parenteral antibiotic in view of possibility of aspiration)- according to hospital antibiotics policy/ guideline
11. Look for & treat complications: pulmonary oedema, liver failure, rhabdomyolysis, Cerebral oedema, DIC, lactic acidosis
12. Continued tepid sponging and keeping the patient in cold area is important since thermoregulatory function may remain unstable for up to a week.

Treatment of complications

• Respiratory failure- consider intubation
• Seizures- give IV benzodiazepine
• Hypotension- administer fluids for volume expansion, consider vasopressors, consider monitoring CVP
• MODS- supportive therapy

Prevention

1. Ancillary measures concerning adequate drinking water supply, clothing, working condition and ventilation.
2. Selection and screening- elimination of those with cardiovascular disease and those who are intolerant to heat.
3. Deliberate acclimatization.

Community health education

• Special care and precaution should be given to elderly and those with heart disease and other ailments.
• Advise to unacclimatized persons not to take part in athletic pursuits, exercise or unaccustomed physical work.
• Not to work/walk under the heat of the sun during these periods.
• People should live and rest under the cool-shady area during the day time.
• Wearing of loose, light colored, cotton clothes.
• Avoidance of tight, dark colored, nylon and woolen clothes.
• Avoidance of taking bath at the river banks or after exposure to heat/sun.
• Taking adequate amount of fluid.
• Avoidance of precipitating factors.
• To seek medical treatment immediately.
• To have a prepared centre where effective cooling treatment can be given at once, without delay, to any patient in need.

Further reading

1. Byers M, Environmental Medicine, Davidson’s Principles and Practice of Medicine, Twenty third edition, 2018
2. Professor U Saw Naing, Heat stroke, Hospital Manual, 2003
3. Therapeutic Manual ; Internal Medicine; First Edition , 2016 , Internal Medicine Society , Myanmar Medical Association

Professor Nyunt Thein, Emeritus Professor in Medicine
Former Head of Department of Medicine, University of Medicine (1) Yangon