By Dr Ananya Mandal, MD
Early diagnosis of heat exhaustion and heat stroke is of vital importance as these conditions may progress to fatal complications.
In most cases diagnosis is made clinically. This involves taking the temperature and assessing the symptoms of heat exhaustion and heat stroke.
Steps to diagnosis of the condition include assessment of core body temperature, blood tests and so forth. (1-4)
Assessment of core body temperature
Usually heat exhaustion may manifest as sweaty and clammy extremities and heat stroke may manifest as hot or warm limbs. The actual body temperature needs to be measured at the core.
Usually the thermometer is placed within the mouth, in the groin folds or armpits to detect the core temperature. A temperature of 40°C (104°F) or above is often a major sign of heatstroke.
Heatstroke however can be diagnosed at lower temperatures and these temperatures are not always indicative of heat stroke as they may be reached by athletes during physical exercise.
A routine blood test is done. This detects other problems like anemia, diabetes and presence of infections.
The blood electrolytes like Sodium, Potassium and bicarbonates are disturbed in heat related health conditions. These are assessed on blood tests.
Liver and kidney function tests are prescribed to check for damage. Blood levels of urate indicates kidney health and levels of creatine kinase detects muscle breakdown or rhabdomyolysis.
Other tests for heat stroke
Other tests performed to diagnose heat stroke include:
- Urine is tested to detect indications of muscle damage by rhabdomyolysis or damage to the kidney due to heat stroke complications
- ECG is performed to see the activity of the heart
- Chest X ray is prescribed to check for aspiration of fluids and lung edema etc.
- MRI and CT scan is advised to detect major abnormalities in the large organs.
Ruling out other conditions when diagnosing heat stroke
Other conditions that must be ruled out in diagnosis as they mimic heat stroke include:
- blood poisoning or sepsis
- cancers that may manifest with malignant hyperpyrexia or fever etc.
There may be a history of intake of antipsychotics leading to side effects like neuroleptic malignant syndrome or antidepressants leading to serotonin syndrome. Both manifest with features like heat stroke.
Heat stroke like features is also seen in drug abusers who use amphetamine, cocaine, ecstasy etc.
Treatment of heat exhaustion and heat stroke
Those with heat exhaustion and heat stroke need the following therapy approaches:
- They need to be taken to a cool place. This is ideally a room with air conditioning or at the most somewhere in the shade.
- If the patient is conscious, he or she is offered cool drinks. This should be water or a rehydration drink, such as a sports drink.
Alcohol and caffeine containing drinks are avoided as they lead to further dehydration. In patients with heat exhaustion the symptoms decrease in an hour or so and leave no long term effects.
- Clothing is loosened and excess clothing is removed. There should be adequate ventilation and air flow to allow further cooling. Fanning often helps.
- Persons’ skin should be cooled using cool but not cold water (15-18°C). This could be done with a cool shower or bath or by application of a wet flannel or facecloth to the skin.
They may be immersed in cool but not cold water. This last step is best performed under medical supervision as the boy may respond with a sudden change in blood pressure especially among those who have heart disease or the elderly.
- Skin is gently massaged to ensure blood circulation
- In case of fits or seizures the patient is moved away from objects that may cause injury. Nothing should be forced into the mouth of the patient.
For vomiting and unconscious patients, position on their side is preferable to avoid choking. In these emergency department must be immediately notified.
- Those who are vulnerable to heat stroke and its complications (like children below two years, elderly, debilitated and long term ill patients with diabetes, kidney and heart disease) need to be shifted to the hospital for better monitoring and care
- In the hospital fluids and electrolytes are administered as necessary while closely monitoring breathing, airway and maintenance of blood circulation.
- Ice packs are applied to the patient's neck, armpits and groins to cool at around 0.1°C/minute. Ice-bath immersion has been shown to be the most effective cooling method.
Cooling is slowed or stopped once the temperature is <38.5ºC, to avoid overcooling. Iced gastric lavage and peritoneal lavage is attempted in severe cases.
- Medications like Benzodiazepines and muscle relaxants are given to control shivering and fits.
- A urinary catheter is placed to measure the exact urine output.
- Complications like respiratory distress, encephalopatrhy (brain disorder), rhabdomyolysis, kidney or liver damage is managed according to severity and symptoms. (1)
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)
Last Updated: Aug 6, 2012