A period of excessive temperature over an area resulting in continuously elevated temperature is called heat wave. It was defined as "period of excessive temperature lasting atleast oneday, but conventionally lasts for many days to several weeks". The criteria varies from area to area as a temperature of 90 degrees in New York may be excessive but for Karachi it is a usual day.
This heat wave leads to clinical effects based upon the degree of exposure and the time the person is exposed to the heat wave. The heat waves are not a new phenomenon, yet the incidence of heat waves is bound to increase due to global warming and the deforestation among other reasons.
The degree and time period of exposure can lead to a spectrum of clinical features which can be summarized as:
- Liver abscess
- Neuroleptic malignant syndrome
- Malignant hyperthermia
- Substance withdrawal syndrome
- Thyroid storm
It requires high index of suspicion and a good history taking in appropriate months for the heat wave.
- The triage would tell how much evaluation is needed. Starting from ABC's.
Usually the Heat rash and Heat edema will not need any further investigation. But for more serious exposure and in right clinical settings, the following labs may be justified.
- CBC with differential.
- Serum chemistries.
- Blood CPK.
- Urine analysis
- Other investigation to rule out important differential may be needed as per treating physicians discretion.
Identification of the magnitude. As the heat wave can be area wide disaster if not reported timely, so whenever the Emergency Physician sees more than usual number of patients exposed to heat, then they should alert the authorities. Management includes: Limiting exposure Institute cooling methods. Support the circulation. Monitor concurrent medical problems.
Most patients with exposure can be discharged home after appropriate monitoring and bringing the temperature to relatively stable degree. Patients with Heat syncope can be observed for 4 to 6 hours and then discharged home with quick follow up and appropriate discharge instructions. Patients with heat exhaustion and Heat stroke need to be hospitalized in appropriate setting.