**1. Introduction**

Heat-related illnesses are increasing rapidly and significantly. In the past two decades, there has been more than 50% increase in heat-related illness, morbidity and mortality particularly in elderly patients. The increase in heat-related illness is closely related to global warming and extreme heat events from east to the west. This increase in heat-related illness is causing a rise in intensive care therapy utilization, hospitalization with simoultenousely significant increase in global health burden and larger economic impact [1].

With further expected rise in global temperature by mid-century will result in a fivefold rise in extreme heat events and instead of occurring once in 50 years, they will increase by 14 times [1]. Hence it is of the utmost importance to be aware of these heat-related illnesses, their management and prevention.

### **2. Risk factors**

The risk of these heat-related illnesses increases significantly when exposed to the extremes of temperature particularly in susceptible individuals such as extremes of age, pregnant and patients with multiple comorbidities. The environmental risk for occurrence of these illnesses ranges from poor socioeconomical status to the limited labor protection and accesses to health care [1].

## **3. Management**

Heat stroke is the most serious of the heat-related illnesses, and it is a medical emergency, classified into exertional which typically occurs in healthy persons and classic heat stroke which occurs in patients with risk factors and comorbidities. In heat stroke, there are abnormalities in dissipation of the excessive body heat leading to the cellular and organ dysfunction including damage to the gastrointestinal system causing endotoxemia and triggering profound systemic inflammatory response syndrome causing further cellular and organ injury. The triad of heat stroke is elevated body temperature (40°C), intravascular coagulopathy and central nervous system disturbances [2].

#### *Heat Illness and Critical Care*

The other heat-related illnesses are heat exhaustion and heat cramps, edema and rash are mild to moderate disease (**Figure 1**). Apart from the above heat-related illnesses, the exposure to extremes of heat with elevated body temperature leads to exacerbation of heart disease, ischemic stroke, respiratory tract infections, kidney diseases, psychiatric disorder and preterm labor and delivery [3].

Heat stroke being a clinical and medical emergency has to be differentiated, and diagnosed quickly with early treatment as it is essential to prevent neurological complications with increased morbidity and mortality.

The most important point in the diagnosis of heat stroke is an accurate and timely measurement of the core body temperature. Usually, the rectal temperature is measured. The signs and symptoms of these heat-related illnesses depend on severity, heat stroke is typically diagnosed by the presence of triad of history of exposure to higher temperature, hyperthermia and neurological dysfunction. The presence of neurological abnormalities differentiates heat stroke from other heat-related illnesses. Heat stroke manifests in three phases, earlier diagnosis is better for clinical outcome. The acute phase is characterized by hyperthermia and neurological dysfunction, the 2nd phase occurs from 24 to 48 hours and is manifested by coagulopathy and enzymatic disorders. The late phase occurs 96 hours or longer after exposure to the extreme temperature and is manifested by multiple organ dysfunction [2].

The treatment of mild to moderate heat-related illnesses is mainly symptomatic and supportive (**Figure 1**) whereas the heat stroke patients should be managed by a multidisciplinary team, in intensive care therapy settings. The corner stone in the treatment of heat stroke is the rapid cooling and achieving the targeted temperature

**Figure 1.** *Showing management and prevention of heat related illnesses.*

(frequently around 38°C) within 30 minutes by rapid blood, esophageal or surface cooling methods along with taking care of airway, breathing and circulation. The pharmacological interventions are not very effective and causes adverse effects. Further in the care of these patients will be organ-supportive therapy [3].
