Introductory Chapter: Heat-Related Illness – Need for Awareness, Attention and Research

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].

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].

Figure 1.

Showing management and prevention of heat related illnesses.

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 (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].

4. Further research

Research and high-quality studies are limited and require advanced knowledge and research regarding the effective rate and method of rapid cooling, when to stop cooling as well as about the medications to be used in heat stroke patients. Further research and reports are required about the impact of heat wave awareness and the use of early warning systems and alerts [4, 5]. Although there are excellent guidelines for the management of heat-related illnesses, more protocols and guidelines are needed in other different settings occurrence of this disease [6].

5. Prevention

Heat-related illnesses are preventable (Figure 1). Hence all the efforts should be taken for identifying patients at risk, educating not only patients but their relatives, care givers, social workers about awareness, preventive measures and seeking early health care. Not only athletes, but spectators, administrators, event organizers, coaches, staff should be educated about heat exposure and heat-related illnesses, and athletes should be acclimatized in advance for shorter training sessions for extreme heat exposure [7]. About 75% of fatalities at work in the extreme of temperature occur during the first week. Outdoor workers and their supervisors should also be educated and made aware about day to day extreme temperatures and risk of heat-related illnesses and encourage them to drink water frequently, remove extra clothes and equipment. We recommend in extreme summer days, outdoor construction and other work should be in the early hours of day and in the evening and to rest in the afternoon when the temperature is maximum. Few countries follow the rule of 20%, in the first week of work in extreme summer, worker should work only 20% of the shift and in further weeks also do 20% work of the day till acclimatize to the extremely warm weather (Figure 1) [5].