With climate change, heat waves are expected to become more frequent in the near future. On an average, more than 25 000 "heat deaths" are estimated to occur in Europe every year. However, heat stress and heat illnesses arise not just when ambient temperatures are high. Physical exertion increases heat production, many times over – if enough heat is not lost, there is a risk of exertional heat stress.

The objective of a recent study published in Deutsches Arzteblatt International was to discusscontributing factors, at-risk groups and diagnosis and treatment of heat illnesses.

In this review, selective literature search was carried out on PubMed. Current guidelines and expert recommendations were also included.

The results revealed that apart from muscular heat production (>70% of converted energy), there are other factors that singly or in combination can give rise to heat stress; vis, clothing, individual factors, as well as climate/acclimatization. Through its insulating properties, clothing reduces the evaporation of sweat—the most effective physiological cooling mechanism. Whereas, a sudden heat wave, or changing the climate zone – as with air travel, increases the risk of a heat-related health event. In addition, overweight, low fitness level, acute infections, illness, dehydration and other factors also reduce heat tolerance. Not only children, but older people are also at risk because of their reduced physiological adaptability, (multi-)morbidity and intake of prescription drugs. A heat illness can progress suddenly to life-threatening heat stroke. Successful treatment depends on rapid diagnosis and cooling the body down as quickly as possible—with the aim to reduce core body temperature to <40 °C within 30 minutes.

In summary, it was stated that immediately effective cooling interventions are the only causal treatment for heat stroke. Prevention (acclimatization, reduced exposure, etc.) and terminating the heat stress in good time (e.g., stopping work) are better than any cure.

Source: Deutsches Arzteblatt International. 2019 Aug 5;116(31-32):537-544.doi:10.3238/arztebl.2019.0537.