The development process and features of the heat stroke clinical practice guidelines 2024

Abstract

Since 2006, the Heatstroke Committee of the Japanese Association for Acute Medicine has conducted nationwide surveys on severe heatstroke, contributing to our understanding of actual conditions and ability to promote effective countermeasures. In 2015, the committee published the “2015 Heatstroke Management Guideline (G2015)” based on Clinical Questions (CQ), providing specific guidance for clinical practice with a Grade Ⅰ to Grade III severity classification system primarily focusing on symptoms. After approximately 10 years, due to climate change-associated increasing incidence of heatstroke and the accumulation of new evidence, the committee deemed it necessary to update the guideline, resulting in the development of the “2024 Heatstroke Management Guideline (G2024).” G2024 refers to the Minds Guideline Development Manual 2020 and adopts the GRADE system. For CQs lacking sufficient recommendations, topics were categorized as Future Research Questions (FRQ) or Background Questions (BQ), clarifying what is currently known and unknown in heatstroke management. Primary updates in G2024 include clarification of the concept of active cooling, introduction of a Grade IV severity classification, establishment of the quick Grade IV (qGrade IV) concept, and a focus on detailed diagnostic and treatment algorithms. Temperature management methods were divided into “Active Cooling” and “Passive Cooling.” Active Cooling includes immersion in cold water, evaporative cooling, and extracorporeal membrane oxygenation (ECMO), and Passive Cooling includes cooling infusions and resting in cool environments suitable for milder cases. The new classification subdivides the former Grade III into more detailed categories, and defines Grade IV as the most severe, with a core body temperature of ≥40.0°C and impaired consciousness (Glasgow Coma Scale ≤8). Early comprehensive treatment, including Active Cooling, is strongly recommended for patients with Grade IV heat stroke. Data from the Heatstroke Surveillance System (HsS) indicate that the in-hospital mortality rate for patients with Grade IV heat stroke is 23.5%, with an odds ratio of 4.5 for mortality compared to those with Grade III (95% confidence interval: 3.24–6.30). For situations where core body temperature measurement is challenging, G2024 introduces qGrade IV criteria: a surface temperature of ≥40.0°C or obvious heat sensation combined with severely impaired consciousness (GCS ≤8 or Japan Coma Scale ≥100). These guidelines emphasize the need for rapid transportation to advanced emergency medical facilities in such cases. G2024 provides clear treatment protocols based on severity assessment and strongly recommends immediate treatment, including Active Cooling, for qGrade IV and Grade IV cases. The guidelines establish 10 CQs, 7 FRQs, and 7 BQs, but few topics currently include definitive recommendations. The field currently lacks high-quality research, including randomized controlled trials. Therefore, further studies are urgently required.