Risk factors for heat illness among British soldiers in the hot Collective Training Environment

Abstract

BackgroundHeat illness is a preventable disorder in military populations. Measures that protect vulnerable individuals and contribute to effective Immediate Treatment may reduce the impact of heat illness, but depend upon adequate understanding and awareness among Commanders and their troops.ObjectiveTo assess risk factors for heat illness in British soldiers deployed to the hot Collective Training Environment (CTE) and to explore awareness of Immediate Treatment responses.MethodsAn anonymous questionnaire was distributed to British soldiers deployed in the hot CTEs of Kenya and Canada. Responses were analysed to determine the prevalence of individual (Intrinsic) and Command-practice (Extrinsic) risk factors for heat illness and the self-reported awareness of key Immediate Treatment priorities (recognition, first aid and casualty evacuation).ResultsThe prevalence of Intrinsic risk factors was relatively low in comparison with Extrinsic risk factors. The majority of respondents were aware of key Immediate Treatment responses. The most frequently reported factors in each domain were increased risk by body composition scoring, inadequate time for heat acclimatisation and insufficient briefing about casualty evacuation.ConclusionsNovel data on the distribution and scale of risk factors for heat illness are presented. A collective approach to risk reduction by the accumulation of ‘marginal gains’ is proposed for the UK military. This should focus on limiting Intrinsic risk factors before deployment, reducing Extrinsic factors during training and promoting timely Immediate Treatment responses within the hot CTE.

Epidemiology of Exertional Heat Illness in the Military: A Systematic Review of Observational Studies

“…The titles and abstracts were screened, and 1502 articles excluded, leaving 154 articles for full-text review. Data in Table S2 depict that 41 articles were included in the review [ 13 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ], comprising 29 descriptive and cross-sectional studies [ 13 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 30 , 31 , 32 , 33 , 34 , 35 …”

“…Heat acclimatisation is defined as an individual’s expected tolerance for a given combination of internal and external heat [ 57 ]. Lack of acclimatisation was identified in three studies as a potential risk factor [ 35 , 37 , 48 ] ( Box 1 ). However, there is limited evidence to show that acclimatisation reduces the risk of EHI ( Table 3 and Table S3 ).…”

“…In six studies, sleep deprivation was identified as a potential risk factor [ 22 , 35 , 37 , 38 , 46 , 48 ] ( Box 1 ). However, as shown in Table S3 , one study reported that sleep deprivation did not increase the risk of hospitalisation for EHI (OR 0.76 95% CI 0.37–1.56) [ 57 ].…”

Heat Adaptation in Military Personnel: Mitigating Risk, Maximizing Performance

“…Mechanisms include a transient gut hypoxemia secondary to blood shunting from the viscera to exercising muscles causing an overwhelming efflux of endotoxins in circulation (Pyne et al, 2014) and systemic inflammatory responses. Immune stress may further potentiate this with military personnel and aid workers, through sleep deprivation (Day and Grimshaw, 2005;Stacey et al, 2015;Moore et al, 2016), psychological stress (Clow and Hucklebridge, 2001) or repeated (particularly gram negative) infection (Wale, 1989;Grainge and Heber, 2005;Howe and Boden, 2007;Cox et al, 2016a) causing a heightened inflammatory state. Attempts have been made to modulate exercise-induced gastrointestinal permeability with nutritional countermeasures.…”

An exertional heat illness triage tool for a jungle training environment

“…Collective organisational responsibility, force preparation and preparedness through effective education and military training may help mitigate the risk, but EHI remains a significant source of morbidity and mortality during military training and operations in thermally stressful environments. This may be due in part to the idiosyncratic response of individual Defence Personnel (DP) to thermal stress 5. Commanders remain challenged to provide realistic training to appropriately prepare DP while also reducing risk as much as possible 6.…”