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Purpose\ud Endurance exercise and hyperthermia are associated with compromised intestinal permeability and endotoxaemia. The presence of intestinal fatty acid-binding protein (I-FABP) in the systemic circulation suggests intestinal wall damage, but this marker has not previously been used to investigate intestinal integrity after marathon running.\ud \ud Methods\ud Twenty-four runners were recruited as controls prior to completing a standard marathon and had sequential I-FABP measurements before and on completion of the marathon, then at four and 24 h later. Eight runners incapacitated with exercise-associated collapse (EAC) with hyperthermia had I-FABP measured at the time of collapse and 1 hour later.\ud \ud Results\ud I-FABP was increased immediately on completing the marathon (T0; 2593 ± 1373 ng·l−1) compared with baseline (1129 ± 493 ng·l−1; p

IntroductionReflex syncope is the most common subtype of syncope and, despite not being associated with increased mortality, often results in significant morbidity and costly diagnostics. Reflex syncope can be of concern for certain occupational groups and may be exacerbated by some occupations. Reflex syncope in the military is anecdotally common but the extent in the UK Armed Forces (UKAF) is unknown. The aim of this study was to assess the incidence and prevalence of reflex syncope in the UKAF.MethodsA retrospective search of the Defence Medical Information Capability Programme using prespecified read-codes was performed at defence primary healthcare centres over the period of 1 January 2019 to 1 January 2020. Data were obtained on 76 103 service personnel (SP) (53% of the UKAF).ResultsThe overall syncope case rate for the UKAF was 10.5 per 1000 person-years (p-yrs). In comparing services there was a significantly increased risk of syncope in the British Army (10.7 per 1000 p-yrs) compared with the Royal Air Force (8.6 per 1000 p-yrs) (p=0.0365), SP who served overseas (16.7 per 1000 p-yrs) in comparison with UK medical centres (10.3 per 1000 p-yrs) (pConclusionsThese data are the first to define the incidence and prevalence of syncope in the UKAF. Orthostasis and heat are probable triggers, although recruits are potentially protected. These data offer opportunities to improve the health and well-being of SP, with economic, logistical and reputational benefits for the UKAF. Further research to identify personnel at risk of future syncopal events may allow for targeted use of countermeasures.

Purpose Heat stress exacerbates post-exercise hypotension (PEH) and cardiovascular disturbances from elevated body temperature may contribute to exertion-related incapacity. Mast cell degranulation and muscle mass are possible modifiers, though these hypotheses lack practical evidence. This study had three aims: (1) to characterise pre–post-responses in histamine and mast cell tryptase (MCT), (2) to investigate relationships between whole body muscle mass (WBMM) and changes in blood pressure post-marathon, (3) to identify any differences in incapacitated runners. Methods 24 recreational runners were recruited and successfully completed the 2019 Brighton Marathon (COMPLETION). WBMM was measured at baseline. A further eight participants were recruited from incapacitated runners (COLLAPSE). Histamine, MCT, blood pressure, heart rate, body temperature and echocardiographic measures were taken before and after exercise (COMPLETION) and upon incapacitation (COLLAPSE). Results In completion, MCT increased by nearly 50% from baseline (p = 0.0049), whereas histamine and body temperature did not vary (p > 0.946). Systolic (SBP), diastolic (DBP) and mean (MAP) arterial blood pressures and systemic vascular resistance (SVR) declined (p $$\Delta $$ Δ SBP (r = − 0.43, p = 0.046). For collapse versus completion, there were significant elevations in MCT (1.77 ± 0.25 μg/L vs 1.18 ± 0.43 μg/L, p = 0.001) and body temperature (39.8 ± 1.3 °C vs 36.2 ± 0.8 °C, p p = 0.107) and significantly lower MAP, DBP and SVR (p Conclusion These data support the hypothesis that mast cell degranulation is a vasodilatory mechanism underlying PEH and exercise associated collapse. The magnitude of PEH is inversely proportional to the muscle mass and enhanced by concomitant body heating.

Heat stress exacerbates post-exercise hypotension (PEH) and cardiovascular disturbances from elevated body temperature may contribute to exertion-related incapacity. Mast cell degranulation and muscle mass are possible modifiers, though these hypotheses lack practical evidence. This study had three aims: (1) to characterise pre-post-responses in histamine and mast cell tryptase (MCT), (2) to investigate relationships between whole body muscle mass (WBMM) and changes in blood pressure post-marathon, (3) to identify any differences in incapacitated runners.24 recreational runners were recruited and successfully completed the 2019 Brighton Marathon (COMPLETION). WBMM was measured at baseline. A further eight participants were recruited from incapacitated runners (COLLAPSE). Histamine, MCT, blood pressure, heart rate, body temperature and echocardiographic measures were taken before and after exercise (COMPLETION) and upon incapacitation (COLLAPSE).In completion, MCT increased by nearly 50% from baseline (p = 0.0049), whereas histamine and body temperature did not vary (p 0.946). Systolic (SBP), diastolic (DBP) and mean (MAP) arterial blood pressures and systemic vascular resistance (SVR) declined (p 0.019). WBMM negatively correlated with Δ SBP (r = - 0.43, p = 0.046). For collapse versus completion, there were significant elevations in MCT (1.77 ± 0.25 μg/L vs 1.18 ± 0.43 μg/L, p = 0.001) and body temperature (39.8 ± 1.3 °C vs 36.2 ± 0.8 °C, p 0.0001) with a non-significant rise in histamine (9.6 ± 17.9 μg/L vs 13.7 ± 33.9 μg/L, p = 0.107) and significantly lower MAP, DBP and SVR (p 0.033).These data support the hypothesis that mast cell degranulation is a vasodilatory mechanism underlying PEH and exercise associated collapse. The magnitude of PEH is inversely proportional to the muscle mass and enhanced by concomitant body heating.

For most individuals residing in Northwestern Europe, maintaining replete vitamin D status throughout the year is unlikely without vitamin D supplementation and deficiency remains common. Military studies have investigated the association with vitamin D status, and subsequent supplementation, with the risk of stress fractures particularly during recruit training. The expression of nuclear vitamin D receptors and vitamin D metabolic enzymes in immune cells additionally provides a rationale for the potential role of vitamin D in maintaining immune homeostasis. One particular area of interest has been in the prevention of acute respiratory tract infections (ARTIs). The aims of this review were to consider the evidence of vitamin D supplementation in military populations in the prevention of ARTIs, including SARS-CoV-2 infection and consequent COVID-19 illness. The occupational/organisational importance of reducing transmission of SARS-CoV-2, especially where infected young adults may be asymptomatic, presymptomatic or paucisymptomatic, is also discussed.

Objective \ud Abnormal biochemical measurements have previously been described in runners following marathons. The incidence of plasma sodium levels outside the normal range has been reported as 31%, and the incidence of raised creatinine at 30%. This study describes the changes seen in electrolytes and creatinine in collapsed (2010–2019 events) and noncollapsed (during the 2019 event) runners during a UK marathon.\ud \ud Methods \ud Point-of-care sodium, potassium, urea and creatinine estimates were obtained from any collapsed runner treated by the medical team during the Brighton Marathons, as part of their clinical care, and laboratory measurements from control subjects.\ud \ud Results \ud Results from 224 collapsed runners were available. Serum creatinine was greater than the normal range in 68.9%. About 6% of sodium results were below, and 3% above the normal range, with the lowest 132 mmol/l. Seventeen percent of potassium readings were above the normal range; the maximum result was 8.4 mmol/l, but 97% were below 6.0 mmol/l. In the control group, mean creatinine was significantly raised in both the collapse and control groups, with 55.4% meeting the criteria for acute kidney injury, but had resolved to baseline after 24 h. Sodium concentration but not the potassium was significantly raised after the race compared with baseline, but only 15% were outside the normal range.\ud \ud Conclusion \ud In this study, incidence of a raised creatinine was higher than previously reported. However, the significance of such a rise remains unclear with a similar rise seen in collapsed and noncollapsed runners, and resolution noted within 24 h. Abnormal sodium concentrations were observed infrequently, and severely abnormal results were not seen, potentially reflecting current advice to drink enough fluid to quench thirst.

This chapter outlines the basic science and theory of environmental medicine required for MRCP Part 1, before addressing the clinical aspects of environmental medicine for MRCP Part 2. To ensure effective revision, material is presented in short sections with bullet lists, tables and boxes to highlight key facts.

Introduction Thermoregulatory induced cardiovascular insufficiency impairs the ability to exercise in the heat. Heat adaption through acclimatisation or acclimation (HA) improves cardiovascular stability by maintaining cardiac output, despite lowering resting heart rate, due to compensatory increases in left ventricular stroke volume. The primary aim of this study was to assess whether 2D transthoracic echocardiography (TTE) could be used to confirm differences in resting cardiovascular responses, before and after isothermic HA. Methods Thirteen male endurance trained cyclists underwent a resting blinded TTE before and after randomisation to either 5 consecutive daily exertional heat exposures of controlled hyperthermia at 32°C with 70% relative humidity (RH) (HOT) or 5-days of exercise in temperate (21°C with 36% RH) environmental conditions (TEMP). Measures of HA included heart rate, gastrointestinal temperature, skin temperature, sweat loss, total non-urinary fluid loss (TNUFL), plasma volume and participant’s ratings of perceived exertion (RPE). Results Following HA, the HOT group demonstrated increased sweat loss (p=0.01) and TNUFL (p=0.01) in comparison to the TEMP group with a significantly decreased RPE (p=0.01). On TTE, post exposure, there was a significant comparative increase in the HOT group in left ventricular end diastolic volume (p=0.029), SV (p=0.009), left atrial volume (p=0.025), inferior vena cava diameter (p=0.041), and a significant difference in mean peak diastolic mitral annular velocity (e’) (p=0.044). Conclusions The significant differences in thermal comfort, sweat loss and TNUFL following the active HA in the HOT group are confirmatory for heat adaptation. Overall, these data demonstrate several concurrent cardiovascular adaptations occurring in response to HA, with the cardinal adaptation probably being that of increased preload driven by an increased plasma volume, in conjunction with enhanced ventricular compliance. Greater cardiac relaxation is likely to reflect cellular adaptations in the myocardium. Echocardiography is a useful tool to demonstrate and quantify cardiac adaptation to heat. This has several implications to utilise TTE as a research tool in elite athletes firefighters, miners, the military or aid workers particularly in the development of tailored rapid HA regimes. Conflict of Interest None

Since the advent of women in ground close combat (WGCC) roles, the impact on women of the attendant risk of heat stress and heat illness has been considered. Much emphasis has been placed on sex differences in thermal physiology. This article considers the application of evidence of sex-associated thermoregulatory variation to the occupational and environmental setting of WGCC, and weighs the relative importance of physiological differences arising from biological sex, and behaviour associated with gender normatives. Quantifying the risk of heat illness to WGCC should draw on data from their real-world occupational context.

Heat stress—arising from strenuous physical exertion, severe environmental conditions, or a combination of both factors—presents a perennial challenge to military organisations.1,2 In the UK and other temperate countries, the Armed Forces are required to maintain physical fitness, undergo

Extreme environments present medical and occupational challenges that extend beyond generic resuscitation, to formulating bespoke diagnoses and prognoses and embarking on management pathways rarely encountered in civilian practice. Pathophysiological complexity and clinical uncertainty call for military physicians of all kinds to balance intuition with pragmatism, adapting according to the predominant patterns of care required. In an era of smaller operational footprints and less concentrated clinical experience, proposals aimed at improving the systematic care of Service Personnel incapacitated at environmental extremes must not be lost to corporate memory. These general issues are explored in the particular context of thermal stress and metabolic disruption. Specific focus is given to the accounts of military physicians who served on large-scale deployments into the heat of Iraq and Kuwait (Operation TELIC) and Oman (Exercise SAIF SAREEA). Generalisable insights into the enduring character of military medicine and future clinical requirements result.

Objectives To investigate changes in renal status from exercise in the heat with acclimatisation and to evaluate surrogates markers of Acute Kidney Injury. Design Prospective observational cohort study. Methods 20 male volunteers performed 60 min standardised exercise in the heat, at baseline and on four subsequent occasions during a 23-day acclimatisation regimen. Blood was sampled before and after exercise for serum creatinine, copeptin, interleukin-6, normetanephrine and cortisol. Fractional excretion of sodium was calculated for corresponding urine samples. Ratings of Perceived Exertion were reported every 5 min during exercise. Acute Kidney Injury was defined as serum creatinine rise ≥26.5 μmol L−1 or fall in estimated glomerular filtration rate >25%. Predictive values of each candidate marker for developing Acute Kidney Injury were determined by ROC analysis. Results From baseline to Day 23, serum creatinine did not vary at rest, but showed a significant (P < 0.05) reduction post-exercise (120 [102, 139] versus 102 [91, 112] μmol L−1). Acute Kidney Injury was common (26/100 exposures) and occurred most frequently in the unacclimatised state. Log-normalised fractional excretion of sodium showed a significant interaction (exercise by acclimatization day), with post-exercise values tending to rise with acclimatisation. Ratings of Perceived Exertion predicted AKI (AUC 0.76, 95% confidence interval 0.65–0.88), performing at least as well as biochemical markers. Conclusions Heat acclimatization is associated with reduced markers of renal stress and AKI incidence, perhaps due to improved regional perfusion. Acclimatisation and monitoring Ratings of Perceived Exertion are practical, non-invasive measures that could help to reduce renal injury from exercise in the heat.

IntroductionHeat stress exacerbates post-exercise hypotension and cardiovascular disturbances from elevated body temperature and may contribute to exertion-related incapacity. Mast cell degranulation and muscle mass are considered likely modifiers, though this hypothesis lacks practical evidence. This study had three aims: 1) to characterise pre-post responses in histamine and mast cell tryptase (MCT); 2) to investigate relationships between whole body muscle mass (WBMM) and changes in blood pressure post marathon; 3) to identify any differences in runners incapacitated from marathon running.Methods24 recreational runners were recruited and successfully completed the 2019 Brighton Marathon (COMPLETION). WBMM was measured by bioimpedance at rested baseline. A further eight participants were recruited from incapacitated runners diagnosed with heat illness (COLLAPSE). Histamine, MCT, blood pressure, heart rate, body temperature and echocardiographic measures were taken before and after exercise (COMPLETION) and upon hyperthermic incapacitation (COLLAPSE).ResultsIn COMPLETION, MCT increased by nearly 50% from baseline (p=0.001), whereas histamine and body temperature did not vary (P>0.9462). Systolic (sBP), diastolic (dBP) and mean (MAP) arterial blood pressures and systemic vascular resistance (SVR) declined (pConclusionsThese data support the hypothesis that mast cell degranulation is a vasodilatory mechanism underlying PEH and exercise associated collapse. The magnitude of PEH is inversely proportional to the muscle mass and enhanced by concomitant body heating.

Background Heat illness (HI) is a growing global concern; its incidence has risen dramatically across the world in recent years. The individual factors whereby elevated core temperature produces HI are not well-understood. Given known physiological differences between men and women pertaining to temperature regulation, we hypothesized that women would be at increased risk of HI than men. Objectives We aimed to determine the relative risk of HI in women compared with men through an exhaustive literature review and meta-analysis. Methods We search PubMed and Ovid Medline databases from inception to Apr 2017. Search terms included all permutations of sex and heat illness (including heatstroke and exertional heat illness) with no language restrictions. We included adult or adolescent human data reporting comparable male and female HI rates. One reviewer identified and screened titles and abstracts. Two independent reviewers applied eligibility criteria. Disagreements were resolved with a third reviewer. Results Of 5888 articles identified by searches, 36 were included in the systematic review and 22 in the meta-analysis. The mean (standard deviation) quality score was 3.31(1.25)/5. Overall the rate among women was consistently lower than men across the lifespan. The male: female pooled IRR was 2.28 (p

Detailed knowledge of the likely volume and nature of the diseases presenting to deployed secondary care facilities aids operational planning. Now the British operation in Afghanistan has ended and a record of the experience is useful to preserve the lessons learned.Over a 2-year period from April 2011, prospective demographic and clinical data were collected on consecutive general internal medicine admissions to the Role 3 Hospital in Camp Bastion, Afghanistan. Up to four different symptoms and diagnoses were coded using the WHO International Classification of Disease, V.10 for each patient.A total of 1368 medical patients were admitted. Of 1131 military admissions, 612 were from the UK (54.1%) and the remainder from 13 allied countries; 237 civilians came from 23 countries. Civilians were older than the military patients (p0.001) but included five children. The 20 most frequent presenting symptoms were identified and there were 1626 diagnoses made. The 10 most frequent diagnoses were infectious gastroenteritis (12.6%), heat illness (4.3%), pneumonia (3.6%), epilepsy (2.6%), cellulitis (2.7%), migraine (1.8%), peptic ulcer disease (1.2%), myocardial infarction (1.2%), venous thromboembolism (1.2%) and pericarditis (0.7%). In 252 cases (18.4%) a firm diagnosis was not reached and a symptom was recorded. The five most frequent of these were undifferentiated febrile illnesses (4.6%), syncope (3.7%), chest pain (2.8%), headache (0.8%) and palpitations (0.7%). The mean hospital length of stay was 1.59 days and 72.2% of UK military patients were 'returned to unit'. Three civilian patients died in hospital or following aeromedical evacuation and there were no deaths of any military patients.This study demonstrates the wide variety of presentations seen by physicians at an established military field hospital. This information informs the core syllabus of military physician training and will help facilitate planning for future medical support to similar military operations.RCDM/Res/Audit/1036/12/0305.

Background Heat 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. Objective To 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. Methods An 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). Results The 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. Conclusions Novel 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.

Background Heat illness in the Armed Forces is considered preventable. The UK military relies upon dual Command and Medical reporting for case ascertainment, investigation of serious incidents and improvement of preventive practices and policy. This process could be vulnerable to under-reporting. Objectives To establish whether heat illness in the British Army has been under-reported, by reviewing concordance of reporting to the Army Incident Notification Cell (AINC) and the Army Health Unit (AHU) and to characterise the burden of heat illness reported by these means. Methods Analysis of anonymised reporting databases held by the AHU and AINC, for the period 2009–2013. Results 565 unique cases of heat illness were identified. Annual concordance of reporting ranged from 9.6% to 16.5%. The overall rate was 13.3%. July was the month with the greatest number of heat illness reports (24.4% of total reporting) and the highest concordance rate (30%). Reports of heat illness from the UK (n=343) exceeded overseas notifications (n=221) and showed better concordance (17.1% vs 12.8%). The annual rate of reported heat illness varied widely, being greater in full-time than reservist personnel (87 vs 23 per100 000) and highest in full-time untrained personnel (223 per100 000). Conclusions The risk of heat illness was global, year-round and showed dynamic local variation. Failure to dual-report casualties impaired case ascertainment of heat illness across Command and Medical chains. Current preventive guidance, as applied in training and on operations, should be critically evaluated to ensure that risk of heat illness is reduced as low as possible. Clear procedures for casualty notification and surveillance are required in support of this and should incorporate communication within and between the two reporting chains.

Military training has been associated with changes in the hypothalamic-pituitary-gonadal axis consistent with central hypogonadism. Often such changes have been associated with body mass loss, though sleep deprivation and other psychological stress may also contribute. The effects of deployment in a combat zone on the hypothalamic-pituitary-gonadal axis in military personnel are not known. The objective was to investigate the hypothalamic-pituitary-gonadal axis in male military personnel deployed in Afghanistan. Eighty-nine Royal Marines were investigated pre-deployment, following 3 months in Afghanistan and following 2 weeks mid-tour leave. Testosterone, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), luteinising hormone (LH), 17-hydroxyprogesterone, androstenedione (AD) and insulin were assayed and body mass recorded. The results showed that body mass (kg) dropped from 83.2 ± 9.2 to 79.2 ± 8.2 kg during the first 3 months of deployment (p < 0.001). Total testosterone did not change, but SHBG increased (30.7 ± 9.7 vs. 42.3 ± 14.1 nmol/L, p < 0.001), resulting in a significant (p < 0.001) fall in calculated free testosterone (435.2 ± 138 vs. 375.1 ± 98 pmol/L). Luteinising hormone and FSH increased by 14.3% (p < 0.001) and 4.9% (p = 0.003) respectively. Free testosterone, SHBG, LH and FSH returned to baseline following 2 weeks of mid-tour leave. Androstenedione (AD) decreased by 14.5% (p = 0.024), and insulin decreased by 26% (p = 0.039), over the course of deployment. In this study of lean Royal Marines, free testosterone decreased during operational deployment to Afghanistan. There was no evidence to suggest major stress-induced central hypogonadism. We postulate that reduced body mass, accompanied by a decrease in insulin and AD synthesis, may have contributed to an elevated SHBG, leading to a decrease in free testosterone.

OBJECTIVE: Understanding the mechanisms that drive weight loss in a lean population may elucidate systems that regulate normal energy homeostasis. This prospective study of British military volunteers investigated the effects of a 6-month deployment to Afghanistan on energy balance and circulating concentrations of specific appetite-regulating hormones. METHODS: Measurements were obtained twice in the UK (during the Pre-deployment period) and once in Afghanistan, at Mid-deployment. Body mass, body composition, food intake, and appetite-regulatory hormones (leptin, active and total ghrelin, PYY, PP, GLP-1) were measured. RESULTS: Repeated measures analysis of 105 volunteers showed body mass decreased by 4.9% ± 3.7% (P CONCLUSIONS: These data suggest that changes in appetite-regulating hormones in front line military personnel occur in response to, but do not drive, reductions in body mass. Language: en

Purpose To study the relationship between serum neutrophil gelatinase-associated lipocalin (NGAL) and military blast and gunshot wound (GSW) to establish whether potential exists for NGAL as a biomarker for blast lung injury (BLI). Method Patients from the intensive care unit (ICU) of the Role 3 Medical Treatment Facility at Camp Bastion, Helmand Province, Afghanistan were studied over a five month period commencing in 2012. Age, mechanism, trauma injury severity score (TRISS) and serum NGAL were recorded on ICU admission (NGAL1). Serum NGAL (NGAL2) and PaO 2 /FiO 2 ratio (P/F ratio2) were recorded at 24 h. Results 33 patients were injured by blast and 23 by GSW. NGAL1 inversely correlated with TRISS ( p = 0.020), pH ( p = 0.002) and P/F ratio 2 ( p = 0.009) overall. When data was stratified into blast and GSW, NGAL1 also inversely correlated with P/F ratio 2 in the blast injured group ( p = 0.008) but not GSW group ( p = 0.27). Conclusion Raised NGAL correlated with increased severity of injury (worse survival probability i.e. TRISS and low pH) in both patient groups. There was an inverse correlation between admission NGAL and a marker of blast lung injury (low P/F ratio) at 24 h in blast injured group but not GSW group that warrants further investigation.

Military employment commonly exposes personnel to strenuous physical exertion. The resulting interaction between occupational stress and individual susceptibility to illness demands careful management. This could extend to prospective identification of high physiological strain in healthy personnel, in addition to recognition and protection of vulnerable individuals. The emergence and ubiquitous uptake of ‘wearable’ physiological and medical monitoring devices might help to address this challenge, but requires that the right questions are asked in sourcing, developing, validating and applying such technologies. Issues that must be addressed include system requirements, such as the likelihood of end users deploying and using technology as intended; interpretation of data in relation to pretest probability, including the potential for false-positive results; differentiation of pathological states from normal physiology; responsibility for and consequences of acting on abnormal or unexpected results and cost-effectiveness. Ultimately, the performance of a single monitoring system, in isolation or alongside other measures, should be judged by whether any improvement is offered versus existing capabilities and at what cost to mission effectiveness.

Purpose To prevent heat-related illnesses, guidelines recommend limiting core body temperature (Tc) ≤ 38 °C during thermal stress. Copeptin, a surrogate for arginine vasopressin secretion, could provide useful information about fluid balance, thermal strain and health risks. It was hypothesised that plasma copeptin would rise with dehydration from occupational heat stress, concurrent with sympathoadrenal activation and reduced glomerular filtration, and that these changes would reflect Tc responses. Methods Volunteers (n = 15) were recruited from a British Army unit deployed to East Africa. During a simulated combat assault (3.5 h, final ambient temperature 27 °C), Tc was recorded by radiotelemetry to differentiate volunteers with maximum Tc > 38 °C versus ≤ 38 °C. Blood was sampled beforehand and afterwards, for measurement of copeptin, cortisol, free normetanephrine, osmolality and creatinine. Results There was a significant (P −1, P r = 0.70, P = 0.004). In volunteers with maximum Tc > 38 °C (n = 8) vs ≤ 38 °C (n = 7) there were significantly greater elevations in copeptin (10.4 vs. 2.4 pmol L−1) and creatinine (10 vs. 2 μmol L−1), but no differences in cortisol, free normetanephrine or osmolality. Conclusions Changes in copeptin reflected Tc response more closely than sympathoadrenal markers or osmolality. Dynamic relationships with tonicity and kidney function may help to explain this finding. As a surrogate for integrated physiological strain during work in a field environment, copeptin assay could inform future measures to prevent heat-related illnesses.

Understanding the nutritional demands on serving military personnel is critical to inform training schedules and dietary provision. Troops deployed to Afghanistan face austere living and working environments. Observations from the military and those reported in the British and US media indicated possible physical degradation of personnel deployed to Afghanistan. Therefore, the present study aimed to investigate the changes in body composition and nutritional status of military personnel deployed to Afghanistan and how these were related to physical fitness. In a cohort of British Royal Marines (n249) deployed to Afghanistan for 6 months, body size and body composition were estimated from body mass, height, girth and skinfold measurements. Energy intake (EI) was estimated from food diaries and energy expenditure measured using the doubly labelled water method in a representative subgroup. Strength and aerobic fitness were assessed. The mean body mass of volunteers decreased over the first half of the deployment ( − 4·6 (sd3·7) %), predominately reflecting fat loss. Body mass partially recovered (mean +2·2 (sd2·9) %) between the mid- and post-deployment periods (Psd3339) kJ) was significantly lower than the estimated daily energy expenditure (mean 15 167 (sd1883) kJ) measured in a subgroup of volunteers. However, despite the body mass loss, aerobic fitness and strength were well maintained. Nutritional provision for British military personnel in Afghanistan appeared sufficient to maintain physical capability and micronutrient status, but providing appropriate nutrition in harsh operational environments must remain a priority.

Reports of death and injury in military populations due to exertional heat illness (EHI) and its most severe form, exertional heat stroke, date from antiquity. Yet, understanding of why one soldier may succumb to EHI, while those around him do not, is incomplete. This paper sets out research questions in support of the health of military populations who may experience exertional heat stress. The mechanisms by which excess body heat arises and is dissipated are outlined and the significance of core temperature measurement during exercise is discussed. Known risk factors for EHI are highlighted and new approaches for identifying individual vulnerability to EHI are introduced. A better understanding of the underlying pathophysiology may allow the effective use of biomarkers in future risk stratification and identification of EHI, allied to emerging genetic technologies. The thermal burden associated with states of dress and personal protection of Service personnel in their worldwide duties should be a focus of research as new equipment is introduced. At all times, the discerning use of existing guidance by Commanders on the ground will remain a mainstay of preventing EHI.

It has been consistently shown that heavy exercise leads to cardiac troponin (cTn) release and variable changes in post exercise cardiac function. This relationship has not been explored at increasing or significant high altitude (HA). This study assessed the effects of exercise at progressively increasing HA on high-sensitivity (hs)-cTnT levels and their relationship to biventricular cardiac function and severity of acute mountain sickness (AMS).Transthoracic echocardiograms, hs-cTnT levels and AMS scores were measured at rest at 1,300 m then repeated post exercise and 12 h later after progressive trekking to 3,440, 4,270 m and at 5,150 m (after trekking to 5,643 m) on 19 healthy subjects (age 35.4 ± years, 52.6 % males).There was a detectable increase (5 ng/L) in post exercise hs-cTnT with exercise at HA which became significant at 5,150 m (5.84 % at 3,440 m, 5.2 % at 4,270 m and 56.3 % at 5,150 m; p = 0.0005). Compared with baseline, HA to 5,150 m led to a significant rise in post exercise Lake Louis AMS scores (p 0.001) pulmonary artery systolic pressure (PASP) (23.7 ± 3.8 vs 37.9 ± 11.7 mmHg: p 0.001), cardiac output (5.2 ± 1.2 vs 7.5 ± 1.3 l/min; p 0.001) and a fall in SpO2 (96.1 ± vs 77.4 ± 12.0 %; p 0.001). There was no change in stroke volume (p = 0.10) or estimated filling pressures (E/E') of the left (p = 0.50) and right ventricles (p = 0.4). On multivariate analysis increasing cardiac output (p = 0.02) and PASP (p = 0.04) and decreasing SpO2 (p = 0.01) were the only independent predictors of increasing cTnT levels (overall R (2) = 0.23, p 0.0001).Moderate intensity exercise at significant HA influences the post exercise increase in hs-cTnT without overt deleterious effects on cardiac function.

Our objective was to evaluate the utility of the natriuretic peptides BNP (brain natriuretic peptide) and NT-proBNP as markers of pulmonary artery systolic pressure (PASP) in trekkers ascending to high altitude (HA). 20 participants had BNP and NT-proBNP assayed and simultaneous echocardiographic assessment of PASP performed during a trek to 5150 m. PASP increased significantly (p=0.006) with ascent from 24+/-4 to 39+/-11 mm Hg at 5150 m. At 5150 m those with a PASP>/=40 mm Hg (n=8) (versus those with PASP/=400 pg/ml) rise in NT-proBNP at 5150 m (n=4) PASP was significantly higher: 45.9+/-7.5 vs. 32.2+/-6.2 mm Hg (p=0.015). BNP and NT-proBNP may reflect elevated PASP, a central feature of high altitude pulmonary oedema, at HA.

Background: Susceptibility to exertional heat illness\ud (EHI) is considered multifactorial in nature. The aims of\ud this study were to (1) review traditional susceptibility\ud factors identified in cases of EHI and (2) determine\ud how they are related to risk of hospitalisation.\ud Methods: Review of an electronic database of EHI\ud reported in the British Army between 1 September\ud 2007 and 31 December 2014. Cases were categorised\ud by demographic, situational and susceptibility\ud variables. Univariate and multivariate logistic regression\ud was performed for the OR for hospitalisation by risk\ud factor.\ud Results: 361 reports were included in the analysis.\ud 33.5% of cases occurred in hot climates, 34.6% in\ud temperate climates during summer months and 31.9%\ud in temperate climates outside of summer months.\ud Traditional susceptibility factors were reported in 193\ud but entirely absent from 168 cases. 137 cases (38.0%)\ud were admitted to hospital. Adjusted OR for\ud hospitalisation was lower for recruits (OR 0.42, 95% CI\ud 0.18 to 0.99, p

Introduction During previous deployments of the British Armed Forces, a significant proportion of aeromedical evacuations were accounted for with recurrent symptoms from a known disease that had often triggered occupational medical downgrading. Many servicemen and women had deployed inappropriately, and by doing so became a burden on the deployed medical facilities. Commanders performing systematic medical risk assessments prior to departure might have prevented these individuals from deploying. This study was designed to assess the avoidable burden from recurrent disease during the current Afghanistan operation. Methods A cross-sectional study reviewing the hospital and computerised primary care medical records of consecutive patients admitted under the General Physicians to the Role 3 Hospital in Camp Bastion over 9 months from April 2011. The occupational medical grading, diagnosis, disposal and whether the disease was recurrent were recorded. Results Of 270 patients admitted, 14 (5.2%) were medically downgraded. The computerised records were unavailable for 31 (11.5%) patients. All those patients who were medically downgraded were graded ‘Medically Limited Deployable’. In the downgraded group, only one patient presented with recurrent symptoms from their pre-existing condition (Crohn9s disease). In the non-downgraded group, two patients presented with symptoms relating to their previous diagnoses. One presented with a second heat illness and should have been medically downgraded and not have been deployed, while the other patient had previously been investigated for recurrent syncope and was upgraded 6 months prior to deploying. All three patients underwent aeromedical evacuation but only two of these were considered to have been avoidable. Discussion The number of general medical admissions to the Role 3 Hospital due to a pre-existing disease is very low.

Acute Mountain Sickness (AMS) is a common clinical challenge at high altitude (HA). A point-of-care biochemical marker for AMS could have widespread utility. Neutrophil gelatinase-associated lipocalin (NGAL) rises in response to renal injury, inflammation and oxidative stress. We investigated whether NGAL rises with HA and if this rise was related to AMS, hypoxia or exercise. NGAL was assayed in a cohort (n=22) undertaking 6 hours exercise at near sea-level (SL); a cohort (n=14) during 3 hours of normobaric hypoxia (FiO2 11.6%) and on two trekking expeditions (n=52) to over 5000 m. NGAL did not change with exercise at SL or following normobaric hypoxia. During the trekking expeditions NGAL levels (ng/ml, mean ± sd, range) rose significantly (P<0.001) from 68 ± 14 (60–102) at 1300 m to 183 ± 107 (65–519); 143 ± 66 (60–315) and 150 ± 71 (60–357) at 3400 m, 4270 m and 5150 m respectively. At 5150 m there was a significant difference in NGAL between those with severe AMS (n=7), mild AMS (n=16) or no AMS (n=23): 201 ± 34 versus 171 ± 19 versus 124 ± 12 respectively (P=0.009for severe versus no AMS;P=0.026for mild versus no AMS). In summary, NGAL rises in response to prolonged hypobaric hypoxia and demonstrates a relationship to the presence and severity of AMS.

High altitude exposure normally leads to a marked natriuresis and diuresis. Acute mountain sickness is often associated with fluid retention, to which an elevated cortisol may contribute. Most investigators report a rise in resting cortisol with ascent, but little data exist regarding the cortisol response to a day trekking. We therefore measured salivary cortisol during ascent to5000 m in a cohort of between 42-45 subjects following a 6-h trek (samples taken between 15:30-16:30 h) and between 15-20 subjects at rest (morning samples taken between 08:00-09:00 h). Morning resting cortisol [nmol/l, mean±sd, (range)] was 5.5±2.9 (2.13-13.61) at 1300 m; 4.7±6.8 (1.4-27.02) at 3400 m, and significantly (p=0.002) rose between 4270 m [3.5±2.1 (1.4-8.34)] and 5150 m [14.5±30.3 (1.9-123.1)]. Post-exercise cortisol [nmol/l, mean±sd, (range)] dropped between 3400 m [7±6 (1.5-33.3)] and 4270 m [4.2±4.8 (1.4-29.5)] (p=0.001) followed by a significant rise in post-exercise cortisol between 4270 m [4.2±4.8 (1.4-29.5)] and 5 150 m [9.2±10.2 (1.4-61.3)] (p0.001). There were no significant associations between severity of acute mountain sickness and cortisol levels. There was a significant though weak correlation between cortisol post-exercise at 5150 m and oxygen saturation at 5150 m (rho= - 0.451, p=0.004). In conclusion, this is the largest cohort to have their resting and post-exercise cortisol levels ascertained at high altitude. We confirm the previous findings of an elevated resting morning cortisol at5000 m, but present the novel finding that the cortisol response to a day trekking at HA appears suppressed at 4270 m.

For the military doctor, an understanding of the metabolic effects of high altitude (HA) exposure is highly relevant. This review examines the acute metabolic challenge and subsequent changes in nutritional homeostasis that occur when troops deploy rapidly to HA. Key factors that impact on metabolism include the hypoxic-hypobaric environment, physical exercise and diet. Expected metabolic changes include augmentation of basal metabolic rate (BMR), decreased availability of oxygen in peripheral metabolic tissues, reduction in VO2 max, increased glucose dependency and lactate accumulation during exercise. The metabolic demands of exercise at HA are crucial. Equivalent activity requires greater effort and more energy than it does at sea level. Soldiers working at HA show high energy expenditure and this may exceed energy intake significantly. Energy intake at HA is affected adversely by reduced availability, reduced appetite and changes in endocrine parameters. Energy imbalance and loss of body water result in weight loss, which is extremely common at HA. Loss of fat predominates over loss of fat-free mass. This state resembles starvation and the preferential primary fuel source shifts from carbohydrate towards fat, reducing performance efficiency. However, these adverse effects can be mitigated by increasing energy intake in association with a high carbohydrate ration. Commanders must ensure that individuals are motivated, educated, strongly encouraged and empowered to meet their energy needs in order to maximise mission-effectiveness.

Infestation of the eye by larval fly forms (ophthalmomyiasis) is rarely seen in the Western world. We present the case of a 21 year old British soldier who developed external ophthalmomyiasis during an operational tour of southern Afghanistan. This case report and discussion illustrates the potential for ophthalmomyiasis in personnel deployed to this theatre; the possibility of infestation without an identifiable episode of exposure; the importance of proper assessment and follow-up in order to identify sight-threatening complications; and the balance between optimal patient care and the risks inherent to casualty evacuation demanded by modern day stability operations.

Undertaking operational patrolling activity in hot environments, carrying heavy loads and wearing personal protective equipment (PPE) presents a significant physiological challenge to Service personnel. Planned research trials involving volunteers exercising in the heat observe an important volunteer withdrawal criterion of attainment of a core body temperature of 39.5 °C. However, trained populations (marathon runners) have been shown to sustain exercise with core temperatures in excess of 40 °C with no recognised adverse health effects [1]. Thus, it could be hypothesised that military personnel with a good level of physical fitness might similarly sustain higher than usual core temperatures, albeit while wearing impermeable PPE. The aim of the present study was to measure the actual thermal response of military personnel while performing operationally specific exercises in the most arduous phase of a military exercise in a hot-dry environment.

This article is an abstract from a new guide, Principles of Best Practice: Minimising Pain at Wound Dressing-Related Procedures. It is an educational initiative of the World Union of Wound Healing Societies (WUWHS). The guide has been inspired by two seminal documents: the European Wound Management Association's position document, Pain at Wound Dressing Changes (EWMA, 2002), and Practical Treatment of Wound Pain and Trauma: A Patient-centred Approach (Reddy et al, 2003). As an international educational initiative, the WUWHS document is aimed at anyone involved in dressing-related procedures anywhere in the world. This article summarises the section on best practice in the assessment of wound pain.

Background It has been consistently shown that heavy exercise leads to cardiac troponin (cTn) release and variable changes in post exercise cardiac function. This relationship has not be explored at increasing or significant HA exposure (>4300 m). Aims This study aimed to assess, for the first time, the effects of exercise at progressively increasing high altitude (HA) on high-sensitivity (hs) cardiac cTnT levels and their relationship to cardiac function and severity of acute mountain sickness (AMS). Methods Transthoracic echocardiograms, hs-cTnT levels and acute mountain sickness scores were measured at rest at 1300 m then repeated post exercise and 12 h later after moderate-intensity progressive trekking to 3440 m, 4270 m and at 5150 m (after trekking to 5643 m) on 19 healthy subjects (age 35.4±years; 52.6% males). Results There was a significant and detectable increase in post exercise hs-cTnT with increasing exercise (29.4% at 3440 m, 15.8% at 4270 m and 68.8% at 5150 m; p=0.02) with the rise only being significant on post test at 5150 m. No values exceed the cut of for observed with myocardail infarction (≥30 ng/l). Increasing HA led to a significant rise in AMS scores, pulmonary artery systolic pressure, cardiac output and a fall in SpO2 without changes in stroke volume. There were no changes in estimated left (E/E9; p=0.5) or right ventricular (E/E9; p=0.43) filling pressures. On multivariate analysis increasing cardiac output (p=0.040) and right ventricular systolic pressures (p=0.046) and decreasing SpO 2 (p=0.03) were the only independent predictors of increasing cTnT levels (overall R2=0.24; p=0.0004). Conclusions Moderate intensity exercise at significant HA does influence the post exercise increase in hs-cTnT without overt deleterious effects on cardiac function.

Heat adaption through acclimatisation or acclimation improves cardiovascular stability by maintaining cardiac output due to compensatory increases in stroke volume. The main aim of this study was to assess whether 2D transthoracic echocardiography (TTE) could be used to confirm differences in resting echocardiographic parameters, before and after active heat acclimation (HA). Thirteen male endurance trained cyclists underwent a resting blinded TTE before and after randomisation to either 5 consecutive daily exertional heat exposures of controlled hyperthermia at 32°C with 70% relative humidity (RH) (HOT) or 5-days of exercise in temperate (21°C with 36% RH) environmental conditions (TEMP). Measures of HA included heart rate, gastrointestinal temperature, skin temperature, sweat loss, total non-urinary fluid loss (TNUFL), plasma volume and participant's ratings of perceived exertion (RPE). Following HA, the HOT group demonstrated increased sweat loss (p = 0.01) and TNUFL (p = 0.01) in comparison to the TEMP group with a significantly decreased RPE (p = 0.01). On TTE, post exposure, there was a significant comparative increase in the HOT group in left ventricular end diastolic volume (p = 0.029), SV (p = 0.009), left atrial volume (p = 0.005), inferior vena cava diameter (p = 0.041), and a significant difference in mean peak diastolic mitral annular velocity (e’) (p = 0.044). Cardiovascular adaptations to HA appear to be predominantly mediated by improvements in increased preload and ventricular compliance. TTE is a useful tool to demonstrate and quantify cardiac HA., Highlights • There are echocardiographic differences in comparing an isothermic heat acclimation regime to equivalent temperate exercise. • Heat acclimation results in an increased LA volume, LVEDV, stroke volume, IVC diameter and LV diastolic function (e’). • The increase in LA volume and IVC diameter would suggest an increase in preload secondary to increased plasma volume. • The rise in the speed of early LV relaxation (e’) during diastole reflects increased LV compliance or reduced LV stiffness. • This gives further insight into the cardiovascular adaptations to heat acclimation.