Wilderness Medical Society practice guidelines for the prevention and treatment of heat-related illness: 2014 update

Desert Medicine

Deserts are defined by their arid nature, characterized by little rainfall, and often featuring vast stretches of sandy terrain with sparse vegetation. The resulting variations in temperature, humidity, and topography predispose patients to medical conditions that practitioners in both rural and urban deserts must recognize and manage. This article will equip medical practitioners with the essential knowledge and tools to navigate these complexities, including a description of specific environmental considerations and challenges encountered while providing care in these desert locations, common conditions associated with extreme heat and solar radiation, and animal encounters.

Nursing Management of Temperature in a Patient with Stroke

Fever is common in patients with stroke and is associated with worse outcomes. Studies in brain injury informed interventions commonly termed therapeutic temperature management (TTM) to improve the monitoring and management of fever. While the role and benefit of TTM in stroke patients has not been well studied, the nurse and healthcare team must extrapolate existing data to determine how to best monitor and apply TTM after stroke. Nurses should be knowledgeable about interventions to monitor and manage complications of TTM (eg, shivering), the studies underway to quantify the impact of fever treatment and emerging technology expected to improve TTM.

Wearable Sensor Technology to Predict Core Body Temperature: A Systematic Review

Heat-related illnesses, which range from heat exhaustion to heatstroke, affect thousands of individuals worldwide every year and are characterized by extreme hyperthermia with the core body temperature (CBT) usually > 40 °C, decline in physical and athletic performance, CNS dysfunction, and, eventually, multiorgan failure. The measurement of CBT has been shown to predict heat-related illness and its severity, but the current measurement methods are not practical for use in high acuity and high motion settings due to their invasive and obstructive nature or excessive costs. Noninvasive predictions of CBT using wearable technology and predictive algorithms offer the potential for continuous CBT monitoring and early intervention to prevent HRI in athletic, military, and intense work environments. Thus far, there has been a lack of peer-reviewed literature assessing the efficacy of wearable devices and predictive analytics to predict CBT to mitigate heat-related illness. This systematic review identified 20 studies representing a total of 25 distinct algorithms to predict the core body temperature using wearable technology. While a high accuracy in prediction was noted, with 17 out of 18 algorithms meeting the clinical validity standards. few algorithms incorporated individual and environmental data into their core body temperature prediction algorithms, despite the known impact of individual health and situational and environmental factors on CBT. Robust machine learning methods offer the ability to develop more accurate, reliable, and personalized CBT prediction algorithms using wearable devices by including additional data on user characteristics, workout intensity, and the surrounding environment. The integration and interoperability of CBT prediction algorithms with existing heat-related illness prevention and treatment tools, including heat indices such as the WBGT, athlete management systems, and electronic medical records, will further prevent HRI and increase the availability and speed of data access during critical heat events, improving the clinical decision-making process for athletic trainers and physicians, sports scientists, employers, and military officers.

Hiking Time Trial Performance in the Heat with Real-Time Observation of Heat Strain, Hydration Status and Fluid Intake Behavior

This study investigated the real-time progression of heat strain in mountain hikers during time trials (TT). Participants (n = 12; 7M/5F; age 21.6 ± 2.47) attempted to climb Tempe Butte (~1.1 mi) four times in HOT and MOD trials (wet bulb globe temperature 31.6 °C vs. 19.0 °C). Performance, physiological outcomes, and fluid intake behavior were measured in real-time. Hot conditions significantly impaired hiking TT performance by 11%, reduced aerobic capacity by 7%, increased peak rate of perceived exertion (RPE) by 19%, and elevated core temperature (T_c) by 0.7 °C compared to MOD (all p < 0.03). Less-aerobically-fit participants were most negatively-affected by heat stress. Based on sweat lost, participants in HOT required 2.26 ± 0.91 L of fluids, brought 1.52 ± 0.83 L, and consumed 1.54 ± 0.49 L, losing an average of 1.1% ± 1.0%BM. Participants in MOD required 1.28 ± 0.39 L of fluids, brought 1.57 ± 1.09 L, and consumed 0.79 ± 0.57 L, losing an average of 1.0% ± 0.8%BM. Morning-after urine specific gravity (USG) values revealed 75% of hikers were hypohydrated (USG ≥ 1.020) after HOT; 67% after MOD. Heat stress impairs hiking TT performance while increasing RPE and T_c. Fitter participants showed less performance and physiological impairment from heat stress. Although hikers in both conditions lost similar body weight, hikers were limited in HOT by fluid availability, whereas in MOD, fluid was available and dehydration was voluntary.

The prognostic value of routine coagulation tests for patients with heat stroke

OBJECTIVE

To evaluate the prognostic value of routine coagulation tests for patients with heat stroke.

METHODS

This was a multi-center retrospective study. Patients who arrived at the hospital <24 h after the onset of Heat Stroke (HS) were included. The routine coagulation variables were detected within 24 h after the onset, including the lowest platelet count (PLC).

RESULTS

60-day mortality rate was 20.9%. The median Prothrombin Time-International Normalized Ratio (PT-INR) of the non-surviving patients was significantly higher than that of the survivors (P < 0.01). The median Activated Partial Thromboplastin Time (APTT) in non-surviving patients was significantly higher than in the surviving patients (P < 0.01). A Cox regression analysis revealed that 60-day mortality was associated with PT-INR (P = 0.032) and APTT (P = 0.004). The optimal PT-INR point for predicting 60-day mortality rate was 1.7. The optimal APTT point for predicting 60-day mortality was 51.45. Patients with increased PT-INR (≥1.7) levels had, overall, a significantly reduced survival time (P < 0.01). Patients with elevated APTT (≥51.45) also had a decrease in survival time (P < 0.01). The prognostic scoring, with increased PT-INR (≥1.7) and prolonged APTT (≥51.45) at one point each, was also demonstrated to be useful in predicting 60-day mortality. Patients whose temperature fell to 38.9 °C within 30 min had significantly lower levels of PT-INR and APTT within 24 h than those who took longer to cool down.

CONCLUSIONS

A prolonged APTT and elevated PT-INR within 24 h are independent prognostic factors of 60-day mortality in HS.

Are Recommended Heat Stroke Treatments Adequate for Australian Workers?

Workers that combine physical exertion with exposure to hot conditions are susceptible to heat-related illnesses, including heat stroke. Despite recognition of cold water immersion as the heat stroke treatment of choice in the peer-reviewed literature, it was not included within recommended treatments of leading Australian healthcare training organizations and was omitted from Safe Work Australia's recently updated 'Managing the risks of working in heat' guidance material. On this basis, the guidance material appears an opportunity lost to assist Australian industry transition their heat stroke management to reflect the evidence. It is recommended that Australian providers of healthcare training, and those reliant on such information, review the efficacy of their heat stroke treatments.

Expert consensus on the diagnosis and treatment of heat stroke in China

Heat stroke (HS) is a fatal disease caused by thermal damage in the body, and it has a very high mortality rate. In 2015, the People's Liberation Army Professional Committee of Critical Care Medicine published the first expert consensus on HS in China, Expert consensus on standardized diagnosis and treatment for heat stroke. With an increased understanding of HS and new issues that emerged during the HS treatment in China in recent years, the 2015 consensus no longer meet the requirements for HS prevention and treatment. It is necessary to update the consensus to include the latest research evidence and establish a new consensus that has broader coverage, is more practical and is more in line with China's national conditions. This new expert consensus includes new concept of HS, recommendations for laboratory tests and auxiliary examinations, new understanding of diagnosis and differential diagnosis, On-site emergency treatment and In-hospital treatment, translocation of HS patients and prevention of HS.

Successful Management of Severe Exertional Heat Stroke with Endovascular Cooling After Failure of Standard Cooling Measures

BACKGROUND

Exertional heat stroke (EHS) is a potentially life-threatening emergency requiring rapid reduction in core body temperature. Methods of cooling include cold water immersion, ice packs, cold water lavage, and chilled saline, among others. We report a case of EHS successfully cooled using an endovascular cooling device after traditional cooling methods failed to reduce core body temperature.

CASE REPORT

A 24-year old soldier collapsed during a 12-mile foot march while training in southern Georgia. His initial rectal temperature was 43.1°C (109.6°F). External cooling measures (ice sheet application) were initiated on site and Emergency Medical Services were called to transport to the hospital. Paramedics obtained a repeat rectal temperature of 42.4°C (108.4°F). Ice sheet application and chilled saline infusion were continued throughout transport to the Emergency Department (ED). Total prehospital treatment time was 50 min. Upon ED arrival, the patient's rectal temperature was 41.2°C (106.2°F). He was intubated due to a Glasgow Coma Scale score of 4, and endovascular cooling was initiated. Less than 45 minutes later his core body temperature was 37.55°C (99.6°F). He was admitted to the intensive care unit, where his mental status rapidly improved. He was found to have rising liver enzymes, and there was concern for his developing disseminated intravascular coagulation, prompting transfer to a tertiary care center. He was subsequently discharged from the hospital 14 days after his initial injury without any persistent sequelae. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The primary treatment for EHS is rapid reduction of core body temperature. When external cooling methods fail, endovascular cooling can be used to rapidly decrease core body temperature.

Calpain-2 protects against heat stress-induced cardiomyocyte apoptosis and heart dysfunction by blocking p38 mitogen-activated protein kinase activation

Cardiovascular dysfunction is a common complication among heatstroke patients, but its underlying mechanism is unclear. This study was designed to investigate the role of calpain-2 and its downstream signal pathway in heat stress-induced cardiomyocyte apoptosis and heart dysfunction. In cultured primary mouse neonatal cardiomyocytes (MNCs), heat stress (43°C for 2 hr) induced a heat-shock response, as indicated by upregulated heat-shock protein 27 (HSP27) expression and cellular apoptosis, as indicated by increased caspase-3 activity, DNA fragmentation and decreased cell viability. Meanwhile, heat stress decreased calpain activity, which was accompanied by downregulated calpain-2 expression and increased phosphorylation of p38, extraceIIuIar signaI-reguIated protein kinase (ERK1/2) and c-Jun N-terminaI kinase (JNK). Calpain-2 overexpression abrogated heat stress-induced apoptosis and phosphorylation of p38 and JNK, but not of ERK1/2. Blocking only p38 prevented heat stress-induced apoptosis in MNCs. In cardiac-specific calpain-2 overexpressing transgenic mice, p38 phosphorylation and cardiomyocyte apoptosis were decreased in the heart tissue of heatstroke mice, as revealed by western blot and terminal deoxynucleotidyl transferase dUTP nick end labelling assays, respectively. M-mode echocardiography also demonstrated that calpain-2 overexpression significantly improved heatstroke-induced decreases in ventricular end-diastolic volume and cardiac output. In conclusion, our study suggests that heat stress reduces calpain-2 expression, which then activates p38, leading to cardiomyocyte apoptosis and heart dysfunction.

Research Gaps in Wilderness Medicine

INTRODUCTION

Wilderness medicine involves the treatment of individuals in remote, austere environments. Given the high potential for injuries as well as the unique treatment modalities required in wilderness medicine, evidence-based clinical practice guidelines are necessary to provide optimal care. In this study, we identify evidence gaps from low-quality recommendations in wilderness medicine clinical practice guidelines and identify new/ongoing research addressing them.

METHODS

We included relevant clinical practice guidelines from the Wilderness Medical Society and obtained all 1C or 2C level recommendations. Patient/Problem/Population, intervention, comparison, outcome (PICO) questions were created to address each recommendation. Using 24 search strings, we extracted titles, clinical trial registry number, and recruitment status for 8899 articles. We categorized the articles by trial design to infer the effect they may have on future recommendations.

RESULTS

Twelve clinical practice guidelines met inclusion criteria. From these we located 275 low-quality recommendations and used them to create 275 PICO questions. Thirty-three articles were relevant to the PICO questions. Heat-related illness had the highest number of relevant articles (n=9), but acute pain and altitude sickness had the most randomized clinical trials (n=6).

CONCLUSION

Overall, few studies were being conducted to address research gaps in wilderness medicine. Heat-related illness had the most new or ongoing research, whereas no studies were being conducted to address gaps in eye injuries, basic wound management, or spine immobilization. Animals, cadavers, and mannequin research are useful in cases in which human evidence is difficult to obtain. Establishing research priorities is recommended for addressing research gaps identified by guideline panels.

Characteristics of Heat Illness during Hajj: A Cross-Sectional Study

Introduction

Data regarding the characteristics and outcomes of heat illness are lacking in the literature. The present study aimed to identify the clinical characteristics, morbidity, management, and mortality associated with heat illness among Hajj participants.

Methods

A cross-sectional study was conducted during the Hajj in 2016 on patients who presented to emergency departments and were diagnosed with heat exhaustion or heatstroke. Data were collected using a structured collection sheet developed based on the literature.

Results

A total of 267 patients were recruited. Of these, 80 (29%) and 187 (67.75%) were diagnosed with heatstroke and heat exhaustion, with 6.3% and 0.0% mortality, respectively. The mean age of the patients was 54.0 ± 16 years. Diabetes mellitus was the most common comorbidity among both heatstroke and heat exhaustion patients. The majority of patients had hyperthermia and electrolyte imbalance. Most of the heat illness cases were treated per heat illness guidelines.

Conclusions

Although authorities are working on research and forming interdisciplinary teams to prevent health problems during the Hajj, the mortality rate from heatstroke is high and the majority of the patients had hyperthermia, varied signs and symptoms, elevated creatinine levels, and electrolyte imbalances.

International Commission for Mountain Emergency Medicine Consensus Guidelines for On-Site Management and Transport of Patients in Canyoning Incidents

Canyoning is a recreational activity that has increased in popularity in the last decade in Europe and North America, resulting in up to 40% of the total search and rescue costs in some geographic locations. The International Commission for Mountain Emergency Medicine convened an expert panel to develop recommendations for on-site management and transport of patients in canyoning incidents. The goal of the current review is to provide guidance to healthcare providers and canyoning rescue professionals about best practices for rescue and medical treatment through the evaluation of the existing best evidence, focusing on the unique combination of remoteness, water exposure, limited on-site patient management options, and technically challenging terrain. Recommendations are graded on the basis of quality of supporting evidence according to the classification scheme of the American College of Chest Physicians.

Heat Stroke: A Medical Emergency Appearing in New Regions

Heat stroke is an acute, life-threatening emergency characterized clinically by elevated body temperature and central nervous system dysfunction. Early recognition and treatment including aggressive cooling and management of life-threatening systemic complications are essential to reduce morbidity and mortality. This case report describes two Danish patients diagnosed with heat stroke syndrome during a heat wave in the summer of 2014. Both patients were morbidly obese and had several predisposing illnesses. However since heat stroke is a rare condition in areas with temperate climate, they were not diagnosed until several days after admittance; hence treatment with cooling was delayed. Both patients were admitted to the intensive care unit, where they were treated with an external cooling device and received treatment for complications. Both cases ended fatally. As global warming continues, more heat waves will occur in previously cooler regions. Therefore it is important to raise awareness of heat stroke since outcome depends on early recognition and rapid cooling.

Exercise-Associated Hyponatremia, Hypernatremia, and Hydration Status in Multistage Ultramarathons

OBJECTIVE

Dysnatremia and altered hydration status are potentially serious conditions that have not been well studied in multistage ultramarathons. The purpose of this study was to assess the incidence and prevalence of exercise-associated hyponatremia (EAH) (Na⁺ <135 mmol·L^-1) and hypernatremia (Na⁺ >145 mmol·L^-1) and hydration status during a multistage ultramarathon.

METHODS

This study involved a prospective observational cohort study of runners competing in a 250-km (155-mile) multistage ultramarathon (in the Jordan, Atacama, or Gobi Desert). Prerace body weight and poststage (stage [S] 1 [42 km], S3 [126 km], and S5 [250 km]) body weight and serum sodium concentration levels were obtained from 128 runners.

RESULTS

The prevalence of EAH per stage was 1.6% (S1), 4.8% (S3), and 10.1% (S5) with a cumulative incidence of 14.8%. Per-stage prevalence of hypernatremia was 35.2% (S1), 20.2% (S3), and 19.3% (S5) with a cumulative incidence of 52.3%. Runners became more dehydrated (weight change <-3%) throughout the race (S1=22.1%; S3=51.2%; S5=53.5%). Body weight gain correlated with EAH (r=-0.21, P = .02). Nonfinishers of S3 were significantly more likely to have EAH compared with finishers (75% vs 5%, P = .001), but there was no difference in either EAH or hypernatremia between nonfinishers and finishers of S5.

CONCLUSIONS

The incidence of EAH in multistage ultramarathons was similar to marathons and single-stage ultramarathons, but the cumulative incidence of hypernatremia was 3 times greater than that of EAH. EAH was associated with increased weight gain (overhydration) in early stage nonfinishers and postrace finishers.

Susceptibility to exertional heat illness and hospitalisation risk in UK military personnel

Background

Susceptibility to exertional heat illness (EHI) is considered multifactorial in nature. The aims of this study were to (1) review traditional susceptibility factors identified in cases of EHI and (2) determine how they are related to risk of hospitalisation.

Methods

Review of an electronic database of EHI reported in the British Army between 1 September 2007 and 31 December 2014. Cases were categorised by demographic, situational and susceptibility variables. Univariate and multivariate logistic regression was performed for the OR for hospitalisation by risk factor.

Results

361 reports were included in the analysis. 33.5% of cases occurred in hot climates, 34.6% in temperate climates during summer months and 31.9% in temperate climates outside of summer months. Traditional susceptibility factors were reported in 193 but entirely absent from 168 cases. 137 cases (38.0%) were admitted to hospital. Adjusted OR for hospitalisation was lower for recruits (OR 0.42, 95% CI 0.18 to 0.99, p<0.05) and for personnel wearing occlusive dress (OR 0.56, 95% CI 0.34 to 0.93, p<0.05) or unacclimatised to heat (OR 0.31, 95% CI 0.15 to 0.66, p<0.01).

Conclusions

The global, year-round threat of EHI is highlighted. Absence of susceptibility factors in nearly half of reports highlights the challenge of identifying EHI-prone individuals. Paradoxical association of traditional susceptibility factors with reduced hospitalisation risk may reflect the contemporary contexts in which severe EHI occurs. These findings also suggest a need for better evidence to inform guidelines that aim to prevent severe EHI concurrent to reducing overall morbidity.

Heat Illnesses in the Emergency Department: A Hot Topic

The RESEARCH TO PRACTICE column is intended to improve the research critique skills of the advanced practice registered nurse (APRN) and to assist with the translation of research into practice. For each column, a topic and a particular research study are selected. The stage is set with a case presentation. The research article is then reviewed and critiqued, and the findings are discussed in relation to the case presented. Our current column discusses factors associated with heat-related hospitalizations and deaths with implications for APRN practice and public health prevention strategies using the following study: . Summertime acute heat illness in U.S. emergency departments from 2006 through 2010: Analysis of a nationally representative sample. Environmental Health Perspectives, 122(11), 1209-1215. Our case involves an adolescent athlete with sickle cell trait participating in athletic practice during the summer.

Simultaneous quantification of multiple volatile active components in rat plasma using a headspace-solid phase dynamic extraction method coupled to gas chromatography-tandem mass spectroscopy: application in a pharmacokinetic study of Longhu Rendan pills

A HS-SPDE-GC-MS/MS method for investigating pharmacokinetics of l-menthol, borneol, isoborneol, and camphor in rat plasma after oral administration of LRPs.