Mitigating the Consequences of Subconcussive Head Injuries.

Subconcussive head injury represents a pathophysiology that spans the expertise of both clinical neurology and biomechanical engineering. From both viewpoints, the terms injury and damage, presented without qualifiers, are synonymously taken to mean a tissue alteration that may be recoverable. For clinicians, concussion is evolving from a purely clinical diagnosis to one that requires objective measurement, to be achieved by biomedical engineers. Subconcussive injury is defined as subclinical pathophysiology in which underlying cellular- or tissue-level damage (here, to the brain) is not severe enough to present readily observable symptoms. Our concern is not whether an individual has a (clinically diagnosed) concussion, but rather, how much accumulative damage an individual can tolerate before they will experience long-term deficit(s) in neurological health. This concern leads us to look for the history of damage-inducing events, while evaluating multiple approaches for avoiding injury through reduction or prevention of the associated mechanically induced damage.

Distribution of Head Acceleration Events Varies by Position and Play Type in North American Football.

OBJECTIVE: The goal of this pilot study was to evaluate the number of head acceleration events (HAEs) based on position, play type, and starting stance. DESIGN: Prospective cohort study. SETTING: Postcollegiate skill development camp during practice sessions and 1 exhibition game. PARTICIPANTS: Seventy-eight male adult North American football athletes. INDEPENDENT VARIABLES: A position was assigned to each participant, and plays in the exhibition game were separated by play type for analysis. During the exhibition game, video data were used to determine the effects of the starting position ("up" in a 2-point stance or "down" in a 3- or 4-point stance) on the HAEs experienced by players on the offensive line. MAIN OUTCOME MEASURES: Peak linear acceleration and number of HAEs greater than 20 g (g = 9.81 m/s2) were measured using an xPatch (X2 Biosystems, Seattle, WA). RESULTS: Four hundred thirty-seven HAEs were recorded during practices and 272 recorded during the exhibition game; 98 and 52 HAEs, the greatest number of HAEs by position in the game, were experienced by the offensive and defensive linemen, respectively. Linebackers and tight ends experienced high percentages of HAEs above 60 g. Offensive line players in a down stance had a higher likelihood of sustaining a HAE than players in an up stance regardless of the type of play (run vs pass). CONCLUSIONS: Changing the stance of players on the offensive line and reducing the number of full-contact practices will lower HAEs.

The Climate-Smart Emergency Department: A Primer.

Climate change and environmental pollution from health care present urgent, complex challenges. The US health care sector produces 10% of total US greenhouse gas emissions, which have negative influences on human and environmental health. The emergency department (ED) is an important place in the hospital to become more environmentally responsible and "climate smart," a term referring to the combination of low-carbon and resilient health care strategies. Our intent is to educate and motivate emergency providers to action by providing a guide to sustainable health care and an approach to creating a climate-smart ED.

Dermatological Progression of a Probable Box Jellyfish Sting.

This case report describes the typical features of the dermatological progression of a patient stung by a (probable) box jellyfish. The purpose is to guide clinicians and patients to an understanding of what to expect after such a sting using the clinical narrative and unique sequential photographs of the injury. With knowledgeable consultation from experienced physicians and meticulous care, this envenomation healed without the need for skin grafting.

Impact of a Half Dome Cable Permitting Process on Search and Rescue Activity, Hiker Mortality Rates, and Operational Costs Above Little Yosemite Valley.

INTRODUCTION: The summit of Yosemite's Half Dome is reached using cable handrails for the final 146 m (480 ft). Access to these cables was restricted to users with permits in 2010. The authors aim to describe the impact of permitting on search and rescue (SAR) in the region of the park most affected by permitting. METHODS: An observational study from 2005 to 2009 and 2011 to 2015 comparing the number of incidents, major incidents (exceeding $500), victims, and fatalities before and after permitting the use of cable handrails on Half Dome in the area above Little Yosemite Valley (LYV) and parkwide. Each year was analyzed separately with t tests and Mann-Whitney U tests. Data are presented as mean±SD. RESULT: The number of hikers in the study area was reduced by up to 66% by permitting. Above LYV from 2005 to 2009, there were 85 SAR incidents, 134 victims, 8 fatalities, 38 major incidents, and annual SAR costs of $44,582±28,972. From 2011 to 2015, the same area saw 54 SAR incidents, 156 victims, 4 fatalities, 35 major incidents, and annual SAR costs of $27,027±19,586. No parameter showed statistical significance. Parkwide SAR incidents decreased from 232 to 198 annual incidents (P=0.013) during the same time period, with parkwide mortality increasing from 8 to 12 deaths annually (P=0.045). CONCLUSIONS: SAR incidents, victims, fatalities, or costs above LYV did not decrease after cable handrail permitting. Parkwide SAR activity decreased during the same intervals. This strongly suggests that overcrowding is not the key factor influencing safety on Half Dome. This discordant trend warrants close observation over 5 to 10 y.

Wilderness Medical Society Clinical Practice Guidelines for the Treatment and Prevention of Drowning: 2019 Update.

The Wilderness Medical Society convened a panel to review available evidence supporting practices for acute management and treatment of drowning in out-of-hospital and emergency medical care settings. Literature about definitions and terminology, epidemiology, rescue, resuscitation, acute clinical management, disposition, and drowning prevention was reviewed. The panel graded available evidence supporting practices according to the American College of Chest Physicians criteria and then made recommendations based on that evidence. Recommendations were based on the panel's collective clinical experience and judgment when published evidence was lacking. This is the first update to the original practice guidelines published in 2016.

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness: 2019 Update.

To provide guidance to clinicians about best preventive and therapeutic practices, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for prevention and treatment of acute mountain sickness, high altitude cerebral edema, and high altitude pulmonary edema. Recommendations are graded based on the quality of supporting evidence and the balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches to prevention and management of each form of acute altitude illness that incorporate these recommendations. This is an updated version of the original WMS Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness published in 2010 and subsequently updated as the WMS Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness in 2014.

Wilderness Medical Society Clinical Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia: 2019 Update.

To provide guidance to clinicians, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for the out-of-hospital evaluation and treatment of victims of accidental hypothermia. The guidelines present the main diagnostic and therapeutic modalities and provide recommendations for the management of hypothermic patients. The panel graded the recommendations based on the quality of supporting evidence and a balance between benefits and risks/burdens according to the criteria published by the American College of Chest Physicians. The guidelines also provide suggested general approaches to the evaluation and treatment of accidental hypothermia that incorporate specific recommendations. This is the 2019 update of the Wilderness Medical Society Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia: 2014 Update.

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Frostbite: 2019 Update.

The Wilderness Medical Society convened an expert panel to develop a set of evidence-based guidelines for prevention and treatment of frostbite. We present a review of pertinent pathophysiology. We then discuss primary and secondary prevention measures and therapeutic management. Recommendations are made regarding each treatment and its role in management. These recommendations are graded on the basis of the quality of supporting evidence and balance between the benefits and risks or burdens for each modality according to methodology stipulated by the American College of Chest Physicians. This is an updated version of the guidelines published in 2014.

Extreme, expedition, and wilderness medicine.

Extreme, expedition, and wilderness medicine are modern and rapidly evolving specialties that address the spirit of adventure and exploration. The relevance of and interest in these specialties are changing rapidly to match the underlying activities, which include global exploration, adventure travel, and military deployments. Extreme, expedition, and wilderness medicine share themes of providing best available medical care in the outdoors, especially in austere or remote settings. Early clinical and logistics decision making can often have important effects on subsequent outcomes. There are lessons to be learned from out-of-hospital care, military medicine, humanitarian medicine, and disaster medicine that can inform in-hospital medicine, and vice-versa. The future of extreme, expedition, and wilderness medicine will be defined by both recipients and practitioners, and empirical observations will be transformed by evidence-based practice.

Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Drowning.

The Wilderness Medical Society convened a panel to review available evidence supporting practices for the prevention and acute management of drowning in out-of-hospital and emergency medical care settings. Literature about definition and terminology, epidemiology, rescue, resuscitation, acute clinical management, disposition, and drowning prevention was reviewed. The panel graded evidence supporting practices according to the American College of Chest Physicians criteria, then made recommendations based on that evidence. Recommendations were based on the panel's collective clinical experience and judgment when published evidence was lacking.

Efficacy of Topical Treatments for Chrysaora chinensis Species: A Human Model in Comparison with an In Vitro Model.

OBJECTIVES: This study sought to create a model for testing topical treatment of jellyfish stings. It sought to determine which treatments 1) stimulate/inhibit nematocyst discharge; 2) decrease pain; and 3) decrease skin inflammation; it also sought to discover whether there is a clinical correlation between stimulated nematocyst discharge observed in vitro to the pain and erythema experienced by humans stung by a particular species of jellyfish, C chinensis. METHODS: Chrysaora chinensis stung 96 human subjects, who were then treated with isopropyl alcohol, hot water, acetic acid, papain meat tenderizer, lidocaine, or sodium bicarbonate. Pain and erythema were measured. In a separate experiment, nematocysts were examined microscopically after exposure to the same topical treatments used in the human experiment. RESULTS: Forearms treated with papain showed decreased mean pain over the first 30 minutes after being stung, relative to placebo, although only by a small amount. The other topical treatments tested did not reach statistical significance. Sodium bicarbonate may reduce erythema after 30 minutes of treatment; sodium bicarbonate and papain may reduce erythema at 60 minutes. The other topical treatments tested did not reach statistical significance. Nematocyst discharge in vitro occurred when tentacles of C chinensis were exposed to acetic acid or isopropyl alcohol. Sodium bicarbonate, papain, heated water, and lidocaine did not induce nematocyst discharge. CONCLUSIONS: Papain-containing meat tenderizer used as a topical treatment for C chinensis stings may decrease pain. Although there is published experimental support for the concept that in vitro nematocyst discharge correlates with in vivo human pain perception, no definitive randomized controlled trial, including ours, has yet provided incontrovertible evidence of this assertion. Despite this study's limitations, it presents a viable basis for future human studies looking at the efficacy of topical treatments for jellyfish stings.

The 6-Minute Walk Test as a Predictor of Summit Success on Denali.

OBJECTIVE: To test whether the 6-minute walk test (6MWT), including postexercise vital sign measurements and distance walked, predicts summit success on Denali, AK. METHODS: This was a prospective observational study of healthy volunteers between the ages of 18 and 65 years who had been at 4267 m for less than 24 hours on Denali. Physiologic measurements were made after the 6MWT. Subjects then attempted to summit at their own pace and, at the time of descent, completed a Lake Louise Acute Mountain Sickness Questionnaire and reported maximum elevation reached. RESULTS: One hundred twenty-one participants enrolled in the study. Data were collected on 111 subjects (92% response rate), of whom 60% summited. On univariate analysis, there was no association between any postexercise vital sign and summit success. Specifically, there was no significant difference in the mean postexercise peripheral oxygen saturation (Spo2) between summiters (75%) and nonsummiters (74%; 95% CI, -3 to 1; P = .37). The distance a subject walked in 6 minutes (6MWTD) was longer in summiters (617 m) compared with nonsummiters (560 m; 95% CI, 7.6 to 106; P = .02). However, this significance was not maintained on a multivariate analysis performed to control for age, sex, and guide status (P = .08), leading to the conclusion that 6MWTD was not a robust predictor of summit success. CONCLUSIONS: This study did not show a correlation between postexercise oxygen saturation or 6MWTD and summit success on Denali.

Detection of concussion using cranial accelerometry.

OBJECTIVE: To determine whether skull motion produced by pulsatile cerebral blood flow, as measured by cranial accelerometry, is altered during concussion. DESIGN: In phase 1, to identify a specific pattern indicative of concussion, cranial accelerometry of subjects who sustained a concussion underwent analysis of waveforms, which was compared with accelerometry from subjects without a concussion (baseline). In phase 2, this concussion pattern was tested against prospectively acquired, blinded data. SETTING: High school tackle football practice and game play. PARTICIPANTS: Eighty-four football players. INTERVENTIONS: Subjects had accelerometry measurements and concurrent 2-lead electrocardiograms. In players with a concussion, multiple sequential measurements were obtained. Sport Concussion Assessment Tool 2 was used to assist clinical determination of concussion. MAIN OUTCOME MEASURES: Whether a characteristic waveform pattern of cranial accelerometry occurs in subjects with concussion. RESULTS: Phase 1 demonstrated a consistent pattern correlated to concussion. Phase 2 found this pattern in 10 of 13 subjects with concussion (76.9% sensitivity). Seventy-nine of 82 baseline plus nine postseason (total = 91) recordings from nonconcussed subjects did not show the concussion pattern (87% specificity). CONCLUSIONS: In subjects with concussion, we observed a unique pattern determined by cranial accelerometry. This may provide a method to noninvasively detect and longitudinally observe concussion. CLINICAL RELEVANCE: There is no objective, real-time, noninvasive, and easily accessible measure for concussion. If accelerometry is validated, it could provide a critical diagnostic tool for sports medicine physicians.

Migraine headache confounding the diagnosis of acute mountain sickness.

A 36-year-old man with a history of migraine headache attempted to hike from Lukla, Nepal, to Mount Everest Base Camp. On the sixth day of hiking, he had a migraine headache. After achieving resolution with typical therapies and rest, he ascended higher. Another headache developed that was interpreted to be a migraine. The headache was treated, and he ascended higher, after which severe symptoms of acute mountain sickness developed, necessitating his evacuation by helicopter. Persons with headaches in daily life may present challenges to diagnosis when traveling to high altitude. Careful evaluation and decision making are needed to achieve proper diagnosis and treatment of acute mountain sickness.

Poly-L-arginine topical lotion tested in a mouse model for frostbite injury.

BACKGROUND: Frostbite injury occurs when exposure to cold results in frozen tissue. We recently reported a novel mouse model for frostbite injury to be used in screening potentially therapeutic drugs and other modalities. OBJECTIVE: We used the mouse skin frostbite model to evaluate the effect of poly-l-arginine contained in lotion (PAL) applied topically to involved skin. METHODS: Sixty mice were studied in a randomized, double-blind method. Standardized 2.9-cm-diameter circles were tattooed on the mouse dorsum. Magnets snap frozen in dry ice (-78.5°C) were used to create a frostbite injury on skin within the circle as a continuous 5-minute freeze. Mice were treated with prefreeze placebo, postthaw placebo, combined prefreeze and postthaw placebo, prefreeze with PAL, postthaw with PAL, or combined prefreeze and postthaw with PAL. Appearance, healing rate, tissue loss, and histology were recorded until the wounds were healed. RESULTS: Application of PAL before inducing frostbite injury resulted in decreased tissue loss as compared with other treatment conditions. CONCLUSIONS: Applying PAL topically to frostbitten mouse skin caused decreased tissue loss. Poly-l-arginine should be studied further to determine whether it is a beneficial therapeutic modality for frostbite injury.

Implementing an emergency medical services system in Kathmandu, Nepal: a model for "white coat diplomacy".

Wilderness medicine providers often visit foreign lands, where they come in contact with medical situations that are representative of the prevailing healthcare issues in the host countries. The standards of care for matters of acute and chronic care, public health, and crisis intervention are often below those we consider to be modern and essential. Emergency medical services (EMS) is an essential public medical service that is often found to be underdeveloped. We describe our efforts to support development of an EMS system in the Kathmandu Valley of Nepal, including training the first-ever class of emergency medical technicians in that country. The purpose of this description is to assist others who might attempt similar efforts in other countries and to support the notion that an effective approach to improving foreign relations is assistance such as this, which may be considered a form of "white coat diplomacy."

Wilderness Medical Society practice guidelines for the prevention and treatment of acute altitude illness: 2014 update.

To provide guidance to clinicians about best practices, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for prevention and treatment of acute mountain sickness, high altitude cerebral edema, and high altitude pulmonary edema. These guidelines present the main prophylactic and therapeutic modalities for each disorder and provide recommendations about their role in disease management. Recommendations are graded based on the quality of supporting evidence and balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches to prevention and management of each disorder that incorporate these recommendations. This is an updated version of the original WMS Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness published in Wilderness & Environmental Medicine 2010;21(2):146-155.

Wilderness Medical Society practice guidelines for the prevention and treatment of frostbite: 2014 update.

The Wilderness Medical Society convened an expert panel to develop a set of evidence-based guidelines for the prevention and treatment of frostbite. We present a review of pertinent pathophysiology. We then discuss primary and secondary prevention measures and therapeutic management. Recommendations are made regarding each treatment and its role in management. These recommendations are graded on the basis of the quality of supporting evidence and balance between the benefits and risks or burdens for each modality according to methodology stipulated by the American College of Chest Physicians. This is an updated version of the original guidelines published in Wilderness & Environmental Medicine 2011;22(2):156-166.