Every two years, the International Society for Mountain Medicine (ISMM) holds its World Congress of Mountain Medicine. The meetings attract scientists and clinicians interested in high altitude medicine, biology, and rescue operations, and who provide care and promote safety and health in mountainous regions around the world. Every four years, the Wilderness Medical Society (WMS) sponsors a World Congress of Wilderness Medicine that deals with the latest research and clinical aspects of all wilderness environments. In 2024, the two organizations joined forces for the 8th World Congress on Mountain and Wilderness Medicine. Presentations by global experts addressed altitude medicine, mountain rescue, diving medicine, wilderness education, emerging diagnostic methods, improvised rescue techniques, disaster medicine, neglected tropical diseases, and more.
The abstracts selected for publication are divided between High Altitude Medicine & Biology, featuring ISMM members and topics, and Wilderness & Environmental Medicine, featuring WMS members and topics. There is some subject and member overlap, and the reader is encouraged to refer to both journals for a complete picture of the breadth and excellence of work in these fields.
Effects of Epoprostenol on the Cold-induced Vasodilation Response: A Double Blind Crossover Design Study to Assess the Effects of an Inhaled Prostacyclin Analogue on Temperature Regulation in Fingers Exposed to Cold Stimulus
Theodore Hartridge, DO1; Brendan Milliner, MD1; Scott McIntosh, MD1; Emad Awad, PhD1; Robert Brickley, MD2
1
University of Utah, Salt Lake City, USA.
2
Intermountain Health, Murray, UT, USA
Introduction/Background—Cold exposure initially induces a sympathetically mediated peripheral vasoconstriction, however after 5-10 minutes distal blood vessels will transiently and cyclically vasodilate in euthermic subjects in what is known as cold-induced vasodilation (CIVD). A greater CIVD response is thought to confer a reduced risk of freezing and nonfreezing cold injuries. [Cheung] Guidelines recommend intravenous infusion of iloprost, a prostacyclin analogue, for deep or proximal cases of frostbite [McIntosh]. The effects of prostacyclin analogues on CIVD is unknown.
Objective—In this study, we assessed the effects of an inhaled prostacyclin analogue, epoprostenol, on CIVD in the fingers of healthy subjects.
Methods—This double-blind crossover design study compared the effects of inhaled nebulized epoprostenol at 50ng/kg/min of ideal body weight versus inhaled nebulized 0.9% saline placebo on finger temperature during two cold water immersion sessions. Results were analyzed with one-tailed paired sample t-tests.
Results—A planned total of 15 subjects completed both cold stress sessions. Epoprostenol sessions were characterized by higher mean finger temperature (9.16 vs 8.34; p = 0.027), mean maxima temperature (10.86 vs 9.88; p = 0.045) and mean minima temperature (7.45 vs 6.80; p = 0.024). No significant difference was detected in the number of cycles (10.0 vs 7.93; p = 0.104). No hypotension, hypothermia, or hypoxia was observed; and no subject requested discontinuation due to side effects. The most commonly reported side effect was mild headache.
Conclusions—This small study found that nebulized epoprostenol raises the mean, minima, and maxima finger temperatures during cold water immersion, implying an augmented CIVD response. These findings demonstrate that inhaled epoprostenol can affect the peripheral microvascular responses to cold exposure and suggest that further study is warranted to assess the use of inhaled epoprostenol as an alternative to intravenous iloprost in the treatment of cold injury.
Keywords cold induced vasodilation, cold injury, frostbite, prostacyclin, epoprostenol, iloprost
FundingWilderness Medical Society 2020 Peter Hackett-Paul Auerbach Grant
Winner of the 2024 Outstanding Research Presentation Award (Oral)
Acetazolamide Use and Effects on Acute Mountain Sickness in Trekkers in Nepal
Sofia Tuttle, MD1; Chong Zhang, MS1; Matthew Widmer, BS2; Scott McIntosh, MD1
1University of Utah, Salt Lake City, USA. 2Touro University College of Osteopathic Medicine, Henderson, USA
Introduction/Background—Acute mountain sickness (AMS) is a form of acute altitude illness that can develop in elevations >2000 meters. Prevention of AMS includes staged ascent, gradual ascent, and pharmacologic interventions such as acetazolamide. Acetazolamide is given a grade 1A recommendation by the WMS for AMS prevention in travelers at moderate-high risk of AMS. Moderate-high risk factors include history of AMS, ascending to high elevations without acclimatization, and ascent rates >500 meters/day. There is limited data showing the utility of acetazolamide in low risk travelers, e.g. travelers with no history of AMS, appropriate acclimatization, or ascent rates <500m per day.
Objective—To understand the effect of acetazolamide use on the incidence of acute mountain sickness (AMS) in trekkers.
Methods—This was a prospective cohort study, examining data from trekkers in Nepal undergoing 7-21 day treks, including 202 trekkers across 23 trips. Lake Louise Scores (LLS) were collected daily, and a LLS score ≥3 was considered to be positive for AMS. Chi squared testing was used to analyze the incidence of AMS between those taking acetazolamide and those not taking acetazolamide.
Results—Of the 202 trekkers, 154 (76%) took acetazolamide. The incidence of AMS was 14% overall; 17% in those taking acetazolamide, and 6% in those not taking acetazolamide, though there was no statistical significance (p=0.07) between these groups. Mean daily elevation gain was 321 meters/day, with a maximum daily elevation gain of 328m.
Conclusions—This study showed no effect of acetazolamide on the development of AMS, and a lower overall incidence of AMS than prior studies.These treks included acclimatization days and avoided ascents >500m per day, making them low-risk for AMS development. Acetazolamide may not be necessary nor effective in preventing AMS during well-planned treks with a slow ascent profile and low inherent risk of AMS development.
Keywordsacetazolamide, altitude sickness, altitude, diamox, carbonic anhydrase inhibitors, mountain sickness
Funding The investigators thank Ian Taylor Trekking and the trekkers who participated in the study. This investigation was supported by the University of Utah Population Health Research (PHR) Foundation, with funding in part from the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health, through Grant UL1TR002538 (formerly 5UL1TR001067-05, 8UL1TR000105 and UL1RR025764).
Winner of the 2024 Outstanding Research Presentation by a Researcher-in-Training Award (Oral)
A Review of Emergency Medical Services in Acadia National Park from 2018 - 2022
Nathan Barott1; Zachary Williams1; Cecily Swinburne, MD, MPH2; Paul Klawitter, MD, PhD1
1
SUNY Upstate Medical University, Syracuse, NY, USA.
2
Northern Light Eastern Maine Medical Center, Bangor, ME, USA
Introduction—Despite its relatively small land area, Acadia National Park remains the 5th most visited national park as of 2023. As outdoor recreation continues to grow in popularity, understanding the dynamics of emergency medical services (EMS) within such environments is critical for optimizing response strategies and enhancing patient outcomes.
Objective—The objective of this study is to understand the demographics and epidemiology of emergency medical and traumatic incidents leading to activation of the Acadia National Park EMS system.
Methods—A retrospective review was conducted using EMS reports obtained from Acadia National Park during calendar years 2018, 2020 and 2022. Information on incident location, chief complaint, response times, patient disposition and activation of local search and rescue (SAR) resources were extracted and compared. Incident acuity was assessed using the Emergency Severity Index (ESI) scoring system.
Results—EMS responses totaled 82 in 2018, 48 in 2020 and 108 in 2022. 44% of calls involved transfer of care to local emergency transport agencies. There were more incidences of trauma calls (76%) than medical calls (22%). Most common injuries involved the lower extremity (45%). 68% of calls were relatively low acuity (ESI scores 4-5). 19% of calls were relatively high acuity (ESI scores 1-2). 51% of incidents occurred within 100 feet of a road and 49% of incidents occurred on wilderness trails. The mean total call time of all incidents was 70.5 minutes. Local SAR resources were activated in 26% of incidents and were associated with lower acuity (71% ESI scores 4-5) and longer total call time (157.9 minutes).
Conclusion—While the majority of EMS calls in Acadia National Park are brief encounters involving rapid transfer of care or patient refusal, a small minority of calls require a large number of resources to evacuate despite the generally low acuity nature of these calls.
Keywordsemergency medical services, national parks, wilderness medicine, emergency medicine, prehospital, rescue work
Winner of the 2024 Outstanding Research Poster Award
Elastic Tourniquets Likely Better at Maintaining Arterial Occlusion
Samuel Slishman, MD
Pre-R, San Luis Obispo, USA
Introduction/Background—When a limb bleeds, its volume decreases, and when a limb is squeezed, fluids shift from areas of high to low pressure. When tourniquets are applied, sometimes bleeding persists, however, fluids always shift from areas of high to low pressure. Therefore, pulses need to be reassessed frequently, because lost arterial occlusion is harmful. While a wide variety of tourniquets may be adequate for achieving rapid arterial occlusion, it is hypothesized that elastic tourniquets excel at maintaining pressure and arterial occlusion.
Objective—Inelastic and elastic tourniquets are compared to better understand pressure maintenance in the settings of fluid shifts and/or ongoing blood loss.
Methods—Seven inelastic and seven elastic tourniquets were tested. A one liter IV bag filled with water with 4 meters of clear, flexible graduated tubing, were fastened to a vertical PVC pipe to become a large manometer. In separate trials, each tourniquet was tightened around the bag and PVC pipe to a target starting pressure of 250cmH20. Using a 60mL syringe and a three-way stopcock connected mid tubing, water was removed from the system in three 20mL increments and pressures were recorded. The process was repeated for each tourniquet from a starting pressure of 300cmH20, and again starting from 350cmH20.
Results—Starting from 250cmH20, inelastic tourniquet pressures dropped an average of 104, 168 and 207cmH20 with 20, 40 and 60mL removed, respectively. For elastic tourniquets, the average pressure drops were 43, 88, 118cmH20. Results were similar starting from 300 and 350cmH20. All elastics but one performed better than all inelastics. Starting from 250cmH20 the Fullstop behaved like the elastics. From 300 and 350, it behaved more like the inelastics. It was the least elastic of the elastics.
Conclusion—Elastic tourniquets are more likely to maintain arterial occlusion in settings of fluid shifts and blood loss.
Keywordstourniquet, elastic, inelastic, arterial occlusion, pressure, bleeding
DisclosureI make a pressure wrap for bleeding control and I think today's tourniquets can be greatly improved. I am also the CMO for Rescue Essentials, which is a company that sells a wide variety of tourniquets.
Wilderness Medicine Training in the City: A Novel, Pilot Urban Medicine Curriculum for MS4s
Nicky Chung, MD, MPH; Ambica Trehan, DO; David Shang, MD; Myungwook Bae, DO, FACEP, FAWM, DiMM
Maimonides Medical Center, Brooklyn, USA
Background—While wilderness medicine is commonly practiced in remote areas with limited resources, certain concepts remain applicable in urban settings. However, best practices on providing this education have not been established.
Objective—The objective of this study was to evaluate medical students’ reactions to and knowledge gained from a novel wilderness medicine curriculum developed for MS4s in an urban environment.
Methods—A 2-week combined didactic and simulation curriculum was created by wilderness- and simulation-trained physicians. The didactic curriculum consisted of lectures, guest speakers, or skills demonstrations, while the simulation sessions consisted of case-based learning and culminated in a multi-scenario “MCI” simulation. The curriculum was evaluated utilizing the Kirkpatrick model. Learner reaction was evaluated via pre- and post-surveys, using Likert scales to assess comfort on core topics. Learner knowledge was evaluated via pre- and post-examinations, consisting of 20 multiple choice questions. Data was summarized using descriptive statistics, and statistical analyses were conducted using t-tests.
Results—7 students enrolled in the elective. Students’ average comfort levels (1-very uncomfortable, 5-very comfortable) with core topics showed a statistically significant increase from before (mean = 2.14, SD = 0.66) to after (mean = 4.36, SD = 0.45) (p = 0.0004). The average score between the pre- (mean = 55.00, SD = 7.64) and post- (mean = 82.86, SD = 17.29) course tests showed a statistically significant improvement (p = 0.006). 100% of the students found the elective “very enjoyable”, citing the combination of didactics and hands-on sessions as effective and would recommend the course to other students.
Conclusion—This study showed providing students with a combined didactic and simulation-styled course was an effective modality to teach wilderness medicine in an urban environment. We plan to enroll more students in the future to increase our sample size to further evaluate the efficacy of this novel program.
Keywordseducation, urban, curriculum, wilderness, simulation, medical student
The Standardized Patient as a Learner: Medical Volunteers Gain Knowledge by Participating in a Wilderness Training Session
Geoffrey Comp, DO, FACEP, FAWM1,2,3; Michael Foggia, DO1,3; Cody Blentlinger, DO1,3; Cornel Popescu, MD1,3; Andrea Ferrari, MD1,3,2
1
Valleywise Health Medical Center, Phoenix, USA.
2
University of Arizona College of Medicine, Phoenix, USA.
3
Creighton University School of Medicine, Phoenix, USA
Introduction—The unpredictable nature of wilderness medicine provides unique challenges and learning opportunities in medical situations, making hands-on, scenario-based learning invaluable and often necessitating innovative instructional techniques. This pilot study explores the educational impact on volunteers acting as standardized patients (SP) in a wilderness medicine context, hypothesizing that volunteers passively acquire medical knowledge and skills related to injury management.
Methods—A descriptive feasibility pilot study was conducted with ten medical students volunteering as SPs in a wilderness medicine course. The study aimed to assess knowledge and skills acquisition quantitatively and qualitatively. Volunteers participated in two scenarios involving splinting and tourniquet placement and were evaluated before and after the intervention through written surveys and skill demonstrations. The study focused on the improvement and increased confidence in performing specific medical tasks.
Results—Participants showed improved self-reported confidence and actual splinting and tourniquet placement. The average increase was 17 points in survey data regarding medical knowledge, 4.6 points in the splinting scenario, and 2.5 points in the tourniquet placement skill demonstration.
Conclusion—This study demonstrated that volunteer medical students acting as SPs in a wilderness medicine training course could passively acquire medical knowledge and improve their skills in injury management. The findings suggest that participating as SPs offers educational benefits, contributing to the broader understanding of medical education. Further research with larger sample sizes is recommended to validate these findings and explore additional educational strategies in medical training.
Keywordsmedical education, simulation in medical education, curriculum wilderness medicine, fractures, laceration
Assessment of Sous Vide Water Baths in the Acute Rewarming of Frostbitten Extremities: A Multi-Center Study
Nicholas Daniel, DO1; Johndavid Storn, MD1; Nicholas Weinberg, MD1; William Galvin, MD1; Hillary Irons, MD2; Aaron Barksdale, MD3; Megan Rischall, MD4; Andrew Nathanson, MD5; Sean Bilodeau, DO5; Jasmine Gale, MD2; Katherine Willet, MD3; Kara Keiper6, Amalya Wilson, BA7; Jessica Chevalier, BS1
1
Dartmouth-Hitchcock Medical Center, Lebanon, USA.
2
UMass Medical Center, Worcester, USA.
3
University of Nebraska Medical Center, Omaha, USA.
4
Hennepin County Medical Center, Minneapolis, USA.
5
Rhode Island Hospital, Providence, USA.
6
Colby-Sawyer College, New London, USA.
7
Dartmouth College, Hanover, USA
Introduction—The current standard of care for acute frostbite rewarming is the use of a circulating warm water bath at a temperature of 37oC (98.6oF) to 39oC (102.2oF). There is no standardized method to achieve this. Manual management of a warm water bath can be inefficient and time consuming. Sous vide devices (SVD) are small, portable, and relatively inexpensive cooking devices that are designed to maintain a circulating warm water bath.
Objective—A prospective, multi-center study was developed to further assess the efficacy, safety, and ease of use of sous vide rewarming (SVR).
Methods—Acutely frostbitten hands and feet of patients presenting to the emergency department were placed in a water bath with a sous vide device attached to the side of the basin and set at 38oC (100.4oF). Water temperatures were recorded every 2 minutes from 2 thermometers and the SVD. Once target temperature was achieved, the extremities were rewarmed for 30 minutes. The provider then answered two questions utilizing Likert scales to rate the SVR ease-of-use and the ease of SVR compared to non-SVR frostbite rewarming.
Results—A total of 16 extremities on 7 subjects were enrolled during the study period, among 4 sites. The water baths required an average of 10 minutes 24 seconds to reach target temperature, from a mean water temperature of 23.6oC (74.5oF). All 16 extremities were clinically thawed in one 30 minute session and there were no adverse events. Providers rated the SVR ease-of-use 2.9/10 (1=Easy, 10=Difficult) and ease in comparison to non-SVR rewarming, 2.4/10 (1=Easier, 10=More Difficult).
Conclusions: Sous vide rewarming is efficacious, safe, and easier than standard methods in rewarming acute frostbite.
Keywordsfrostbite rewarming, cold, acute frostbite, sous vide, wilderness medicine, hypothermia
FundingNational Institutes of Health (NIH) via New Hampshire IDeA Network of Biomedical Research Excellence (NH-INBRE) SEED Grant
Trailblazing Leadership: Assessing the Impact of Wilderness Medicine Electives on Perceived Leadership Skills
Mary Town, MD; Joshua Timpe, MD; Hershall Raff, PhD
Medical College of Wisconsin, Milwaukee, USA
Background—Physicians take on leadership roles in a variety of healthcare teams which focus on individual patients, local communities, and even entire populations. Emergency medicine physicians in particular lead teams where tasks must be accomplished in an expedited manner with limited data on patient populations with high risk for decompensation. Developing leadership skills such as situational control, resource utilization, and conflict management is therefore a vital part of medical education. Wilderness medicine- being concerned with medical care in remote environments where situations are often tenuous, resources are scarce, and group cooperation is essential for success- is particularly suited to developing these leadership skills, and medical school level education in wilderness medicine may improve leadership ability. There is yet very little research evaluating the potential impact of this type of education on a student’s perceived leadership skills.
Objectives—To evaluate the perceived effect of a one-month wilderness medicine elective on a medical student’s leadership skills.
Methods—Between 2019-2023 students taking a one-month wilderness medicine elective were asked to take pre- and post-course surveys evaluating their perceptions of their own leadership skills. A second group of students taking an elective devoted to the art of medicine also took the same surveys and acted as a control group. All surveys were coded to maintain anonymity. The results were then evaluated for pre- and post-survey differences as well as between group differences.
Results and Conclusions—Several areas of the survey showed statistically significant differences in the pre- and post- surveys in the students taking the wilderness medicine elective, whereas this was not seen in the control group. This data suggests that students perceive their leadership skills improved by participating in a wilderness medicine course, adding to the body of literature that wilderness medicine education can add value to a student’s medical training.
Keywordseducation, leadership skills, physician leader, leadership training, wilderness medicine, medical school elective
Optimal Bladder Dwell Time for Rewarming Hypothermic Patients
J Daniel Gumayan, MD; Justin Gardner, DO; Carver Haines, MD; Stephanie Lareau, MD
Carilion Clinic Virginia Tech, Roanoke, USA
Introduction/Background—Bladder lavage is an active internal rewarming technique that can be used to treat a patient with hypothermia. Current guidelines recommend instilling warmed fluids into the urinary bladder for 15-minute dwells, draining the fluid, and repeating the process until goal temperature is reached. There is limited data on the appropriate time to change the dwell fluid.
Objective—The objective was to determine the time interval at which the bladder lavage dwells should be exchanged and whether the timing should be adjusted depending on the patient's core temperature.
Methods—A model was constructed to represent a hypothermic patient and urinary bladder. Given the specific gravity of a human is roughly that of water, a 60L insulated vessel was used to represent the thermal mass of a hypothermic patient. The simulated patient temperature was maintained using two ANOVA sous vide cookers. A latex balloon filled with 350mL of water represented the human bladder. The fluid temperature in the balloon was measured with an Elitech RC-5+ thermometer; was warmed to 42°C via warm water bath and was placed into the simulated patient water bath. Temperature data was sampled every 10 seconds until the balloon temperature reached the water bath temperature. This was performed at water bath temperatures of 20°C, 22°C, 24°C, 26°C, 28°C, and 30°C. The temperature data was plotted with temperature changes over time along with their derivative.
Results—Bladder lavage at bath temperatures of 20°C reached steady state by 310 seconds, 22°C by 390 seconds, 24°C by 400 seconds, 26°C by 300 seconds. The temperatures at 28°C, 30°C, 32°C stabilized by 380 sec. Mean time of 363 seconds to reach steady state.
Conclusion—Current guidelines overestimate the duration of bladder lavage dwells. Replacing the fluid about every 6 minutes will likely improve patient rewarming regardless of patient temperature.
Keywords
hypothermia, urinary, bladder, dwelling, temperature, optimal time
Epidemiological Review of Human Exposures to Scorpions as Reported to the National Poison Data System
Annalee Holstege1; Rita Farah, PhD, MPH, PharmD2; Conner McDonald, MD2; Scott Schmalzried, DO2; Christopher Holstege, MD2
1
Christopher Newport University, Newport News, USA.
2
University of Virginia, Charlottesville, USA
Background—Exposure due to scorpions is a risk with outdoor activities in the United States (U.S.). The America’s Poison Centers National Poison Data System (NPDS) contains a comprehensive dataset of U.S. poisonings and envenomations.
Objective—We sought to research trends in the human exposures due to scorpions called to U.S. poison centers and descriptively assess the relevant demographic and clinical characteristics of such exposures using NPDS.
Methods—The NPDS was queried for all closed, human exposures to scorpions calls from 01/01/07 through 12/31/23 using generic code identifier 0205240. Data extracted included Age, Clinical Effect, Exposure Site, Gender, Level of Healthcare, Medical Outcome, Reason, Start Date Month, and Therapy.
Results—During the study period, there were 236,509 human exposures to scorpions called to poison centers. The majority were female (57.4%). Of the exposures, 21,251 (9.0%) were evaluated in a healthcare facility. Medical outcomes documented 11,534 (4.9%) had moderate effects, 428 (0.2%) major effects, and 3 deaths. Of those evaluated at a healthcare facility, 19,836 (93.3%) were seen in the emergency department and released, 784 (3.7%) admitted to a noncritical care unit, and 631 (3.0%) admitted to a critical care unit. Pediatric cases comprised 29.1% of the total calls, but 48.1% of cases evaluated in a healthcare facility. Clinical effects of those in a healthcare facility were puncture wound (86.4%), pain at the dermal site (80.9%), numbness (50.9%), nystagmus (25.8%), fasciculations (16.3%), agitation (12.3%), and excess secretions (11.6%). Therapies given most commonly were benzodiazepines, antivenom, antihistamines, opioids, antiemetics, steroids, and antibiotics.
Conclusions—Human exposure calls due to scorpions are commonly reported to U.S. poison centers. Children were more likely to be evaluated in a healthcare facility compared to adults. Of those evaluated in a healthcare facility, the majority were released to home. Benzodiazepines, antivenom, antihistamines, and opioids were the primary treatments given.
Keywordsenvenomation, scorpion, poison center, antivenom
Epidemiological Review of Human Exposures to Marine Animals as Reported to the National Poison Data System
Conner McDonald, MD1; Rita Farah, PhD, MPH, PharmD1; Scott Schmalzried, DO1; Annalee Holstege, DO2; Christopher Holstege, MD1
1
University of Virginia, Charlottesville, USA.
2
Christopher Newport University, Newport News, USA
Background—Exposure due to United States (U.S.) marine animals is a risk in outdoor water-related activities. The America’s Poison Centers National Poison Data System (NPDS) contains a comprehensive dataset of U.S. poisonings and envenomations.
Objective—We sought to research trends in the human exposures due to marine animals called to U.S. poison centers and descriptively assess the relevant demographic and clinical characteristics of such exposures.
Methods—The NPDS was queried for all closed, human exposures to marine animals from 01/01/07 through 12/31/23 using generic code identifiers 0232000 (fish stings), 0231000 (coelenterate stings), and 0164248 (other marine bites and/or envenomations). Data extracted included Age, Clinical Effect, Gender, Level of Healthcare, Month of Exposure, and Therapy.
Results—During the study period, there were 19,719 human exposures to marine animals reported with 10,979 fish stings (55.7%), 6,249 coelenterate stings (31.7%), and 2,534 unknown marine bites/envenomations (12.9%). Clinical effects revealed 12,537 (63.6%) reported pain at the dermal site, 11,522 (58.4%) had a puncture wound, 4,014 (20.4%) had edema, and 853 (4.3%) reported pain other than dermal. Pediatric cases comprised 6,408 (32.5%). The majority were male (61%). There were 3 deaths. A total of 4,511 (22.9%) were seen in a healthcare facility and released, 571 (2.9%) were admitted to a noncritical care unit, and 151 (0.8%) admitted to a critical care unit. Therapies given most commonly to those evaluated at a healthcare facility were antibiotics, antihistamines, steroids, opioids. Only 7 required intubation and 9 required vasopressors.
Conclusions—Human exposure calls due to marine animals are commonly reported to America’s Poison Centers. The calls encountered were associated with higher levels of care than expected, likely representing a bias for calling centers when symptoms are severe. Clinicians in poison centers should be well trained on the appropriate management for various marine exposures.
Keywordsmarine, envenomation, poison center, toxin
Epidemiological Review of Human Exposures to Fire Ants as Reported to the National Poison Data System
Scott Schmalzried, DO1; Rita Farah, PhD, MPH, PharmD1; Conner McDonald, MD1; Annalee Holstege, MD2; Christopher Holstege, MD1
1
University of Virginia, Charlottesville, USA.
2
Christopher Newport University, Newport News, USA
Background—Exposure due to fire ants (genus Solenopsis) is a risk in outdoor activities in the United States (U.S.). The America’s Poison Centers National Poison Data System (NPDS) contains a comprehensive dataset of U.S. poisonings and envenomations.
Objective—We sought to research trends in the human exposures due to fire ants called to U.S. poison centers and descriptively assess the relevant demographic and clinical characteristics of such exposures using NPDS.
Methods—The NPDS was queried for all closed, human exposures to fire ants from 01/01/07 through 12/31/23 using generic code identifier 0209240. Data extracted included Age, Clinical Effect, Exposure Site, Gender, Level of Health Care, Medical Outcome, Reason, Month of exposure, and Therapy.
Results—During the study period, there were 15,026 human exposures to fire ants reported. The majority were female (55.5%). Pediatric cases comprised 7032 (46.8%). Clinical effects revealed 54.5% with a puncture wound/sting, 47.0% pain/irritation at the dermal site, 25.7% edema, 23.7% erythema, and 6.9% hives. Medical outcomes documented 860 (5.7%) had moderate effects and 31 (0.2%) major effects. There were 3 deaths. A total of 915 were evaluated in a healthcare facility and released (6.1%), 53 (0.3%) were admitted to a noncritical care unit, and 51 (0.3%) admitted to a critical care unit. Therapies given most commonly were antihistamines, steroids, and antibiotics. A total of 17 required intubation with mechanical ventilation and 32 required vasopressors. Exposures occurred during every month of the year, with the highest frequency between June and September (57%).
Conclusions—Human exposure calls due to fire ants are commonly reported to America’s Poison Centers. Few exposures required health care evaluation and a small number had life threatening clinical effects. Clinicians in poison centers should be trained on the appropriate management for fire ant exposures.
Keywordsfire ant, Solenopsis, envenomation, poison center
Outcomes of the Anticoagulated Major Trauma Patient in the Wilderness
Emma DeLoughery, MD; Thomas DeLoughery, MD, MACP, FAWM
Oregon Health & Science University, Portland, USA
Introduction—The risk of bleeding with anticoagulants can lead to questions about activity limitations, particularly recreational or wilderness activities.
Objective—Compare mortality and length of stay outcomes in anticoagulated patients in the wilderness with both non-anticoagulated and non-wilderness counterparts.
Methods—Data from 2017-2021 came from the National Trauma Data Bank. Cohorts included those on anticoagulant therapy with their trauma taking place in a wilderness/recreational setting. Two separate control groups were identified – one of non-anticoagulated patients injured in a recreational/wilderness setting (A), and one of anticoagulated patients injured in a non-recreational/wilderness setting (B). Both control groups were matched on age, sex, injury severity score (ISS), and several comorbidities. For all groups, only those with ISS > 15, the major trauma cutoff, were included.
Results—Groups A (317 patients each): Cohort A had a higher rate of hospital mortality (8.6% cohort vs 4.7% control, P = 0.05). There was no difference in length of stay (9.7 vs 8.9 days, P = 0.5) or rate of discharge home from the hospital among survivors (56.8% vs 61.7%, P = 0.26).
Groups B: (338 cohort, 344 control): Cohort B had a lower hospital mortality rate (11.0% vs 21.1%, P < 0.001). Cohort B had a non-significantly higher rate of discharge home from the hospital (52.1% vs 44.4%, P = 0.07). There was no difference in length of stay (8.6 vs 8.1 days, P = 0.5)
Conclusions—In major trauma, anticoagulated patients in the wilderness have a slightly higher rate of mortality than their non-anticoagulated counterparts and a lower mortality than anticoagulated patients injured not in the wilderness. Despite efforts to match for comorbidities, anticoagulated patients in the wilderness may be healthier than their non-wilderness counterparts. Additional limitations include incomplete registry data and possibility of inclusion of patients on anti-platelets and those with bleeding disorders.
Keywordswounds and injuries, anticoagulants, wilderness, wilderness medicine, recreation, mortality
Accuracy of Identification of Regional Snakes by Voluntary Survey Participants
Conner McDonald, MD1; Kimberly Quedado, PhD2; Mason Tatro2; Joseph Hansroth, MD2
1
University of Virginia, Charlottesville, USA.
2
West Virginia University, Morgantown, USA
Introduction—Two species of venomous snakes live in West Virginia, the copperhead snake (Agkistrodon contortrix) and the timber rattlesnake (Crotalus horridus). West Virginia is also home to 18 other species of non-venomous snakes. There is little data published on whether the general public is able to reliably identify which snakes are venomous or not. This information may be useful to clinicians when determining treatment and disposition of snake bite victims.
Objective—The primary outcome of this study was to assess the public’s ability to correctly identify the indigenous snakes of their region as venomous or non-venomous. Secondary outcomes included assessing whether demographic factors such as age, location, outdoor hobby interests, and time outdoors correlated with correctly identifying venomous snakes.
Methods—A QR code linking to a survey was placed in the waiting room of two emergency departments. The study consisted of demographic information including age, state of residence, amount of participation in recreational outdoor activities, and outdoor activities of interest. Participants were then shown pictures of 10 snakes sequentially and answered whether they believed the snake to be venomous or not. Overall, 115 surveys were completed. All snakes were native to the state of WV and 4 of the 12 pictures were of venomous snakes.
Results—Participants were able to correctly identify venomous snakes as venomous 85.59% of the time. Participants correctly identified non-venomous snakes as non-venomous 64.51% of the time. There was no statistically significant correlation with self-reported age, hours spent outdoors, or outdoor activities. Participants incorrectly identified the eastern hognose snake as venomous 79.6% of the time.
Conclusions—When assessing pictures, participants are less accurate at identifying non-venomous snakes as non-venomous and there may be regional variations.
Keywordssnake, identification, West Virginia, survey, picture
Implementation of the EFAST Exam into Care and Management of US Ski and Snowboard Team Athletes
Zachary J Ryan, MS1; Harrison Steins, MS1; Michael Miller, MPH1; Jaron Santelli, MD, CAQSM2; K Dean Gubler, DO, MPH, FACS, FCCM1
1
Rocky Vista University COM, Parker, USA.
2
US Ski and Snowboard Team, Park City, USA
Introduction—Elite US Ski and Snowboard Team (USST) athletes perform at the limits of human capabilities. Due to the extreme nature of their competitions and training, athletes can experience pneumothorax, solid organ lacerations, musculoskeletal injuries, and cardiac arrests. Point of Care Ultrasound (POCUS) may be advantageous for USST physicians because of its portability, expanded diagnostic capabilities, and ability to enhance triage decisions.
Objective—Evaluate the efficacy of a novel POCUS training for Extended Focused Assessment with Sonography in Trauma (EFAST) at the Medical Emergencies in Skiing and Snowboarding training in January 2024 in Park City, Utah.
Methods—This training included a one hour didactic session, 30 minute hands-on scanning session, and 30 minute competition-style group and individual assessment. Pre- and post-testing was administered to evaluate procedure proficiency and knowledge retention. All hands-on training used live human models using a variety of POCUS machines.
Results—The cohort consisted of 60 attending/fellow physicians of varying specialties with a 67% response rate (n=40). Post-training scores showed a significant improvement in knowledge, increased by 33% (p<0.01) compared to pre-training scores, and controlled for prior ultrasound experience. Self-rated ‘Novices’ in ultrasound experience had the greatest score increase (0.50±0.31; p< 0.01), while self-rated ‘Experts’ had the smallest score increase (0.10±0.14; p<0.01). The majority (95%) of respondents reported that POCUS would be “Moderately to Very Beneficial” for emergency management of athletes in remote settings with prolonged transport times, and 80% either “Somewhat Agreed” or “Strongly Agreed” that POCUS would be a beneficial tool in the care of USST athletes following the training.
Conclusion—These results indicate our novel EFAST training was effective at teaching the EFAST procedure, normal anatomy, pathology, and clinical decisions based on findings. Participants believe POCUS could be a valuable tool for use in the emergency care and management of USST athletes.
KeywordsEFAST, trauma, ultrasound, POCUS, training, education
Funding The research group received a one-time $1,000 grant from Rocky Vista University via a “Shark Tank” style competition held at the University. These funds were used for supplies to complete the training and incentivize participation.
Prevalence of anemia among pediatric population in high altitudes: a systematic review and meta-analysis
Surya Prakash Joshi1,2; Sanjeev Kharel1; Anil Bist1;
Suraj Bhatta, MBBS2; Sanyukta Gurung, MBBS, MD
Clinical Physiology3; Ghan Bahadur Thapa, MD, DiMM2,4
1
Maharajgunj Medical Campus, Institute of Medicine, Kathmandu, Nepal.
2
Mountain Medicine Society of Nepal, Kathmandu, Nepal.
3
Department of Clinical Physiology and Yogic Sciences, Madan Bhandari Academy of Health Sciences, Hetauda, Nepal.
4
Grande International Hospital, Kathmandu, Nepal
Introduction—Anemia among children is a concerning issue where 40% of children aged 6 months to 59 months is estimated to be affected by the World Health Organization (WHO). Anemia in some regions of high altitude has been associated with factors like poverty, malnourishment, area of residence, and maternal sociodemographic and health. Anemia plays a crucial role in the physical and psychological growth of children. This knowledge would help to understand overall health outcomes among children living at high altitudes.
Objective—This study aims to quantify the prevalence of anemia among children in high-altitude regions through meta-analysis and systematic review.
Methods—PubMed and EMBASE, along with additional sites, were searched from January 2000 to December 2023. Pediatric populations ranging from 6 months to 18 years were included in this study. A total of 11 studies were included after reviewing 228 published articles. An elevation of more than 1500 meters above sea level was considered high altitude. A pooled effect size with 95% CI was used to find the prevalence among included studies. STATA software version 16 (StataCorp) was used to perform analysis on the data. Sensitivity analysis was also done to check the robustness of the analysis.
Results—The pooled prevalence of anemia at high altitudes in children was found to be 34% (95% C.I:0.22-0.46, p<0.05) ranging from 3% to 65%. However, there was severe heterogeneity (I2 = 99.37%, p<0.05), and subgroup analysis was done according to geographical regions. The highest pooled prevalence was observed in the African region i.e. 49% (95% CI:0.43-0.56) and the lowest pooled prevalence was observed in the Asian region i.e. 24% (95% CI:0.06-0.41).
Conclusions—Considering the high prevalence, the associated mitigating factors should be taken into consideration by the concerned authorities to reduce the prevalence of anemia among the pediatric population in high altitudes.
Keywordsanemia, high altitude, pediatric
DVT/PE Presenting After Minor Leg Trauma at Everest's Khumbu Icefall: A Case Report
Suraj Bhatta, MBBS1; Surya Prakash Joshi2,1; Rajesh Sharma, MBBS1,3; Nishant Joshi, MBBS1;
Shama Bhandari, MBBS1; Suraj Shrestha, MBBS1
1
Mountain Medicine Society of Nepal, Kathmandu, Nepal.
2
Maharajgunj Medical Campus, Kathmandu, Nepal.
3
Drug and Toxicology Center, Poison Information Center, Tribhuvan University Teaching Hospital, Nepal, Kathmandu, Nepal
Introduction—Thrombosis at high altitude is thought to be caused by a combination of hypoxia, dehydration, elevated fibrinogen levels, elevated platelet counts, and platelet activation, together with erythrocytosis. Venous thromboembolism (VTE) includes two major manifestations; Pulmonary Embolism (PE) and Deep Vein Thrombosis (DVT). Physicians who frequently operate at high altitudes have a tendency to disregard the possibility of high altitude DVT/PTE in favour of treating minor musculoskeletal(MSK) injuries, which could be fatal.
Objective—To consider the possibility of DVT/PE in a patient presenting with MSK injuries at high altitude.
Methods—We are describing a case seen at Everest ER.
Case presentation—Thirty-seven years young female with good ascent profile and well acclimatised, presented with bilateral lower leg pain after twisting her leg at Khumbu ice fall during her rotation from Everest Camp 2. There was no history of any risk factor like smoking, use of OCPs. No obvious sign of DVT noted besides lower limb pain on examinations. Distal neurovascular status was intact. Vitals were stable at presentation. She was managed symptomatically initially which subsided her pain but later on the third day of symptoms she started having breathlessness on exertion and mild chest pain. Based on her history we suspected DVT with PE. Due to the limited availability of resources, she was referred to a higher centre based at Kathmandu immediately, where she underwent various investigations including D-dimer test, CECT pulmonary angiography and DVT screening. All of the investigations were consistent with DVT with PE.
Conclusions—Musculoskeletal injuries, including pain in the lower limbs, are often seen at high elevations. When dealing with such patients in resource-constrained situations, doctors should additionally consider the possibility of life-threatening conditions like DVT/PE.
KeywordsDVT, high altitude, musculoskeletal injuries, pulmonary embolism
Lift-Served Mountain Biking: Elevated Fun or Elevated Risk? A Descriptive Analysis of Lift-Served vs. Traditional Mountain Biking Injuries
Noah Jennis, BA1; Andrew Potyk, BS1; Laura Baumann, MD, MPH2; Andrew Crockett, MD1,2
1
Geisel School of Medicine at Dartmouth, Hanover, NH, USA.
2
Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
Introduction/Background—Lift-served, downhill-specific mountain biking is increasing in availability and popularity. Risks and injury patterns in this patient population have not been well described.
Objective—To characterize patients presenting to a rural Level I trauma center with mountain bike-associated injuries who were engaged in lift-served vs. traditional mountain biking.
Methods—A 10-year retrospective chart review of mountain biking injuries was performed. Patients were identified from the institutional trauma registry at an ACS-verified Level I trauma center in rural New England between Jan. 2013 and Dec. 2022. Patient demographics, injuries, outcomes, dispositions, and injury locations (lift-served vs. traditional) were analyzed. Statistical differences were assessed with Chi-Square or Student’s T-Tests.
Results—One hundred eighty seven patients [91 (48.7%) lift-served, 83 (44.4%) traditional, 13 (7.0%) unknown] suffered a total of 440 injuries. Patients were predominantly male [158 (84.5%)] and helmeted [177 (94.7%)]. The most common injuries included chest [83 (18.9%)], spine [75 (17.0%)], and head [69 (15.7%)]. Comparing lift-served vs. traditional subgroups, lift-served patients were statistically younger [0-14 yrs: 13 (14.4%) vs 9 (11.1%), 15-39 yrs: 46 (51.1%) vs 24 (29.6%), 40-64 yrs: 30 (33.3%) vs. 38 (46.9%), >65 yrs: 1 (1.1%) vs 10 (12.4%)] and more likely to be helmeted [91 (100.0%) vs 75 (90.4%)]. Hemothorax was more frequent in the lift-served group [14 (6.3%) vs 3 (1.6%)]. Otherwise, no statistically significant differences in injuries were noted. There was no statistical difference in ISS, GCS, hospital LOS, discharge disposition, or mortality between groups.
Conclusion—No significant difference in injury pattern, severity, or patient outcome was identified. For those requiring care at a Level-1 Trauma center, lift-served mountain biking is not more dangerous than traditional mountain biking.
Keywordsmountain bike, cycling, downhill mountain biking, lift-served mountain biking, recreation related trauma, bike park
Differentiating Pneumonia and HAPE in Children
Christine Ebert-Santos, MD1; Sean Finnegan, BS, MPS
1
Ebert Family Clinic, Frisco, USA
Health care providers familiar with high altitude-related conditions can readily identify and manage classic high altitude pulmonary edema (C-HAPE). Newly assigned or rotating providers in mountainous areas may find distinguishing C-HAPE and other forms of HAPE (reentry, resident, and highlander) challenging especially when X-rays appear normal. Accurate diagnosis is crucial due to the preventable recurrence risk and unnecessary antibiotic exposure in children with HAPE.
This analysis aims to raise awareness of varied HAPE presentations and differentiate HAPE from pneumonia in acute settings.
We reviewed 246 charts pulled for hypoxia and relevant diagnosis codes from St. Anthony Summit EMR located in Frisco, Colorado at 2762 masl. After manual sorting and elimination of cases with confounding variables, an expert in high altitude pediatric medicine assessed remaining cases for HAPE, pneumonia, or both.
Correlations were found between O2 saturation, heart rate, respiratory rate, gender, physical exam, and radiographic findings, but not with temperature, age, or illness duration. These correlations formed the basis for a scoring system called the “Frisco Score” to aid clinicians in diagnosing HAPE, pneumonia, or both.
This is the largest contemporary cohort of children with hypoxia at high altitude which have been reviewed as a primary source.. There are few health care facilities located at high-altitude in the US, and these are among the highest. The Frisco Score offers initial guidance to clinicians on key clinical components for distinguishing HAPE from pneumonia. Although the prediction tool is currently a model, heightened awareness, screening, and data collection on HAPE can lead to significant data enabling validation for practical clinical implementation.
Keywordspneumonia, HAPE, pediatric, hypoxia, x-rays, mountains
Functional Evaluation using Enhanced Techniques for Precision Imaging in Climbing Shoes
Quinn M. Krause, BS1; Neil A. Segal, MD, MS2; Owen Burroughs, M.Res.3; Bradford L. Burns, BS4; David G. Naylor, MD5
1
Univeristy of Kansas School of Medicine, Kansas City, USA.
2
Department of Physical Medicine and Rehabilitation, Kansas University Medical Center, Kansas City, USA.
3
Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, USA.
4
University of Washington School of Medicine, Laramie, USA.
5
Department of General & Hospital Medicine, Kansas University Medical Center, Kansas City, USA
Introduction—Climbing shoes are associated with increased rates of chronic foot pathologies. Downsizing climbing shoes compare to street shoe is common among recreational and professional athletes. Intracorporeal imaging of feet in climbing shoes is limited, and no imaging of feet engaged in rock climbing exists.
Objective—To image rock climbing feet in climbing shoes using weight-bearing CT (WBCT) in both weight-bearing standing and weight-bearing climbing position and compare these measurement against climbing shoe size and survey data.
Methods—Recreational rock climbers (n=24) from the Midwest were recruited. Survey data were collected on climbing habits and street/climbing shoe usage. Participants were scanned using the Planmed XFI WBCT in a standing position with climbing shoes and while engaged on a small, gym-style rock climbing wall placed inside the CT scanner. Joint angle was measured for hallux valgus angle (HVA), interphalangeal angle (IMA), and first intermetatarsal angle (IPA). HVA and IMA were selected due to clinical correlation with hallux valgus deformity which are common among rock climbers.
Results—Participants’ mean age was 36 (SD=11). Median measured climbing shoe size was smaller than reported street shoe size (EU 41 vs 42.5, p<0.001). Participants reported climbing 2.8 times per week for 6.8 hours per week. In the standing position, the mean HVA=20.2° (SD=6.92), IPA=15.3° (SD=6.64), and IMA=9.9° (SD=1.60). In the climbing position, the mean HVA=20.5° (SD=7.84), IPA=18.7° (SD=6.69), and IMA=11.6° (SD=2.17). Both IPA and IMA were estimated to be significantly greater in the climbing position than in the standing position (p<0.001 for each).
Conclusions—This novel approach allowed an inside examination of foot architecture while standing and engaged on rock-climbing footholds. Climbing shoes were found to cause more excessive joint angulation while climbing. For this reason, care should be taken when selecting appropriately sized shoes as the size indicated by the manufacturer is often misrepresented.
Keywordshallux valgus, weight-bearing, exercise, x-ray computed tomography, wilderness medicine, athletic injuries
FundingWilderness Medical Society 2023 Houston Grant 2023
Gender Distribution of Study Participants and Authors in Rock Climbing Research
Danielle Lee, BA1; Shyamala Subramanian, BS1; Linda Keyes, MD2; Ziva Petrin, MD3
1
Rutgers New Jersey Medical School, Newark, NJ, USA.
2
Department of Emergency Medicine, University of Colorado, Aurora, CO, USA.
3
Department of Physical Medicine and Rehabilitation, Rutgers New Jersey Medical School, Newark, NJ, USA
Introduction—While rock climbing is approaching gender parity in participation, women’s representation in rock climbing research remains to be investigated.
Objective—This study evaluated the gender distribution of research participants and authorship in rock climbing literature.
Methods—We conducted a systematic review with PubMed and Embase to identify original research articles involving rock climbers. We categorized articles by research topic and extracted data on the sex (female and male) of study participants and authors. Author gender was classified with Genderize.io, an automated probability-based assessment software.
Results—We found 298 original research articles for analysis, dating from 1973 to 2023. Among the 266 that reported participant gender, women comprised a weighted average of 35.9% of climber participants. Eighty-two (30.8%) articles had all-male climber participants, while 7 (2.6%) had an all-female cohort. Female climbers were the most underrepresented in articles related to chronic climbing injuries (12.5% female), imaging studies (15.1%), and injury rehabilitation studies (20.3%), while female representation was highest in studies about youth climbing (42.8%) and epidemiology (36.1%). There were 1360 total authorships, 290 (21.3%) of which were female. Women were first authors for 54 (4.0%) articles and last authors for 53 (3.9%) articles. Articles with female first authors had a higher proportion of female study participants compared to those with male first authors (39.2% vs. 35.9%, p<0.001), while the proportion did not differ between articles with female vs. male last authors (36.1% vs. 35.9%, p = 0.592).
Conclusions—Female representation in climbing research and authorship is limited. As most research was performed in male climbers, it is possible that the recognition and treatment of injuries are suboptimal for female climbers.
Keywordssports medicine, gender bias, sports injuries, sports performance
Cardiovascular Changes in Long-distance Thru-hikers: A Nutrition Controlled, Prospective Observational Study on Healthy Bolunteers.
Hannah Frederick, MD1; Alexander Noonan-Shueh1; Alexis Salerno, MD1; Daniel Gingold, MD1;
Daniel Craighead, PhD2; Douglas Sward, MD1
1
University of Maryland School of Medicine, Baltimore, USA.
2
University of Colorado Boulder, Boulder, USA
Background—With only a backpack on one's body to fulfill all survival needs, long-distance thru-hiking pushes one's mental and physical limits. Thru-hiking has been shown to worsen cardiovascular function (i.e., decrease vascular endothelial function, increase arterial stiffness and blood pressure), possibly increasing cardiovascular disease risk. However, the role of diet in mediating these effects has not been established.
Objective—Our objective was to evaluate cardiovascular health markers on four hikers completing thru-hikes and nutrition control periods. We hypothesized that they would experience decreased endothelial function, increased arterial stiffness, and higher diastolic blood pressure (DBP) post-hike and post-nutrition control.
Methods—Two men and two women (average age 24, SD = 0.5) completed thru hikes that were 150 or 800 miles from May to July 2023. Measurements were taken at three time points: baseline, after a two-week trail diet period without hiking (nutrition control), and post-hike (thru-hiking plus trail diet). Endothelial function was determined as brachial artery flow-mediated dilation (FMD; brachial artery dilation following a period of ischemia) measured via ultrasound. Arterial stiffness was assessed as pulse wave velocity (PWV), measured via ultrasound of the participants’ carotid and femoral arteries. DBP was measured with an automatic blood pressure machine. Descriptive analysis of the data was performed.
Results—Compared to baseline, FMD increased by 4.68% (SD = 4.03) after nutrition control and decreased by 14.82% (SD = 15.97) after thru-hiking. Carotid-femoral PWV decreased 2.4% (SD = 13.85) after nutrition control and increased 4.5% (SD=24.24) after thru-hiking. Average DBP was 63 mmHg (SD = 13.44) before thru-hiking and 71 mmHg (SD = 2.64) after thru-hiking. The men had an average increase of DBP of 18 mmHg (SD = 2.82) before and after hiking compared to the women who had an average decrease of 1 mmHg (SD = 4.24).
Conclusion—Cardiovascular function worsened following thru-hiking but not nutrition control, suggesting nutrition does not drive cardiovascular dysfunction following thru-hiking. Further studies should be performed on the negative effects that thru-hiking has on cardiovascular health.
Keywordswilderness medicine, ultrasonography, emergency medicine, sports medicine, carotid-femoral pulse wave velocity, physical endurance
Utilizing Portable Ultrasound to Examine Rectus Femoris Changes in Long-distance Thru-hikers: A Nutrition Controlled, Observational Study on Healthy Volunteers
Alexander Noonan-Shueh1; Hannah Frederick, MD1; Alexis Salerno, MD1; Daniel Gingold, MD1; Daniel Craighead, PhD2; Douglas Sward, MD1
1
University of Maryland School of Medicine, Baltimore, USA.
2
University of Colorado Boulder, Boulder, USA
Background—Long-distance thru-hiking pushes one’s mental and physical limits. Body composition, including muscle mass, may worsen with thru-hiking. However, there is no information on how thru-hiking impacts the rectus femoris muscle and the role of nutrition in any potential changes. It is important to analyze how rectus femoris morphology changes with thru-hiking to better educate hikers on how to train appropriately.
Objective—Our objective was to assess whether leg muscles would atrophy or hypertrophy in four thru-hikers, hypothesizing decreased rectus femoris muscle thickness while controlling for nutrition.
Methods—Using ultrasound, we measured rectus femoris muscle thickness at the mid-femur level at baseline, after a two-week trail diet without hiking (nutrition control), and after hiking 150 or 800 miles (thru-hiking plus trail diet). Additionally, two hikers carried a portable ultrasound and recorded measurements four times during their hike. Descriptive analysis of the data was performed.
Results—There was an average increase in rectus muscle thickness of 7.86% (SD = 16.11) after nutrition control compared to an average decrease in size of 10.09% (SD = 6.6) after thru-hiking. Males exhibited a more pronounced decrease (-14.6%, SD = 6.48) compared to females (-5.6%, SD = 4.41). In the two hikers who brought a portable ultrasound on trail, the rectus femoris increased in the first 12 days, and then decreased in size by day 16.
Conclusion—Long distance hiking caused adaptive morphological changes in the rectus femoris that cannot be explained by nutrition alone. The rectus femoris decreased in size after thru-hiking in all four hikers which did not occur during the nutrition control period. Revealing how the rectus femoris adapts to long-distance thru-hiking may reveal to hikers, coaches, and physicians how to appropriately train for such hikes to reduce injuries.
Keywordswilderness medicine, ultrasonography, emergency medicine, sports medicine, quadriceps muscle, physical endurance
Trailside Screening for Neurocognitive Impairment in Acute Altitude Illness
Vincent L Kan, MD1; Aaron M Blau, MD2;
Cecily J Swinburne, MD, MPH3; Hillary R Irons, MD, PhD1
1
UMass Chan Medical School, Worcester, USA.
2
University of Utah, Salt Lake City, USA.
3
Northern Light Eastern Maine Medical Center, Bangor, USA
Introduction/Background—Early detection of acute altitude illness is crucial to prevent deterioration. A significant need exists for an objective, portable, quantitative assessment tool to measure cognitive and physical impairment related to altitude illness to be administered quickly in the field to guide symptom management and evacuation decisions. Mild traumatic brain injuries manifest many of the same psychomotor and cognitive deficits as altitude illness.
Objective—This pilot study adapted sideline concussion assessment tools to measure cognitive impairment of altitude illness in the field.
Methods—The Sports Concussion Assessment Tool (SCAT3), ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing), King-Devick, and Sway Balance sideline concussion tests were administered to subjects recruited from the WMS 2018 Everest Experience Trek to Basecamp. Baseline assessment was completed in Kathmandu (1400m) >24 hours after arrival. Additional testing occurred during ascent to Namche (3445m), Pheriche (4300m), Lobuche (4930m), Everest BaseCamp (5360m) at 2-8 hours and 24-36 hours, and return to Kathmandu including vital signs, LLS, adapted SCAT3, ImPACT, Sway Balance, and King-Devick tests were recorded. A subset wore sleep tracking devices. Generalized linear mixed models were used for statistical analysis adjusted for age, sex, medical history, medications, and vital signs.
Results—25 subjects were recruited from WMS 2018 Everest Experience Trek from March 25 to April 16, 2018. Symptoms and concussion test results varied with elevation and time. Some tasks were individual dependent. Overall, attention and motor tasks including balance and reaction times better correlated with altitude. Immediate memory and orientation did not change significantly. Sleep was impacted at all altitudes including Kathmandu.
Conclusions—Neurocognitive assessments similar to sideline concussion tools may be a starting point to develop an objective screening tool to guide “return-to-climb” decisions. Future directions include identifying the most sensitive subtasks to design an altitude-specific tool and test it on a larger subject pool.
Keywordsaltitude illness, acute mountain sickness, neurocognitive testing, trailside field screening, concussion/mtbi
FundingWilderness Medical Society 2016 Research-in-Training Grant.
Backpack Weight and its Influence on Perceived Exertion and Heart Rate in Recreational Hiking
Joseph Mueller, MD; Lavinia Turian, MD; Jannet Castaneda Sanchez, Susanne Spano, MD
UCSF Fresno, Fresno, USA
Introduction—Backpacking is a popular recreational activity where base pack weight (BPW) is a major consideration. Available recommendations for ideal BPW are inconsistent and rely on anecdotal evidence. A past survey of Pacific Crest Trail thru-hikers revealed a difference of 2 lbs in BPW between those who completed the trail and those who did not.
Objective—Determine if there is a psychometric or physiological difference between carrying 17 or 19 lbs in BPW.
Methods—A study was performed with 17 participants. Subjects were randomized and blinded to carry either 17 or 19 lbs BPW. Rated Perceived Exertion (RPE) score was measured at the end of an uphill, downhill, and after a total hike of 8 miles. Continuous heart rate (HR) data was recorded. The participants completed a second trial with the other BPW 1-2 weeks later. HR and RPE were calculated at each point and compared using paired-samples t-test and bootstrap t-test.
Results—Using paired samples t-test, total RPE was significantly higher for the 19-pound group than 17-pound group, and resting heart rate was significantly higher in 17 lbs than 19 lbs using boot strap T test. Otherwise, no significant difference was found between RPE and average HR measurements in all conditions. End HR between the 17 lb vs 19 lb groups was 123 and 126 bpm (p = 0.383) with a RPE of 11.3 vs 12.2 (p = 0.048) respectively. Uphill RPE between 17 lb vs 19 lb groups was 12.1 vs 12.9 (p = 0.284). Downhill RPE between 17 lb vs 19 lb groups was 11.3 vs 12.2 (p = 0.209).
Conclusions—A 2 lb increment of weight between 17 and 19 lb BPW may impart a psychometric difference but likely no physiological difference over the course of an 8 mile hike. Further data collection may improve sensitivity.
Keywordsbiological science, physiological phenomena, cardiovascular system, exercise, circulatory and respiratory physiology, recreation
Hot off the Press: Exertional Heat Stroke at the Vermont City Marathon Exceeds that of Boston Marathon
Emily Speck MD; Aaron Brillhart MD; Katie Dolbec MD; Andrew Park MD; Sameer Sethi MD; Sarah Schlein MD
Department of Emergency Medicine, University of Vermont, Burlington, Vermont
Introduction—Exertional heat stroke (EHS) is a leading cause of mortality in endurance sports. EHS is encountered during long distance running events, including at New England spring season races such as the Vermont City Marathon (VCM) and Boston Marathon (BM). With increasing global temperatures, understanding EHS trends remains relevant for prehospital, environmental, and wilderness medicine.
Objective—This study analyzes EHS cases at VCM to understand trends, to aid in future prevention efforts, and to compare VCM data with BM.
Methods—For the 10 years 2012-19 and 2022-23, VCM race medical service data were retrospectively reviewed (no spring race 2020-21). Demographic and treatment data were examined and compared with BM published data from 2015-19.
Results—Of 22,224 marathon starters over the study period there were 26 EHS cases, yielding an incidence of EHS of 12/10,000 (0.12%). Wet bulb globe temperature (WBGT) averaged 20°C. Compared with all VCM marathon starters, EHS patients were younger (mean age 33 vs 39 yrs) and trended toward more commonly male (62% vs 54%). Maximum core temperature for EHS patients averaged 41°C. All EHS patients were treated with ice water bath immersion and survived. Overall, 50% of EHS patients required hospital transport, but since 2016 that number declined to 23%. Compared with the BM, EHS at VCM was 3.2 times more frequent (12 vs 3.7/10,000), mean WBGT was higher (20° vs 14°C), and age and sex findings were similar.
Conclusion—Despite the northerly location and spring season of VCM, WBGT averaged warmer and EHS occurred more frequently than at BM. Educational opportunities exist for all runners in order to prevent EHS, especially in warmer years, and particularly with younger runners. Continued preparation for EHS, including ice water baths and early recognition, remains critical at VCM. Efforts appear life-saving.
Characteristics of Medical Evacuations on Mount Aconcagua during the 2022-24 Climbing Seasons
Aaron Brillhart MD1; Bernabé Abramor MD2; Rodrigo Duplessis MD2; Roxana Pronce MD2; Javier Seufferheld MD2
1Department of Emergency Medicine, University of Vermont, Burlington, Vermont. 2Extreme Medicine, Aconcagua Provincial Park, Argentina
Introduction—Mount Aconcagua (6962m) is the highest peak in world outside of Asia and attempted by over 3000 climbers annually. The medical service of Aconcagua Provincial Park (APP) performs screening exams on all climbers, and cares for all ill or injured patients including those requiring rescue evacuation. To date, no comprehensive report on evacuations from Aconcagua has been published in the medical literature.
Objective—This study seeks to characterize patients and conditions requiring medical evacuation among climbers on Aconcagua in order to assist with future preparation and prevention efforts within APP and globally.
Methods—Demographic, medical, and logistics data provided by APP on climbers requiring evacuation during the two most recent climbing seasons spanning 2022-2024 were retrospectively reviewed.
Results—Of 6491 total climbers, 340 required evacuation, yielding an evacuation rate of 5.2%. Mean age was 42. Reasons for evacuation included high altitude pulmonary edema (HAPE) (47%), trauma/musculoskeletal (17%), acute mountain sickness (11%), general medical and cardiac (11.2%, cardiac only 3.5%), frostbite (7.1%), high altitude cerebral edema (HACE) (2.6%), death (2.4%), lost/aid (2.4%), psychiatric (0.89%), HAPE and HACE (0.59%). All medical causes represented 71% and all altitude illness was 59% of evacuees. Most were flown by helicopter (94%), with flight location primarily from 4200-4300m base camps (76%), and between 5300-5970m (14%). Most evacuees were European (35%), North American (30%), or South American (20%).
Conclusions—Of climbers attempting Mount Aconcagua, 5.2% required evacuation. Unlike Denali, on Aconcagua HAPE was the most common reason for evacuation (47% vs 11%), all altitude illness was higher (59% vs 20%), trauma was less common (17% vs 39%), and overall rate of rescue evacuation was higher (5.2% vs 1.2%). With a lower death rate on Aconcagua than Denali despite high rates of HAPE, increased evacuation frequency and medical oversight appear to save climber lives in APP.
Climber Mortality on Mount Aconcagua, 2013-2024
Aaron Brillhart MD1; Bernabé Abramor MD2; Rodrigo Duplessis MD2; Roxana Pronce MD2; Javier Seufferheld MD2
1Department of Emergency Medicine, University of Vermont, Burlington, Vermont. 2Extreme Medicine, Aconcagua Provincial Park, Argentina
Introduction—Mount Aconcagua (6962m) is the highest peak in the Americas. Thousands of climbers attempt its summit annually. Aconcagua Provincial Park (APP) manages operations for the mountain, including rescues and fatality recovery. Mortality data were last reported over a decade ago in the medical literature. With an evolving APP medical service as well as climber practices, an update is currently due.
Objective—This study seeks to update current global knowledge regarding climber characteristics and causes of death on Mount Aconcagua, and to aid APP in prevention efforts.
Methods—Mortality data for the 10 most recent climbing seasons from 2013-24 were provided by APP, retrospectively reviewed, and compared with historical data.
Results—Over the study period, 29,666 climbers obtained summit permits and there were 21 deaths, yielding a fatality rate of 0.71/1,000, or 0.071%. For fatalities, mean age was 50 and 86% were male. Continent of origin was primarily Europe (43%) and North America (43%). Most fatalities (90%) occurred over 6000m. Most deaths had an unspecified medical cause (81%), often speculated as altitude, hypothermia, or cardiac. Trauma represented 19% of deaths. Compared to a prior Aconcagua study, fatalities currently are older (50 vs 41 yrs), at higher elevation (90% vs 39% over 6000m extrapolated from old figure, prior mean 5570m), comprise more North Americans (43% vs 12%), and no deaths occurred below base camps or on steeper South Face routes.
Conclusions—The fatality rate on Mount Aconcagua is currently 0.071%, which is similar to 0.077% from a prior study. However, mean age is now older and location of fatality is now primarily over 6000m. Deaths from medical causes at extreme altitude appear most common. The Aconcagua fatality rate remains 3.1 times more than Mount Kilimanjaro (0.023%), 4.4 times less than Denali (0.31%), and 11 times less than Mount Everest (0.8%).
Acclimatization Practices of Climbers on Mount Aconcagua During the 2023-2024 Climbing Season
Sameer Sethi, MD1; Aaron Brillhart, MD1; Andrew Park, DO, MPH1; Bernabé Abramor, MD2; Rodrigo Duplessis, MD2; Roxana Pronce, MD2; Javier Seufferheld, MD2; Sarah Schlein, MD1
1
Department of Emergency Medicine, University of Vermont, Burlington, Vermont.
2
Extreme Medicine, Aconcagua Provincial Park, Argentina
Introduction—Mount Aconcagua (6962m) in Argentina is the highest peak in the Americas and each year attempted by over 3000 climbers. The normal route is nontechnical, with high camps to 5970m elevation. High altitude illness has been a common reason for evacuation and mortality on Aconcagua.
Objective—This study surveyed acclimatization practices of climbers on Aconcagua in order to gain knowledge that could aid in future illness prevention efforts.
Methods—Aconcagua climbers completed surveys primarily at 4300m base camp during January 2024. Surveys queried demographics, ascent rate, pre-acclimatization, training, medication use, recent virus exposure, and reported vital signs if known.
Results—Of 42 climbers completing surveys, mean age was 39, with 36% female, and the majority European (62%). Few climbers used pre-trip staged ascent (10%), hypoxic tents (5%), or acetazolamide (19%) for prophylaxis of altitude illness. Prior altitude illness, mainly acute mountain sickness, was reported by 64% of climbers. Fitness preparation averaged 11 hours of aerobic exercise per week. Recent viral symptoms were common (29%), but not Covid (2%). Mean vital signs reported were SpO2 86%, heart rate 87 bpm, and blood pressure 139/86. Climbers spent an average of 2 nights camping over 3000m while ascending to the 4300m base camp, and 5 nights at base camp. On average, climbers planned for 10 nights over 3000m prior to summit attempt, yielding a median sleeping elevation ascent rate of 270m/day (IQ range 248-330m).
Conclusions—This study documents acclimatization practices of climbers on Mount Aconcagua, one of the world’s highest mountains and frequently attempted. These data allow a better understanding of climber habits, ascent rates, and vital signs. The ascent rate is less than previously reported. This information provides a potential basis for analysis and prevention efforts of high altitude illness on Aconcagua and globally.
Characteristics of Climbers with High Altitude Pulmonary Edema on Mount Aconcagua
Andrew Park, DO1; Aaron Brillhart, MD1; Sameer Sethi, MD1; Bernabé Abramor, MD2; Rodrigo Duplessis, MD2; Roxana Pronce, MD2; Javier Seufferheld, MD2;
Sarah Schlein, MD1
1Department of Emergency Medicine, University of Vermont, Burlington, Vermont. 2Extreme Medicine, Aconcagua Provincial Park, Argentina
Introduction—Mount Aconcagua (6962m) in Argentina is the highest peak in the Americas and attempted by over 3000 climbers annually, primarily via a non-technical route. High-altitude pulmonary edema (HAPE) has been a leading cause of mortality and evacuation on Aconcagua.
Objective—This study sought to better understand the characteristics of climbers who developed HAPE on Aconcagua in order to aid in future prevention efforts.
Methods—Climbers on Aconcagua with HAPE diagnosed by Aconcagua park physicians during January 2024 were surveyed regarding their illness development, ascent pattern, vital signs, and treatment. Climbers who developed HAPE were compared with healthy controls from a separate acclimatization study.
Results—HAPE was diagnosed in 17 climbers during the study period. These climbers were similar to climbers without HAPE in age, sex, origin, home elevation, hypoxic tent use, staged ascent, recent virus exposure, fitness metrics, and overall ascent rate plans. Climbers with HAPE spent less nights at 4300m base camp (3.6 vs 5.0 nights, p=0.01). Climbers who developed HAPE trended toward more commonly taking acetazolamide (47% vs 19%, p=0.05). Prior to developing HAPE, 71% of patients reported acute mountain sickness symptoms which did not resolve. HAPE onset median elevation was 5500m (IQ range 4300-5500m), with median of 8.0 days over 3000m (IQ range 5-13d), and median lowest SpO2 of 60% (IQ range 54-69%) at diagnosis. All surveyed HAPE patients descended, were evacuated by helicopter, and survived.
Conclusion—This study examined climbers who developed HAPE while on Mount Aconcagua, and yields implications for high altitude illness prevention efforts and further study. An emphasis on sufficient nights at 4300m base camp, caution regarding unresolved AMS symptoms, and further evaluation of acetazolamide use appear warranted.
Ex vivo Human Cadaveric Ultrasound Analysis of Efficacy Across Cactus Spine Removal Techniques
Harrison Fillmore, MSc1; Matthew D. Johnson, BA1;
Ryan M. Leone, MSc1; Christopher Tedeschi, MD, MA2
1
Columbia University Vagelos College of Physicians and Surgeons, New York, USA.
2
Department of Emergency Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, USA
Background—Embedded cactus spines can be painful and lead to granulomatous reactions without proper removal. While some spines can be removed by hand, others warrant alternative methods, such as tweezers, adhesive tape, or pre-operative hair removal gloves. Finer spines are harder to visualize macroscopically, so bedside ultrasound might be an effective tool for visualizing their presence.
Objective—This study combines ultrasound visualization with a comparison of standard wilderness-ready removal techniques to investigate the efficacy of (1) ultrasound in finding retained foreign bodies difficult to see with the naked eye, and (2) commonly used techniques for removing cactus spines.
Methods—This experiment involved eight cadavers, each with two ultrasound-scannable sites - the bilateral gluteus maximus with overlying skin. Four 2 cm2 fields at each site were struck with a cholla cactus (Cylindropuntia imbricata var. arborescens) arm before applying randomized spine removal techniques. Each field was scanned using a high-frequency linear array ultrasound probe before cactus exposure, after exposure, and after a removal trial with the assigned technique. Sonographers interpreted scans asynchronously and were blinded to how many spines were initially embedded and which technique (tweezers, duct tape, or pre-operative hair removal gloves) was used in each field. Each successfully embedded spine was counted as one binary trial. A positive outcome was removal measured by ultrasound or naked-eye observation.
Results—Sonographers could not reliably distinguish cactus spines from surrounding soft tissues (Cohen’s kappa statistic κ = 0.03). Using naked eye data, binary logistic regression showed that when compared with surgical gloves, the odds of successful removal while using duct tape are 1.34 (p < 0.05), and the odds of successful removal while using tweezers was 1.97 (p < 0.001).
Conclusions—Portable ultrasound was ineffective in identifying retained cactus spine fragments invisible to the naked eye when collected by a layperson and interpreted asynchronously by an expert. The efficacy of tweezers was statistically greater than both other methods.
