Selected Abstracts from the Wilderness Medical Society's 2008 Annual Scientific Meeting

Wilderness and Environmental Medicine, 20, 176 180 (2009)

Selected Abstracts from the Wilderness Medical Society’s 2008 Annual Scientific Meeting Shaving Cream as a First-Line Treatment for Jellyfish Stings Current first-line treatments for jellyfish stings include vinegar (acetic acid), hot water irrigation or immersion, and papain (a meat tenderizer). Occasionally it is noted that after the use of a primary treatment modality, the remaining inactivated nematocysts may be removed by applying shaving cream and then scraping with a butter knife, credit card, or other similar item. We report a series of 3 cases in which the successful initial treatment of jellyfish stings consisted of applying shaving cream, scraping to remove nematocysts, and irrigating with salt water. Each individual was stung by a jellyfish while in the Atlantic Ocean off the coast of Edisto Island, South Carolina. In each case, treatment resulted in immediate relief of symptoms. Often travelers do not have vinegar or papain immediately available. They also may not have means readily available to heat water, or if they do, there is a significant period in which the patient remains in pain while the water is being heated. Shaving cream is a common item carried by many travelers, requires no special preparation, and provided immediate relief of symptoms in this small case series. We recognize the study is limited by its size, as well as lack of identification of the specific type of jellyfish causing the stings. Shaving cream has been successfully used as a first-line therapy for jellyfish stings when other recommended treatment modalities were unavailable. Further study into this as a recommended first line of therapy is warranted. Michael J. Caudell, MD Wakili S. Yarima, MD Augusta, GA, USA

The Effects of Altitude on Energy Balance in Sherpas on Mount Everest Exposure to high altitude is typically accompanied by negative energy balance and subsequent altitude-induced weight loss in lowlanders. It is unknown if Sherpas experience these same adverse effects. The aim of the present study was to determine the effect of extreme altitude on energy balance in Sherpas participating in the SuperSherpas Everest Expedition. In this observational study, 8 elite Sherpa climbers (mean 35.8 ⫾ 10.3 years; range 20–47 years) wore portable armbands throughout the expedition to estimate total daily energy expenditure and resting energy expenditure. Body weights were also recorded in Kathmandu, Nepal, and 1 day after the summit was reached (n ⫽ 4). Urine samples were collected at base camp (5300 m) upon initial arrival and return from camps 1 through 4 to measure urine specific gravity. Mean total daily energy expenditure was 3686 ⫾ 291 kcal/d (range 2032–5791 kcal/d). Resting

energy expenditure remained stable throughout the expedition, with a mean value of 1753 ⫾ 103 kcal/day (range 1646–1863 kcal/day). Mean body weight decreased 0.5 ⫾ 2.9 kg. One Sherpa gained 3.4 kg, whereas the remaining 3 Sherpas lost 0.2, 1.8, and 3.4 kg, respectively. Throughout the expedition, mean urine specific gravity was 1.025 ⫾ 0.003 (range 1.015– 1.030). In conclusion, unlike most lowlanders, the Sherpas were able to maintain energy balance while working at extreme altitude. Further, Sherpa performance was unaffected by negative hydration status. Future research is warranted to understand the mechanisms responsible for these findings. Stacie L. Wing-Gaia, PhD, RD Staci Nix, MS, RD Scott McIntosh, MD, MPH Salt Lake City, UT, USA

Occupational Injuries in Aquarium Store Workers Aquarium stores have many potential hazards. Daily exposure to venomous animals, biting fishes, and overloaded electrical circuits are serious risks to employees. This study seeks to define which animals and hazards are most frequently encountered to improve safety in this occupation. A 15-question survey was distributed to employees of the largest net sales aquarium store in the Twin Cities, MN, area. Questions included type of injury, mechanism of injury, treatment required, and demographic information. Nine of 14 employees returned completed surveys. The average age of respondents was 32.8 years, and 78% were male. Experience working at aquarium stores varied from less than 1 year (1 respondent) to more than 10 years (2 respondents) (average 5.5 years). All 9 respondents reported sustaining a bite or sting while at work. Two were from foxface rabbitfish (Siganus sp), 2 from live rock (calcium carbonate skeletons of dead corals or other calcareous organisms), and 1 each from triggerfish (family Balistidae), lionfish (Pterois sp), oscar fish (Astronotus ocellatus), and catfish (family Siluriformes). None of these injuries required medical care beyond first aid. Six respondents reported sustaining lacerations. Sources included broken glass and surgeonfish (Acanthurus sp). Five respondents reported electrical injury: 3 from aquarium equipment and 2 from electric catfish. Two respondents reported serious allergic reactions. One was from zoanthid coral, resulting in tongue and eye swelling and an emergency department visit. Another respondent reported severe hand swelling whenever contact occurred with an anemone. Both individuals have modified their work by now wearing gloves when contacting these animals. Several other injuries were reported. One infection of Mycobacteria marinus requiring long-term antibiotics was sustained. An-

Selected Abstracts from the Wilderness Medical Society’s 2008 ASM other employee reported contact chemical dermatitis from handling a dry salt mixture. There are many potential sources of injury in the aquarium hobby. Individuals most at risk are those with the most exposure, including aquarium store workers. This study found that a wide variety of animals and electrical and chemical causes were responsible for injury. Jennifer M. Bahr, MD Minneapolis, MN, USA

A Comparison of Bacterial Colony Forming Units in Water Bottles and Hydration Bags Among Outdoor Enthusiasts Introduction.—Transporting clean drinking water in an easily accessible container is a priority for many outdoor enthusiasts. Two basic hydration systems are commonly used to provide water: the water bottle and the hydration bladder. The authors tested the hypothesis that there were different levels of microbiological contamination between these 2 systems. Methods.—Sixty-seven water samples were collected using sterile techniques from outdoor enthusiasts at several outdoor recreational locations. These users were then asked to complete a brief survey that reported demographic information and details of water container use. Water samples were then plated on sheep blood agar, and the colony forming units were counted after 24 hours of growth. The 2 groups were compared using Student’s t test. Results.—The 2 groups using water bottles or hydration bladders did not show significant differences in participant age or gender, duration of outdoor activity, container age or duration since last cleaning. The groups differed slightly in their composition of hikers/walkers/runners vs cyclists. The water bottle group had a mean colony forming unit count of 37 (95% CI 26–48), and the hydration bladder had a mean of 27 (95% CI 17–35). Conclusion.—There was no statistically significant difference between hydration bladders and water bottles in microbial contamination or colonization. Judging from the available data, outdoor enthusiasts should select their water container based on criteria other than the relative exposure to pathogenic microbes. Additional study is required to replicate this finding in other locations and with improved sampling methodology. Andrew H. Brainard, MD, MPH Bethlehem, PA, USA Joe Alcock, MD, MS Albuquerque, NM, USA

Aerobic Fitness and Body Composition as Predictors of Success for Thru-hiking the Appalachian Trail Thru-hiking the Appalachian Trail (completing the entire 2175 miles from Georgia to Maine) is attempted by about 1500 individuals each year. Approximately 20% of all hikers who start thru-hiking the trail ultimately complete the entire hike. It is not known what factors are important in determining success in this long hike.

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The purpose of this study was to look at the role of initial aerobic fitness level and body composition as predictors of success in completing a thru-hike of the Appalachian Trail. Fifty-one healthy subjects attempting to thru-hike the trail were tested the day before they started their hike in Georgia. Maximum oxygen consumption, percent body fat, and body weight were measured in each subject. Maximum oxygen consumption was measured using a graded maximal exercise test that involved stepping up and down on a 10-inch step at 3 speeds (80, 90, and 100 steps/min). Once top speed was met, weight in increments of 10 pounds was added to a hiking pack until exhaustion. Percent body fat was measured using a 3-site skinfold measurement. Thirty-one of the 51 subjects starting the hike (61%) ultimately completed the entire 2175 miles. Subjects who completed the entire hike had a higher VO2max (39.5 ⫾ 5.4 ml/kg/min vs 33.4 ⫾ 6.2 ml/kg/min), a lower percent body fat (19.6 ⫾ 5.8% vs 25.7 ⫾ 5.4%), and lower body weights (76.0 ⫾ 12.7 kg vs 88.1 ⫾ 24.2 kg) than those subjects who did not complete the trail. All of these differences were significant at P ⬍ .05. Initial aerobic fitness, body composition, and body weight are all good predictors of success for completing a thru-hike of the Appalachian Trail. Individuals preparing for a thru-hike should consider these factors in their training for the hike. John E. Davis, PhD Alma, MI, USA

Nutritional Intake, Caloric Deficit, and Body Weight Changes in Appalachian Trail Thru-Hikers Caloric balance and nutritional balance are important considerations during long-distance hiking. Few studies have examined these factors during hiking, and none have comprehensively studied them in Appalachian Trail thru-hikers. Therefore, it was the purpose of this study to examine nutritional balance and caloric consumption vs caloric expenditure in Appalachian Trail thru-hikers. Fifty-nine healthy, active hikers on the Appalachian Trail volunteered for this study. Twenty-eight males and 31 females (mean ⫾ SD: 29.7 ⫾ 9.7 years, 67.8 ⫾ 3.4 inches) completed a nutritional survey asking them to recall 3 typical trail days of food consumption. In addition, the number of miles hiked was collected to determine caloric expenditure. All of the subjects had hiked at least 500 miles on the trail. Body weights were measured at the start of the trail and after 500 miles hiked. The data were then compiled and analyzed using the Diet Analysis ⫹ (Version 8.0) software package. Overall, men and women had diets that fell into normal macronutrient ranges. Forty-nine percent of their caloric intake was carbohydrate, 37% was fat, and 14% was protein. Male subjects incurred an average daily caloric deficit of 2200 calories, and women had a caloric deficit of 1700 calories. Interestingly, in spite of these significant caloric deficits, subjects only averaged a 5-pound weight loss. The lack of significant weight loss probably reflects eating strategies on and off the trail. The nutritional analysis in this study was on the trail only where pack weight was a serious consideration.

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Selected Abstracts from the Wilderness Medical Society’s 2008 ASM

Off the trail, thru-hikers consumed large numbers of calories to offset the significant caloric deficit on the trail. Thru-hikers on the Appalachian Trail demonstrated appropriate macronutrient levels while having a negative caloric deficit, but only moderate weight loss. John E. Davis, PhD Brett D. Knight, BS Alma, MI, USA

Effects of Hiking the Appalachian Trail on Energy Availability, Body Composition, and Menstrual Cycle Function Previous studies have demonstrated that various types of exercise result in a wide variety of menstrual irregularities. Although these irregularities are caused by many different factors, 2 that have been implicated in these responses are changes in body composition and reduced energy availability. Menstrual irregularities in long-distance hikers have not been extensively studied, yet they most likely exist in these individuals. This study examined the effects of hiking the Appalachian Trail on the caloric balance, body fat, and menstrual cycles of female long-distance hikers. Thirty-six females of varying fitness levels (30.2 ⫾ 8.3 years, 148.9 ⫾ 30.9 lb, 65.6 ⫾ 2.7 inches) completed a questionnaire indicating changes in menses while hiking the Appalachian Trail. Three-day food records were obtained to determine caloric balance of the hikers, and skinfold and body mass measurements were taken to determine changes in weight and percent body fat. Thirty-six women completed the 2006 TREMIN Program Health Report Form. Of the regularly menstruating women, 16% (4 of 25) used oral contraceptive pills. Forty-eight percent (12 of 25) of the women had menstrual changes, 2 of which were using oral contraceptive pills. The most common change in menses was a lighter flow (n ⫽ 9). Twenty-eight percent (7 of 25) reported a shortened duration of menses. Mid-cycle, breakthrough bleeding occurred in 3 women, 1 of which used oral contraceptive pills. Average caloric deficit was 4558 ⫾ 3385 kcal, and average weight loss was 5.3 ⫾ 10.3 lb. The sum of the skinfold measurements decreased by 25.3 ⫾ 20.2 mm by mile 459 of the trail, and average percent body fat for the same women decreased by 6.2 ⫾ 4.1%. Although incidences of amenorrhea were not found, other menstrual changes were discovered among the female hikers. These data suggest that a sustained caloric deficit in women thru-hiking the Appalachian Trail results in some modest menstrual changes. John E. Davis, PhD Lillian K. Peterson, BS Alma, MI, USA

Effects of Hiking the Appalachian Trail on Maximal Oxygen Consumption, Heart Rate, and Blood Lactate Levels Long-distance hiking has become a popular form of exercise for individuals of all ages. Furthermore, ultraendurance races have captured media attention in recent years. One activity that

incorporates both of these is thru-hiking the Appalachian Trail. This 2175-mile hike is attempted by about 1500 individuals each year. No studies have documented the cardiorespiratory changes that occur as a result of hiking the trail. The purpose of this study was to examine the cardiorespiratory effects of hiking the Appalachian Trail. Twenty-one healthy subjects (mean ⫾ SD: 31.3 ⫾ 10.4 years, 74.2 ⫾ 14.3 kg, 174.4 ⫾ 9.3 cm), with varying fitness levels, hiking the Appalachian trail completed 2 graded maximal exercise tests that involved stepping up and down on a 10-inch step at 3 speeds (80, 90, 100 steps per minute). Once top speed was met, weight in increments of 10 pounds was added to a hiking pack until exhaustion. The first test was performed the evening before subjects started hiking the Appalachian Trail. The second test was duplicated approximately 2 months later after subjects had hiked an average of 519 miles of the Appalachian Trail (range 360–622 miles). Heart rate and oxygen consumption were measured at each level of the exercise test. Five minutes after test completion, blood lactate levels were measured from a venous blood sample. After an average of 519 miles hiked, VO2max increased significantly (pretest 38.1 ⫾ 5.0 vs post-test 45.0 ⫾ 8.9 mL·kg·min, P ⬍ .05). The subjects’ heart rates decreased significantly at each workload (P ⬍ .05) in the post-test compared with the pretest. Maximum heart rates were also lower (pretest 183.9 ⫾ 13.1 vs post-test 174.1 ⫾ 17.9 beats/min, P ⬍ .05). Blood lactate levels decreased from pretest to post-test but not significantly (P ⫽ .07). Daily long-duration hiking improves cardiorespiratory fitness levels among thru-hikers on the Appalachian Trail. John E. Davis, PhD Alex F. Wagner, BS Alma, MI, USA

Can Hand Pump Water Filters be used to Effectively Irrigate Wounds in the Backcountry? Study Objective.—Wound management in the backcountry is an important step in preventing infections and improving wound healing. The pressure at which fluid is delivered has been found to be an important factor in reducing wound infections. Wounds contaminated with soil then cleaned with fluid at 15 pounds per square inch (psi) had only a 7% infection rate compared with a 100% infection rate with 1 psi. The purpose of this study was to determine if hand pump water filters can produce pressures effective for irrigating wounds. The hypothesis of the study was that hand pump water filters used with an angiocatheter attached can effectively deliver more than 15 psi for wound irrigation. Methods.—Fifteen different hand pump water filters were evaluated. Tested filters were produced by MSR (Washington), Katadyn (Minnesota), General Ecology, Inc. (Pennsylvania), and Proctor and Gamble (Ohio). Each water filter had a quarter-inch tube attached to the outlet with an angiocatheter attached to the end. A fluid manometer was placed in the tubing above the angiocatheter to measure psi. The filter and manometer were kept at the same level, and the filter was hand

Selected Abstracts from the Wilderness Medical Society’s 2008 ASM pumped until a maximum pressure was consistently obtained. Angiocatheters tested were both 16 and 18 gauges. Results.—With the 16-gauge angiocatheter, the average pressure produced by the 15 models was 17.6 psi, with 8 of 15 pumps producing pressures greater than 15 psi. With the 18-gauge angiocatheter, the average output was 28 psi, with all pumps achieving greater than 15 psi. Conclusion.—Backpacking hand pump water filters with an 18-gauge angiocatheter attachment can produce pressures that would be effective for proper wound irrigation. Daniel M. Gee, MD Steve Weiss, MD Sam Slishman, MD Albuquerque, NM, USA

Development of a High-Efficiency, Low-Pollution Wilderness Emergency Medical Service Response Vehicle Emergency vehicle costs represent a significant cost for wilderness emergency medical service (WEMS) teams. In addition, services that operate in wilderness environments may have a particular obligation to implement environmentally sustainable operations. The objective of this study was to determine if a midsize hybrid electrical-gasoline vehicle would be suitable as a WEMS response vehicle. Specific questions were addressed. Would a midsize sports utility vehicle have enough cargo space? Would the hybrid electrical system support emergency lights and sirens? Was the hybrid system reliable enough for emergency responses? Would there be an economic and environmental benefit to hybrid technology? The Ford Escape Hybrid, a commercially available 4-wheel drive partial zero emission hybrid electrical-gasoline sports utility vehicle was purchased, carbon balanced, and equipped as a WEMS quick response vehicle (QRV). Its performance was studied for 2 years. We found that the hybrid electricalgasoline QRV could complete WEMS operations in the study environment without difficulty over a 2-year period. Operational performance was never knowingly impaired by the hybrid engine system, and reliability appeared equivalent to traditional EMS fleet vehicles. Although the study vehicle provides less carrying and towing capacity than traditional QRVs, equipment availability was never impaired. There were additional unexpected benefits, such as a substantial reduction in ambient noise during operations. Fuel efficiency averaged 25 to 35 miles per gallon, depending on mission characteristics. Based on published specifications, hybrid QRVs would be less expensive to purchase (by 5%–18%) and operate, use approximately 50% less fossil fuel, and produce approximately 50% less greenhouse gas emissions than would traditional WEMS QRVs. WEMS systems will increasingly need to consider environmental impact and fuel efficiency in their vehicle fleet. Many options are available to improve these operational parameters. This study suggests that hybrid QRVs may be a viable option

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for reducing environmental impact and improving fleet fuel efficiency. Seth C. Hawkins, MD, FAWM Cullowhee, NC, USA

UK Mountain Rescues: 2002–2006 Background.—The UK remote and rural setting is often challenging, with high winds and freezing temperatures. Every year, people find themselves in difficulty and require the unique skills of volunteer UK mountain rescue teams (MRTs). Some have serious injuries, and even the most benign medical problems are complicated by distance from care. This is a major challenge for rescue and health care services. This study is the first of its kind to combine rescue data from across the UK. Aim.—To describe the nature of nonfatal casualties assisted by UK MRTs. Methods.—Casualty information from 2002 to 2006 was retrieved from the Mountain Rescue Committees of Scotland and of England and Wales. Results.—Summer months (May–August) and the midday period from 1200 to 1600 hours were the peak times for callouts. Data on 3152 casualties were analyzed. Males comprised 60.8% with the greatest proportion (17.9%) being aged 50 to 59 years. Mountain incidents accounted for most casualties (84.6%), of which 75% arose from summer and winter hill walking. Trauma was reported in 77.2% of casualties, and 10.4% had some form of medical illness. Fracture was the most commonly reported injury (57%), the lower extremity being the most commonly injured (53%). Head injury was reported in 13.1% of trauma cases. Casualties had multiple injuries 10.8% of the time. Conclusion.—Volunteer mountain rescue teams in the UK deal with a wide range of casualties, including those with serious and multiple injuries, in difficult weather conditions and terrain. This has implications for training and equipping of teams. Alasdair Mort, MSc Inverness, Scotland, UK

Canoe and Kayak Unintentional Death and Injury in the United States, 1997–2006 A 10-year review of US Coast Guard annual boating statistics reports for 1997 to 2006 indicate that unintentional death and injury for canoeists and kayakers vary markedly from those of recreational boaters in general. During the period reviewed, canoeing and kayaking accounted for 13% of the total reported recreational boating deaths in the United States but an estimated 29% of deaths due to hypothermia and an estimated 17% of deaths due to drowning. Conversely, canoeing and kayaking accounted for less than 1% of the estimated deaths due to trauma. Consistent with recreational boating in general, the failure to wear a personal floatation device appears to be a primary factor in the accidental drowning of canoeists and kayakers.

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Nonfatal injury reports reflect a similar trend, with 4 of the top 5 reported injuries for all recreational boaters suggestive of traumatic injury, while hypothermia accounted for more nonfatal canoeist and kayaker injuries than all other canoeist and kayaker injury reports combined. Consistent with these findings, during the period reviewed, collision with another vessel or collision with a fixed object accounted for more than half of all reported accidents for general recreational boaters. For canoeists and kayakers, however, capsizing appears to be by far the most common precipitating event for unintentional injury and/or death, indicated in more than two thirds of the accident reports. Whitewater activity was specifically indicated in only 3% of the total recreational boater fatality reports, but these data were not separated by type of vessel, which includes at least one more category (‘‘inflatable’’) that is likely to be used in whitewater river running. It should be noted that the reporting methodology makes it quite likely that fatalities caused by a boating accident would be included in the US Coast Guard data, but the likelihood of injuries being reported and included in the database decreases as the severity of the injury decreases. James A. Padfield, PhD Kirksville, MO, USA

The Perception of Injuries and Medical Conditions Among Kayakers Paddling in the Sea Environment Although research has been conducted on the health effects of white water and competitive kayaking, little appears to be published that specifically focuses on activities in the sea environment. Four hundred questionnaires focusing on the perception, nature, and rate of injuries and medical conditions were distributed to kayakers at coastal launch sites in West Wales. One hundred and seventy-eight completed questionnaires were returned. Respondents paddled a range of boats, including sea kayaks, general purpose kayaks, sit-on kayaks, and play boats. The main activities were coastal touring and surfing. The perceived most common injuries and medical conditions were cuts and abrasions and sprains and pulled muscles. The majority of respondents reported that they had not received injuries or developed medical conditions as a result of kayaking in the sea. Most respondents regarded injuries and medical conditions as uncommon and not serious. Ninety-six percent of the respondents reported both physiological and psychological benefits associated with kayaking activity. The back was identified as the most common part of the body injured. This was followed by the hands and then the shoulders. The rank order of the perceived most common injury or medical condition, the perception of the most common part of the body injured, and the most serious and most common injuries and medical conditions actually encountered differed according to the type of activity and the type of boat used. People who kayak in the sea vary in terms of age, activity,

boat use, experience, skill level, duration and frequency of participation, and environments encountered. The significance and nature of injuries and medical conditions and the associated causal factors may vary according to these characteristics. Prevention strategies need to be sensitive to such characteristics to ensure the appropriate design and targeting of initiatives. Colin Powell, BSc (tech), FHEA Cardiff, Wales, UK

Fear and Love of Heights: The Pathophysiology and Psychology of Height Imbalance Background and Objectives.—Individual physiological and psychological responses to height vary as a continuum from acrophobia, height intolerance, height tolerance, to height enjoyment. This paper summarizes the physiological and psychological factors that define individual differences in response to heights. Material and Methods.—This paper reviews the English literature on the pathophysiology and psychology of stationary postural response to heights. Results.—Perceptual cues to height arise from vision. Normal postural sway of 2 cm for peripheral objects within 3 feet increases as eye-object distances increases. Postural sway greater than 10 cm results in a fall. A minimum of 20 minutes of peripheral retinal arch is required to detect motion change. Trigonometry dictates that a 20-minute peripheral retinal arch can no longer be achieved in a standing position at an eyeobject distance of greater than 20 m. At this distance, the visual cues conflict with the somatosensory and vestibular systems and result in the danger of height instability. Cooccurring deficits in the visual, vestibular, somatosensory systems can significantly increase height instability. An individual’s psychological makeup, influenced by learned and genetic factors, can influence reactions to the danger of height instability. The psychological interpretation is rarely exaggerated to acrophobia, normally perceived as an intolerable or tolerable situation and sometimes enjoyed, resulting in height-seeking activities. Enhancing peripheral vision, vestibular, and proprioceptive functions may improve height imbalance. Psychotherapy may improve the troubling subjective sensations to heights. Conclusions.—Individualized reactions to height cues involve complex physiological and psychological relationships. Eye-object distances greater than 20 m in a stationary position produce visual misinformation to the somatosensory and vestibular systems and may provoke height instability. The interpretation of this instability varies with the psychosocial characteristics of the individual. Enhancing physiological and psychological functions may improve height imbalance. John R. Salassa, MD David Zapala, PhD Jacksonville, FL, USA