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Objective.—To determine the prophylactic effect of Ginkgo biloba (doses 80 mg/12 h, 24 h before high-altitude ascension and with continued treatment) in preventing acute mountain sickness (AMS) at 3696 m in participants without high-altitude experience.
Methods.—Thirty-six participants who reside at sea level were transported to an altitude of 3696 m (Ollagüe). The participants were divided into 3 groups and received G biloba (n = 12) 80 mg/12 h, acetazolamide (n = 12) 250 mg/12 h, or placebo (n = 12) 24 hours before ascending and during their 3-day stay at high altitude. The Lake Louise Questionnaire constituted the primary outcome measurement at sea level and at 3696 m. A Lake Louise Self-Report Score greater than 3 was indicative of AMS. Oxygen saturation, heart rate, and arterial pressure were taken with each evaluation for AMS.
Results.—A significant reduction in AMS was observed in the group that received G biloba (0%, P < .05) comparison with the groups receiving acetazolamide (36%, P < .05) or placebo (54%). No difference was observed in arterial oxygen saturation in the G biloba (92 ± 2) vs the acetazolamide (89 ± 2) groups. However, a marked increased saturation in arterial oxygen was seen in comparison with the placebo group (84 ± 3, P < .05). No statistically significant differences were observed in mean arterial pressure or heart rate.
Conclusions.—This study provides evidence supporting the use of G biloba in the prevention of AMS, demonstrating that 24 hours of pretreatment with G biloba and subsequent maintenance during exposure to high altitude are sufficient to reduce the incidence of AMS in participants with no previous high-altitude experience.
Objective.—Antarctic expeditioners face extremes of environmental conditions along with isolation which affect normal human activity at a polar station. Diets of polar expeditioners consist of products that have been kept in storage for more than a year. Processing and preservation adversely affect the nutritive value of the food products, especially water-soluble vitamins. This study was conducted to determine water-soluble vitamin status of Antarctic expeditioners consuming processed canned food.
Methods.—Twenty-two healthy male volunteers age 26 to 56 years (39.5 ± 8.5, mean ± SD) participated in the study. The study was conducted in 3 phases: at Goa, India (phase I), 48 hours after arriving in Antarctica (phase II) and after 1 month in Antarctica (phase III). Water-soluble vitamin status in erythrocytes was assessed at each phase with evaluation of riboflavin, thiamine, and pyridoxine status. Urinary N-methyl nicotinamide and methylmalonic acid (MMA) levels were measured to assess niacin and vitamin B12 status. Blood plasma assays were used to assess ascorbic acid status.
Results.—No significant changes in riboflavin, thiamine, and pyridoxine status in erythrocytes and urinary excretion levels were observed after 1 month in Antarctica. Vitamin C levels decreased significantly (P < .001) after 1 month in Antarctica compared with basal values (1.31 ± 0.076 mg/dL during phase I to 0.81 ± 0.063 mg/dL during phase III). However, these levels were still within the normal reference range.
Conclusion.—This study found no water-soluble vitamin deficiencies in participants consuming processed and canned food after 1 month in Antarctica.
Category 1 Continuing Medical Education credit for physicians is available to Wilderness Medical Society members for this article. Go to http://wms.org/cme/cme.asp?whatarticle=1841 to access the instructions and test questions.
Objective.—Avalanche fatalities occur on a yearly basis in Utah. The purpose of this study was to assess avalanche safety practices of different backcountry users in Utah and to identify groups that can be targeted for avalanche safety education.
Methods.—We surveyed 353 winter backcountry users to determine the percentage of participants in each group who were traveling with one or more partners; the percentage who were carrying avalanche transceivers, shovels, probes, or AvaLungs; and the percentage who had taken an avalanche safety course. A measure of minimum safe practice was defined as 1) traveling with a partner, 2) carrying an avalanche transceiver, and 3) carrying a shovel. Participants in this study were backcountry skiers, snowboarders, snowshoers, snowmobilers, and out-of-bounds resort skiers/snowboarders traveling in the Wasatch and Uinta Mountains of Utah during the winter of 2005–06.
Results.—The percentage of backcountry recreationists traveling with one or more partners was not significantly different (P = .0658) among backcountry skiers, snowboarders, snowshoers, snowmobilers, and out-of-bounds resort skiers/snowboarders. These groups did, however, differ in the percentage who carried avalanche transceivers (P < .0001), shovels (P < .0001), probes (P < .0001), and AvaLungs (P = .0020), as well as in the percentage who had taken an avalanche safety course (P < .0001) and the percentage who were carrying out minimum safe practices (P < .0001). Backcountry skiers showed the highest level of avalanche preparedness, with 98% carrying avalanche transceivers, 98% carrying shovels, 77% carrying probes, 86% having taken an avalanche safety course, and 88% carrying out minimum safe practices. Out of bounds snowboarders were the least prepared with 9% carrying avalanche transceivers, 9% carrying shovels, 7% carrying probes, 33% having taken an avalanche safety course, and 2% carrying out minimum safe practices.
Conclusions.—There are significant differences in the avalanche safety practices of the various groups of backcountry travelers in Utah. Backcountry skiers and snowboarders were the most prepared, while snowmobilers, snowshoers, and out-of-bounds skiers/snowboarders were relatively less prepared.
Category 1 Continuing Medical Education credit for physicians is available to Wilderness Medical Society members for this article. Go to http://wms.org/cme/cme.asp?whatarticle=1842 to access the instructions and test questions.
Objective.—Bouldering is a type of rock climbing in which the climber ascends small boulders with pads and spotters in lieu of ropes, with an emphasis on ascending the most difficult surface possible. We sought to investigate the prevalence and incidence of injuries, and we hypothesized boulderers who enlisted preventative measures and those who bouldered indoors would have fewer injuries.
Methods.—This cross-sectional cohort study assessed incidence and pattern of injury among indoor and outdoor boulderers over 1 year.
Results.—Spotting other boulderers resulted in few injuries, but both climbing and falling were associated with diffuse injuries. Finger and ankle injuries were common. Traditional preventative measures were ineffective, and there were few differences between indoor and outdoor boulderers.
Conclusions.—Bouldering outdoors has an increased risk of injury to the fingers. Preventative measures appear largely ineffective in reducing the number of injuries in both cohorts.
Objective.—Venomous and nonvenomous snakes are found throughout most of the United States. While the literature on treatment is robust, there is not a current national epidemiologic profile of snakebite injuries in the United States. National estimates of such injuries treated in emergency departments (EDs) are presented along with characteristics of the affected population.
Methods.—Data on snakebite injuries were abstracted from the National Electronic Injury Surveillance System–All Injury Program (2001–04). Variables included age, gender, body part affected, cause, disposition, and treatment date. When available, location, intentionality of the interaction, and snake species were coded based on narrative comments. Estimates were weighted and analyzed with SPSS Complex Samples.
Results.—An estimated 9873 snakebites were treated in US EDs each year between 2001 and 2004. Males were more frequently seen in the ED for snakebites than were females (males: 72.0% [95% confidence interval (CI), 68.0–75.7]; females: 28.0% [95% CI, 24.3–32.0]). Approximately 32% of patients were known to be bitten by venomous species. Overall, more than one quarter of patients were hospitalized (27.9% [95% CI, 15.9–44.2]), although 58.9% of patients with known venomous bites were hospitalized (95% CI, 41.5–74.3).
Conclusions.—While they are rare events, snakebites cause nearly 10 000 visits to EDs for treatment every year. Epidemiologic data regarding snakebites provide practicing physicians with an understanding of the population affected and can help guide public health practitioners in their prevention efforts.
Objective.—To evaluate animal-caused fatalities in New Mexico using data collected during medicolegal death investigations, including toxicology, survival interval, and circumstances.
Methods.—A retrospective review of the computerized database and hard copies of files from a centralized, statewide medical examiner's office, excluding deaths due to zoonotic diseases and motor vehicle collisions involving animals.
Results.—Between 1993 and 2004, 63 deaths caused by animals were reported in New Mexico. The majority of decedents were male (46/63, 73%) and non-Hispanic white (33/63, 52%). Horses were the most commonly implicated animals, with 43 (68%) deaths due to a person being thrown from, crushed, dragged, or kicked by a horse. Cattle caused 9 deaths (14%), dogs caused 3 (5%), and venomous animals caused 3, whereas a bear was responsible for 1 death. Ten decedents (16%) had alcohol present at the time of death, and 8 would have been over the legal blood alcohol concentration for driving (0.08%). Ten deaths (16%) were work-related and included deaths of jockeys and ranch workers. The majority of deaths (42/63, 67%) occurred in remote locations, potentially delaying access to treatment. Survival intervals ranged from 1 day to 33 years.
Conclusions.—Whereas both human and animal behavior can be difficult to predict, a review of animal-caused fatalities investigated by a medical examiner revealed that in many cases, deaths could have been prevented by either the use of protective gear or alterations in human behavior.
Objective.—Avalanches pose a life-threatening risk to participants of outdoor winter activities. Determining the causes of death in avalanche fatalities can aid rescue and resuscitation strategies and hopefully improve survival.
Methods.—The study population included all avalanche fatalities in Utah from the 1989–90 to 2005–06 winter seasons. The Utah Avalanche Center and Medical Examiner records were reviewed to identify accident circumstances, autopsy findings, and causes of death.
Results.—Fifty-six avalanche deaths were identified during the study period. Most deaths occurred while participating in recreational backcountry activities; 85.7% of deaths were due to asphyxiation, 8.9% were due to a combination of asphyxiation and trauma, and 5.4% were due to trauma alone. Head injuries were frequent in those killed solely by trauma.
Conclusions.—Most avalanche deaths in Utah result from asphyxia. Therefore, most victims are alive in the postavalanche period and have the potential for live recovery. Rescue strategies that employ rapid recovery as well as techniques that prolong survival while buried provide the best means of improving outcome.
Category 1 Continuing Medical Education credit for physicians is available to Wilderness Medical Society members for this article. Go to http://wms.org/cme/cme.asp?whatarticle=1843 to access the instructions and test questions.
Objective.—Expedition activities such as mountaineering, rock climbing, river running, sea kayaking, and canoeing all involve an element of risk. Organizations that provide group wilderness and adventure experiences are responsible for managing the risk of their courses. The leaders and medical providers of these trips must therefore be prepared to anticipate and manage medical problems that may arise. The aim of this study is to provide the medical community with a better understanding of the specific injuries and illnesses that occur on wilderness expeditions.
Methods.—A retrospective descriptive study was done examining the medical incidents that occurred on wilderness-based courses during the 3-year period from September 1, 2002, through August 31, 2005. Participants and staff of the National Outdoor Leadership School (NOLS) served as the study population.
Results.—Injuries occurred at a rate of 1.18 per 1000 program days, and illnesses at a rate of 1.08 per 1000 program days. There were no fatalities during the time period. Athletic injuries (sprains, strains) and gastrointestinal illnesses were the most common medical incidents. Hypothermia, seizures, appendicitis, heat stroke, and pregnancy occurred but with low frequency. Fractures, dental emergencies, tick fever, athletic injuries, and nonspecific body pains were the conditions most frequently requiring evacuation.
Conclusions.—The rate of medical incidents on NOLS courses declined during the 1990s and has remained relatively steady apart from a slight increase in 2004 and 2005. Athletic injuries continue to be a difficulty, as they frequently result in evacuation even though their ultimate outcome is usually benign. Evacuation decisions should be made considering both the potential severity of the medical condition as well as patient comfort. Wilderness medical personnel must be familiar with a diverse range of medical conditions in order to provide optimal care.
Objective.—Acute hypoxia causes vasoconstriction in the pulmonary arteries. This hypoxic pulmonary vasoconstriction (HPV) has been reported to be common in subjects exposed to high altitude. In the past, it has been difficult to directly measure this HPV because of the invasive nature of tests, but the recent availability of portable color flow Doppler ultrasound has enabled measurements of pulmonary artery systolic pressure (PASP) in the field. We set out to study the feasibility of this method to detect changes related to HPV at 4250 m. We hypothesized that significant changes in the cardiopulmonary circulation are seen at high altitude and are detectable with Doppler echocardiography. In addition, we hypothesized that detected changes are related to the syndrome of acute mountain sickness (AMS) and could be reversed using 100% oxygen.
Methods.—Over a 10-week period in the spring of 1998, 56 healthy lowlanders not normally residing at altitude were studied while visiting 4250 m in Nepal having walked from 2774 m. This was a cross-sectional observational study conducted by a single experienced observer at high altitude, using transthoracic color flow continuous wave Doppler echocardiography. Subjects were initially assessed for significant tricuspid regurgitation (TR) to measure PASP. After estimating PASP under ambient conditions at altitude, oxygen was delivered and PASP remeasured.
Results.—Of 56 subjects, 36 had Doppler signals appropriate for estimation of pulmonary artery systolic pressure. In these 36, a wide range of PASP was observed (mean 25 mm Hg, range 18–36 mm Hg), but none fell outside of the normal range. After oxygen administration, PASP was reduced (from mean 25 mm Hg to mean 18 mm Hg, P < .0001) suggesting that a degree of hypoxic pulmonary vasoconstriction was present. No subjects in the study group reported clinical AMS.
Conclusions.—We found PASP at 4250 m to be within the normal range but higher than would be expected at sea level; however, unlike previous reports, we found such increases to be mild and reversible with oxygen. In addition, the observed incidence of AMS was low when compared with earlier studies, perhaps related to adequate acclimatization.
Objective.—Studies on the neurologic effects of high-altitude travel have focused on psychometric and cognitive testing and the long-term effects of hypoxia on memory and cognition. Few authors have discussed overt clinical psychiatric illness during high-altitude travel, and those few have focused on patients with preexisting psychiatric diagnoses. We describe a series of patients with new-onset anxiety disorders at high altitude treated at the Himalayan Rescue Association (HRA) clinic in Pheriche, Nepal (4240 m) in the spring season of 2006.
Methods.—We report on all 6 cases of anxiety-related illness diagnosed at the HRA Pheriche Clinic during the spring season, 2006. Three cases, representing the 3 discrete types of illness we encountered, are described in detail.
Results.—Six of 76 foreign patients and none of the 224 Nepalis seen during the season had anxiety-related primary diagnoses. None of the 6 patients had a history of psychiatric disorders or anxiety-related problems at low altitude. Three of the 6 patients were seen after hours, and all 6 required multiple visits. We describe 3 types of anxiety-related disorders: limited-symptom panic attacks induced by nocturnal periodic breathing, excessive health-related anxiety, and excessive emotionality.
Conclusions.—Anxiety-related illness requires significant use of medical resources by high-altitude travelers. Further research is needed to define the epidemiology of anxiety-related disorders at high altitude, to quantify the contributions of various etiologic factors, and to identify safe, effective treatments.