Category 1 Continuing Medical Education credit for WMS member physicians is available for this article. Go to  http://wms.org/cme/cme.asp?whatarticle=1821 to access the test questions.

Objectives.—In India, venomous snakebite remains an enigma. Although ineffective first aid treatments that are centuries old continue to be used by people bitten by snakes, important factual information, such as the importance and uniqueness of bites by the northern saw-scaled viper (Echis sochureki), has been largely lost and forgotten. In this paper, we report the first systematically gathered data on the clinical course of envenoming by E sochureki in Rajasthan, India. Clinical information is reported on 12 victims bitten by definitively identified E sochureki, and 2 clinical cases are described in greater detail to illustrate the severity of envenoming by this snake.

Methods.—A data collection form was developed and used to prospectively gather clinical information regarding patients who were bitten by E sochureki and who brought the dead snake with them to hospital. All snakes were definitively identified by an experienced herpetologist. Information on symptoms and signs, management (both first aid and hospital), and outcomes was collected.

Results.—All 12 victims had evidence of systemic envenoming, including abnormal 20-minute whole blood clotting tests (with systemic bleeding in 7). All received polyvalent antivenom made, in part, with Echis carinatus venom from southern India. Antivenom was relatively ineffective in restoring coagulation to these patients. All patients survived, although 1 patient suffered an intracranial bleed with residual hemiparesis.

Conclusions.—Echis sochureki causes severe bites in Rajasthan. Work needs to be done to alter the first aid practices used for snakebites in this area, to encourage more rapid presentation to hospital, and to develop antivenom that is more effective against E sochureki.

Objective.—Closed-circuit oxygen rebreathers may provide high concentrations of oxygen at extremely low flow rates appropriate for field use with limited oxygen supplies. The performance of the preproduction, second-generation remote emergency medical oxygen (REMO₂) system developed for Divers Alert Network was evaluated.

Methods.—The unidirectional circuit was made up of a solid, prepackaged CO₂ scrubber canister (984 ± 14 [SD] g scrubber mass), standard 22-mm-inside-diameter anesthesia circuit hoses, 5-L breathing bag, 5-cm H₂O positive end-expiratory pressure valve, and oronasal mask. Oxygen flow, inspired oxygen, expired CO₂, peak inspired and expired mask pressures, time to reach scrubber canister saturation or “breakthrough” (postscrubber CO₂ concentration reaching 3.8 mm Hg), and subject tolerance were measured under standard laboratory conditions.

Results.—Six trials were completed using healthy volunteers (94.7 ± 19.6 kg). Five of the 6 completed trials did not reach breakthrough at the planned trial limit of 8 hours. Mean average oxygen flow rate was 1.00 ± 0.17 L·min⁻¹. Mean peak inspired and expired mask pressures were −5.0 ± 1.9 and 6.5 ± 1.9 cm H₂O, respectively. Subjects generally reported good tolerance to circuit breathing.

Conclusions.—The second-generation REMO₂ was well tolerated by healthy subjects during 8-hour laboratory evaluation trials. The device provided high mean inspired oxygen fractions at low mean oxygen flow rates, relatively modest mean maximal inspired and expired pressures, and excellent scrubber canister duration. Further evaluation of field performance with a patient population is warranted.

Category 1 Continuing Medical Education credit for WMS member physicians is available for this article. Go to  http://wms.org/cme/cme.asp?whatarticle=1822 to access the test questions.

Objectives.—The purpose of this study was to derive and validate a rule for duration of search (ie, search time) that maximizes survivors and after which a search and rescue (SAR) mission may be considered for termination.

Methods.—This was a retrospective cohort study of all SAR missions initiated in Oregon over a 7-year period, which were documented in a population-based administrative database. The following types of search missions were excluded from analysis: redundant reports of a single search; lost helicopters and airplanes; support of organized events; law-enforcement searches; searches for persons actively avoiding rescue; body recovery missions; and cases without outcome information. The cohort was divided into a derivation cohort (searches from 1997–2000) and a validation cohort (2001–2003). The primary outcome was survival. Variables considered in the model included age, gender, minimum and maximum daily temperatures, precipitation, search time, and whether the search involved an air or water incident. Missing data were handled using multiple imputation. Classification and regression tree (CART) methods were used to derive the model.

Results.—The derivation cohort included 1040 searches involving 1509 victims, 70 (4.6%) of whom died. The validation cohort included 1262 searches involving 1778 victims; 115 (6.5%) died. Search time was the only variable retained in the final model, with a cut-point of 51 hours. The derivation model was 98.9% sensitive; the same model run using the validation cohort was 99.3% sensitive.

Conclusions.—This time-based model may aid search managers in the decision about starting a search or changing search tactics for missing persons.

Category 1 Continuing Medical Education credit for WMS member physicians is available for this article. Go to  http://wms.org/cme/cme.asp?whatarticle=1823 to access the test questions.

Background/Objective.—Traumatic brain injury (TBI) is an important cause of morbidity and mortality in skiing and snowboarding. Although previous studies have advocated the use of a helmet to reduce the incidence of TBI, only a minority of skiers and snowboarders wear helmets. The low use of helmets may be partially due to controversy regarding their effectiveness in a high-speed crash. The protective effect of a ski helmet is diminished at the high speeds a skier or snowboarder can potentially obtain on an open slope. However, ski areas have undergone significant changes in the past decade. Many skiers and snowboarders frequent nontraditional terrain such as gladed areas and terrain parks. Since these areas contain numerous physical obstacles, we hypothesized that skiers and snowboarders would traverse these areas at speeds slow enough to expect a significant protective effect from a helmet.

Methods.—Speed data were obtained via radar analysis of 2 groups of expert level skiers and snowboarders traversing a gladed woods trail and terrain park.

Results.—A total of 113 observations were recorded. Forty-eight observations were made of 9 skiers and snowboarders in gladed terrain, and 65 observations were conducted of 21 skiers and snowboarders in the terrain park. In 79% of the cases in gladed terrain and 94% of the instances in the terrain park, observed speeds were less than 15 mph.

Conclusions.—Skiers and snowboarders navigate nontraditional terrain at speeds slower than on open slopes. At the observed velocities, a helmet would be expected to provide significant help in diminishing the occurrence of TBI. Medical authorities should advocate the use of helmets as an important component of an overall strategy to reduce the incidence of TBI associated with skiing and snowboarding.

Objective.—To study the changes in pulmonary function of human male volunteers from 2 different populations: Indians and Kyrgyzis before and after ascent to 3200 m and during a 4-week stay at that altitude.

Methods.—Ten healthy soldiers of the Indian army (22–25 years of age) and 10 Kyrgyzis recruits (19–20 years of age ), height and weight matched, were volunteers in this study. Their pulmonary functions were evaluated at baseline (Bishkek, 760 m); on days 2, 13, and 25 at a mountain clinic at Tuya Ashuu pass (3200 m) in the northern Tien Shan Range; and on return to Bishkek. A dry spirometer was used to measure lung function at each location.

Results.—Results indicated that Kyrgyzis had significantly larger forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV₁) than those of the Indians, but their peak expiratory flow rate (PEF), forced expiratory flow rate at 25% to 75% of FVC (FEF_25–75%), and maximal voluntary ventilation (MVV) measures were comparable. At high altitude (HA), FVC showed significant reduction on day 2, with subsequent recovery in the Kyrgyzis; but in the Indians, FVC showed gradual reduction, and on day 25, it was significantly reduced compared with the baseline value. FEV₁ did not show any change with altitude in either group. Expiratory flow rates and MVV showed significantly higher values at HA in both groups. However, after air density correction for the 2 altitudes, PEF and MVV showed no changes from their baseline values, and the mid-expiratory flow rate (FEF_25–75%) was actually reduced in both groups: on day 2 in the Kyrgyzis and on day 25 in the Indians. On day 2 of return from a 4-week stay at HA, all test measures were back to their baseline values.

Conclusions.—The major difference between the 2 populations was larger lung volumes in the Kyrgyzis compared with the Indians, with no differences seen in their flow rate measures. Also, there was a different time schedule of altitude-induced reductions in FVC and FEF_25–75%.

Objective.—To describe the general characteristics and epidemiology of search and rescue (SAR) in Yosemite National Park (YNP) and identify possible areas for intervention directed at reduction in use of these services.

Methods.—Yosemite Search and Rescue (YOSAR) personnel record every search and rescue mission on a Search and Rescue Incident Report. The information contained in these reports was used to perform a retrospective review of all SAR missions within YNP during the 10-year study period between January 1990 and December 1999.

Results.—YOSAR performed 1912 SAR missions, assisting 2327 individuals and recording 2077 injuries and illnesses. Popular trails in and around Yosemite Valley collectively accounted for 25% of all individuals needing SAR services. Lower extremity injuries and dehydration/hypovolemia/hunger were commonly identified reasons to need SAR services. The duration of SAR missions averaged 5 hours, used 12 SAR personnel, and cost $4400. Helicopter was the primary mode of transport in 28% of SAR incidents. There were 112 fatalities, yielding a SAR case fatality rate of 4.8%. The majority of fatalities occurred while hiking/snowshoeing, with falling the most common mechanism of lethal injury.

Conclusions.—Day-hikers in and around Yosemite Valley use a large portion of SAR services, with lower extremity injuries and dehydration/hypovolemia/hunger the most common reasons. It seems reasonable to direct future intervention to prevention of these commonly identified problems in this particular population of Park visitors.

Attacks on humans by wild boar (Sus scrofa) are occasionally reported in rural areas of Turkey. While fatalities are rare, individuals may sustain significiant soft tissue trauma. Lower extremity lacerations of up to 10 cm in length and 4 cm deep were seen in the 3 cases reviewed. Injuries to the upper abdomen and chest occured in one case. Attacks frequently occur in forested areas covered by dense brushwood, and their incidence is increased during the rutting season. In contrast to other large, feral animal attacks, injuries sustained from wild boar typically are limited to the lower extremities. This case series examines 3 attacks by wild boar in rural Turkey.

I report on a case of left main bronchus occlusion by an inhaled foreign body at a remote Antarctic scientific base during the austral winter. The dilemmas of on-site treatment and the challenges of aeromedical evacuation from such a remote environment are presented.

Objective.—To study sleep parameters and mood profiles of a female explorer traveling solo and unaided to the South Pole during the winter.

Methods.—During the 44-day expedition, global activity and sleep were assessed using a wrist actigraph (AW) worn on the nondominant wrist. Mood was assessed using an adapted Profile of Mood States questionnaire. Pre- and postexpedition physiologic profiles were conducted to assess body composition, strength and power, and aerobic capacity.

Results.—The AW data revealed decreasing sleep duration throughout the expedition, with an average sleep time of 5 hours (range, 8 hours and 14 minutes to 1 hour and 42 minutes), with sleep times consistently <3 hours during the final third of the expedition. Mood responses indicated a progressive reduction in vigor and increase in fatigue. Sleep time was positively related to vigor and inversely related to depression and fatigue, a finding that is consistent with the notion that positive feelings (high vigor and low fatigue) are linked with sleep.

Conclusions.—This account provides insight to help understand the limits of human tolerance and may be directly applicable when planning future expeditions of this nature.

Background.—Hypothermia is a frequent complication of cold weather exposure and/or wilderness injuries. Anecdotal reports have postulated that patients suffering from acute hypothermia are at significantly increased risk of developing lethal cardiac dysrhythmias secondary to the physical stimulation from moving and transporting patients.

Objective.—To develop a model to attempt to determine if rough handling and sudden movement can induce lethal cardiac dysrhythmias in a controlled animal study of mild to severe hypothermia.

Methods.—Ten anesthetized swine had continuous cardiac and invasive blood pressure (BP) monitoring. Core body temperature (CBT) was measured with an esophageal probe. Animals were secured to a backboard in a supine position for the duration of the study and their CBT was serially lowered by external cooling measures. At preset intervals (every 3°C lowered from the baseline CBT of 38°C), the animals were lifted via the backboard and rolled 90 degrees to the left and held for 5 seconds and then rolled to the right and held for 5 seconds. After rolling, the swine were lifted via the backboard 6 inches off the surgical table and dropped back onto the table, and after 15 seconds this was repeated at 12 inches. If no signs of dysrhythmia were noted, external cooling was continued. Data were analyzed by tests of proportion on mortality associated with hypothermia and mechanical stimulation. To determine whether hypothermia and mechanical stimulation were independent effects, a one-sided McNemar's test of matched pairs was employed.

Results.—No animal developed a dysrhythmia at a CBT > 25°C with or without stimulation. Fifty percent of the animals developed fatal dysrhythmias (3 ventricular fibrillation, 2 asystole) with no stimulation but at CBT ≤ 25°C (average CBT 22.7°C). Twenty percent (2/10) developed fatal dysrhythmias (ventricular fibrillation) during mechanical stimulation. For hypothermia, a binomial test of the observed proportion 0.70 (fatality during hypothermia) against a hypothetical proportion of 0 (no fatality in the absence of hypothermia) yielded P < .001 with power = 1.00. For mechanical stimulation, a binomial test of the observed proportion 0.20 (fatality from mechanical stimulation); against a hypothetical proportion of 0 yielded P < .001 with power = 1.00. The test of matched pairs yielded P < .037, indicating that the variables of mechanical stimulation and hypothermia jointly caused mortality.

Conclusion.—Profound hypothermia induces fatal dysrhythmias both with and without mechanical stimulation in a swine model.

Background/Objective.—We examined the changes in ventilation during sleep at high altitude using the LifeShirt monitoring system on 2 climbers who were attempting to summit Mount Aconcagua (6956 m).

Methods.—Prior to the summit attempt, we measured cardiovascular and pulmonary function at 401 m (Rochester, MN) and gathered respiratory and cardiovascular data during sleep using the LifeShirt monitoring system with exposure to normobaric normoxia and normobaric hypoxia (simulated 4300 m). We then monitored the ventilatory response during sleep at 3 altitudes (4100 m, 4900 m, and 5900 m).

Results.—During normoxic sleep, subjects had normal oxygen saturation (O_2sat), heart rate (HR), respiratory rate (RR), tidal volume (V_T) and minute ventilation (V_E), and exhibited no periodic breathing (O_2sat = 100 ± 2%, HR = 67 ± 1 beats/min, RR = 16 ± 3 breaths/min, V_T = 516 ± 49 mL, and V_E = 9 ± 1 L/min, mean ± SD). Sleep during simulated 4300 m caused a reduction in O_2sat, an increase in HR, RR, V_T, and V_E, and induced periodic breathing in both climbers (O_2sat = 79 ± 4%, HR = 72 ± 14 beats/min, RR = 20 ± 3 breaths/min, V_T = 701 ± 180 mL, and V_E = 14 ± 3 L/min). All 3 levels of altitude had profound effects on O_2sat, HR, and the ventilatory strategy during sleep (O_2sat = 79 ± 2, 70 ± 8, 60 ± 2%; HR = 70 ± 12, 76 ± 6, 80 ± 3 beats/min; RR = 17 ± 6, 18 ± 4, 20 ± 6 breaths/min; V_T = 763 ± 300, 771 ± 152, 1145 ± 123 mL; and V_E = 13 ± 1, 14 ± 0, 22 ± 4 L/min; for 4100 m, 4900 m, and 5900 m, respectively). There were strong negative correlations between O_2sat and V_E and ventilatory drive (V_T/T_i, where T_i is the inspiratory time) throughout the study.

Conclusions.—Interestingly, the changes in ventilatory response during simulated altitude and at comparable altitude on Aconcagua during the summit attempt were similar, suggesting reductions in FiO₂, rather than in pressure, alter this response.