bluuebunny/crossref_metadata_2025 huggingface dataset:
Psittacosis: a case report and review of the literature
Authors: Craig T.J.
Published: January 2011

Psittacosis should be considered in any patient with fever of undetermined origin. The only clues to diagnosis may be failure to respond to antibiotics or history of bird exposure. Birds may be asymptomatic and able to transmit disease, thus quarantine and treatment of imported birds does not guarantee freedom from disease. An ELISA test limited to avian feces may be inadequate; cultures increase sensitivity. In most cases, diagnosis is not confirmed for 4–6 weeks. In order to prevent significant complications, therapy should be started on suspicion. Rapid response to tetracycline should be expected. The case of psittacosis presented emphasizes multiple salient features of the disease. History of animal exposure, including avian, should be a part of every history and physical examination.
Whitewater medicine
Authors: Weiss E.A.
Published: January 2011

Whitewater rafting, kayaking, and canoeing have attracted a growing number of participants in the past ten years. With the present number of 200000 Whitewater enthusiasts increasing by an estimated 15% each year, it is not surprising that there has also been an alarming increase in related accidents and deaths. This article reviews the inherent risks for injury during Whitewater sports and their medical ramifications. Recommendations for prevention and treatment are discussed.
Iron status on a high iron diet during exposure to moderate altitudes
Authors: Warme J.D. , Moser-Veillon P.B. , Douglass L.W. , Deuster P.A.
Published: January 2011

Changes in iron status in normal subjects consuming a dehydrated ration were studied to assess whether polycythemia from the hypoxia of moderately high altitudes would induce iron deficiency. Data were collected on 10 subjects two months before exposure, four times during the 31 day period at altitude and one month after exposure. Mean dietary iron consumption was 30.8 ± 1.06 mg (mean ± SEM) per day over the duration of the study. Hematocrit and hemoglobin values rose significantly by day 18 at altitude and returned to pre-exposure levels by one month after exposure ( p<0.01). Serum transferrin concentrations increased progressively over the 31 day period and returned to pre-exposure values by one month after exposure. No significant changes in transferrin saturation or serum ferritin were noted over the study phases. Further, no subject had serum ferritin values < 12 g l−1 during altitude exposure or while consuming the dehydrated ration before exposure. Lack of a decline in serum ferritin suggests that adequate amounts of iron were available from other sources to meet the polycythemic demand without depleting iron stores. It is unknown whether this iron was gained from an increase in iron absorption. The results indicate that with iron intake three times the RDA, polycythemia of altitude does not result in a state of iron depletion. Whether iron depletion or deficiency would result at intakes comparable to the RDA cannot be determined from this study.
Rations for use in a cold environment
Authors: Edwards Lt Col J.S.A. , Roberts D.E. , Mutter S.H.
Published: January 2011

This study compares the nutritional support provided by two military field rations, one containing primarily fully reconstituted (wet pack), ready to eat foods items and one containing all dried food items, in an arctic environment. The subjects ( n = 80 per group) were soldiers in two companies of light infantry involved in an 8-day winter field exercise in Alaska. Each group was issued approximately 4600 kcal daily. Measurements included food and water intake, food preference ratings of individual food items, and the subjects’ hydration status. Mean caloric intakes were 2729 kcal for the group consuming the wet pack foods (MRE/supp) and 2943 kcal for the group consuming dried foods (RCW). Mean weight losses were 2.8 lb (1.6%) and 2.9 lb (1.7%), respectively. Mean daily water intake was 3.4 liters per day for the MRE/supp group and 3.7 liters per day for the RCW group. The mean urine specific gravities were 1.020 for the MRE/supp group and 1.021 for the RCW group, indicating adequate hydration. We conclude that both rations were similar in terms of caloric intake and ability to maintain hydration status. The MRE received slightly higher food preference ratings, but neither experimental group consumed sufficient calories to meet the Military Recommended Dietary Allowances (MRDA) and maintain body weight. Choice of rations should be based not on nutritional criteria, but on consideration such as water availability, size and volume of load, resupply schedule, financial and logistical considerations, and the task at hand.
The effect of an electrical current on snake venom toxicity
Authors: Davis D. , Branch K. , Egen N.B. , Russell F.E. , Gerrish K. , Auerbach P.S.
Published: January 2011

An electric current (twenty 11 A, 7000 V spikes s−1 for 90 s) from a commercial stun gun was applied directly to a rattlesnake venom solution in an electrolysis cell with 2 electrode compartments and a central compartment, in order to evaluate the effect that high voltage electroshock might have on the lethality of the venom. The venom was electroshocked for 18 times longer than recommended by stun gun manufacturers. There was no measurable inactivation of the venom using LD50 determinations in mice. A venom sample was electrolyzed at a voltage lower than that from the stun gun, but with 4–5 times the total charge delivered from the stun gun. This inactivated the venom at the electrodes, but not within the central compartment, demonstrating that there was no direct effect of the electric field on the activity of the snake venom.
Dexamethasone for prophylaxis and treatment of acute mountain sickness
Authors: Rabold Mark B.
Published: January 2011

Acute mountain sickness (AMS) is a syndrome induced by hypobaric hypoxia in individuals who ascend rapidly to altitudes above 2500 m and may represent an early form of high altitude cerebral edema (HACE). Dexamethasone (DMS) has been advocated for treatment of HACE; several recent studies have sought to investigate its therapeutic role in AMS. Success with DMS in prophylaxis of AMS has been mixed. Five out of seven studies showed statistically significant decreases in the incidence of AMS when compared with placebo. However, all three studies investigating the treatment of AMS with DMS documented significant efficacy. The effective dose for both prophylaxis and treatment is 4 mg orally every 6–8 h at altitudes above 2050 m. In four studies, significant side effects were noted on discontinuation of DMS. The origin of rebound phenomena is uncertain, but may relate to adrenal suppression. DMS appears to be a useful adjunct to descent for the treatment of AMS. Prophylactic use should be limited to unavoidably rapid ascents, such as in rescue situations, and possibly to persons allergic or intolerant to acetazolamide.
Urinary pH and excretion of albumin and zinc in elementary school children after mountain climbing
Authors: Shoji S. , Fujimori K. , Nomoto S.
Published: January 2011

To examine sex differences in response to strenous, high altitude exercise in children, we measured urine pH and urinary excretion of albumin and zinc before and after mountain climbing. Participants were elementary school children of both sexes in the age range 11.3–12.3 years. Urine pH decreased after mountain climbing (altitude 2763 m) in both sexes, but the decrease was significant only in girls. Albumin excretion did not differ significantly after mountain climbing in either sex when creatinine was used as a reference. Zinc excretion increased after mountain climbing in the girls and decreased in the boys; the difference in zinc excretion between the sexes was significant when creatinine was used as a reference. This study suggests that renal compensation for metabolic alkalosis induced by mountain climbing is greater in girls. Albumin excretion in urine did not change significantly; urinary excretion of zinc is greater in girls than in boys after mountain climbing.
Pulmonary vascular remodelling at high altitude
Authors: Heath Donald , Williams David
Published: January 2011

Pulmonary vascular remodelling in man and mammals at high altitude is complex. The structural changes which occur center upon the response to hypobaric hypoxia of the vascular smooth muscle cells in the walls of pulmonary arteries and veins. Their nature, however, depends on the species involved and the biological status of the subject in relation to the mountain environment. Thus, different forms of remodelling are associated with genetic adaptation, lack of initial acclimatization, and established natural acclimatization to high altitude.
Intravenous dose-lethality study of American pit viper venoms in mice using standardized methods
Authors: Consroe Paul , Gerrish Kevin , Egen Ned , Russell Findlay E.
Published: January 2011

An intravenous dose-lethality study of 14 clinically important North and South American pit viper venoms was carried out in mice using standardized, rigorous protocols developed to meet international (WHO) guidelines and US government (FDA) regulations for the development of new treatment products. The study was undertaken in order to establish baseline LD50values for the ongoing testing of a new crotalid antivenin FABprepared from sheep immunoglobulin (IgG). The venoms (lyophilized and pooled from juvenile and adult snakes of both sexes) were taken from 10 rattlesnake (nine Crotalus and one Sistrurus) species, two Agkistrodon species, and two Bothrops species. The dose-response data were subjected to probit analysis. Median lethal dose (LD50) values and their 95% confidence limits (CL) were calculated and statistical comparisons between the median potencies were made. The intravenous LD50s (and 95% CL) ranged from a low of 0.13 (0.10–0.15) mg kg–1for Crotalus durissus terrificus, to a high of 6.32 (5.76–6.94) mg kg–1for Crotalus horridus horridus. Significant positive rank-order correlations were also found for comparisons between the present LD5Os and published LD5Os for intravenous, intraperitoneal, and subcutaneous administration.
The six hour observation rule for grade I crotalid envenomation: is it sufficient? Case report of delayed envenomation
Authors: Swindle G.M. , Seaman K.G. , Arthur D.C. , Almquist T.D.
Published: January 2011

A 16-year-old male was evaluated in the Emergency Department for a rattlesnake bite on the left calf. He was released following 6 h of observation, as recommended in standard references, without complaints or objective criteria present to indicate envenomation. The patient returned 36 h later complaining of severe pain at the bite site and showing objective evidence for systemic envenomation. He was successfully treated for crotalid envenomation with antivenin. This case demonstrates that initial systemic signs and symptoms may begin more than 6 h after crotalid envenomation. Therefore, we recommend that snake bite care must be coupled with close outpatient follow-up for 24 h.
Ambulatory electrocardiographic monitoring at high altitude
Authors: Hashimoto Fred , Appenzeller Otto , Abrams Jonathan , Qualls Clifford
Published: January 2011

High altitude trekking has been associated with hypoxemia, moderate tachycardia and resting electrocardiographic changes. We performed ambulatory electocardiographic monitoring (24 h) on nine men and two women (age range 24 to 64 years) at 4700 m to study a varied population for cardiac rate, rhythm, and possible ischemic effects during physically demanding trekking. Six participants, randomly chosen, were taking pentoxifylline. Sinus tachycardia was sustained particularly in the five older trekkers (mean age 51 years). Their maximum heart rates during trekking averaged 91% of the individual predicted maximum heart rates or 154 beats per minute; their highest mean one hour rates averaged 78% of predicted maximum heart rates or 132 beats per minute. During sleep at 4700 m, the differences between the nadir and the mean rate were significantly (p = .02) greater than at baseline altitude (1524 m). Ambulatory electrocardiographic abnormalities were minimal and no significant drug effects were observed.
Neutralization of Micrurus distans distans venom by antivenin (Micrurus fulvius)
Authors: Dart R.C. , O’Brien P.C. , Garcia R.A. , Jarchow J.C. , Mcnally J.
Published: January 2011

Neutralization of Micrurus distans distans venom by antivenin (Micrurus fulvius) was investigated. Pooled, lyophilized venom from a single specimen was used in all experiments. Micro-Ouchterlony demonstrated multiple precipitin lines between M. distans distans venom and M. fulvius antivenin (AV). The efficacy of M. fulvius AV in neutralizing M. distans distans and M. fulvius venoms in vivo was tested using CD-I mice. All mice received venom plus saline or AV. Survival times were improved in all animals receiving AV. Clinical observation in both groups showed that modes of death were similar. Antivenin (M. fulvius) Wyeth may be useful in the treatment of M. distans distans envenomation.
Current challenges in marine envenomation: an overview
Authors: Williamson John
Published: January 2011

Marine envenomation is a common, frequently serious, and sometimes neglected medical event. Studies in marine envenomation are now on a firm scientific basis, but remain unfledged in many respects. Present ignorance includes the taxonomy of the Cubozoan and Physalia ‘jellyfish’, the world distribution and life cycle related to Irukandji and ciguatoxic fishes, and the true incidence of human fatalities from envenomations by stonefish, sea snakes, chirodropids, Carybdea organisms, and sting rays. Toxinologic study of marine venoms indicates that Irukandji and Chironex venoms are of particular significance. Little is known about stingray or crown-of-thorns starfish venom chemistry. Venom retrieval, purification, fractionation, lability, and immunology (including antibody cloning) are current research challenges. International appreciation of the value of the Australian first-aid technique of compression/immobilization bandaging in selected envenomation situations, and the availability of safe and specific antivenoms for marine envenomations are future goals. Although the International Consortium for Jellyfish Stings is active, worldwide collaboration is still fragmentary. Crucial to advances in this subject is the exchange of multi-disciplinary information between epidemiologists, chemists, biologists, immunologists, medical clinicians, and divers working in the field.
Acclimatization and tolerance to extreme altitude
Authors: West John B.
Published: January 2011

During the last ten years, two major experiments have elucidated the factors determining acclimatization and tolerance to extreme altitude (over 7000 m). These were the American Medical Research Expedition to Everest, and the low pressure chamber simulation, Operation Everest II. Extreme hyperventilation is one of the most important responses to extreme altitude. Its chief value is that it allows the climber to maintain an alveolar PO2 which keeps the arterial PO2 above dangerously low levels. Even so, there is evidence of residual impairment of central nervous system function after ascents to extreme altitude, and maximal oxygen consumption falls precipitously above 7000 m. The term ‘acclimatization’ is probably not appropriate for altitudes above 8000 m, because the body steadily deteriorates at these altitudes. Tolerance to extreme altitude is critically dependent on barometric pressure, and even seasonal changes in pressure probably affect climbing performance near the summit of Mt Everest. Supplementary oxygen always improves exercise tolerance at extreme altitudes, and rescue oxygen should be available on climbing expeditions to 8000 m peaks.
Effect of cooling time on survival in classical heatstroke
Authors: Ramsey Cecelia B. , Watson William A. , Robinson William A.
Published: January 2011

Although rapid cooling is considered a cornerstone of the treatment of heatstroke, there are little data to correlate rapid cooling with improved outcome. We performed a retrospective analysis of 31 classical heatstroke patients who were classified as rapid coolers (temperature ≤ 38.9° C within 1 h of emergency department [ED] presentation) or delayed coolers (temperature > 38.9° C 1 h after ED presentation) independent of cooling method. Rapid coolers had a much lower mortality (12% vs 36%); however, this finding was not statistically significant ( p = 0.12). These preliminary data suggest that continued investigation is warranted to further define the relationship between cooling time and mortality.
Mountaineering sojourn: effects on body composition of prolonged exposure to high altitude in a cold environment
Authors: Bales B. , Hackney A.C. , Coyne J.T. , Shaw E. , McAninch G. , Kramer A. , Brownsberger R.
Published: January 2011

This study characterizes the basal body composition status of mountain climbers and examines changes in composition during a climbing expedition to high altitude. Subjects had selected physical and anthropometric (circumferences, skinfolds) measures taken immediately before ( n=93) and after ( n=29) an expedition to climb Mt McKinley, Denali National Park, Alaska. The anthropometric results were used to calculate the estimated percent body fat, lean body weight, and fat weight of the subjects. Climbing was attempted in elevation segments of 300 m per day to the summit (6193 m), and the length of the expeditions was 24.2 ± 0.8 days (mean ± se). All before- and after-expedition measures were statistically analyzed with a two-tailed t-test for dependent samples. The basal status results showed the climbers to be better than average in compositional status for their age group. Statistical analysis of the before- and after-expedition measures indicated that there were significant reductions in all of the anthropometric measures. Additionally, body weight (74.5 ± 1.7 kg vs 71.6 ± 1.5 kg), percent fat (15.6 ± 0.7% vs 13.8 ± 0.7%), lean body weight (62.8 ± 1.3 kg vs 61.7 ± 1.2 kg), and fat weight (11.7 ± 0.7 kg vs 10.0 ± 0.6 kg) were all significantly ( p < 0.01) reduced following the expedition. These data indicate mountain climbing to high altitudes significantly impacts overall body composition, reducing both fat and lean mass. However, these reductions appear more so in the adipose reserves than in the lean tissues of the body.
The use of isotonic sodium chloride in the early treatment of cholera diarrhea: the Peruvian experience
Authors: Vargas M. , Huicho L. , Salcedo V. , Monge E.
Published: January 2011

Due to the limited supply in Peru of polyelectrolitic solutions recommended for the initial treatment of cholera diarrhea, a massive amount of isotonic sodium chloride solution was used during the recent cholera epidemic. This treatment proved adequate based on the low mortality rate, which compared favorably with international mortality rate reports. A preliminary observation of six adult Peruvian patients hospitalized with hypovolemic shock and metabolic acidosis secondary to cholera diarrhea showed remission of hypovolemic manifestations and significant improvement of serum bicarbonate, pCO2, and base excess after rapid intravenous infusion of a solution of isotonic sodium chloride. This intravenous solution seems adequate as the initial intravenous fluid for patients with severe cholera, as a logical alternative to currently recommended polyelectrolitic solutions containing bicarbonate or lactate.
The QT interval in lightning injury with implications for the ‘cessation of metabolism’ hypothesis
Authors: Andrews C.J. , Colquhoun D.M. , Darveniza M.
Published: January 2011

An hypothesis is presented to provide an alternative explanation to the ‘cessation of metabolism’ hypothesis often invoked in lightning injury. ‘Cessation of metabolism’ has been proposed to explain the observation of good recovery after a prolonged period of cardiac arrest in some lightning injured patients. Re-examination of the cases used to support ‘cessation of metabolism’, however, reveals little evidence to justify the hypothesis. Re-evaluation of ECGs from lightning injured patients demonstrates a high incidence of QT prolongation. It is hypothesized that QT prolongation could promote a state of episodic induction of and recovery from Torsades de pointes ventricular tachycardia (VT). As lightning injury is not classically regarded as a cause of QT prolongation, the cardiological literature should include it in future tabulations of causes.
Increase of biologically effective ultraviolet radiation with altitude
Authors: Ambach W. , Blumthaler M. , Schöpf T.
Published: January 2011

Applying Green's radiation model, the increase with altitude of ultraviolet radiation effective to produce erythema, keratitis, and cataract have been calculated. The reflectance of the terrain yields the most significant influence. With regard to erythema, keratitis, and cataract, the increase with altitude of irradiation onto a horizontal plane varies between 1.07–1.59 per 3000 m dependent on solar elevation, step in altitude, and albedo of the terrain. If the eyes are directed towards the terrain, as usually practiced when hiking in high mountain regions, the ocular exposures of ultraviolet radiation effective to produce keratitis and cataract increase by a factor of 16 at the transition from snow-free to snow-covered terrain.
First aid treatment of the sting from the hydroid Lytocarpus philippinus: the structure of, and in vitro discharge experiments with its nematocysts
Authors: Rifkin Jacqueline F. , Fenner Peter J. , Williamson John A.H.
Published: January 2011

Brush contact with colonies of the stinging hydroid Lytocarpus philippinus by divers and snorkellers causes itchy painful weals for which no first aid measures have yet been devised. Laboratory experiments were performed using common household substances to observe whether or not they caused Lytocarpus nematocyst discharge. Fresh and salt water, distilled water, aloe vera and ‘Stingose’ caused no in vitro discharge in nematocysts in situ. Urine and vinegar caused discharge in up to 10% and 15% of polyps per mm2 of colony portion, respectively. Methylated spirits caused discharge in all polyps containing mature mastigophores. The results indicate that vinegar (used to inactivate the discharge mechanism of nematocysts in cubozoan stings) activates the discharge mechanism of the nematocysts of this hydroid. Therefore, dousing thoroughly with water to dislodge adhering undischarged nematocyst material, followed by application of ice for pain relief, is advised. This is the same first aid treatment recommended for most non-cubozoan jellyfish stings.
Fish surface mucin hypersensitivity
Authors: Warpinski James R. , Folgert Jeffrey , Voss Martin , Bush Robert K.
Published: January 2011

Most reports of allergy to fish describe systemic symptoms upon ingestion of fish muscle or contact urticaria in commercial fish handlers. We report three recreational fishermen with symptoms of asthma, angioedema, rhinitis and urticaria upon exposure to surface mucin from bluegills (Lepomis machrochirus). All three had symptoms upon handling bluegills. Subsequently, two of them experienced wheezing and/or angioedema while in proximity to contaminated fishing clothing. One of them later developed symptoms upon eating bluegills. Prick skin testing was positive to crude bluegill surface mucin in all three individuals and to bluegill and cod muscle in one.

Bluegill surface mucin was defatted in ether and acetone and extracted in phosphate buffered saline. Sodium dodecyl-polyacrylamide gel electrophoresis (SDS–PAGE) showed at least 20 distinct protein bands by Coomassie Blue staining. Many of these were glycoproteins by periodic acid schiff (PAS) staining. Immunoblotting showed at least seven IgE binding protein bands with molecular weights between 10 and 100 kDa.

Radioallergosorbent (RAST) assay using a bluegill surface-mucin solid phase demonstrated that serum IgE binding in the three individuals was 4–25 times that of pooled serum from nonatopic controls. IgE binding using a serum pool from the three allergic patients was inhibited by extracts of bluegill mucin and muscle and cod muscle but not by tuna, crab or peanut.

Our results demonstrate that bluegill surface mucin contains specific glycoproteins which bind IgE in sensitive individuals. Hypersensitivity to these surface proteins may cause systemic allergic symptoms.
Injury rates in rock climbers
Authors: Humphries David
Published: January 2011

The popular perception of rock climbing is often of a high risk sport, with serious injury a common outcome of participation. To date, little data exists to test this hypothesis. The purpose of this study was to determine injury rates and associated data in a group of Australian rock climbers. A retrospective survey was undertaken and data collected from 59 active rock climbers. Analysis of the data collected suggests that rock climbing has a relatively low injury rate, in terms of injuries sustained per 1000 h of participation, in comparison with many other popular sports.
An outbreak of ciguatera poisoning in a group of scuba divers
Authors: Adams Mary Jane
Published: January 2011

Eight people developed ciguatera poisoning on a scuba diving cruise in a remote atoll in the Coral Sea. Symptoms included abdominal pain, vomiting, diarrhea, weakness, difficulty breathing, headache, myalgia, arthralgia, hypotension, bradycardia, paresthesias and pruritus. The outbreak was diagnosed by physician passengers who treated the victims during the remainder of the cruise. Intravenous mannitol on the eighth day was of no benefit. Symptoms persisted for weeks to months. Divers should be aware of ciguatera and the similarity of symptoms to those of decompression sickness. A new immunochemical method of detecting ciguatoxins in fish will be available soon in the form of a test kit.
Rescue operations in the Swiss Alps in 1990 and 1991
Authors: Durrer Bruno
Published: January 2011

Every year in the Swiss Alps, there are approximately 3000 accidents. Over 90% of victims (1990/1991: n = 3500–3800) are rescued by helicopter. In approximately 20% of accidents, a helicopter winch mission is necessary (1990/1991: n = 600–700 rescued persons). Swiss Air Rescue (REGA) is responsible for two thirds of all rescues in the off-road areas (1990/1991: n = 1958/2321 persons). All REGA rescue missions are registered according to medical (National advisory committee for aeronautics (NACA)) and topographical index. Over two thirds of all winch operations take place in accessible, and one third in difficult accessible sites of accidents. Of these, 2% are extremely difficult rescues, e.g. upon the north faces of the Eiger or the Matterhorn. Over 75% of all winch-rescued persons were rated NACA III–VII, where medical assistance is considered to be necessary at the site of accident. The assignment of experienced emergency doctors, trained in alpine techniques, improves the quality of preclinical treatment even in difficult sites, although clinical demands are not always completely practicable in the field and the possibilities of treatment are often limited by adverse climate and/or topography. An efficient medical-assisted helicopter rescue service has an important impact on the survival chances following alpine sport accidents.
Relevant laboratory findings in patients with sickle cell disease living at high altitude
Authors: Adzaku Festus , Mohammed Samir , Annobil Samuel , Addae Stephen
Published: January 2011

In an attempt to assess the physiological changes that occur in a patient suffering from the sickle cell disease (SCD) and living permanently at a high altitude, hematological parameters (hemoglobin concentration, RBC count, reticulocyte count, MCH, MCHC, MCV, Hb S, F and A2 levels) and biochemical parameters (serum bilirubin, erythrocyte 2,3-DPG, serum iron, TIBC and haptoglobin levels) were measured in patients with two sickle cell syndromes (homozygous Hb SS and heterozygous Hb S/β°-thalassemia) matched with Hb AA normal controls living at an altitude of 3000m. These parameters were compared with values obtained in similar groups of subjects residing at sea level.

Our results confirm that normal controls permanently residing at altitude have higher hemoglobin concentrations and erythrocyte 2,3-DPG levels than do normal counterparts living at sea level. Patients with SCD living permanently at high altitude show a marked increase in 2,3-DPG levels with little or no change in hemoglobin concentration. Normal serum iron and total iron binding capacity (TIBC) levels in our patients exclude iron deficiency as a possible reason for the poor expected erythropoietic response to altitude. We suggest that the marked rise in 2,3-DPG may be an important aid to oxygen delivery to tissues of SCD patients living at high altitude.
Hyponatremia in recreational hikers in Grand Canyon National Park
Authors: Backer Howard D. , Shopes Ellen , Collins Sherrie L.
Published: January 2011

Symptomatic hyponatremia has been reported in athletes participating in marathon and ultra-marathon events. We report four cases of symptomatic hyponatremia in hikers in the Grand Canyon. These are the first cases reported in recreational hikers in a wilderness setting. The overall fluid status of these patients is not well defined. In most instances this probably represents dilutional hyponatremia from sweat loss replaced with plain water. Recreational wilderness participants may require electrolyte replacement similar to endurance athletes.
A comparative study of pulmonary hemodynamics in six lowlanders at an altitude of 15 400 ft in China
Authors: Miao Chengyu , Yang Liangrui , Yang Jingyi
Published: January 2011

Six immigrants were studied with cardiac catheterization at Tuotuohe village of Qinghai, China (15400 ft above sea level, barometric pressure 470 torr) to study the pulmonary hemodynamic changes.
Carbonic anhydrase inhibition in the immediate therapy of acute mountain sickness
Authors: Wright Alexander D. , Winterborn Michael H. , Forster Peter J. , Delamere John P. , Harrison Ginette L. , Bradwell Arthur R.
Published: January 2011

The objective was to assess the effectiveness of acetazolamide and the relative speed of response to acetazolamide and methazolamide on blood gases and symptoms of acute mountain sickness (AMS). Thirty-seven subjects suffering from AMS were given 1–1.5 g acetazolamide or 400–500 mg methazolamide in randomized, double-blind trials during three expeditions to high altitude (3200–5486 m). Both drugs improved PaO2 by 7.7–8.0 mmHg, with a more rapid response at 3 h following methazolamide. Symptom scores improved over 24 h following both drugs, but headaches were induced in 28% of subjects. It was concluded that treatment with acetazolamide and methazolamide improves arterial oxygenation and symptoms of AMS. The differences in time of response between the two drugs were not proven to be clinically important.
Eastern massasauga rattlesnake envenomations in an urban wilderness
Authors: Sing Kimberly , Erickson Timothy , Aks Steven , Rothenberg Heidi , Lipscomb Jack
Published: January 2011

The eastern massasauga rattlesnake (Sistrurus catenatus), one of the few members of the Crotalidae family indigenous to the Great Lakes region, is considered to be more reclusive and docile than other types of rattlesnake. We report three cases of eastern massasauga rattlesnake envenomation within the Chicagoland area which required therapy with Crotalidae antivenin. Although bites are relatively uncommon, provoked snakes can inflict significant morbidity.
Exercise heat stress in rats: performance and biochemical effects
Authors: Bourdon Lionel , D’Aleo Philippe , Perrault Hélène , Pouzeratte Nadine , Cure Michel
Published: January 2011

Disturbed mental status (DMS) is the most obvious sign of exertional heatstroke in humans, and is one of the main complications of severe exercise heat-stress (SHS). The cause of exertional heat-stroke has been attributed to many factors such as thermoregulatory failure or impairment of muscular function. This investigation was designed to assess muscle energy metabolism in two groups of rats running at 34 °C. One group ( n = 17) stopped because of DMS (SHS rats), while the other group (n = 21) stopped because of mild or moderate exercise heat-stress (MHS rats). SHS rats ran longer and had a higher final rectal temperature ( Tre): 66.5 ± 4.2 °C vs 47.3 ± 3.8 °C, p <0.05 and 42.7 ± 0.12 °C vs42.2 ± 0.15 °C, p < 0.05, respectively. SHS rats also had a slower rate of change of Tre (0.054 ± 0.007 °C min−1 vs 0.072 ± 0.008 °C min−1) and a lower mean rate of dehydration: 0.065 ± 0.006 vs 0.084 ± 0.005% bodyweight min−1, p < 0.05. There were no significant differences between the two groups for skeletal muscle concentration of high energy phosphates and glycogen, but lactate was higher in SHS than in MHS rats: 25.0 ± 6.7 vs 11.8 ± 1.6 μmoles per mg protein respectively, p <0.05. These data suggest that DMS may be linked to Tre and that there is muscular functional impairment caused by SHS.
A field survey of the emergency preparedness of wilderness hikers
Authors: Kogut Kevin T. , Rodewald Lance E.
Published: January 2011

The objective was to describe the health, first aid needs, supplies, and knowledge of wilderness hikers. A cross sectional survey was designed using a structured interview and carried out in Yosemite National Park; July 1991. The subjects were overnight hikers ( n = 301) representing 146 groups, spending a minimum of one night at one of nine sites. The average age was 34 years (range 12–84); 63% were male and 37% were female. Of the subjects, 11% had no previous experience and 40% had been on more than ten trips. Over 96% self reported being in excellent or good health; only 10% were smokers. 50% had pre-existing medical conditions requiring additional preparedness; 10% had insect allergies, 6% had asthma. The most common medical problems encountered were insect bites (82%), minor cuts (24%), blisters (24%) and sunburn (22%). Acute mountain sickness (AMS) (6%) and asthma attacks (3%) were the most common serious problems. 6% shortened their current trip due to first aid reasons. Most groups (141 = 99%) had some first aid equipment. On average, groups carried only 48% of the recommended categories of first aid supplies appropriate for their trip duration. The amount of first aid equipment was significantly associated with the maximal score per group on a generalized first aid knowledge test (p < 0.001). 45% had taken at least one first aid course in the last five years; CPR (27%) and basic first aid (20%). 86% desired to learn more wilderness first aid; 85% were willing to take a basic first aid course; 26% felt that proof of first aid knowledge should be required for taking an overnight backpacking trip. Although these wilderness hikers were healthy people, injuries and illnesses requiring first aid attention were common. Current recommendations for minimum first aid supplies were consistent with the medical problems hikers commonly encountered, but groups were not adequately prepared for such situations. Subjects demonstrated considerable knowledge about common first aid topics, while knowledge about injuries with high morbidity and mortality was lacking.
Lateral rectus palsy at high altitude
Authors: Murdoch David R.
Published: January 2011

A number of focal neurological conditions have been described at high altitude. This report presents two cases of isolated unilateral lateral rectus palsies developing shortly after ascent to high altitude. In both cases concomitant altitude illness was not present and symptoms resolved completely within weeks to months. Possible etiologies are discussed.
Portable hyperbaric medicine, some history
Authors: Dubois Claude , Herry Jean-Pierre , Kayser Bengt
Published: January 2011

Since the beginning of this century several portable hyperbaric chambers have been designated for the treatment or prevention of various health problems. The first one was presented in 1919 for the treatment of decompression sickness. Other types were invented to treat allergic disease, to protect from toxic gas in wartime, to transport patients suffering from decompression sickness and to pressurize patients during flight in non-pressurized airplanes. All these chambers have been light enough to be carried and are simple to operate. Since 1979, three portable hyperbaric chambers have been designed specifically for the treatment of altitude sickness. Presently, two of these are frequently used. Working pressures of 104–165 Torr ensure an increase in inspiratory oxygen pressure, significantly increasing oxygen saturation of arterial blood, and as such provide an elegant and inexhaustible means of additional oxygen for patients suffering from altitude sickness. Several studies have reported beneficial effects of pressurization. Portable hyperbaric chambers should be included in the medical equipment of every expedition or trek going to high altitude.
Nocturnal periodic breathing and arterial oxygen desaturation in acute mountain sickness
Authors: Matsuzawa Yukinori , Kobayashi Toshio , Fujimoto Keisaku , Yamaguchi Shinji , Shinozaki Shiro , Kubo Keishi , Sekiguchi Morie , Hayashi Ryoichi , Sakai Akio , Ueda Gou
Published: January 2011

The objective of this case-control study was to investigate the relationship between periodic breathing (PB) and acute mountain sickness (AMS). Nine volunteers, healthy lowlanders between the age of 20 and 36 years stayed at a simulated altitude of 3700 m (485 Torr) for 24 h in a hypobaric chamber. A sleep study was carried out for more than 6 h. Arterial oxygen saturation (SaO2) was monitored by finger oximetry on all subjects. PB was determined by a polysomnography (EEG, EOG, thoracic movement) in six subjects and was indirectly measured by studying the cyclic change of SaO2 in three other subjects. The severity of AMS was assessed with the Environmental Symptoms Questionnaire. All subjects showed lower SaO2 during sleep than when awake (65.0 ± 6.4% versus 72.6 ± 6.4%, p < 0.01), and symptoms of AMS were more intense the next morning. PB was observed in eight of the nine subjects; however, the time spent in PB (%PB) ranged from 0% to 57.8%. There was a positive correlation between %PB and stage 1 sleep, suggesting an important role of PB in poor sleep quality at high altitude. Percent PB, however, was not significantly correlated with the degree of sleep desaturation, the severity of AMS, and ventilatory responses to hypoxia and hypercapnia. These results suggest that PB may not be a critical factor for sleep desaturation and in the development of AMS for high-altitude newcomers.
Energy and nutrient intakes during high-altitude acclimatization
Authors: Fenn C.E.
Published: January 2011

Information on the food intake of free living individuals during the initial stage of an expedition, when the diet is based on fresh and locally available foods, is scarce. A weighed dietary survey was carried out by 10 healthy unacclimatized male subjects who walked from an altitude of 2430 m to Everest Base Camp (5400 m) in 10 days. All food and fluids consumed during the study period were weighed using dietary scales and recorded in food record books. The mean daily energy intake was 10.03 (SE 1.26) MJ. The average body weight loss was 2.07 (SE 0.6) kg and there was no change in percentage body fat calculated from skinfold thickness measurements. The percentage energy from carbohydrates in the diet was significantly higher ( p < 0.05) in the final 3 days (59%, SE 2.0) compared with the first 3 days of the study period (51%, SE 3.6). It is likely that the high carbohydrate intake reflected the availability of foods at this time. With the exception of folic acid and vitamin C, the mean daily intakes of B vitamins, iron, and zinc exceeded the UK Dietary Reference Values. However, these values refer to healthy populations but not to those exposed to high altitude when nutrient requirements may be increased.
Dexamethasone for prophylaxis against acute mountain sickness during rapid ascent to 5334 m
Authors: Bernhard William N. , Schalick Lisa Miller , Gittelsohn Alan
Published: January 2011

Twenty-three volunteers participated in a double-blind, randomized trial comparing the steroid dexamethasone 4 mg to placebo every 12 h as prophylaxis against acute mountain sickness (AMS) during a rapid ascent to a shelter on Mt Chaclataya, Bolivia. From sea level, subjects were transported by air and land vehicles to 5334 m within a 72-h period. They were evaluated by cerebral scores derived from the Environmental Symptom Questionnaire and confirmed by AMS-C and AMS-R scores. After 6–8 h at high altitude (day 3), the number of ill persons in the dexamethasone group was less than those ill in the placebo group (χ2 = 7.43, p = 0.01) by chi-square and Fisher's exact tests. After 20 h at high altitude (day 4), the contrast between groups diminished (χ2 = 2.10, p = 0.214). ANOVA and t-test showed that mean cumulative AMS scores of the dexamethasone group were significantly lower ( p = 0.01, p = 0.02) than those of the placebo group for both days at high altitude, despite an approximate 82% increase in the mean cumulative score of the dexamethasone group from day 3 to day 4. We conclude that dexamethasone 4 mg every 12 h, though initially effective, was not sufficient to sustain prophylaxis from AMS symptoms at 5334 m.
Relationship of client attributes and guides’ techniques to client satisfaction at a climbing school
Authors: Michael Kahn E. , Yardley Nicholas J.
Published: January 2011

Our goals were to (1) conduct a preliminary investigation of the relationships of client characteristics, guide's techniques, and client satisfaction with their guided experience, (2) offer guides practical information about steps they could take to increase client satisfaction, and (3) refine theories, hypotheses, and measurement techniques for further study.

Climbing school clients were surveyed regarding their personal attributes, perceptions of guide's actions and performance, and satisfaction with the guided experience. Eighty-seven clients and eight guides were included in the sample.

Clients stated that they learned better through supervised practice than through demonstration and explanation. Clients who came with clear objectives felt a greater sense of accomplishment. Key dimensions of guide activity were Technical, Planning, and Support. Key dimensions of client satisfaction were Valuing, Pleasure, Accomplishment, and Comfort. Guides and clients may tend to focus on technical factors; however, indirect measures show the importance of providing emotional support.
Ambulatory sleep–wake recording in an acclimatized mountaineer over 8 days at high altitude
Authors: Buguet Alain , Pivot Annie , Montmayeur Alain , Tapie Philippe
Published: January 2011

Continuous ambulatory polygraphy (electroencephalogram and electrooculogram) was recorded on a 34-year-old female mountaineer acclimatized to an altitude of 5350 m, using a portable Oxford Medilog 9000 cassette recorder over 8 consecutive days. The recordings at altitudes of 5000 to 7600 m were performed while attempting to climb Mount Everest without an oxygen mask. The subject slept only at night. Altitude sleep measures were compared to data obtained at 300 m altitude during one 24-h recording performed before the expedition departed. The sleep–wake organization was barely influenced by altitude. Intrasleep wakefulness was augmented, leading to a decrease in sleep efficiency. No slow-wave-sleep curtailment was found, and day-to-day sleep–wake variations were more likely due to anxiety, fatigue owing to strenuous effort, nighttime cold, or daytime heat exposure.
A stress fracture of the phalanx from rock climbing: a case report
Authors: Young Craig C. , Raasch William G.
Published: January 2011

Sport climbers are at high risk for overuse injuries. These injuries are usually soft tissue injuries. The following is the first case report of a stress fracture of the phalanx in a rock climber and a review of the literature of sport climbing injuries.
Multireservoir optimisation in discrete and continuous domains
Authors: Haddad Omid Bozorg , Afshar Abbas , Mariño Miguel A.
Published: January 2011

In this paper, the honey-bee mating optimisation (HBMO) algorithm, which is based on the mating procedure of honey-bees in nature, is presented and tested with three benchmark multireservoir operation problems in both discrete and continuous domains. To test the applicability of the algorithm, results are compared with those from different analytical and evolutionary algorithms (linear programming, dynamic programming, differential dynamic programming, discrete differential dynamic programming and genetic algorithm). The first example is a multireservoir operation optimisation problem in a discrete domain with discrete decision and state variables. It is shown that the performance of the model compares well with results of the well-developed genetic algorithm. The second example is a four-reservoir problem in a continuous domain that has recently been approached with different evolutionary algorithms. The third example is a ten-reservoir problem in series and parallel. The best solution obtained is quite comparable with the linear programming solution, and slightly better than the best result reported by other investigators using genetic algorithms. In all three cases, convergence of the solutions in different runs to near-global optima and its rapid convergence rate compared to genetic algorithm demonstrates the applicability and efficiency of the proposed algorithm in solving water-resource optimisation problems in both discrete and continuous domains.
Nitrogen Response and Economics for Irrigated Corn in Nebraska
Authors: Dobermann A. , Wortmann C. S. , Ferguson R. B. , Hergert G. W. , Shapiro C. A. , Tarkalson D. D. , Walters D. T.
Published: January 2011

Nitrogen management recommendations may change as yield levels and efficiency of crop production increase. The mean yield with nutrients applied in 32 irrigated corn (Zea mays L.) trials conducted across Nebraska from 2002 to 2004 to evaluate crop response to split‐applied N was 14.8 Mg ha−1 The mean economically optimal nitrogen rates (EONR) for irrigated corn varied with the fertilizer N/grain price ratio. At a fertilizer N/corn price ratio of 7 the EONR was 171, 122, and 93 kg ha−1, respectively, for cropping systems with corn following corn (CC), soybean [Glycine max (L.) Merr.] (CS), and drybean (Phaseolus vulgaris L.) (CD). At this price ratio the present University of Nebraska (UNL) recommendation procedure gave mean N recommendations that were 17.2 and 68.1 kg ha−1 higher than the mean EONR determined in this study for CC and CD, respectively, but essentially equal to mean EONR for CS. The UNL algorithm, adjusted for mean cropping system EONR gave more accurate prediction of site‐year EONR than alternative N rate predictions for CC and CD with returns to applied nitrogen (RTN) of –$22 and –$13 ha−1 compared with measured site‐year EONR. Prediction of site‐year EONR using mean EONR adjusted for soil organic matter was more accurate for CS than other methods with an RTN of –$6 ha−1 compared with measured site‐year EONR. Further research is needed to extend the results to: lower yield situations, alternatives to split application of N, and adjustment of EONR to protect against inadequate N in atypical seasons or for environmental protection.