The aim is to describe the impact of altitude upon sleep, the physiology that underpins these changes and the therapeutic solutions that are currently in place. On ascending to altitude, lowland residents commonly experience some degree... more
The aim is to describe the impact of altitude upon sleep, the physiology that underpins these changes and the therapeutic solutions that are currently in place. On ascending to altitude, lowland residents commonly experience some degree of sleep disturbance. Occasionally, this can prove very uncomfortable and impact upon daytime activities. Historically, the underlying cause of sleep disturbance was thought to be due to the effect of periodic breathing. However, recent research has shown that the link between periodic breathing, lighter stages of sleep and arousals is far from convincing. Instead, it appears that hypoxia has a far wider effect upon sleep at altitude than was previously thought. A number of new approaches to the treatment of sleep disturbance at altitude have recently been identified. Whereas some treat the underlying hypoxia through pharmacological or technological means, others seek to address the symptoms of sleep disturbance more directly. Many of the current app...
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Research Interests: Humans, Female, Male, Heart rate, Altitude Sickness, and 4 moreOxygen, Acclimatization, Oximetry, and Oxygen Consumption
This study examines the effect of supplemental oxygen on acclimatized mountaineers at high altitude during rest and submaximal exercise. Three healthy, acclimatized participants undertook nine periods of data collection lasting 10 min... more
This study examines the effect of supplemental oxygen on acclimatized mountaineers at high altitude during rest and submaximal exercise. Three healthy, acclimatized participants undertook nine periods of data collection lasting 10 min each over 2 consecutive days at 5700 m. These occurred at rest and exercise (40 and 80 W), breathing ambient air or supplemental oxygen (2 and 4 L m min') through an open-circuit breathing system. As minute ventilation increased during exercise, the fraction of inspired oxygen (FIO2) fell from 0.31 at rest to 0.23 with 2 L x min(-1) of oxygen and from 0.36 to 0.26 with 4 L x min(-1). Oxygen at both flow rates resulted in a significant increase in the arterial blood saturation of oxygen (SaO2) (Rest: 79% to 96% to 97%; 40 W: 80% to 95% to 97%; 80 W: 76% to 94% to 98%) and reduction in respiratory rate (RR) (Rest: 28 to 22 to 24; 40 W: 36 to 25 to 25; 80 W: 41 to 26 to 26). Tidal volume (VT, ml x s(-1)) was found to increase with the addition of oxyg...
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... But whatever the explanation for Jimmy's appearance, I know now that I wouldn't have reached the summit ... of Mount Everest on the 24 May 2007 accompanied by Ang Kaji Sherpa, Dawa TenjiSherpa, Lila Chhombe Basnet, Michael... more
... But whatever the explanation for Jimmy's appearance, I know now that I wouldn't have reached the summit ... of Mount Everest on the 24 May 2007 accompanied by Ang Kaji Sherpa, Dawa TenjiSherpa, Lila Chhombe Basnet, Michael Brown, Pemba Gyalzen Sherpa ...
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... References Hackett PH, and Roach RC (2001 ... Address correspondence to: Jeremy S. Windsor Centre for Altitude, Space and Extreme Environment Medicine University College London Charterhouse Building, Archway Campus Highgate Hill,... more
... References Hackett PH, and Roach RC (2001 ... Address correspondence to: Jeremy S. Windsor Centre for Altitude, Space and Extreme Environment Medicine University College London Charterhouse Building, Archway Campus Highgate Hill, London N19 5LW United Kingdom ...
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Research Interests: Epidemiology, Public Health, Adolescent, Medicine, British medical history, and 18 moreSeasonality, Sudden Death, Hypothermia, Humans, Child, Mountaineering, Female, Male, Weather, Aged, Middle Aged, Altitude Sickness, Adult, Public health systems and services research, Retrospective Studies, BMJ, High Altitude, and Mortality rate
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Damage to the teeth during general anaesthesia is a frequent cause of morbidity for patients and a source of litigation against anaesthetists. Most injuries occur as a result of laryngoscopy. The use of an oropharyngeal airway as a bite... more
Damage to the teeth during general anaesthesia is a frequent cause of morbidity for patients and a source of litigation against anaesthetists. Most injuries occur as a result of laryngoscopy. The use of an oropharyngeal airway as a bite block can increase the risk of dental damage and should be avoided. Bite blocks should be made from an appropriate material
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The number of persons visiting high altitude regions for various purposes (recreation, business etc.), and the age of people who do so, increases. Therefore there are more and more patients who need specific and individual advice to... more
The number of persons visiting high altitude regions for various purposes (recreation, business etc.), and the age of people who do so, increases. Therefore there are more and more patients who need specific and individual advice to prevent emergency situations at altitude and to deal with emergencies if the safety strategy should fail. Since literature concerning cardiocirculatory diseases at altitude is scarce and studies with a controlled setting and high evidence level are missing, UIAA MedCom has checked all available literature for specific information to enable physicians who are active in travel or high altitude medicine to advise the patients at the highest possible level of evidence. It must be pointed out that there are several other medical fields where such information is mandantory, e.g. in occupational medicine, when employees depart to high altitude destinations for business purposes. The recommendations are based on a detailed literature research (databases, handboo...
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Objective To examine patterns of mortality among climbers on Mount Everest over an 86 year period. Design Descriptive study. Setting Climbing expeditions to Mount Everest, 1921- 2006. Participants 14138 mountaineers; 8030 climbers and... more
Objective To examine patterns of mortality among climbers on Mount Everest over an 86 year period. Design Descriptive study. Setting Climbing expeditions to Mount Everest, 1921- 2006. Participants 14138 mountaineers; 8030 climbers and 6108 sherpas. Main outcome measure Circumstances of deaths. Results The mortality rate among mountaineers above base camp was 1.3%. Deaths could be classified as involving trauma (objective
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The growing popularity of activities such as hiking, climbing, skiing and snowboarding has ensured that the number of visitors to mountain environments continues to increase. Since such areas place enormous physical demands on... more
The growing popularity of activities such as hiking, climbing, skiing and snowboarding has ensured that the number of visitors to mountain environments continues to increase. Since such areas place enormous physical demands on individuals, it is inevitable that deaths will occur. Differences in the activities, conditions and methods of calculation make meaningful mortality rates difficult to obtain. However, it is clear that the mortality rate for some mountain activities is comparable to hang gliding, parachuting, boxing and other pastimes that are traditionally viewed as dangerous. Deaths in the mountains are most commonly due to trauma, high altitude illness, cold injury, avalanche burial and sudden cardiac death. This review describes the mortality rates of those who undertake recreational activities in the mountains and examines the aetiology that lies behind them.
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The number of persons visiting high altitude regions for various purposes (recreation, business etc.), and the age of people who do so, increases. Therefore there are more and more patients who need specific and individual advice to... more
The number of persons visiting high altitude regions for various purposes (recreation, business etc.), and the age of people who do so, increases. Therefore there are more and more patients who need specific and individual advice to prevent emergency situations at altitude and to deal with emergencies if the safety strategy should fail. Since literature concerning cardiocirculatory diseases at altitude is scarce and studies with a controlled setting and high evidence level are missing, UIAA MedCom has checked all available literature for specific information to enable physicians who are active in travel or high altitude medicine to advise the patients at the highest possible level of evidence. It must be pointed out that there are several other medical fields where such information is mandatory, e.g. in occupational medicine, when employees depart to high altitude destinations for business purposes. The recommendations are based on a detailed literature research (databases, handbooks and the respective references). For easier use the paper has been structured as follows: general information, cardiocirculatory system and ECG at altitude, several cardiocirculatory diseases and their specific recommendations. The commission concludes, that a general "don't go!" is no state-of-the-art advice for the patients. With the information presented here a safe trip to altitude should be possible for many patients.
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Research Interests: Carbon Dioxide, High altitude environments, Humans, Anoxia, High Altitude Medicine, and 19 moreMountaineering, Female, Male, Young Adult, Oxygen Transfer, Atmospheric Pressure, High altitude Physiology, Middle Aged, Oxygen, Adult, New England, Dissolved Oxygen, Altitude, High altitude mountaineering, Blood gas analysis, Lactic Acid, Hydrogen-Ion Concentration, New England Journalof Medicine, and Hemoglobins
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An ascent to altitude places considerable demands on the cardiovascular system. Changes in the rate, rhythm, and morphology of the electrocardiogram reflect the fall in the partial pressure of inspired oxygen (PiO2) and the adaptive... more
An ascent to altitude places considerable demands on the cardiovascular system. Changes in the rate, rhythm, and morphology of the electrocardiogram reflect the fall in the partial pressure of inspired oxygen (PiO2) and the adaptive responses that the human body makes. The effect of hypoxia on the autonomic nervous system results in changes to the heart rate during rest and exercise. Although this is raised during rest and submaximal exercise, maximal heart rate at altitude is reduced as a result of changes in parasympathetic activity. Hypoxic pulmonary vasoconstriction leads to a rise in pulmonary artery pressure and morphological changes on the electrocardiogram. Right axis deviation, right bundle branch block, and changes to P and T wave amplitudes are commonly found on ascent and resolve only after a return to low altitude. Although atrial and ventricular ectopic activity is also common, tachyarrhythmias are rare in healthy individuals. However, in those with significant cardiac disease, the hypoxic environment can be hazardous, exposing individuals to ischemia and the risk of sudden cardiac death.
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Windsor, Jeremy S., and George W. Rodway. Supplemental oxygen and sleep at altitude. High Alt. Med. Biol. 7:307-311, 2006.--The purpose of this study was to examine the effect supplemental oxygen has on the respiratory and cardiovascular... more
Windsor, Jeremy S., and George W. Rodway. Supplemental oxygen and sleep at altitude. High Alt. Med. Biol. 7:307-311, 2006.--The purpose of this study was to examine the effect supplemental oxygen has on the respiratory and cardiovascular system of a mountaineer during sleep at high altitude by using a novel ambulatory, multisensor, continuous monitoring device. Supplemental oxygen was administered to a healthy subject via a nasal demand system (0, 16.7, 33.3, or 50 mL/sec per pulse dose delivered over 1 sec) during the first three nights of sleep at 4900 and 5700 m. Increases in pulse dose resulted in a consistent rise in Sa(O(2)) and a fall in minute ventilation (p < 0.05). The 50-mL pulse dose resulted in the greatest changes, with an increase in Sa(O(2)) from 68.5% to 81% (p < 0.05) and a fall in minute ventilation from 13.1 to 10.9 L/min (p < 0.05) being noted. Changes in Sa(O(2)) and minute ventilation also coincided with a fall in apnea/hypopnea index (AHI). At 4900 m the AHI fell from 12.5-52.3 (breathing air) to 0-7.5 (50-mL oxygen pulse), whereas at 5700 m a decrease from 49.1-80.4 to 3.5-10.0 was observed. No changes in respiratory rate or heart rate were identified when different pulse doses were compared (p < 0.05). The multisensor monitoring device proved to be a highly effective system, demonstrating marked improvements in Sa(O(2)), tidal volume, and AHI in our participant when supplemental oxygen was administered via a nasal demand system.
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Research Interests: Photography, Tibet, Nepal, Humans, Mountaineering, and 3 moreMale, Medical Physiology, and Expeditions
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We have previously demonstrated that prophylactic intake of dexamethasone improves maximal oxygen uptake (Vo(2)max) in high altitude pulmonary edema (HAPE) susceptible subjects 4 to 6 h after a 2-day climb to 4559 m. However, since with... more
We have previously demonstrated that prophylactic intake of dexamethasone improves maximal oxygen uptake (Vo(2)max) in high altitude pulmonary edema (HAPE) susceptible subjects 4 to 6 h after a 2-day climb to 4559 m. However, since with this ascent protocol HAPE usually develops after the first night at 4559 m or later, we hypothesized that a continued dexamethasone prophylaxis would result in an even more pronounced improvement of Vo(2)max after an additional night at high altitude. Vo(2)max of 24 HAPE susceptibles was evaluated on a bicycle ergometer at an altitude of 490 m and at 24 h after rapid ascent to 4559 m. Subjects were divided into two groups: The control group (n=14) performed both tests without dexamethasone, whereas the dexamethasone group (n=10) received dexamethasone 8 mg twice a day (b.i.d), starting 24 h prior to ascent. At 4559 m, Vo(2)max was 61% ± 6% of the baseline value in the control group and 70% ± 9% in the dexamethasone group (p=0.025). Similarly, O(2) pulse (Vo(2)/heart rate) was 68% ± 7% and 77% ± 11% of baseline, respectively (p=0.043). Arterial O(2) saturation at maximal exercise did not differ between groups, whereas at rest it was 83% ± 10% in the control group and 91% ± 4% in the dexamethasone group (p=0.009). Dexamethasone prophylaxis increased Vo(2)max of HAPE-susceptible individuals after the first night at 4559 m without affecting arterial O(2) saturation at maximal exercise. This might be explained by a sustained effect of dexamethasone on maximal cardiac output and pulmonary O(2) diffusion, both resulting in enhanced convectional O(2) transport to the locomotor muscles.