Acute Mountain Sickness in a General Tourist Population at Moderate Altitudes

Honigman, Benjamin; Theis, Mary Kay; Koziol‐McLain, Jane; Roach, Robert C.; Yip, Ray; Houston, C. Stuart; Moore, Lorna G.

doi:10.7326/0003-4819-118-8-199304150-00003

Cited by 390 publications

(297 citation statements)

References 21 publications

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“…Increased susceptibility to acute mountain sickness among younger persons was also noted by Hackett and Rennie [2]. Levine et al [3]and Roach et al [4]both noted that the elderly appear to acclimatize well to 2,500 m. These findings are surprising because some physiological components of gas exchange that maintain oxygenation, such as vital capacity and hypoxic ventilatory drive, decrease with age [1, 5, 6]. Levine et al [3]noted that moderate altitude exposure in the elderly is associated with hypoxemia, sympathetic activation, and pulmonary hypertension resulting in a reduced exercise capacity.…”

Section: Introductionmentioning

confidence: 66%

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Geriatric Men at Altitude: Hypoxic Ventilatory Sensitivity and Blood Dopamine Changes

et al. 2000

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Background: Short-term exposure to high-altitude hypoxia increases hypoxic ventilatory sensitivity (HVS) in healthy humans. Dopamine (DA) is the implicated neurotransmitter in carotid body (CB) chemoreceptor response, and the microenvironmental conditions in CB tissue are comparable to blood. Continuous DA infusion affected ventilation in animals and humans. Age-related oscillations in blood DA levels may influence peripheral chemoreflexes. Objective: Hypoxic ventilatory responses (HVR) relative to blood DA concentration and its precursor, dihydroxyphenylalanine (DOPA) was measured in young and elderly men during short-term altitude adaptation. Methods: Nine elderly climbers (group 1: 61 ± 1.4 years) and 7 young healthy subjects (group 2: 23 ± 2 years) were tested at sea level on day 0, on day 3 after passive transport to 2,200 m, and on day 14 after climbing to 4,200 and 5,642 m. Results: Sea level HVR in group 1 was 47% lower than in group 2, accompanied by higher blood DOPA (300%) and DA (37%) content. Initial DA and DOPA concentrations showed a negative correlation with initial HVR but a positive correlation with age. Passive transport to middle altitude (2,200 m) increased HVS, doubling HVR slopes in groups 1 and 2 and producing increased maximum expired minute ventilation during isocapnic rebreathing (29 and 28%, respectively). Day 3 2,200-meter blood DOPA content decreased by 22% in group 1 and increased by 300% in group 2. DA increased in both groups. Conclusion: The relationship between HVR and the reciprocal DA and DOPA values seen in both groups is associated with age, producing decreased DA receptor sensitivity and enhanced DA reuptake during adaptation to high altitude.

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Section: Introductionmentioning

confidence: 66%

“…Honigman et al [1]reported that 25% of the visitors from 16 to 87 years of age traveling to moderate elevations developed acute mountain sickness, but this phenomenon occurred mostly in the younger age group. Increased susceptibility to acute mountain sickness among younger persons was also noted by Hackett and Rennie [2].…”

Section: Introductionmentioning

confidence: 99%

Geriatric Men at Altitude: Hypoxic Ventilatory Sensitivity and Blood Dopamine Changes

et al. 2000

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“…Hackett et al [10] studied 278 hikers at Pheriche in Nepal, and their results showed that gender did not predispose one to developing AMS. Honigman et al [11] showed that women may be less susceptible to HAPE, but equally as prone to AMS as men. Wang et al [12] also showed no difference in prevalence of AMS between genders.…”

Section: Discussionmentioning

confidence: 99%

Identifying risk factors that contribute to acute mountain sickness

Mahomed¹,

Martin²,

Gilbert³

et al. 2015

S. Afr. j. sports med

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Background. Acute mountain sickness (AMS) is an ever-increasing burden on the health sector. With reported incidences of greater than 50%, coupled with the fact that recreational activities at high altitude are gaining increasing popularity, more persons are developing AMS. Physicians are therefore increasingly faced with the task of managing and preventing AMS. Objectives. The pathophysiology of AMS is poorly understood, with little understanding of risk factors for the development of AMS. This research aimed to identify epidemiological and physiological risk factors for development of AMS. Methods. This study is a questionnaire-based study conducted in London and at Everest Base Camp, in which 116 lowlanders were invited to participate and fill in a questionnaire to identify potential risk factors in their history that may have contributed to development of or protection against AMS. Results. A total of 89 lowlanders enrolled in the study. Thirty-seven of the participants had AMS at Everest Base Camp, giving a prevalence of 42%. Of the demographic variables, only weight and body mass index (BMI) were statistically significantly associated with AMS, with those who weighed less or had a lower BMI more likely to get AMS. Previous high-altitude experience was also associated with AMS, with those who had such experience less likely to get AMS. Conclusion. Predicting AMS and furthering our understanding of the pathophysiology of AMS will be of tremendous benefit. Further research is needed in this regard.

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“…Maximum altitude gained too influences the likelihood of AHAI-AMS typically develops at altitudes>2,500, HAPO at > 3000 m and HACO between 4000 m -5000 m 18 . A large body of evidence points towards individual susceptibility as an interactive outcome between: genetic and environmental factors 18,19 . Studies on Tibetan and Andean populations have revealed different genetic phenotypes 20 .…”

Section: Epidemiology and Riskmentioning

confidence: 99%

Physiology and Medicine at High Altitude: The Exposure and the Stress

Gurtoo

2018

Def. Life. Sc. Jl.

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, it was sometimes in the mid-nineteenth century that, Bert first showed the association between hypobaria triggered lowering of PiO 2 and high altitude illness 2 . This relationship is best captured by the gas-law equation:PV = nRT where P = pressure, V = volume, n = number of gas molecules, R = universal gas constant, and T = absolute temperature. Since, the partial pressure of a gas, P = Fi x B, at sea level given a B of 760 mmHg (P B ), the partial pressure of inspired O 2 becomes = 20.9 x 760 =159 mm Hg. This fall is most dramatic at 5,486 meters, which is the upper level of functional acclimatisation where a PB of = 395 mm Hg yields a Pi O 2 of 82 mmHg (20.9 x 395), which is nearly half that at sea level. Even at 3000 m, the height of Leh, the barometric pressure (P B ) and inspired PO 2 (PiO 2 ) are only 70 per cent of the sea level values. On the summit of Mt. Everest, at 8848 m, the PiO 2 is less than 30 per cent of its sea level value. These values signify the stress and challenge to the physiology at high altitude. The ADApTATIONTaken suddenly to the top of Mt. Everest (8848 m), a person would lose consciousness in less than 3 min 3 . Taken slowly the same person remains alive and functional. In fact the lowest recorded P A O 2 in a healthy individual at 8400 m on Everest by the Caudwell Xtreme Everest expedition was 19 mmHg (2.55 KPa). The stark contrast between the two scenarios is accounted for by the adaptive process called acclimatisation that tends to increase the oxygen delivery (DO 2 ) to the tissues. The ClAssIC MODelThe classic model holds that this increase in DO 2 is affected by an optimisation between: (i) Pulmonary (ii) haematological and, (iii) cardiovascular processes. Pulmonary process optimisation is the first response to hypobaric hypoxia: hyperventilation is triggered by a combination of stimulation of peripheral chemoreceptor and inhibition of the central chemoreceptors that leads to an increased respiratory rate and depth. This hypoxic ventilator response (HVR) triggers in within a few hours of exposure to hypobaric hypoxia. This HVR tends to restore the falling oxygen gradient across the physiology and Medicine at high Altitude: The exposure and the stress Anil GurtooLady Hardinge Medical College, ABsTRACT Increase in altitude causes decrease in atmospheric barometric pressure that results in decrease of inspired partial pressure of oxygen, a source for stress and pose a challenge to climbers/trekkers or persons posted on high altitude areas. This review discusses about the high altitude sickness, their incidence rates, pathophysiology and the classic model of acclimatisation, which explains about how oxygen requirement in extreme environment is achieved by complex interplay among pulmonary, hematological and cardiovascular processes. The acute high altitude illness (AHAI) is basically composed of two syndromes: cerebral and pulmonary that can afflict un-acclimatised climbers/trekkers. The cerebral syndrome includes acute mountain sickness (AMS) and high altitude cerebral oedem...

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Acute Mountain Sickness in a General Tourist Population at Moderate Altitudes

Cited by 390 publications

References 21 publications

Geriatric Men at Altitude: Hypoxic Ventilatory Sensitivity and Blood Dopamine Changes

Geriatric Men at Altitude: Hypoxic Ventilatory Sensitivity and Blood Dopamine Changes

Identifying risk factors that contribute to acute mountain sickness

Physiology and Medicine at High Altitude: The Exposure and the Stress

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