scholarly journals Sea-Level Assessment of Dynamic Cerebral Autoregulation Predicts Susceptibility to Acute Mountain Sickness at High Altitude

Stroke ◽  
2011 ◽  
Vol 42 (12) ◽  
pp. 3628-3630 ◽  
Author(s):  
Nicholas J. Cochand ◽  
Michael Wild ◽  
Julien V. Brugniaux ◽  
Peter J. Davies ◽  
Kevin A. Evans ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Cerebral Autoregulation ◽  
Acute Mountain Sickness ◽  
Mountain Sickness ◽  
Dynamic Cerebral Autoregulation

scholarly journals Benzolamide improves oxygenation and reduces acute mountain sickness during a high-altitude trek and has fewer side effects than acetazolamide at sea level

2016 ◽  
Vol 4 (3) ◽  
pp. e00203 ◽  
Author(s):  
David J. Collier ◽  
Chris B. Wolff ◽  
Anne-Marie Hedges ◽  
John Nathan ◽  
Rod J. Flower ◽  
...  
Keyword(s):  
Side Effects ◽  
High Altitude ◽  
Sea Level ◽  
Acute Mountain Sickness ◽  
Mountain Sickness

scholarly journals Baseline psychological traits contribute to Lake Louise Acute Mountain Sickness score at high altitude

2021 ◽  
Author(s):  
Benjamin James Talks ◽  
Catherine Campbell ◽  
Stephanie J Larcombe ◽  
Lucy Marlow ◽  
Sarah Louise Finnegan ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Acute Mountain Sickness ◽  
Symptom Burden ◽  
Control Group ◽  
Physiological Changes ◽  
Symptom Experience ◽  
Psychological Traits ◽  
Bodily Sensations ◽  
Mountain Sickness

Background: Interoception refers to an individuals ability to sense their internal bodily sensations. Acute mountain sickness (AMS) is a common feature of ascent to high altitude that is only partially explained by measures of peripheral physiology. We hypothesised that interoceptive ability may explain the disconnect between measures of physiology and symptom experience in AMS. Methods and Material: Two groups of 18 participants were recruited to complete a respiratory interoceptive task three times at two-week intervals. The control group remained in Birmingham (140m altitude) for all three tests. The altitude group completed test 1 in Birmingham, test 2 the day after arrival at 2624m, and test 3 at 2728m after an 11-day trek at high altitude (up to 4800m). Results: By measuring changes to metacognitive performance, we showed that acute ascent to altitude neither presented an interoceptive challenge, nor acted as interoceptive training. However, AMS symptom burden throughout the trek was found to relate to sea-level measures of anxiety, agoraphobia, and neuroticism. Conclusions: This suggests that the Lake Louise AMS score is not solely a reflection of physiological changes on ascent to high altitude, despite often being used as such by researchers and commercial trekking companies alike.

Acclimatization at high altitude in gradual and acute induction

1995 ◽  
Vol 79 (2) ◽  
pp. 487-492 ◽  
Author(s):  
S. S. Purkayastha ◽  
U. S. Ray ◽  
B. S. Arora ◽  
P. C. Chhabra ◽  
L. Thakur ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Time Course ◽  
Physiological Responses ◽  
Acute Mountain Sickness ◽  
Blood Gases ◽  
Blood Gas ◽  
Mountain Sickness ◽  
High Altitude Illness ◽  
In Transit

The study assessed physiological responses to induction to high altitude first to 3,500 m and then to 4,200 m and compared the time course of altitude acclimatization in two groups of male volunteers. The acutely inducted group was transported by aircraft (AI) to 3,500 m in 1 h, whereas the gradually inducted group was transported by road (RI) in 4 days. Baseline recordings of basal cardiovascular, respiratory, and blood gas variables were monitored at sea level as well as at 3,500 m on days 1, 3, 5, and 7. Blood gases were measured on day 10 also. After 15 days at 3,500 m, the subjects were inducted to 4,200 m by road, and measurements were repeated on days 1, 3, and 5, except blood gas variables, which were done on day 10 only. Acute mountain sickness symptoms were recorded throughout. The responses of RI were stable by day 3 of induction at 3,500 m, whereas it took 5 days for AI. Four days in transit for RI appear equivalent to 2 days at 3,500 m for AI. Acclimatization schedules of 3 and 5 days, respectively, for RI and AI are essential to avoid malacclimatization and/or high-altitude illness. Both groups took 3 days at 4,200 m to attain stability for achieving acclimatization.

scholarly journals Oxidative stress and erythropoietin response in altitude exposure

2008 ◽  
Vol 31 (6) ◽  
pp. 380 ◽  
Author(s):  
Hsien-Hao Huang ◽  
Chih-Ly Han ◽  
Horng-Chin Yan ◽  
Woei-Yau Kao ◽  
Chu-Dang Tsai ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
High Altitude ◽  
Sea Level ◽  
Ferritin Level ◽  
Acute Mountain Sickness ◽  
Thiobarbituric Acid ◽  
Altitude Exposure ◽  
Delayed Recovery ◽  
Mountain Sickness ◽  
Stress Burden

Purpose: Oxidative stress and erythropoietin (EPO) levels are increased following high altitude exposure. We hypothesized that the altitude-oxidative stress and EPO response would be associated with the presence or absence of acute mountain sickness (AMS) in subjects exposed at high altitude. Methods: The study enrolled 29 healthy volunteers exposed at altitudes without strenuous physical exercise. Oxidative stress was determined by the spectrophotometric measurement of the colour occurring during the reaction of malondialdehyde (MDA) with thiobarbituric acid (TBA) on blood samples. Ferritin and EPO were also measured simultaneously. Results: During a rise in altitude at 2000 and 3000 m, there were no changes in plasma ferritin level in either of the 2 groups with or without AMS. In contrast, EPO increased at an altitude of 3000 m and after returning to sea level (28.2±2.7, 26.9±3.3 vs 12.2±1.4 and 17.1±1.6, P < 0.05, in group without AMS; 29.3±4.5, 22.8±2.7 vs 10.6±1.0 and 16.1±1.5, # P < 0.05, in group with AMS; compared with the baseline level and at the height of 2000 meters). At a height of 3000 m, plasma MDA level was elevated compared with that at the altitude of baseline and 2000 m in both groups of subjects with and without AMS (3.77±0.29 vs 1.14±0.17, and 1.64±0.22, P < 0.001, in subjects with AMS; 3.65±0.39 vs 1.71±0.21, and 1.73±0.21, P < 0.001, in subjects without AMS) . After returning to sea level, subjects without AMS had lower MDA oxidative stress compared with those with AMS (2.58±0.26 vs 3.51±0.24, P = 0.0223). Along with a rise in altitude, the oxidative stress in these both groups was not correlated with the changes in EPO (r2 = 0.0728, P = 0.1096). Conclusion: High altitude-induced oxidative stress, detected by MDA assay, is not different between the two groups of subjects with and without AMS. Upon return to sea level, subjects without AMS had lower MDA oxidative stress burden and higher EPO level than those with AMS. Whether the subjects with altitude illness had delayed recovery from oxidative stress merits further investigation.

scholarly journals Effects of acetazolamide and dexamethasone on cerebral hemodynamics in hypoxia

2011 ◽  
Vol 110 (5) ◽  
pp. 1219-1225 ◽  
Author(s):  
Andrew W. Subudhi ◽  
Andrew C. Dimmen ◽  
Colleen G. Julian ◽  
Megan J. Wilson ◽  
Ronney B. Panerai ◽  
...  
Keyword(s):  
Cerebral Autoregulation ◽  
Acute Mountain Sickness ◽  
Artery Blood Flow ◽  
Hemodynamic Parameters ◽  
Simulated Altitude ◽  
Hemodynamic Changes ◽  
Double Blind ◽  
Cerebral Hemodynamic ◽  
Mountain Sickness ◽  
Dynamic Cerebral Autoregulation

Previous attempts to detect global cerebral hemodynamic differences between those who develop headache, nausea, and fatigue following rapid exposure to hypoxia [acute mountain sickness (AMS)] and those who remain healthy have been inconclusive. In this study, we investigated the effects of two drugs known to reduce symptoms of AMS to determine if a common cerebral hemodynamic mechanism could explain the prophylactic effect within individuals. With the use of randomized, placebo-controlled, double-blind, crossover design, 20 healthy volunteers were given oral acetazolamide (250 mg), dexamethasone (4 mg), or placebo every 8 h for 24 h prior to and during a 10-h exposure to a simulated altitude of 4,875 m in a hypobaric chamber, which included 2 h of exercise at 50% of altitude-specific V̇o2max. Cerebral hemodynamic parameters derived from ultrasound assessments of dynamic cerebral autoregulation and vasomotor reactivity were recorded 15 h prior to and after 9 h of hypoxia. AMS symptoms were scored using the Lake Louise Questionnaire (LLQ). It was found that both drugs prevented AMS in those who became ill on placebo (∼70% decrease in LLQ), yet a common cerebral hemodynamic mechanism was not identified. Compared with placebo, acetazolamide reduced middle cerebral artery blood flow velocity (11%) and improved dynamic cerebral autoregulation after 9 h of hypoxia, but these effects appeared independent of AMS. Dexamethasone had no measureable cerebral hemodynamic effects in hypoxia. In conclusion, global cerebral hemodynamic changes resulting from hypoxia may not explain the development of AMS.

scholarly journals MEDEX 2015: Prophylactic Effects of Positive Expiratory Pressure in Trekkers at Very High Altitude

2021 ◽  
Vol 12 ◽  
Author(s):  
Thomas Rupp ◽  
Claire Maufrais ◽  
Guillaume Walther ◽  
François Esteve ◽  
Jamie Hugo Macdonald ◽  
...  
Keyword(s):  
Cardiac Output ◽  
High Altitude ◽  
Sea Level ◽  
Near Infrared ◽  
Acute Mountain Sickness ◽  
Hypoxic Exposure ◽  
2D Echocardiography ◽  
Mountain Sickness ◽  
Very High ◽  
Positive Expiratory Pressure

Purpose: Positive expiratory pressure (PEP) breathing has been shown to increase arterial oxygenation during acute hypoxic exposure but the underlying mechanisms and consequences on symptoms during prolonged high-altitude exposure remain to be elucidated.Methods: Twenty-four males (41 ± 16 years) were investigated, at sea level and at 5,085 m after 18 days of trekking from 570 m. Participants breathed through a face-mask with PEP = 0 cmH2O (PEP0, 0–45th min) and with PEP = 10 cmH2O (PEP10, 46–90th min). Arterial (SpO2), quadriceps and prefrontal (near infrared spectroscopy) oxygenation was measured continuously. Middle cerebral artery blood velocity (MCAv, transcranial Doppler), cardiac function (2D-echocardiography), extravascular lung water accumulation (UsLC, thoracic ultrasound lung comets) and acute mountain sickness (Lake Louise score, LLS) were assessed during PEP0 and PEP10.Results: At 5,085 m with PEP0, SpO2 was 78 ± 4%, UsLC was 8 ± 5 (a.u.) and the LLS was 2.3 ± 1.7 (all P &lt; 0.05 versus sea level). At 5,085 m, PEP10 increased significantly SpO2 (+9 ± 5%), quadriceps (+2 ± 2%) and prefrontal cortex (+2 ± 2%) oxygenation (P &lt; 0.05), and decreased significantly MCAv (−16 ± 14 cm.s–1) and cardiac output (−0.7 ± 1.2 L.min–1) together with a reduced stroke volume (−9 ± 15 mL, all P &lt; 0.05) and no systemic hypotension. PEP10 decreased slightly the number of UsLC (−1.4 ± 2.7, P = 0.04) while the incidence of acute mountain sickness (LLS ≥ 3) fell from 42% with PEP0 to 25% after PEP10 (P = 0.043).Conclusion: PEP10 breathing improved arterial and tissue oxygenation and symptoms of acute mountain sickness after trekking to very high altitude, despite reduced cerebral perfusion and cardiac output. Further studies are required to establish whether PEP-breathing prophylactic mechanisms also occur in participants with more severe acute mountain sickness.

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