scholarly journals Acute Mountain Sickness Symptoms Depend on Normobaric versus Hypobaric Hypoxia

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Dana M. DiPasquale ◽  
Gary E. Strangman ◽  
N. Stuart Harris ◽  
Stephen R. Muza
Keyword(s):  
Hypobaric Hypoxia ◽  
Assessment Tool ◽  
Classification Tree ◽  
Acute Mountain Sickness ◽  
Self Report ◽  
Shortness Of Breath ◽  
Classification Tree Analysis ◽  
Appetite Loss ◽  
Mountain Sickness ◽  
Normobaric Normoxia

Acute mountain sickness (AMS), characterized by headache, nausea, fatigue, and dizziness when unacclimatized individuals rapidly ascend to high altitude, is exacerbated by exercise and can be disabling. Although AMS is observed in both normobaric (NH) and hypobaric hypoxia (HH), recent evidence suggests that NH and HH produce different physiological responses. We evaluated whether AMS symptoms were different in NH and HH during the initial stages of exposure and if the assessment tool mattered. Seventy-two 8 h exposures to normobaric normoxia (NN), NH, or HH were experienced by 36 subjects. The Environmental Symptoms Questionnaire (ESQ) and Lake Louise Self-report (LLS) were administered, resulting in a total of 360 assessments, with each subject answering the questionnaire 5 times during each of their 2 exposure days. Classification tree analysis indicated that symptoms contributing most to AMS were different in NH (namely, feeling sick and shortness of breath) compared to HH (characterized most by feeling faint, appetite loss, light headedness, and dim vision). However, the differences were not detected using the LLS. These results suggest that during the initial hours of exposure (1) AMS in HH may be a qualitatively different experience than in NH and (2) NH and HH may not be interchangeable environments.

Elevated plasma S100B levels in high altitude hypobaric hypoxia do not correlate with acute mountain sickness

2014 ◽  
Vol 36 (9) ◽  
pp. 779-785 ◽  
Author(s):  
Craig D. Winter ◽  
Timothy R. Whyte ◽  
John Cardinal ◽  
Stephen E. Rose ◽  
Peter K. O’Rourke ◽  
...  
Keyword(s):  
High Altitude ◽  
Hypobaric Hypoxia ◽  
Acute Mountain Sickness ◽  
Elevated Plasma ◽  
Mountain Sickness

Intermittent altitude exposures reduce acute mountain sickness at 4300 m

2004 ◽  
Vol 106 (3) ◽  
pp. 321-328 ◽  
Author(s):  
Beth A. BEIDLEMAN ◽  
Stephen R. MUZA ◽  
Charles S. FULCO ◽  
Allen CYMERMAN ◽  
Dan DITZLER ◽  
...  
Keyword(s):  
Acute Mountain Sickness ◽  
Urine Volume ◽  
Barometric Pressure ◽  
Self Report ◽  
Altitude Exposure ◽  
Cerebral Symptom ◽  
Cycle Training ◽  
Mountain Sickness ◽  
End Tidal ◽  
Rest And Exercise

Acute mountain sickness (AMS) commonly occurs at altitudes exceeding 2000–2500 m and usually resolves after acclimatization induced by a few days of chronic residence at the same altitude. Increased ventilation and diuresis may contribute to the reduction in AMS with altitude acclimatization. The aim of the present study was to examine the effects of intermittent altitude exposures (IAE), in combination with rest and exercise training, on the incidence and severity of AMS, resting ventilation and 24-h urine volume at 4300 m. Six lowlanders (age, 23±2 years; body weight, 77±6 kg; values are means±S.E.M.) completed an Environmental Symptoms Questionnaire (ESQ) and Lake Louise AMS Scoring System (LLS), a resting end-tidal partial pressure of CO2 (PETCO2) test and a 24-h urine volume collection at sea level (SL) and during a 30 h exposure to 4300 m altitude-equivalent (barometric pressure=446 mmHg) once before (PreIAE) and once after (PostIAE) a 3-week period of IAE (4 h·day-1, 5 days·week-1, 4300 m). The previously validated factor score, AMS cerebral score, was calculated from the ESQ and the self-report score was calculated from the LLS at 24 h of altitude exposure to assess the incidence and severity of AMS. During each IAE, three subjects cycled for 45–60 min·day-1 at 60–70% of maximal O2 uptake (VO2 max) and three subjects rested. Cycle training during each IAE did not affect any of the measured variables, so data from all six subjects were combined. The results showed that the incidence of AMS (%), determined from both the ESQ and LLS, increased (P<0.05) from SL (0±0) to PreIAE (50±22) at 24 h of altitude exposure and decreased (P<0.05) from PreIAE to PostIAE (0±0). The severity of AMS (i.e. AMS cerebral symptom and LLS self-report scores) increased (P<0.05) from SL (0.02±0.02 and 0.17±0.17 respectively) to PreIAE (0.49±0.18 and 4.17±0.94 respectively) at 24 h of altitude exposure, and decreased (P<0.05) from PreIAE to PostIAE (0.03±0.02 and 0.83±0.31 respectively). Resting PETCO2 (mmHg) decreased (i.e. increase in ventilation; P<0.05) from SL (38±1) to PreIAE (32±1) at 24 h of altitude exposure and decreased further (P<0.05) from PreIAE to PostIAE (28±1). In addition, 24-h urine volumes were similar at SL, PreIAE and PostIAE. In conclusion, our findings suggest that 3 weeks of IAE provide an effective alternative to chronic altitude residence for increasing resting ventilation and reducing the incidence and severity of AMS.

Effect of repeated normobaric hypoxia exposures during sleep on acute mountain sickness, exercise performance, and sleep during exposure to terrestrial altitude

2011 ◽  
Vol 300 (2) ◽  
pp. R428-R436 ◽  
Author(s):  
Charles S. Fulco ◽  
Stephen R. Muza ◽  
Beth A. Beidleman ◽  
Robby Demes ◽  
Janet E. Staab ◽  
...  
Keyword(s):  
Heart Rate ◽  
Exercise Performance ◽  
Hypobaric Hypoxia ◽  
Sham Group ◽  
Acute Mountain Sickness ◽  
Time Trial ◽  
Normobaric Hypoxia ◽  
Performance Decrement ◽  
Mountain Sickness ◽  
End Tidal

There is an expectation that repeated daily exposures to normobaric hypoxia (NH) will induce ventilatory acclimatization and lessen acute mountain sickness (AMS) and the exercise performance decrement during subsequent hypobaric hypoxia (HH) exposure. However, this notion has not been tested objectively. Healthy, unacclimatized sea-level (SL) residents slept for 7.5 h each night for 7 consecutive nights in hypoxia rooms under NH [ n = 14, 24 ± 5 (SD) yr] or “sham” ( n = 9, 25 ± 6 yr) conditions. The ambient percent O2 for the NH group was progressively reduced by 0.3% [150 m equivalent (equiv)] each night from 16.2% (2,200 m equiv) on night 1 to 14.4% (3,100 m equiv) on night 7, while that for the ventilatory- and exercise-matched sham group remained at 20.9%. Beginning at 25 h after sham or NH treatment, all subjects ascended and lived for 5 days at HH (4,300 m). End-tidal Pco2, O2 saturation (SaO2), AMS, and heart rate were measured repeatedly during daytime rest, sleep, or exercise (11.3-km treadmill time trial). From pre- to posttreatment at SL, resting end-tidal Pco2 decreased ( P < 0.01) for the NH (from 39 ± 3 to 35 ± 3 mmHg), but not for the sham (from 39 ± 2 to 38 ± 3 mmHg), group. Throughout HH, only sleep SaO2 was higher (80 ± 1 vs. 76 ± 1%, P < 0.05) and only AMS upon awakening was lower (0.34 ± 0.12 vs. 0.83 ± 0.14, P < 0.02) in the NH than the sham group; no other between-group rest, sleep, or exercise differences were observed at HH. These results indicate that the ventilatory acclimatization induced by NH sleep was primarily expressed during HH sleep. Under HH conditions, the higher sleep SaO2 may have contributed to a lessening of AMS upon awakening but had no impact on AMS or exercise performance for the remainder of each day.

High altitude deterioration

1954 ◽  
Vol 143 (910) ◽  
pp. 40-42 ◽  
Keyword(s):  
High Altitude ◽  
Individual Variation ◽  
Acute Mountain Sickness ◽  
Hard Work ◽  
High Altitudes ◽  
Appetite Loss ◽  
Prolonged Stay ◽  
Loss Of Weight ◽  
The Subject ◽  
Mountain Sickness

High altitude deterioration means a gradual diminution in man’s capacity to do work at great heights. This is associated with insomnia, lack of appetite, loss of weight and increasing lethargy. These symptoms appear after a prolonged stay above 18000 ft. and there is great individual variation. Man would deteriorate after a time at these heights even under the best con­ditions: if he is doing hard work and is subjected to many strains, mental and physical, other factors are brought to bear which will aggravate this basic state. Such factors are illness, exhaustion, starvation and dehydration. Symptoms similar to those of deterioration, but more acute in onset, appear if man goes too quickly to high altitudes without first acclimatizing. These symptoms of acute mountain sickness disappear if the subject returns to lower levels for some time. If he goes to moderate heights when acclimatizing he will be able to stay for reasonably long periods without undue trouble. Exhaustion at high altitudes is often only cured by coming down to lower levels, as above a certain height there seems to be little or no recovery.

Acute mountain sickness, chemosensitivity, and cardiorespiratory responses in humans exposed to hypobaric and normobaric hypoxia

2014 ◽  
Vol 116 (7) ◽  
pp. 945-952 ◽  
Author(s):  
Normand A. Richard ◽  
Inderjeet S. Sahota ◽  
Nadia Widmer ◽  
Sherri Ferguson ◽  
A. William Sheel ◽  
...  
Keyword(s):  
Ventilatory Response ◽  
Minute Ventilation ◽  
Acute Mountain Sickness ◽  
Blood Oxygenation ◽  
Normobaric Hypoxia ◽  
Hypoxic Exposure ◽  
Hypoxic Ventilatory Response ◽  
Before And After ◽  
Mountain Sickness ◽  
Normobaric Normoxia

We examined the control of breathing, cardiorespiratory effects, and the incidence of acute mountain sickness (AMS) in humans exposed to hypobaric hypoxia (HH) and normobaric hypoxia (NH), and under two control conditions [hypobaric normoxia (HN) and normobaric normoxia (NN)]. Exposures were 6 h in duration, and separated by 2 wk between hypoxic exposures and 1 wk between normoxic exposures. Before and after exposures, subjects ( n = 11) underwent hyperoxic and hypoxic Duffin CO2 rebreathing tests and a hypoxic ventilatory response test (HVR). Inside the environmental chamber, minute ventilation (V̇e), tidal volume (Vt), frequency of breathing ( fB), blood oxygenation, heart rate, and blood pressure were measured at 5 and 30 min and hourly until exit. Symptoms of AMS were evaluated using the Lake Louise score (LLS). Both the hyperoxic and hypoxic CO2 thresholds were lower after HH and NH, whereas CO2 sensitivity was increased after HH and NH in the hypoxic test and after NH in the hyperoxic test. Values for HVR were similar across the four exposures. No major differences were observed for V̇e or any other cardiorespiratory variables between NH and HH. The LLS was greater in AMS-susceptible than in AMS-resistant subjects; however, LLS was alike between HH and NH. In AMS-susceptible subjects, fB correlated positively and Vt negatively with the LLS. We conclude that 6 h of hypoxic exposure is sufficient to lower the peripheral and central CO2 threshold but does not induce differences in cardiorespiratory variables or AMS incidence between HH and NH.

scholarly journals Assessment of Acute Mountain Sickness: How to integrate the advantages of the Lake Louise Score and the Chinese AMS Score

2020 ◽  
Author(s):  
Yu Wu ◽  
Peng Li ◽  
Zhifeng Zhong ◽  
Jiaxin Xie ◽  
Simin Zhou ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Positive Predictive Value ◽  
Predictive Value ◽  
Significant Positive Correlation ◽  
Acute Mountain Sickness ◽  
Shortness Of Breath ◽  
Chest Tightness ◽  
Kappa Value ◽  
Mountain Sickness ◽  
Systematic Cluster

Abstract Aims: To compare the differences in acute mountain sickness (AMS) incidence between two AMS diagnostic scoring criteria, including the Lake Louise Score and the Chinese AMS Score. Methods: A total of 2486 young men completed questionnaires after flying from Chendu (500 m) to Lasha (3658 m). The AMS incidence was investigated using a questionnaire that contained the scoring criteria for the LLS and CAS. To determine the grouping of all the symptoms on the AMS questionnaire, a systematic cluster analysis and two-step cluster analysis were used to analyse various symptoms and cases separately.Results: The AMS incidence was 37.5% (n = 932) according to the LLS, in which the cut-off point depended on headache and a total score ≥ 3, and 59.3% (n = 1473) according to the CAS, in which the cut-off point depended on headache, vomiting or a total score ≥ 5. The LLS and CAS outcomes had a significant positive correlation (Spearman’s rho = 0.918, P < 0.05) and were moderately consistent (kappa value = 0.488, P < 0.001). The positive AMS incidence determined by the CAS was significantly higher than that by the LLS (P < 0.001). Compared with the LLS, the sensitivity was 100%, the specificity was 65.23%, the positive predictive value was 63.34%, and the negative predictive value was 100% for the CAS in the diagnosis of AMS. The CAS identified all AMS subjects diagnosed by the LLS, and an additional 541 subjects. Of all the symptoms investigated, the dominant symptoms were fatigue (59.3%), dizziness (55.0%), headache (50.6%), chest tightness (40.4%), and shortness of breath (37.2%), and the last two symptoms were not included in the LLS. The cluster analysis show that chest distress, shortness of breath and palpitations were relatively independent of the major symptoms assessed by the LLS. Conclusion: The CAS had testing characteristics for diagnosing AMS similar to those of the Lake Louise Questionnaire Score, and the CAS diagnosed a higher prevalence of AMS than the LLS. It is suggested that chest distress and shortness of breath should be paid adequate attention and taken into account in AMS diagnostic criteria in the next revision to better diagnosis and study AMS.

Acute Mountain Sickness Symptomology in Normobaric vs Hypobaric Hypoxia

2015 ◽  
Vol 47 ◽  
pp. 604
Author(s):  
Dana M. DiPasquale ◽  
Gary E. Strangman ◽  
N. Stuart Harris ◽  
Stephen R. Muza
Keyword(s):  
Hypobaric Hypoxia ◽  
Acute Mountain Sickness ◽  
Mountain Sickness
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