Acute Mountain Sickness Symptoms Depend on Normobaric versus Hypobaric Hypoxia

DiPasquale, Dana M.; Strangman, Gary E.; Harris, N. Stuart; Muza, Stephen R.

doi:10.1155/2016/6245609

Cited by 13 publications

(12 citation statements)

References 21 publications

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“…DiPasquale et al . ). These two conditions are probably perceived with a different level of stress by the subjects, which represents another important confounding factor.…”

Section: Equivalent Fnormalio2 For a Given Altitude At Three Differementioning

confidence: 97%

CrossTalk opposing view: Barometric pressure, independent of , is not the forgotten parameter in altitude physiology and mountain medicine

Richalet

2020

The Journal of Physiology

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“…DiPasquale et al . ). These two conditions are probably perceived with a different level of stress by the subjects, which represents another important confounding factor.…”

Section: Equivalent Fnormalio2 For a Given Altitude At Three Differementioning

confidence: 97%

CrossTalk opposing view: Barometric pressure, independent of , is not the forgotten parameter in altitude physiology and mountain medicine

Richalet

2020

The Journal of Physiology

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“…However, the air altitude equivalent model speculating that only PI O 2 is influential, with no specific effect of the barometric pressure, is now being strongly challenged (9,10,17). Recent research has pointed out differences in physiological adaptations to hypobaric versus normobaric hypoxia (9,20,29,35) that may influence the occurrence of sleep disturbances (20) and/or signs/symptoms of AMS (11,14). These results also raise the question of whether interventions aimed at preventing the occurrence of AMS (including PEP breathing) may induce different effects in NH versus HH.…”

Section: Similar Improvement In Arterial Oxygenation With Pep Breathing In Hh and Nhmentioning

confidence: 99%

Positive expiratory pressure improves arterial and cerebral oxygenation in acute normobaric and hypobaric hypoxia

Rupp

Saugy

Bourdillon

et al. 2019

American Journal of Physiology-Regulatory, Integrative and Comp

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Positive expiratory pressure (PEP) has been shown to limit hypoxia-induced reduction in arterial oxygen saturation, but its effectiveness on systemic and cerebral adaptations, depending on the type of hypoxic exposure [normobaric (NH) versus hypobaric (HH)], remains unknown. Thirteen healthy volunteers completed three randomized sessions consisting of 24-h exposure to either normobaric normoxia (NN), NH (inspiratory oxygen fraction, [Formula: see text] = 13.6%; barometric pressure, BP = 716 mmHg; inspired oxygen partial pressure, [Formula: see text] = 90.9 ± 1.0 mmHg), or HH (3,450 m, [Formula: see text] = 20.9%, BP = 482 mmHg, [Formula: see text] = 91.0 ± 0.6 mmHg). After the 6th and the 22nd hours, participants breathed quietly through a facemask with a 10-cmH2O PEP for 2 × 5 min interspaced with 5 min of free breathing. Arterial ([Formula: see text], pulse oximetry), quadriceps, and cerebral (near-infrared spectroscopy) oxygenation, middle cerebral artery blood velocity (MCAv; transcranial Doppler), ventilation, and cardiovascular responses were recorded continuously. [Formula: see text]without PEP was significantly lower in HH (87 ± 4% on average for both time points, P < 0.001) compared with NH (91 ± 3%) and NN (97 ± 1%). PEP breathing did not change [Formula: see text] in NN but increased it similarly in NH and HH (+4.3 ± 2.5 and +4.7 ± 4.1% after 6h; +3.5 ± 2.2 and +4.1 ± 2.9% after 22h, both P < 0.001). Although MCAv was reduced by PEP (in all sessions and at all time points, −6.0 ± 4.2 cm/s on average, P < 0.001), the cerebral oxygenation was significantly improved ( P < 0.05) with PEP in both NH and HH, with no difference between conditions. These data indicate that PEP could be an attractive nonpharmacological means to improve arterial and cerebral oxygenation under both normobaric and hypobaric mild hypoxic conditions in healthy participants.

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“…This condition is termed AMS. It is a clinical syndrome in which the body decompensates in response to acute hypoxic conditions [2–4]; AMS is exacerbated by exercise and can be disabling [5]. More seriously, if symptoms are ignored, AMS can develop into life-threatening high-altitude cerebral edema [6].…”

Section: Introductionmentioning

confidence: 99%

Sex-based differences in the prevalence of acute mountain sickness: a meta-analysis

Hou

Tan³

et al. 2019

Military Med Res

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BackgroundWhen lowlanders rapidly ascend to altitudes > 2500 m, they may develop acute mountain sickness (AMS). The individual susceptibility, ascending velocity, time spent at altitude, activity levels and altitude reached are considered risk factors for AMS. However, it is not clear whether sex is a risk factor. The results have been inconclusive. We conducted a meta-analysis to test whether there were sex-based differences in the prevalence of AMS using Lake Louise Scoring System.MethodsSystematic searches were performed in August 2019 in EMBASE, PubMed, and Web of Science for prospective studies with AMS data for men and women. The titles and abstracts were independently checked in the primary screening step, and the selected full-text articles were independently assessed in the secondary screening step by the two authors (YPH and JLW) based on pre-defined inclusion criteria. The meta-analysis was performed using by the STATA 14.1 software program. A random-effects model was employed.ResultsEighteen eligible prospective studies were included. A total of 7669 participants (2639 [34.4%] women) were tested. The results showed that there was a statistically significant higher prevalence rate of AMS in women than in men (RR = 1.24, 95%CI 1.09–1.41), regardless of age or race. Howerver, the heterogeneity was significant in the analysis (Tau2 = 0.0403, Chi2 = 50.15, df = 17; I2 = 66.1%, P = 0.000), it was main caused by different numbers of subjects among the studies (coefficient = − 2.17, P = 0.049). Besides, the results showed that there was no evidence of significant publication bias in the combined studies on the basis of Egger’s test (bias coefficient = 1.48, P = 0.052) and Begg’s test (P = 0.130).ConclusionsAccording to this study, the statistically significant finding emerging from this study was that women have a higher prevalence of AMS. However, the authors could not exclude studies where patients were on acetazolamide. Our analysis provided a direction for future studies of the relationship of sex and the risk of AMS, such as the pathological mechanism and prevention research.

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Acute Mountain Sickness Symptoms Depend on Normobaric versus Hypobaric Hypoxia

Cited by 13 publications

References 21 publications

CrossTalk opposing view: Barometric pressure, independent of , is not the forgotten parameter in altitude physiology and mountain medicine

CrossTalk opposing view: Barometric pressure, independent of , is not the forgotten parameter in altitude physiology and mountain medicine

Positive expiratory pressure improves arterial and cerebral oxygenation in acute normobaric and hypobaric hypoxia

Sex-based differences in the prevalence of acute mountain sickness: a meta-analysis

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