Effect of Six Days of Staging on Physiologic Adjustments and Acute Mountain Sickness during Ascent to 4300 Meters

Beidleman, Beth A.; Fulco, Charles S.; Muza, Stephen R.; Rock, Paul; Staab, Janet E.; Forte, Vincent; Brothers, Michael D.; Cymerman, Allen

doi:10.1089/ham.2009.1004

Cited by 71 publications

(60 citation statements)

References 22 publications

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“…Animals were delivered from sea level and spent a week at local conditions (4500 ft) to acclimatize prior to altitude exposure, which could affect study results. A step-wise increase in altitude was found to temper the physiological impact of high rate ascent in humans at altitude (Beidleman et al, 2009), implying that our results may be more moderate than expected. Also, all behavioral experiments were done at local conditions of 4500 ft.…”

Section: Discussionmentioning

confidence: 53%

Hypobaric Hypoxia Induces Depression-like Behavior in Female Sprague-Dawley Rats, but not in Males

Kanekar

Bogdanova

Olson

et al. 2015

High Altitude Medicine & Biology

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Kanekar, Shami, Olena V. Bogdanova, Paul R. Olson, Young-Hoon Sung, Kristen E. D'Anci, and Perry F. Renshaw. Hypobaric hypoxia induces depression-like behavior in female Sprague-Dawley rats, but not males. High Alt Med Biol 16:52-60, 2015-Rates of depression and suicide are higher in people living at altitude, and in those with chronic hypoxic disorders like asthma, chronic obstructive pulmonary disorder (COPD), and smoking. Living at altitude exposes people to hypobaric hypoxia, which can lower rat brain serotonin levels, and impair brain bioenergetics in both humans and rats. We therefore examined the effect of hypobaric hypoxia on depression-like behavior in rats. After a week of housing at simulated altitudes of 20,000 ft, 10,000 ft, or sea level, or at local conditions of 4500 ft (Salt Lake City, UT), Sprague Dawley rats were tested for depression-like behavior in the forced swim test (FST). Time spent swimming, climbing, or immobile, and latency to immobility were measured. Female rats housed at altitude display more depression-like behavior in the FST, with significantly more immobility, less swimming, and lower latency to immobility than those at sea level. In contrast, males in all four altitude groups were similar in their FST behavior. Locomotor behavior in the open field test did not change with altitude, thus validating immobility in the FST as depression-like behavior. Hypobaric hypoxia exposure therefore induces depression-like behavior in female rats, but not in males.

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Section: Discussionmentioning

confidence: 53%

Hypobaric Hypoxia Induces Depression-like Behavior in Female Sprague-Dawley Rats, but not in Males

Kanekar

Bogdanova

Olson

et al. 2015

High Altitude Medicine & Biology

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“…Spending time at moderate altitude before ascending to the target elevation, described as "staged ascent", augments the beneficial physiological responses seen following ascent and decreases the incidence of acute altitude illness [106]. Studies have reported conflicting results regarding intermittent normobaric or hypobaric hypoxic exposures, with some studies showing benefit [107] and others not demonstrating a clear effect [108,109].…”

Section: Preacclimatisationmentioning

confidence: 99%

Acute high-altitude sickness

2017

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At any point 1-5 days following ascent to altitudes ⩾2500 m, individuals are at risk of developing one of three forms of acute altitude illness: acute mountain sickness, a syndrome of nonspecific symptoms including headache, lassitude, dizziness and nausea; high-altitude cerebral oedema, a potentially fatal illness characterised by ataxia, decreased consciousness and characteristic changes on magnetic resonance imaging; and high-altitude pulmonary oedema, a noncardiogenic form of pulmonary oedema resulting from excessive hypoxic pulmonary vasoconstriction which can be fatal if not recognised and treated promptly. This review provides detailed information about each of these important clinical entities. After reviewing the clinical features, epidemiology and current understanding of the pathophysiology of each disorder, we describe the current pharmacological and nonpharmacological approaches to the prevention and treatment of these diseases.

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“…No differences between groups existed for age, weight, height, PET CO 2 during rest under SL and NH (1 h of exposure to 93 mmHg ambient PO2) conditions, and peak and TT exercise performance (Table 1). 1 During the sleep-treatment phase, a squad reported each night at 2200 to a large room containing two identical 2.4 m wide ϫ 3.0 m Fig. 1.…”

Section: Experimental Design Overviewmentioning

confidence: 99%

“…Ventilatory acclimatization (VEacc) can be characterized by the progressive decrease in the end-tidal PCO 2 (PET CO 2 ) that leads to an increase in arterial O 2 saturation (Sa O 2 ) during the first several days of moderate-to high-altitude residence [hypobaric hypoxia (HH), reduced barometric pressure (P B ) and 20.9% O 2 ] (7, 28). The enhanced oxygenation is closely linked with reduced acute mountain sickness (AMS) and improved exercise performance during HH residence (1,11,12,14). Some studies show that VEacc can also be induced by 1-4 h of HH exposure repeated daily at altitudes of 4,300 -4,500 m in as few as 7 days and that this method of HH exposure is as beneficial as continuous HH residence for reducing AMS and improving exercise performance (2, 4, 18).…”

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confidence: 99%

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

Fulco

Muza

Beidleman

et al. 2011

American Journal of Physiology-Regulatory, Integrative and Comp

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Fulco CS, Muza SR, Beidleman BA, Demes R, Staab JE, Jones JE, Cymerman A. Effect of repeated normobaric hypoxia exposures during sleep on acute mountain sickness, exercise performance, and sleep during exposure to terrestrial altitude. Am J Physiol Regul Integr Comp Physiol 300: R428 -R436, 2011. First published December 1, 2010; doi:10.1152/ajpregu.00633.2010.-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 ϭ 14, 24 Ϯ 5 (SD) yr] or "sham" (n ϭ 9, 25 Ϯ 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 PCO 2, O2 saturation (Sa O 2 ), 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 PCO 2 decreased (P Ͻ 0.01) for the NH (from 39 Ϯ 3 to 35 Ϯ 3 mmHg), but not for the sham (from 39 Ϯ 2 to 38 Ϯ 3 mmHg), group. Throughout HH, only sleep Sa O 2 was higher (80 Ϯ 1 vs. 76 Ϯ 1%, P Ͻ 0.05) and only AMS upon awakening was lower (0.34 Ϯ 0.12 vs. 0.83 Ϯ 0.14, P Ͻ 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 Sa O 2 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. ventilatory acclimatization; physical performance; hypobaric hypoxia; arterial oxygen saturation ALTITUDE ACCLIMATIZATION RESULTS from numerous interrelated physiological adjustments that compensate for hypoxemia, with augmented ventilation being one of the most important and consistently reported (17,18,22,28). Ventilatory acclimatization (VEacc) can be characterized by the progressive decrease in the end-tidal PCO 2 (PET CO 2 ) that leads to an increase in arterial O 2 saturation (Sa O 2 ) during the first several days of moderate-to high-altitude residence [hypobaric hypoxia (HH), reduced barometric pressure (P B ) and 20.9% O 2 ] (7, 28). The enhanced oxygenation is closely linked with reduced acute mountain sickness (AMS) and improved exercise performance during HH residence (1,11,12,14). Some studies show that VEacc can also be induced by 1-4 h of HH exposure repeated daily at altitudes of 4,300 -4,500 m ...

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Effect of Six Days of Staging on Physiologic Adjustments and Acute Mountain Sickness during Ascent to 4300 Meters

Cited by 71 publications

References 22 publications

Hypobaric Hypoxia Induces Depression-like Behavior in Female Sprague-Dawley Rats, but not in Males

Hypobaric Hypoxia Induces Depression-like Behavior in Female Sprague-Dawley Rats, but not in Males

Acute high-altitude sickness

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

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