Effects of intermittent hypoxia on the isocapnic hypoxic ventilatory response and erythropoiesis in humans

Garcia, Nathalie; Hopkins, Susan R.; Powell, Frank L.

doi:10.1016/s0034-5687(00)00145-6

Cited by 79 publications

(74 citation statements)

References 27 publications

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“…The repeated daily exposures to hypoxia produced a marked enhancement of the initial ventilatory response to hypoxia by the end of the 14 days, a finding similar to that of others using a variety of repeated exposure protocols (Levine et al 1992;Savourey et al 1996;Katayama et al 1998;Serebrovskaya et al 1999;Garcia et al 2000b). We also observed that during each 20 min exposure to hypoxia the ventilatory response declined slowly, again a finding similar to that of others (e.g.…”

Section: Changes In Chemoreflex Characteristicssupporting

confidence: 90%

“…For the second type, involving daily exposures to hypoxia, several studies in humans have demonstrated that the initial ventilatory response to hypoxia is enhanced (Levine et al 1992;Savourey et al 1996;Katayama et al 1998;Serebrovskaya et al 1999;Garcia et al 2000b). Most of these studies involved subjects spending time in hypobaric chambers at simulated altitudes: 30 min daily for 6 days at 4 500 m (Katayama et al 1998) or 8 h daily for 5 days, day 1 at 4500 m, day 5 at 8500 m (Savourey et al 1996), or 45 min daily for 5 days week _1 for 5 weeks (Levine et al 1992), with the latter complicated by exercise during the exposures.…”

Section: Repeated Hypoxic Exposures Change Respiratory Chemoreflex Comentioning

confidence: 99%

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Repeated hypoxic exposures change respiratory chemoreflex control in humans

Mahamed

Duffin

2001

The Journal of Physiology

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A group of seven volunteers (5 male, 2 female) were exposed to 20 min isocapnic (eucapnic) hypoxia once daily for 14 consecutive days. Their chemoreflexes were measured before and after each exposure. The same volunteers repeated the exposures with air substituted for the hypoxic gas mixture in a pseudorandom crossover design. On day 1 an initial ventilatory response to hypoxia and subsequent decline was discernible in two volunteers, but the mean response for all volunteers at this stage was not significant. However, the response gradually increased, and by day 14 was discernible in six volunteers making the mean response for all volunteers significant. No change was observed over the 14 days of air exposure. Only the chemoreflex threshold measured in iso‐oxic (hypoxic) modified rebreathing tests changed significantly, and only for the series of exposures to hypoxia. Over 14 days, the mean ±s.e.m. threshold for all volunteers fell proportionately, from 42 ± 1.1 mmHg on day 1 to 39 ± 1.0 mmHg on day 14. By contrast, the mean ±s.e.m. threshold, for all volunteers and all days, rose from 40 ± 0.4 mmHg before to 42 ± 0.5 mmHg after the hypoxic exposures. We conclude that the enhancement of the initial ventilatory response to hypoxia induced by repeated hypoxic exposure is produced by a decrease in chemoreflex threshold. However, the decline in the ventilatory response during a single exposure is produced by an increase in the chemoreflex threshold. Since threshold changes were only found for hypoxic (iso‐oxic) modified rebreathing tests, we conclude that only the peripheral chemoreflex changed.

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Section: Changes In Chemoreflex Characteristicssupporting

confidence: 90%

Section: Repeated Hypoxic Exposures Change Respiratory Chemoreflex Comentioning

confidence: 99%

Repeated hypoxic exposures change respiratory chemoreflex control in humans

Mahamed

Duffin

2001

The Journal of Physiology

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“…Even short exposures 2-4 h are expected to have some effect on acclimatization (Burtscher et al, 2008). This corresponds to findings in physiology and molecular biology which proved effects of intermittent hypoxia with simulated altitude for hypoxic ventilatory drive, hyperventilation, and arterial oxygen saturation (Levine et al, 1992;Richalet et al, 1992;Garcia et al, 2000a;Garcia et al, 2000b;Bernardi et al, 2001a;Bernardi et al, 2001b;Beidleman et al, 2004;Jones et al, 2006;Lusina et al, 2006;Muza et al, 2006) or for hypoxia inducible factor alpha (HIF-1a), 2,3-diphosphorglycerate, and others (Chilov et al, 1999;Richard et al, 1999;Hofer et al, 2001;Heinicke et al, 2002) during several hours. A detailed survey about this topic is given in (Küpper and Schoffl, 2009).…”

Section: Aspects Of Occupational Safety and Healthsupporting

confidence: 81%

Work in Hypoxic Conditions-Consensus Statement of the Medical Commission of the Union Internationale des Associations d'Alpinisme (UIAA MedCom)

Küpper

Milledge

Hillebrandt³

et al. 2011

The Annals of Occupational Hygiene

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Objectives: The Commission gives recommendations on how to provide health and safety for employees in different kinds of low oxygen atmospheres. So far, no recommendations exist that take into account the several factors we have outlined in this report.Methods: The health and safety recommendations of several countries were analysed for their strength and deficiencies. The scientific literature was checked (Medline, etc.) and evaluated for relevance of the topic. Typical situations of work in hypoxia were defined and their specific risks described. Specific recommendations are provided for any of these situations.Results: We defined four main groups with some subgroups (main risk in brackets): short exposure (pressure change), limited exposure (acute altitude disease), expatriates (chronic altitude disease), and high-altitude populations (re-entry pulmonary oedema). For healthy unacclimatized persons, an acute but limited exposure down to 13% O 2 does not cause a health risk. Employees should be advised to leave hypoxic areas for any break, if possible. Detailed advice is given for any other situation and pre-existing diseases.Conclusions: If the specific risk of the respective type of hypoxia is taken into account, a pragmatic approach to provide health and safety for employees is possible. In contrast to other occupational exposures, a repeated exposure as often as possible is of benefit as it causes partial acclimatization. The consensus statement was approved by written consent in lieu of a meeting in July 2009.

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“…In contrast to Katayama's study significant acclimatization was found after 25 days of exposure only [31]. The most prominent effects of intermittent hypoxia with simulated altitude were found for HVD, hyperventilation and arterial oxygen saturation [21][22][23][24]27,28,[30][31][32][33].…”

Section: Which Group May Benefit From Pre-acclimatization?mentioning

confidence: 96%

“…There was no difference between exposure combined with some or without activity reported [23]. At moderate altitude there was no significant influence on several physiological factors by intermittent hypoxia [25], but several changes as usual in normal ("real") hypoxia in the mountains were found when the exposure exceeded a corresponding altitude of 2500 m [21,23,[26][27][28]. In some investigations an increase of performance [21,23,24] or mood status was found [29].…”

Section: Which Group May Benefit From Pre-acclimatization?mentioning

confidence: 99%

Pre-Acclimatization for High Altitude Sojourns in Hypoxic Chambers

Küpper¹,

Schoeffl²

2012

Med Sport

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More and more people go to high altitude without enough time for proper acclimatization. If there is a lack of time for any reason hypoxic chambers may be used for pre-acclimatization to avoid altitude diseases. Since there are different protocols and the data differ, there is no general consensus about the standard how to perform pre-acclimatization by simulated altitude. We review different types of exposure and focus target groups which may get benefit from pre-acclimatization. We suggest to perform pre-acclimatization by sleeping some nights at a simulated altitude which follows the altitude profile of the "Gold Standard" for high altitude acclimatization. Until there are more detailed data about intermittent hypoxia this method should provide the best effect.

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Effects of intermittent hypoxia on the isocapnic hypoxic ventilatory response and erythropoiesis in humans

Cited by 79 publications

References 27 publications

Repeated hypoxic exposures change respiratory chemoreflex control in humans

Repeated hypoxic exposures change respiratory chemoreflex control in humans

Work in Hypoxic Conditions-Consensus Statement of the Medical Commission of the Union Internationale des Associations d'Alpinisme (UIAA MedCom)

Pre-Acclimatization for High Altitude Sojourns in Hypoxic Chambers

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