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Dexamethasone improves maximal exercise capacity of individuals susceptible to high altitude pulmonary edema at 4559 m


Siebenmann, C; Bloch, K E; Lundby, C; Nussbamer-Ochsner, Y; Schoeb, M; Maggiorini, M (2011). Dexamethasone improves maximal exercise capacity of individuals susceptible to high altitude pulmonary edema at 4559 m. High Altitude Medicine and Biology, 12(2):169-177.

Abstract

We have previously demonstrated that prophylactic intake of dexamethasone improves maximal oxygen uptake (Vo(2)max) in high altitude pulmonary edema (HAPE) susceptible subjects 4 to 6 h after a 2-day climb to 4559 m. However, since with this ascent protocol HAPE usually develops after the first night at 4559 m or later, we hypothesized that a continued dexamethasone prophylaxis would result in an even more pronounced improvement of Vo(2)max after an additional night at high altitude. Vo(2)max of 24 HAPE susceptibles was evaluated on a bicycle ergometer at an altitude of 490 m and at 24 h after rapid ascent to 4559 m. Subjects were divided into two groups: The control group (n=14) performed both tests without dexamethasone, whereas the dexamethasone group (n=10) received dexamethasone 8 mg twice a day (b.i.d), starting 24 h prior to ascent. At 4559 m, Vo(2)max was 61% ± 6% of the baseline value in the control group and 70% ± 9% in the dexamethasone group (p=0.025). Similarly, O(2) pulse (Vo(2)/heart rate) was 68% ± 7% and 77% ± 11% of baseline, respectively (p=0.043). Arterial O(2) saturation at maximal exercise did not differ between groups, whereas at rest it was 83% ± 10% in the control group and 91% ± 4% in the dexamethasone group (p=0.009). Dexamethasone prophylaxis increased Vo(2)max of HAPE-susceptible individuals after the first night at 4559 m without affecting arterial O(2) saturation at maximal exercise. This might be explained by a sustained effect of dexamethasone on maximal cardiac output and pulmonary O(2) diffusion, both resulting in enhanced convectional O(2) transport to the locomotor muscles.

We have previously demonstrated that prophylactic intake of dexamethasone improves maximal oxygen uptake (Vo(2)max) in high altitude pulmonary edema (HAPE) susceptible subjects 4 to 6 h after a 2-day climb to 4559 m. However, since with this ascent protocol HAPE usually develops after the first night at 4559 m or later, we hypothesized that a continued dexamethasone prophylaxis would result in an even more pronounced improvement of Vo(2)max after an additional night at high altitude. Vo(2)max of 24 HAPE susceptibles was evaluated on a bicycle ergometer at an altitude of 490 m and at 24 h after rapid ascent to 4559 m. Subjects were divided into two groups: The control group (n=14) performed both tests without dexamethasone, whereas the dexamethasone group (n=10) received dexamethasone 8 mg twice a day (b.i.d), starting 24 h prior to ascent. At 4559 m, Vo(2)max was 61% ± 6% of the baseline value in the control group and 70% ± 9% in the dexamethasone group (p=0.025). Similarly, O(2) pulse (Vo(2)/heart rate) was 68% ± 7% and 77% ± 11% of baseline, respectively (p=0.043). Arterial O(2) saturation at maximal exercise did not differ between groups, whereas at rest it was 83% ± 10% in the control group and 91% ± 4% in the dexamethasone group (p=0.009). Dexamethasone prophylaxis increased Vo(2)max of HAPE-susceptible individuals after the first night at 4559 m without affecting arterial O(2) saturation at maximal exercise. This might be explained by a sustained effect of dexamethasone on maximal cardiac output and pulmonary O(2) diffusion, both resulting in enhanced convectional O(2) transport to the locomotor muscles.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Division of Surgical Intensive Care Medicine
04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology

04 Faculty of Medicine > Center for Integrative Human Physiology
04 Faculty of Medicine > University Hospital Zurich > Clinic for Pneumology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2011
Deposited On:10 Nov 2011 17:05
Last Modified:05 Apr 2016 15:05
Publisher:Mary Ann Liebert
ISSN:1527-0297
Additional Information:This is a copy of an article published in the High Altitude Medicine and Biology © 2011 copyright Mary Ann Liebert; High Altitude Medicine and Biology is available online at: http://www.liebertonline.com
Publisher DOI:https://doi.org/10.1089/ham.2010.1075
PubMed ID:21718165
Permanent URL: https://doi.org/10.5167/uzh-50841

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