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Background To investigate the effect of asthma rehabilitation at high altitude (3100 m, HA) compared to low altitude (760 m, LA). Methods For this randomized parallel-group trial insufficiently controlled asthmatics (Asthma Control Questionnaire (ACQ) > 0.75) were randomly assigned to 3-week in-hospital rehabilitation comprising education, physical-&breathing-exercises at LA or HA. Co-primary outcomes assessed at 760 m were between group changes in peak expiratory flow (PEF)-variability, and ACQ) from baseline to end-rehabilitation and 3 months thereafter. Results 50 asthmatics were randomized [median (quartiles) LA: ACQ 2.7(1.7;3.2), PEF-variability 19%(14;33); HA: ACQ 2.0(1.6;3.0), PEF-variability 17%(12;32)]. The LA-group improved PEF-variability by median(95%CI) -7%(− 14 to 0, p = 0.033), ACQ − 1.4(− 2.2 to − 0.9, p < 0.001), and after 3 months by − 3%(− 18 to 2, p = 0.103) and − 0.9(− 1.3 to − 0.3, p = 0.002). The HA-group improved PEF-variability by − 10%(− 21 to − 3, p = 0.004), ACQ − 1.1(− 1.3 to − 0.7, p < 0.001), and after 3 months by − 9%(− 10 to − 3, p = 0.003) and − 0.2(− 0.9 to 0.4, p = 0.177). The additive effect of HA vs. LA directly after the rehabilitation on PEF-variability was − 6%(− 14 to 2), on ACQ 0.3(− 0.4 to 1.1) and after 3 months − 5%(− 14 to 5) respectively 0.4(− 0.4 to 1.1), all p = NS. Conclusion Asthma rehabilitation is highly effective in improving asthma control in terms of PEF-variability and symptoms, both at LA and HA similarly. Trial registration Clinicaltrials.gov: NCT02741583 , Registered April 18, 2016. Electronic supplementary material The online version of this article (10.1186/s12890-019-0890-y) contains supplementary material, which is available to authorized users.

Key Points Question Does preventive dexamethasone treatment mitigate altitude-related nocturnal hypoxemia in lowlanders with chronic obstructive pulmonary disease traveling to a high altitude? Findings In this randomized clinical trial of 118 patients with chronic obstructive pulmonary disease who lived below 800 m, dexamethasone, 4 mg, orally twice daily, starting 24 hours before ascent and while staying in a clinic at 3100 m, significantly mitigated the altitude-induced decrease in mean arterial oxygen saturation during 2 nights at 3100 m by 2% to 3%. In addition, dexamethasone therapy prevented emergence of central sleep apnea and improved subjective sleep quality. Meaning Patients with chronic obstructive pulmonary disease traveling to a high altitude may benefit from preventive dexamethasone treatment in terms of nocturnal oxygenation and sleep quality.

Objective: To evaluate the effects of acute exposure to high altitude and preventive dexamethasone treatment on postural control in patients with chronic obstructive pulmonary disease (COPD).Methods: In this randomized, double-blind parallel-group trial, 104 lowlanders with COPD GOLD 1-2 age 20–75 years, living near Bishkek (760 m), were randomized to receive either dexamethasone (2 × 4 mg/day p.o.) or placebo on the day before ascent and during a 2-day sojourn at Tuja-Ashu high altitude clinic (3100 m), Kyrgyzstan. Postural control was assessed with a Wii Balance BoardTM at 760 m and 1 day after arrival at 3100 m. Patients were instructed to stand immobile on both legs with eyes open during five tests of 30 s each, while the center of pressure path length (PL) was measured.Results: With ascent from 760 to 3100 m the PL increased in the placebo group from median (quartiles) 29.2 (25.8; 38.2) to 31.5 (27.3; 39.3) cm (P < 0.05); in the dexamethasone group the corresponding increase from 28.8 (22.8; 34.5) to 29.9 (25.2; 37.0) cm was not significant (P = 0.10). The mean difference (95% CI) between dexamethasone and placebo groups in altitude-induced changes (treatment effect) was -0.3 (-3.2 to 2.5) cm, (P = 0.41). Multivariable regression analysis confirmed a significant increase in PL with higher altitude (coefficient 1.6, 95% CI 0.2 to 3.1, P = 0.031) but no effect of dexamethasone was shown (coefficient -0.2, 95% CI -0.4 to 3.6, P = 0.925), even when controlled for several potential confounders. PL changes were related more to antero-posterior than lateral sway. Twenty-two of 104 patients had an altitude-related increase in the antero-posterior sway velocity of >25%, what has been associated with an increased risk of falls in previous studies.Conclusion: Lowlanders with COPD travelling from 760 to 3100 m revealed postural instability 24 h after arriving at high altitude, and this was not prevented by dexamethasone.Trial Registration: clinicaltrials.gov Identifier: NCT02450968.