Abstract
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.
Highlights
Today many settlements worldwide are located at high altitudes, with regular working places even above 3000 m
Multivariable regression analysis confirmed a significant increase in path length (PL) with higher altitude but no effect of dexamethasone was shown, even when controlled for several potential confounders
Lowlanders with chronic obstructive pulmonary disease (COPD) travelling from 760 to 3100 m revealed postural instability 24 h after arriving at high altitude, and this was not prevented by dexamethasone
Summary
Today many settlements worldwide are located at high altitudes (above 2500 m), with regular working places even above 3000 m. Other studies in healthy volunteers at a higher altitude (Mount Rosa, 4559 m) and in hypobaric chambers (Holness et al, 1982; Cymerman et al, 2001) have demonstrated worsening of PC. The underlying mechanisms are poorly understood but it is presumed, that hypoxia affects different sensory functions (visual, somatosensory and vestibular) as well as the central nervous system that controls posture-regulating muscles especially in the lower limbs and trunk within a few minutes of exposure to altitudes of 2438 m (8000 ft) or higher (Wagner et al, 2011; Chiba et al, 2016). During sojourns of more than a few hours at high altitude PC may be disturbed by acute mountain sickness (AMS), which causes headache, ataxia, weakness, dizziness, and decrements of alertness
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