Blood pressure response to exposure to moderate altitude in patients with COPD

Abstract

Purpose

Patients with COPD might be particularly susceptible to hypoxia-induced autonomic dysregulation. Decreased baroreflex sensitivity (BRS) and increased blood pressure (BP) variability (BPV) are markers of impaired cardiovascular autonomic regulation and there is evidence for an association between decreased BRS/increased BPV and high cardiovascular risk. The aim of this study was to evaluate the effect of short-term exposure to moderate altitude on BP and measures of cardiovascular autonomic regulation in COPD patients.

Materials and methods

Continuous morning beat-to-beat BP was noninvasively measured with a Finometer^® device for 10 minutes at low altitude (490 m, Zurich, Switzerland) and for 2 days at moderate altitude (2,590 m, Davos Jakobshorn, Switzerland) – the order of altitude exposure was randomized. Outcomes of interest were mean SBP and DBP, BPV expressed as the coefficient of variation (CV), and spontaneous BRS. Changes between low altitude and day 1 and day 2 at moderate altitude were assessed by ANOVA for repeated measurements with Fisher’s exact test analysis.

Results

Thirty-seven patients with moderate to severe COPD (mean±SD age 64±6 years, FEV₁ 60%±17%) were included. Morning SBP increased by +10.8 mmHg (95% CI: 4.7–17.0, P=0.001) and morning DBP by +5.0 mmHg (95% CI: 0.8–9.3, P=0.02) in response to altitude exposure. BRS significantly decreased (P=0.03), whereas BPV significantly and progressively increased (P<0.001) upon exposure to altitude.

Conclusion

Exposure of COPD patients to moderate altitude is associated with a clinically relevant increase in BP, which seems to be related to autonomic dysregulation.

Clinical trial registration

ClinicalTrials.gov (NCT1875133).

Keywords:

• COPD
• hypobaric hypoxia
• baroreflex sensitivity
• blood pressure variability

Acknowledgments

This work was supported by a Swiss National Science Foundation grant (32003B_143875) and the Clinical Research Priority Program (CRPP) Sleep and Health of the University of Zurich. The sponsors had no role in the design or conduct of the study, analysis and interpretation of the data, or writing the manuscript. The abstract of this paper was presented at the Annual Conference of the Schweizerische Gesellschaft für Pneumologie in Lugano, Switzerland (16–17 April 2015) as a conference talk and at the Annual Congress of the European Respiratory Society in Amsterdam, the Netherlands (26–30 September 2015) as a poster. The poster’s abstract was published in a supplement of the European Respiratory Journal, 1 September 2015, volume 46, issue suppl 59. DOI 10.1183/13993003.congress-2015.PA2309.

Author contributions

Drafting the article: EIS. All authors contributed to data analysis, revising the article, gave final approval of the version to be published, and agree to be accountable for all aspects of the work.

Disclosure

The authors declare no conflict of interest in this work.