Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Oct:99:100-101.
doi: 10.1016/j.ijid.2020.07.014. Epub 2020 Jul 11.

Silent hypoxia in patients with SARS CoV-2 infection before hospital discharge

Natascha Josephine Ulstrand Fuglebjerg  1 , Tomas Oestergaard Jensen  1 , Nils Hoyer  1 , Camilla Koch Ryrsø  1 , Birgitte Lindegaard  1 , Zitta Barrella Harboe  2
Affiliations

Silent hypoxia in patients with SARS CoV-2 infection before hospital discharge

Natascha Josephine Ulstrand Fuglebjerg et al. Int J Infect Dis. 2020 Oct.

Abstract

Objective: To assess the degree of hypoxia and subjective dyspnea elicited by a 6-minute walking test (6MWT) in COVID-19 patients prior to discharge.

Methods: A 6MWT was performed in 26 discharge-ready COVID-19 patients without chronic pulmonary disease or cardiac failure. Heart rate, oxyhemoglobin saturation (SpO2), respiratory rate, and subjective dyspnea measured on the Borg CR-10 scale were measured before and immediately after the 6MWT, with continuous monitoring of SpO2 and heart rate during the 6MWT. The 6MWT was terminated if SpO2 dropped below 90%. A historical cohort of 204 patients with idiopathic pulmonary fibrosis (IPF) was used for comparison.

Results: 13 (50%) of the COVID-19 patients developed exercise-induced hypoxia (SpO2 < 90%) during the 6MWT, of which one third had pulmonary embolism. COVID-19 patients experienced less hypoxia-related dyspnea during the 6MWT compared with patients with IPF.

Conclusion: The 6MWT is a potential tool in the diagnosis of asymptomatic exercise-induced hypoxia in hospitalized COVID-19 patients prior to discharge. Due to important methodological limitations, further studies are needed to confirm our findings and to investigate their clinical consequences.

Keywords: COVID-19; Discharge; Dyspnea; Exercise test; Hypoxia.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Decline in oxygen saturation (SpO2) and Borg CR-10 dyspnea scale rating after 6MWT in patients with COVID-19 (blue) and idiopathic pulmonary fibrosis (red). Each dot represents one patient. The lines are based on univariate linear regression.
See this image and copyright information in PMC

References

    1. ATS Committee on Proficiency Standards for Clinical Pulmonary Function Laboratories ATS statement: Guidelines for the six-minute walk test. Am J Respir Crit Care Med. 2002;166(1):111–117. doi: 10.1164/ajrccm.166.1.at1102. - DOI - PubMed
    1. Borg E., Kaijser L. A comparison between three rating scales for perceived exertion and two different work tests. Scand J Med Sci Sport. 2006;16(1):57–69. doi: 10.1111/j.1600-0838.2005.00448.x. - DOI - PubMed
    1. Borg G.A. Psychophysical bases of perceived exertion. Med Sci Sports Exerc. 1982;14(5):377–381. - PubMed
    1. Casanova C., Celli B.R., Barria P., Casas A., Cote C., de Torres J.P. Six Minute Walk Distance Project (ALAT). The 6-min walk distance in healthy subjects: Reference standards from seven countries. Eur Respir J. 2011;37:150–156. doi: 10.1183/09031936.00194909. - DOI - PubMed
    1. Couzin-Frankel J. The mystery of the pandemic’s ‘happy hypoxia’. Science. 2020;368(6490):455–456. doi: 10.1126/science.368.6490.455. - DOI - PubMed