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

Fuglebjerg, Natascha Josephine Ulstrand; Jensen, Tomas; Hoyer, Nils; Ryrsø, Camilla Koch; Lindegaard, Birgitte; Harboe, Zitta Barrella

doi:10.1016/j.ijid.2020.07.014

Cited by 65 publications

(63 citation statements)

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“…We agree with Tobin et al [1] that "the essential point about happy hypoxemia is that patients can be profoundly hypoxic and yet exhibit no abnormality in breathing pattern". This is worrying indeed, as the severity of hypoxemia is independently associated with inhospital mortality and in particular of concern among patients with chronic compromised organ perfusion such as ischemic heart disease [3][4][5]. However, in our experience, subtle changes in breathing pattern may serve as early warning signs of impending hypoxemic respiratory failure in COVID-19.…”

Section: Lettermentioning

confidence: 90%

Conceptions of the pathophysiology of happy hypoxemia in COVID-19

et al. 2021

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In their letter-to-the-editor entitled “Misconceptions of pathophysiology of happy hypoxemia and implications for management of COVID-19”, Tobin et al. (Respir Res 21:249, 2020) debated our views on happy hypoxemia in COVID-19 (Respir Res 21:198, 2020). We thank the authors for their interesting comments and alternative viewpoints, and we would like to clarify several important aspects raised.

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Section: Lettermentioning

confidence: 90%

Conceptions of the pathophysiology of happy hypoxemia in COVID-19

et al. 2021

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“…Our review ndings, combined with what is known about the pathophysiology of acute Covid-19 [8,12,13,35], suggest a conservative and risk adverse approach to exercise desaturation testing, especially in the home environment. The levels of desaturation observed with brief exercise tests in patients with chronic lung disease [27, 39-41, 43, 44, 46, 47, 49] may be even more marked in those with acute Covid-19.…”

Section: Implications For Practicementioning

confidence: 91%

“…In a small study of 26 COVID-19 patients assessed prior to discharge from hospital, Fuglebjurg et al used the 6MWT to assess the degree of exertional hypoxia; symptoms of subjective dyspnoea were noted [35]. 13 patients developed exercise-induced hypoxia (de ned as SpO 2 < 90%) during the 6MWT, of whom four had pulmonary embolism (a perfusion defect).…”

Section: Exertional Tests For Measuring Desaturation In Covid-19mentioning

confidence: 99%

What is the Efficacy and Safety of Rapid Exercise Tests for Exertional Desaturation in Covid-19: A Rapid Systematic Review 

Kalin

Javid

Knight

et al. 2020

Preprint

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BackgroundEven when resting pulse oximetry is normal in the patient with acute Covid-19, hypoxia can manifest on exertion. We sought to summarise the literature on the performance of different rapid tests for exertional desaturation. Main research questionWhat tests have been formally evaluated for the rapid assessment of exertional hypoxia in patients with lung disease against a gold standard exercise test such as the 6MWT and CPET? MethodAMED, CINAHL, EMBASE MEDLINE, Cochrane and PubMed using LitCovid, Scholar and Google databases were searched to September 2020. Studies where participants had Covid-19 or another lung disease and underwent any form of exercise test which was compared to a reference standard were eligible. Risk of bias was assessed using QUADAS 2. Heterogeneity of study design precluded meta-analysis. ResultsOf 47 relevant papers, 15 were empirical studies, of which 11 described an attempt to validate one or more exercise desaturation tests in lung diseases other than Covid-19. In all but one of these, methodological quality was poor or impossible to fully assess. None had been designed as a formal validation study (most used simple tests of correlation). Only one validation study (comparing a 1-minute sit-to-stand test [1MSTST] with the reference standard 6-minute walk test [6MWT] in 107 patients with interstitial lung disease) contained sufficient raw data for us to calculate the sensitivity (88%), specificity (81%), and positive and negative predictive value (79% and 89% respectively) of the 1MSTST. The other 4 empirical studies included two predictive studies on patients with Covid-19, and two on HIV-positive patients with suspected pneumocystis pneumonia. We found no studies on the 40-step walk test (a less demanding test that is widely used in clinical practice to assess Covid-19 patients). DiscussionExertional desaturation tests have not yet been validated in patients with (or suspected of having) Covid-19. Whilst there is limited evidence for the diagnostic accuracy of the 1MSTST in other diseases, specific features of this disease (e.g. exertional hypoxia is common and many assessments are done remotely with no clinician present to resuscitate) may raise safety issues. The less strenuous 40-step walk test should be urgently evaluated.

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“…In a small study of 26 COVID-19 patients assessed prior to discharge from hospital, Fuglebjurg et al used the 6MWT to assess the degree of exertional hypoxia; symptoms of subjective dyspnoea were noted [37]. 13 patients developed exercise-induced hypoxia (de ned as SpO 2 < 90%) during the 6MWT, of whom four had pulmonary embolism (a perfusion defect).…”

Section: Exertional Tests For Measuring Desaturation In Covid-19mentioning

confidence: 99%

Direct and indirect evidence of efficacy and safety of rapid exercise tests for exertional desaturation in Covid-19: A rapid systematic review

Kalin

Javid

Knight

et al. 2021

Preprint

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BackgroundEven when resting pulse oximetry is normal in the patient with acute Covid-19, hypoxia can manifest on exertion. We summarise the literature on the performance of different rapid tests for exertional desaturation and draw on this evidence base to provide guidance in the context of acute COVID-19.Main research questions1. What exercise tests have been used to assess exertional hypoxia at home or in an ambulatory setting in the context of Covid-19 and to what extent have they been validated?2. What exercise tests have been used to assess exertional hypoxia in other lung conditions, to what extent have they been validated and what is the applicability of these studies to acute Covid-19?MethodAMED, CINAHL, EMBASE MEDLINE, Cochrane and PubMed using LitCovid, Scholar and Google databases were searched to September 2020. Studies where participants had Covid-19 or another lung disease and underwent any form of exercise test which was compared to a reference standard were eligible. Risk of bias was assessed using QUADAS 2. A protocol for the review was published on the Medrxiv database.ResultsOf 47 relevant papers, 15 were empirical studies, of which 11 described an attempt to validate one or more exercise desaturation tests in lung diseases other than Covid-19. In all but one of these, methodological quality was poor or impossible to fully assess. None had been designed as a formal validation study (most used simple tests of correlation). Only one validation study (comparing a 1-minute sit-to-stand test [1MSTST] with reference to the 6-minute walk test [6MWT] in 107 patients with interstitial lung disease) contained sufficient raw data for us to calculate the sensitivity (88%), specificity (81%), and positive and negative predictive value (79% and 89% respectively) of the 1MSTST. The other 4 empirical studies included two predictive studies on patients with Covid-19, and two on HIV-positive patients with suspected pneumocystis pneumonia. We found no studies on the 40-step walk test (a less demanding test that is widely used in clinical practice to assess Covid-19 patients). Heterogeneity of study design precluded meta-analysis.DiscussionExertional desaturation tests have not yet been validated in patients with (or suspected of having) Covid-19. A stronger evidence base exists for the diagnostic accuracy of the 1MSTST in chronic long term pulmonary disease, the relative intensity of this test may raise safety concerns in remote consultations or unstable patients. The less strenuous 40-step walk test should be urgently evaluated.

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

Abstract: Highlights Anecdotal reports of asymptomatic ‘silent hypoxia’ in COVID-19 are emerging A minimal increase in dyspnea was seen with worsening hypoxia during exercise The 6-minute walking test is a potential tool in discharge assessment

Cited by 65 publications

References 8 publications

Conceptions of the pathophysiology of happy hypoxemia in COVID-19

Conceptions of the pathophysiology of happy hypoxemia in COVID-19

What is the Efficacy and Safety of Rapid Exercise Tests for Exertional Desaturation in Covid-19: A Rapid Systematic Review

Direct and indirect evidence of efficacy and safety of rapid exercise tests for exertional desaturation in Covid-19: A rapid systematic review

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

Abstract: Highlights Anecdotal reports of asymptomatic ‘silent hypoxia’ in COVID-19 are emerging A minimal increase in dyspnea was seen with worsening hypoxia during exercise The 6-minute walking test is a potential tool in discharge assessment

Cited by 65 publications

References 8 publications

Conceptions of the pathophysiology of happy hypoxemia in COVID-19

Conceptions of the pathophysiology of happy hypoxemia in COVID-19

What is the Efficacy and Safety of Rapid Exercise Tests for Exertional Desaturation in Covid-19: A Rapid Systematic Review&nbsp;

Direct and indirect evidence of efficacy and safety of rapid exercise tests for exertional desaturation in Covid-19: A rapid systematic review

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What is the Efficacy and Safety of Rapid Exercise Tests for Exertional Desaturation in Covid-19: A Rapid Systematic Review