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Comment
. 2021 Jan 6;22(1):4.
doi: 10.1186/s12931-020-01604-9.

Happy hypoxemia, or blunted ventilation?

Josuel Ora  1 , Paola Rogliani  2   3 , Mario Dauri  4 , Denis O'Donnell  5
Affiliations
Comment

Happy hypoxemia, or blunted ventilation?

Josuel Ora et al. Respir Res. .

Abstract

Happy hypoxemia is an unspecified definition that is used in COVID-19 patients to define hypoxemia without dyspnoea. Dyspnoea is a very complex symptom, and although hypoxemia can cause breathlessness, dyspnoea is not related to hypoxemia, but is more closely related to inspiratory drive and mechanical alterations. The lack of dyspnoea in the early stages of the disease is likely related to the absence of increased inspiratory drive due to compensatory mechanisms of hypoxemia, while in the advanced stages there is no evidence of a lack of dyspnoea in COVID-19 patients.

Keywords: COVID-19; Dyspnea; Dyspnea descriptors; Hypoxemia; Respiratory drive.

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Conflict of interest statement

JO, MD, PR, DO have no conflicts of interest concerning this topic.

Figures

Fig. 1
Fig. 1
Dyspnea model in COVID-19. The increase in dyspnea correlates with the increase in ventilation. In the early stages of COVID-19 the alterations are mainly due to alterations of gas exchange and do not cause major changes in respiratory mechanics and mechanical constraints (normal elastance), with a good relationship between respiratory drive and mechanical coupling, and dyspnea will be described as increased work/effort, in the advanced stages there are alterations of respiratory mechanics with mechanical constraint (high elastance) and neuromechanical dissociation and dyspnea will be described as air hunger or difficult inspiration. If hypoxemia is not accompanied by increased ventilation, it will not cause dyspnea and it could be defined “happy or silent hypoxia”. NMD neuromechanical dissociation, V/Q ventilation/perfusion, IND inspiratory drive
See this image and copyright information in PMC

Comment on

References

    1. Dhont S, Derom E, Van Braeckel E, et al. The pathophysiology of ‘happy’ hypoxemia in COVID-19. Respir Res. 2020;21:198. doi: 10.1186/s12931-020-01462-5. - DOI - PMC - PubMed
    1. Tobin MJ, Jubran A, Laghi F. Misconceptions of pathophysiology of happy hypoxemia and implications for management of COVID-19. Respir Res. 2020;21:249. doi: 10.1186/s12931-020-01520-y. - DOI - PMC - PubMed
    1. Ora J, Liguori C, Puxeddu E, et al. Dyspnea perception and neurological symptoms in non-severe COVID-19 patients. Neurol Sci. 2020;41:2671–2674. doi: 10.1007/s10072-020-04632-x. - DOI - PMC - PubMed
    1. Guan W-J, Ni Z-Y, Hu Y, et al. Clinical characteristics of coronavirus disease 2019 in China. N Engl J Med. 2020;382:1708–1720. doi: 10.1056/NEJMoa2002032. - DOI - PMC - PubMed
    1. Huang C, Wang Y, Li X, et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet. 2020;395:497–506. doi: 10.1016/S0140-6736(20)30183-5. - DOI - PMC - PubMed