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. 2021 Mar 8;7(1):00737-2020.
doi: 10.1183/23120541.00737-2020. eCollection 2021 Jan.

Chest computed tomography and alveolar-arterial oxygen gradient as rapid tools to diagnose and triage mildly symptomatic COVID-19 pneumonia patients

Marlise P de Roos  1 , Iris D Kilsdonk  2 , Pieter-Paul W Hekking  1 , Jan Peringa  2 , Nynke G Dijkstra  1 , Peter W A Kunst  1 , Paul Bresser  1 , Herre J Reesink  1
Affiliations

Chest computed tomography and alveolar-arterial oxygen gradient as rapid tools to diagnose and triage mildly symptomatic COVID-19 pneumonia patients

Marlise P de Roos et al. ERJ Open Res. .

Abstract

Background: In the coronavirus disease 2019 (COVID-19) pandemic, rapid clinical triage is crucial to determine which patients need hospitalisation. We hypothesised that chest computed tomography (CT) and alveolar-arterial oxygen tension ratio (A-a) gradient may be useful to triage these patients, since they reflect the severity of the pneumonia-associated ventilation/perfusion abnormalities.

Methods: A retrospective analysis was performed in 235 consecutive patients suspected for COVID-19. The diagnostic protocol included low-dose chest CT and arterial blood gas analysis. In patients with CT-based COVID-19 pneumonia, the association between "need for hospitalisation" and A-a gradient was investigated by a multivariable logistic regression model. The A-a gradient was tested as a predictor for need for hospitalisation using receiver operating characteristic curve analysis and a logistic regression model.

Results: 72 out of 235 patients (mean±sd age 55.5±14.6 years, 40% female) screened by chest CT showed evidence for COVID-19 pneumonia. In these patients, A-a gradient was shown to be a predictor of need for hospitalisation, with an optimal decision level (cut-off) of 36.4 mmHg (95% CI 0.70-0.91, p<0.001). The A-a gradient was shown to be independently associated with need for hospitalisation (OR 1.97 (95% CI 1.23-3.15), p=0.005; A-a gradient per 10 points) from CT severity score (OR 1.13 (95% CI 0.94-1.36), p=0.191), National Early Warning Score (OR 1.19 (95% CI 0.91-1.57), p=0.321) or peripheral oxygen saturation (OR 0.88 (95% CI 0.68-1.14), p=0.345).

Conclusion: Low-dose chest CT and the A-a gradient may serve as rapid and accurate tools to diagnose COVID-19 pneumonia and to select mildly symptomatic patients in need for hospitalisation.

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Conflict of interest statement

Conflict of interest: M.P. de Roos has nothing to disclose. Conflict of interest: I.D. Kilsdonk has nothing to disclose. Conflict of interest: P-P.W. Hekking has nothing to disclose. Conflict of interest: J. Peringa has nothing to disclose. Conflict of interest: N.G. Dijkstra has nothing to disclose. Conflict of interest: P.W.A. Kunst has nothing to disclose. Conflict of interest: P. Bresser has nothing to disclose . Conflict of interest: H.J. Reesink has nothing to disclose.

Figures

FIGURE 1
FIGURE 1
Coronavirus disease 2019 (COVID-19) suspected patients admitted to the Corona Screening Unit (CSU). CO-RADS: COVID-19 Reporting and Data System; ABG: arterial blood gas; LOS: length of stay.
FIGURE 2
FIGURE 2
Alveolar-arterial oxygen tension ratio (A-a) gradient to predict the need for hospitalisation in coronavirus disease 2019 patients. AUC: area under the curve.
FIGURE 3
FIGURE 3
Computed tomography-severity score (CT-SS) to predict the need for hospitalisation in COVID-19 patients. AUC: area under the curve.
FIGURE 4
FIGURE 4
Age adjusted alveolar-arterial oxygen tension ratio (A-a) gradient to predict the need for hospitalisation in COVID-19 patients. AUC: area under the curve.
See this image and copyright information in PMC

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