Alveolar-to-arterial oxygen gradient: role in the management of COVID-19 infection mild population

Farina, Gabriele; Gianstefani, Alice; Salvatore, V.; Anziati, Martina; Baldassarri, Francesca; Beleffi, Michelle; Cannizzaro, Alfredo; Casadei, Elena; Fantini, Jacopo; Tubertini, Eleonora; Nava, Stefano; Giostra, Fabrizio

doi:10.21203/rs.3.rs-100668/v1

“…However, their cutoff value was 56.6 ± 17.5 in the ICU group and 25.9 ± 9.7 in the non-ICU group; given small sample size, strong emphasis cannot be laid upon results. Farina et al 10 also investigated the role of A–a gradient in predicting the need for hospitalization, the survival rate, and identifying pneumonia in patients with SARS-CoV-2 infection. They reported that out of 168 patients with AaDO 2 ≤27, only 3 (1.8%) required readmission within 7 days; it could be attributed to the inclusion of patients with less disease severity.…”

Section: Discussionmentioning

confidence: 99%

Arterial Blood Gas as a Predictor of Mortality in COVID Pneumonia Patients Initiated on Noninvasive Mechanical Ventilation: A Retrospective Analysis

Gupta

¹

,

Jain

²

,

Chandrakar

³

et al. 2021

Indian Journal of Critical Care Medicine

17

1

0

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Background: The alveolar–arterial oxygen (A–a) gradient measures the difference between the oxygen concentration in alveoli and the arterial system, which has considerable clinical utility. Materials and methods: It was a retrospective, observational cohort study involving the analysis of patients diagnosed with acute COVID pneumonia and required noninvasive mechanical ventilation (NIV) over a period of 3 months. The primary objective was to investigate the utility of the A–a gradient (pre-NIV) as a predictor of 28-day mortality in COVID pneumonia. The secondary objective included the utility of other arterial blood gas (ABG) parameters (pre-NIV) as a predictor of 28-day mortality. The outcome was also compared between survivors and nonsurvivors. The outcome variables were analyzed by receiver-operating characteristic (ROC) curve, Youden index, and regression analysis. Results: The optimal criterion for A–a gradient to predict 28-day mortality was calculated as ≤430.43 at a Youden index of 0.5029, with the highest area under the curve (AUC) of 0.755 ( p <0.0001). On regression analysis, the odds ratio for the A–a gradient was 0.99. A significant difference was observed in ABG predictors, including PaO 2 , PaCO 2 , A–a gradient, AO 2 , and arterial–alveolar (a–A) (%) among nonsurvivors vs survivors ( p -value <0.001). The vasopressor requirement, need for renal replacement therapy, total parenteral requirement, and blood transfusion were higher among nonsurvivors; however, a significant difference was achieved with the vasopressor need ( p <0.001). Conclusion: This study demonstrated that the A–a gradient is a significant predictor of mortality in patients initiated on NIV for worsening respiratory distress in COVID pneumonia. All other ABG parameters also showed a significant AUC for predicting 28-day mortality, although with variable sensitivity and specificity. Key messages: COVID-19 pneumonia shows an initial presentation with type 1 respiratory failure with increased A–a gradient, while a subsequent impending type 2 respiratory failure requires invasive ventilation. A significant difference was observed in ABG predictors, including PaO 2 , PaCO 2 , A–a gradient, AO 2 , and a–A (%) among nonsurvivors vs survivors. ( p -value <0.001). The vasopressor requirement, need for renal replacement therapy, total parenteral requirement, and blood transfusion need were higher among nonsurvivors than survivors; however, a significant difference was achieved with the vasopressor need ( p <0.001). How to cite this article: Gupta B, Jain G, Chandrakar S, Gupta N, Agarwal A. Arterial Blood Gas as a P...

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“…As noted, COVID-19 pneumonia is characterized by both an alveolar and vascular damage [ 3 ]. Even though, few studies have been performed to assess the accuracy of D(A-a)O 2 in early identifying severe COVID-19 pneumonia, and, as far as we know, no previous studies have compared the performance of D(A-a)O 2 and PaO 2 /FiO 2 in this context [ 12 , 13 , 14 , 15 , 16 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

Alveolar–Arterial Gradient Is an Early Marker to Predict Severe Pneumonia in COVID-19 Patients

Pipitone

¹

,

Camici

²

,

Granata

³

et al. 2022

Infectious Disease Reports

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Background: One of the main challenges in the management of COVID-19 patients is to early assess and stratify them according to their risk of developing severe pneumonia. The alveolar–arterial oxygen gradient (D(A-a)O2) is defined as the difference between the alveolar and arteriolar concentration of oxygen, an accurate index of the ventilatory function. The aim of this study is to evaluate D(A-a)O2 as a marker for predicting severe pneumonia in COVID-19 patients, in comparison to the PaO2/FiO2. Methods: This retrospective, multicentric cohort study included COVID-19 patients admitted to two Italian hospitals between April and July 2020. Clinical and laboratory data were retrospectively collected at the time of hospital admission and during hospitalization. The presence of severe COVID-19 pneumonia was evaluated, as defined by the Infectious Diseases Society of America (IDSA) criteria for community-acquired pneumonia (CAP). Patients were divided in severe and non-severe groups. Results: Overall, 53 COVID-19 patients were included in the study: male were 30/53 (57%), and 10/53 (19%) had severe pneumonia. Patients with severe pneumonia reported dyspnea more often than non-severe patients (90% vs. 39.5%; p = 0.031). A history of chronic obstructive pulmonary disease (COPD) was recalled by 5/10 (50%) patients with severe pneumonia, and only in 6/43 (1.4%) of non-severe cases (p = 0.023). A ROC curve, for D(A-a)O2 >60 mmHg in detecting severe pneumonia, showed an area under the curve (AUC) of 0.877 (95% CI: 0.675–1), while the AUC of PaO2/FiO2 < 263 mmHg resulted 0.802 (95% CI: 0.544–1). D(A-a)O2 in comparison to PaO2/FiO2 had a higher sensibility (77.8% vs. 66.7%), positive predictive value (75% vs. 71.4%), negative predictive value (94% vs. 91%), and similar specificity (94.4% vs. 95.5%). Conclusions: Our study suggests that the D(A-a)O2 is more appropriate than PaO2/FiO2 to identify COVID-19 patients at risk of developing severe pneumonia early.

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The Association Between Alveolar–Arterial Oxygen Tension Difference and the Severity of COVID-19 in Patients

Xie

¹

,

Deng

²

,

Li

³

et al. 2023

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Introduction Coronavirus disease 2019 (COVID-19) emerged as a global pandemic and resulted in a significantly high death toll. Therefore, there is an urgent need to find a potential biomarker related to the disease severity that can facilitate early-stage intervention. Methods In the present study, we collected 242 laboratory-confirmed COVID-19-infected patients. The patients were grouped according to the alveolar to arterial oxygen tension difference (P A-a O 2 ) value of COVID-19 infection after admission. Results Among the 242 laboratory-confirmed COVID-19- infected patients, 155 (64.05%) had an abnormal P A-a O 2 value on admission. Compared with the normal P A-a O 2 group, the median age of the abnormal P A-a O 2 group was significantly older ( p = 0.032). Symptoms such as fever, cough, and shortness of breath were more obvious in the abnormal P A-a O 2 group. The proportion of severe events in the abnormal P A-a O 2 group was higher than the normal P A-a O 2 group (10.34% vs. 23.23%, p = 0.013). The abnormal P A-a O 2 group had a higher possibility of developing severe events compared with the normal P A-a O 2 group (HR 2.622, 95% CI 1.197–5.744, p = 0.016). After adjusting for age and common comorbidities (hypertension and cardiovascular disease), the abnormal P A-a O 2 group still exhibited significantly elevated risks of developing severe events than the normal P A-a O 2 group (HR 2.986, 95% CI 1.220–7.309, p = 0.017). Additionally, the abnormal P A-a O 2 group had more serious inflammation/coagulopathy/fibrinolysis parameters than the normal P A-a O 2 group. Conclusion Abnormal P A-a O 2 value was found to be common in COVID-19 patients, was strongly related to severe event development, and could be a potential biomarker for the prognosis of COVID-19 patients. Supplementary Information The online version contains supplementary material available at 10.1007/s40121-022-00752-3.

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Alveolar-to-arterial oxygen gradient: role in the management of COVID-19 infection mild population

Cited by 3 publications

References 6 publications

Arterial Blood Gas as a Predictor of Mortality in COVID Pneumonia Patients Initiated on Noninvasive Mechanical Ventilation: A Retrospective Analysis

Arterial Blood Gas as a Predictor of Mortality in COVID Pneumonia Patients Initiated on Noninvasive Mechanical Ventilation: A Retrospective Analysis

Alveolar–Arterial Gradient Is an Early Marker to Predict Severe Pneumonia in COVID-19 Patients

The Association Between Alveolar–Arterial Oxygen Tension Difference and the Severity of COVID-19 in Patients

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