Microvascular Injury and Distal Thrombosis in COVID-19

Study Overview
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Brief Summary
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Investigators aimed to better understand the pathophysiology of SARS-CoV-2 pneumonia in non-critically ill hospitalized patients secondarily presenting with clinical deterioration and increase in oxygen requirement

Detailed Description
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Investigators plan to consecutively enrol 25 patients without clinical or biological evidence for superinfection, without left ventricular dysfunction and for whom a pulmonary embolism was discarded by computed tomography pulmonary angiography. Investigators will investigate lung ventilation and perfusion (LVP) by LVP scintigraphy, and, 24 hours later, left and right ventricular function by 99mTc-labelled albumin gated-blood-pool scintigraphy with late (60 mn) tomographic albumin images on the lungs to evaluate lung albumin retention that could indicate microvascular injuries with secondary edema

Official Title
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Microvascular Injury With Secondary Edema, and Distal Peripheral Vascular Thrombosis Contribution to Clinical Deterioration of Non-critically Ill Patients Hospitalized for SARS-CoV-2 Pneumonia Without Evidence of Pulmonary Embolism: a Preliminary Prospective Observational Study

Conditions
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SARS-CoV-2 Infection

Intervention / Treatment
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* Diagnostic Test: lung ventilation/perfusion scintigraphy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Non-critically ill patients hospitalized in the COVID-19 Unit of the Centre Hospitalier Princesse Grace of Monaco Presenting with a sudden clinical deterioration defined by a respiratory rate impairment and/or a rise of oxygen flow to reach a peripheral capillary oxygen saturation (SpO2) of more than 95% during at least 48 hours a diagnosis of pulmonary embolism was discarded by CT pulmonary angiography no clinical or biological (procalcitonin levels) evidence of lung superinfection without clinical evidence for LV dysfunction Exclusion Criteria: Non confirmed COVID-19 pneumonia according to the WHO guidance by a positive result of RT-PCR assay of nasal and pharyngeal swabs, Patients without peripheral pulmonary ground-glass opacities or air-space consolidation on their chest CT scan at admission and common laboratory findings including lymphocytopenia, eosinopenia, significantly elevated markers of organ inflammation such as fibrinogen and C-reactive protein. Patients could not be included if their medical condition was unstable or precluded a safe transfer to the nuclear medicine department, if they were under mechanical ventilation (either non-invasive or invasive), if they required critical care unit, or in case of a pregnancy.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Diagnostic Test: lung ventilation/perfusion scintigraphy|Chest CT-scan will be performed with blocked inspiration. Lung ventilation/perfusion scintigraphy imaging will be performed within 24hrs after CT pulmonary angiography, 410MBq of Technegas will be inhaled by patients and ventilation tomography performed thereafter. Then, 185MBq 99mTc-macroaggegates will be injected intravenously followed by the perfusion tomography. A combined CT acquisition will be performed. The day following lung ventilation/perfusion scintigraphy, 740MBq of Tc99m labeled albumin will be intravenously administered. Cardiac gated-blood-pool scintigraphy will be then performed in best septal left anterior oblique and left profile according to specific parameters. 45-60 min after injection, a non-gated tomographic acquisition over the lungs will be done, with the same parameters than for PS SPECT, resulting in a late albumin acquisition.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Scintigraphic pattern of peripheral lung thrombosis | Determination of the number of patients/pulmonary segments with scintigraphic pattern of peripheral lung thrombosis on the basis of a mismatch between normal ventilation and abnormal perfusion | During hospitalization | 
| Pulmonary microvascular injury | Determination of the number of patients/pulmonary segments with evidence for microvascular injury on the basis of a lung 99mTc albumin retention, calculated as albumin uptake normalized by the macro-aggregates perfusion uptake | During hospitalization | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Prognosis evolution at 15 days | Determination of prognosis using categorical variables: worsening or stability vs improvement in the 15 following days, delay to the recovery of a 95% or more SpO2 in ambient air below vs above 15 days, hospitalization duration below vs above 15 days | 15 days after hospitalization | 
| CT abnormalities prognostic value | The prognostic value of the extent of CT abnormalities, a right ventricular ejection fraction below vs above 50%, a significant albumin uptake (AI/PI) above or equal to 1.7, and the presence and/or number of paradoxically hypoventilated and hypoperfused normal segments will be evaluated by Fisher's exact test and Mann Whitney U test | 15 days after hospitalization | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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lung thrombosis, pulmonary embolism, lung scintigraphy, alveolar albumin uptake