Abstract
Background: Coronavirus disease 2019 (COVID-19) causes an atypical acute respiratory distress syndrome associated with thromboembolism and high shunt fraction. Shunt may be intrapulmonary, or extrapulmonary. Handheld devices are increasingly being used for point-of-care ultrasound, but their use to characterize shunt has not been reported.
Objectives: Determine the feasibility of using handheld ultrasound to detect and characterize anatomical substrates of hypoxia and deep vein thrombosis (DVT) in patients with COVID-19 suspected to have severe shunt.
Methods: A handheld ultrasound device (iQ, Butterfly, USA) was used to perform lung ultrasound, vascular assessment for DVT, and limited transthoracic echocardiography (TTE) with color Doppler and saline microbubble contrast in patients with COVID-19 suspected to have severe shunt. Images were reassessed by an independent reviewer.
Results: After screening 40 patients, six patients who fulfilled the inclusion criteria were identified. Two were excluded because palliation had been initiated. So, four patients were studied. Interpretable images were obtained in all cases. Interobserver agreement was good. All patients had abnormal lung ultrasound (lung ultrasound score range 17-22). Identified lung pathology included interstitial syndrome with light beams and small peripheral consolidation (4), lobar consolidation (1), and pleural effusion (1). Abnormal echocardiographic findings included interatrial shunt (2), intrapulmonary shunt (1), and dilated right ventricle with tricuspid valve regurgitation (1). Significant DVT was not detected.
Conclusion: Use of handheld ultrasound to perform combined lung ultrasound, DVT ultrasound, and limited TTE with color Doppler and saline microbubble contrast is feasible, and may be able to characterize shunt in critically hypoxic patients. Serial studies could be used to monitor changes in shunt. Further studies are required to determine whether this can guide treatment to improve the outcomes of patients with refractory hypoxia.