Lung, Heart, Vascular, and Diaphragm Ultrasound Examination of COVID-19 Patients: A Comprehensive Approach

Abstract

Lung ultrasound (LU) has a multitude of features and capacities that make it a useful medical tool to assist physicians contending with the pandemic spread of novel coronavirus disease-2019 (COVID-19) caused by coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Thus, an LU approach to patients with suspected COVID-19 is being implemented worldwide. In noncritical COVID-19 patients, 2 new LU signs have been described and proposed, the "waterfall" and the "light beam" signs. Both signs have been hypothesized to increase the diagnostic accuracy of LU for COVID-19 interstitial pneumonia. In critically ill patients, a distinct pattern of LU changes seems to follow the disease's progression, and this information can be used to guide decisions about when a patient needs to be ventilated, as occurs in other disease states similar to COVID-19. Furthermore, a new algorithm has been published, which enables the automatic detection of B-lines as well as quantification of the percentage of the pleural line associated with lung disease. In COVID-19 patients, a direct involvement of cardiac function has been demonstrated, and ventilator-induced diaphragm dysfunction might be present due to the prolonged mechanical ventilation often involved, as reported for similar diseases. For this reason, cardiac and diaphragm ultrasound evaluation are highly important. Last but not least, due to the thrombotic tendency of COVID-19 patients, particular attention also should be paid to vascular ultrasound. This review is primarily devoted to the study of LU in COVID-19 patients. The authors explain the significance of its "light and shadows," bearing in mind the context in which LU is being used-the emergency department and the intensive care setting. The use of cardiac, vascular, and diaphragm ultrasound is also discussed, as a comprehensive approach to patient care.

Keywords: cardiac ultrasound, diaphragm ultrasound, COVID-19; lung ultrasound.

Fig. 1

The “light beam” LU sign has been proposed as a characteristic sign of COVID-19. Corresponding to ground glass opacification in computed tomography scans, it is represented by a shining band-form artifact spreading down from a large portion of a regular pleural line (white star). See also Video 1.

Fig. 2

The flowchart summarizes the clinical and LU approach to the adult patient with suspected COVID-19 arriving in the emergency department. LU, lung ultrasound; RT-PCR, reverse transcription-polymerase chain reaction via nasal swab.

Fig. 3

(A) Bilateral B-lines are visualized both in separate and coalescent forms. (B) They can arise from small peripheral subpleural consolidations (white arrows) and spread down like rays, maintaining their brightness until the edge of the screen. See also Video 1.

Fig. 4

Dilated right heart ventricle with a small left ventricle secondary left heart compression. See also Video 2; a transesophageal 55 Hz probe showing an intrahepatic inferior vena cava thrombus. LV, left ventricle; RV, right ventricle.

Fig. 5

Right diaphragm excursion. DE, diaphragmatic excursion; Slope, diaphragmatic contraction speed; Tinsp, inspiration time.

Fig. 6

Diaphragm thickening fraction (DTF) assessment in a difficult to wean 52-year-old man affected by COVID-19 respiratory distress following 10 days of invasive ventilation (see also supplemental video 3). Legend: AB (end of expiration thickness); CD (end of inspiration thickness).