The SARS-CoV-2 pandemic is undermining the ability of many advanced healthcare systems worldwide to provide quality care [1, 2]. COVID-19 is the disease caused by infection with SARS-CoV-2, a virus with specific tropism for the lower respiratory tract in the early disease stage . Computed tomography scans of patients with COVID-19 typically show a diffuse bilateral interstitial pneumonia, with asymmetric, patchy lesions distributed mainly in the periphery of the lung [4,5,6]. In the context of a pandemic, rapid case identification, classification of disease severity and correct treatment allocation are crucial for increasing surge capacity. Overtriage to admission and to intensive care by clinicians working in the department of emergency medicine (ED) will overwhelm system capacity. Undertriage can lead to loss of life and cross infections. Similarly, selection of those patients most likely to respond to specific treatments and determining the response to treatment in the intensive care unit (ICU) can conserve scarce resources. Lung ultrasound (LUS) is well known for its feasibility and high accuracy when used at the bedside for diagnosing pulmonary diseases [7, 8]. As the most striking manifestation of COVID-19 disease is in the pulmonary system, LUS performed by a trained and knowledgeable clinician may aid precisely in triage, classification of disease severity and treatment allocation in both the ED and the ICU. In this paper, we describe the use of LUS in treating patients with COVID-19.
Case identification and classification of disease severity
Pending RT-PCR test results, other patients (or staff) may be unnecessarily exposed to those carrying the disease. Verifying that patients have COVID-19 therefore remains the rate-limiting step in patient triage. Alternatively, redundant implementation of precautions may lead to unnecessary resource consumption. The use of LUS in this context could revolutionize patient triage.
The LUS technique described in this paper is detailed in the supplementary material (Online Resources Supplementary file 12 LUS_TECHNIQUE.docx and Figure_1-6 and Video_1-2). The pretest probability of gaining useful information from LUS is likely to be highest when the clinician seeks to correlate clinical findings with those seen in LUS and knows what information to seek in order to do so. COVID-19 presents with not only specific LUS signs but also with typical patterns of LUS findings.
The signs seen in the LUS of patients with COVID-19 are similar to those extensively described in patients with other types of pneumonia . These include various forms of B-lines, an irregular or fragmented pleural line, consolidations, pleural effusions and absence of lung sliding (see Online Resources Video_3-10) . The LUS of patients with COVID-19 usually shows an explosion of multiform vertical artifacts and separate and coalescent B-lines. The pleural line may be irregular or fragmented as is commonly observed in ARDS. As stated above none of these signs is pathognomonic to COVID-19 pneumonia and their presence is variable.
Conversely, a typical artifact that we named “light beam” is being observed invariably in most patients with pneumonia from COVID-19. This artifact corresponds to the early appearance of “ground glass” alterations typical of the acute disease that may be detected in computed tomography. This broad, lucent, band-shaped, vertical artifact moves rapidly with sliding, at times creating an “on–off” effect as it appears and disappears from the screen. The bright artifact typically arises from an entirely regular pleural line interspersed within areas of normal pattern or with separated B-lines (Online Resources Video_5). At times it seems to cover the A-lines, concealing them entirely. At other times A-lines may still be visualized in the background as it is observed. The light beam is observed also in other conditions with ground glass alterations. Nevertheless, the importance of this sign is given by the contingency of the terrible pandemic of COVID-19 that we are experiencing in our EDs. A multicenter study in progress is investigating the accuracy of this sign. To date, a pilot analysis of a monocenter series of 100 patients suspected for COVID-19 revealed the presence of multiple light beams in 48 of the 49 patients with confirmed disease and pneumonia. The same sign was never observed in 12 patients with alternative pulmonary diagnoses and negative swab test (unpublished data).
The LUS findings of patients with COVID-19 are unique in both combination and distribution. Therefore, patients presenting to the ED may be classified into four broad categories based on the presence of specific patterns of LUS findings (see Table 1). Patients presenting with the pattern described in category A have little or no pulmonary involvement and are therefore unlikely to have COVID-19 disease (i.e., asymptomatic SARS-CoV-2 carriers or patients with no lung disease). In patients presenting with any of the LUS patterns described in category B (Online Resources Video_11-14) alternative diagnoses should be sought. These patients are most likely to have a condition other than COVID-19 causing their pulmonary disease. Patients presenting with the pattern of LUS findings described in category C (Online Resource Video_15) may have COVID-19 disease, whereas those presenting with the patterns of LUS findings described in category D (Online Resources Video_16-21 and Figure_7-8) probably have COVID-19 disease.
The presence of large consolidations with air bronchograms mainly in the bases of the lungs should always raise suspicion of bacterial cross-infection. As noted above, LUS findings are always most informative when they are interpreted in light of the clinical context; some asymptomatic or mildly symptomatic patients may have surprisingly impressive high probability LUS findings. Conversely, in our experience, patients with COVID-19 disease who suffer from severe respiratory failure are not likely to have no or mild LUS alterations.
There are several ways LUS may be used to determine allocation of treatment resources to those patients most likely to respond. These include early quantification of the severity of lung involvement, periodic assessment for the appearance of findings suggestive of atelectasis or pneumonia and monitoring the effects of changes in mechanical ventilation and recruitment maneuvers on lung aeration.
The use of LUS to quantify and monitor changes in aeration has been described in critically ill patients with ARDS [10, 11]. It is our impression that, contrary to what has been described in ARDS, interstitial patterns and consolidations contribute almost equally to lack of aeration in patients with COVID-19 . Rather, the severity of respiratory impairment seems to be related to the overall proportion of lung tissue showing ground-glass alterations . Early quantification of the severity of lung involvement in patients with COVID-19 may be obtained by estimating the overall amount of lung areas detected as being pathological with ultrasound. Documenting the ultrasound images obtained enables later assessment of lesion size and more precise calculation of the proportion of diseased lung. The diseased lung is identified by the presence of any pathological finding (e.g., separated and coalescent B-lines, light beams, consolidations) and the areas of diseased lung are measured. For each video clip, the proportion of involved lung is estimated (0–30-50-70-100%) and the overall proportion is then calculated. This method of semi-quantification may be used to estimate the extent of lung involvement which could serve to identify at least some of the patients more likely to require invasive ventilation.
Periodic assessment for the appearance of findings suggestive of atelectasis or pneumonia can be highly informative. Identification of interstitial patterns or consolidations typical of pneumonia in patients with COVID-19 should lead to a change in care. Modifying ventilation parameters is simple but may not suffice for recruitment. We are adopting pronation guided mainly by LUS detection of extended lesions in the dorsal areas both in patients treated with continuous positive airway pressure (CPAP) and in invasively ventilated patients.
In patients that are invasively ventilated we suggest following evidence-based suggestions for monitoring aeration changes [10, 11]. The lung is studied in oblique scans in two anterior, two lateral and two posterior areas per side. Each area is assigned a score ranging from 0 to 3 (0 = normal A-lines, 1 = multiple separated B-lines, 2 = coalescent B-lines or light beam, 3 = consolidation). The sum of all the areas represents the aeration score. The dynamic changes in aeration can then be quantified by reassigning a new score to re-aerated areas (see Table 2). New methods for automated computer-aided measurement of aeration could be considered when available, with the advantage of a more standardized quantitative approach for monitoring .
In the setting of critically ill COVID-19 patients with severe pneumonia, the possibility of thromboembolic disease should be considered . Even if there are no published studies thus far, COVID-19 patients are likely at increased risk for thromboembolism . Critically ill patients should be treated accordingly and monitored by cardiac and venous ultrasound to diagnose deep venous thrombosis and cardiac signs of acute pulmonary embolism . We show a case of COVID-19 with sudden deterioration and cardiac arrest due to acute pulmonary embolism with popliteal thrombosis (Online Resources Video_22-23).
Hospital flooding of patients with COVID-19 imposes a huge burden on the medical system. This burden can be somewhat mitigated with optimization of patient identification, triage and management. LUS is noninvasive and can be performed very rapidly. LUS may be used in the ED to identify likely COVID-19 patients and to identify those patients with more extensive pulmonary involvement who should probably be referred to the ICU. It may serve to differentiate between patients with acute signs of respiratory failure, patients with mild symptoms and normal respiratory function, patients with preexisting chronic cardiac or pulmonary diseases (see flow charts in Online Resources Figure_9-11). In the ICU, LUS may be used to identify areas of poor lung aeration and to monitor the effect of changes in ventilation and recruitment maneuvers on lung aeration.
Xie J, Tong Z, Guan X et al (2020) Critical care crisis and some recommendations during the COVID-19 epidemic in China. Intensive Care Med. https://doi.org/10.1007/s00134-020-05979-7
Arabi YM, Murthy S, Webb S (2020) COVID-19: a novel coronavirus and a novel challenge for critical care. Intensive Care Med. https://doi.org/10.1007/s00134-020-05955-1
Phelan AL, Katz R, Gostin LO (2020) The novel Coronavirus originating in Wuhan, China: challenges for global health governance. JAMA. https://doi.org/10.1001/jama.2020.1097
Wu J, Wu X, Zeng W et al (2020) Chest CT findings in patients with corona virus disease 2019 and its relationship with clinical features. Invest Radiol. https://doi.org/10.1097/RLI.0000000000000670
Zhao W, Zhong Z, Xie X, Yu Q, Liu J (2020) Relation between chest CT findings and clinical conditions of coronavirus disease (COVID-19) pneumonia: a multicenter study. AJR Am J Roentgenol. https://doi.org/10.1097/RLI.0000000000000670
Zhou S, Wang Y, Zhu T, Xia L (2020) CT features of coronavirus disease 2019 (COVID-19) pneumonia in 62 patients in Wuhan, China. AJR Am J Roentgenol China. https://doi.org/10.2214/AJR.20.22975
Volpicelli G, Elbarbary M, Blaivas M et al (2012) International evidence-based recommendations for point-of-care lung ultrasound. Intensive Care Med 38(4):577–591
Nazerian P, Volpicelli G, Vanni S et al (2015) Accuracy of lung ultrasound for the diagnosis of consolidations when compared to chest computed tomography. Am J Emerg Med 33(5):620–625
Peng Q, Wang X, Zhang L (2020) Findings of lung ultrasonography of novel corona virus pneumonia during the 2019–2020 epidemic. Intensive Care Med. https://doi.org/10.1007/s00134-020-05996-6
Bouhemad B, Brisson H, Le-Guen M, Arbelot C, Lu Q, Rouby JJ (2011) Bedside ultrasound assessment of positive end-expiratory pressure-induced lung recruitment. Am J Respir Crit Care Med 183(3):341–347
Mongodi S, Via G, Girard M et al (2016) Lung ultrasound for early diagnosis of ventilator-associated pneumonia. Chest 149(4):969–980
Gattinoni L, Chiumello D, Caironi P et al (2020) COVID-19 pneumonia: different respiratory treatment for different phenotypes? Intensive Care Med. https://doi.org/10.1007/s00134-020-06033-2
Brusasco C, Santori G, Bruzzo E et al (2019) Quantitative lung ultrasonography: a putative new algorithm for automatic detection and quantification of B-lines. Crit Care 23(1):288
Tavazzi G, Civardi L, Caneva L, Mongodi S, Mojoli F (2020) Thrombotic events in SARS-Cov 2 patients: an urgent call for ultrasound screening. Intensive Care Med. https://doi.org/10.1007/s00134-020-06040-3
Driggin E, Madhavan MV, Bikdeli B et al (2020) Cardiovascular considerations for patients, health care workers, and healthsystems during the coronavirus disease 2019 (COVID-19) pandemic. J Am Coll Cardiol. https://doi.org/10.1016/j.jacc.2020.03.031
Nazerian P, Volpicelli G, Gigli C, Lamorte A, Grifoni S, Vanni S (2018) Diagnostic accuracy of focused cardiac and venous ultrasound examinations in patients with shock and suspected pulmonary embolism. Intern Emerg Med 13(4):567–574
We sincerely thank Prof. Sharon Einav (General Intensive Care, Shaare Zedek Medical Centre and Hebrew University Faculty of Medicine, Jerusalem, Israel) for her fundamental contribution to the general revision of the manuscript and final editing. All the ultrasound videos in the section Online Resources have been recorded in the ED and ICU of San Luigi Gonzaga University Hospital. We thank the staff nurses and physicians who helped the collection of data. We thank the patients who gave their consent to publish the material. We thank Dr. Ana Vieira (Department of Nephrology, Santa Casa de Misericórdia de Barbacena and University of Medicine of Barbacena, Department of Point of Care Ultrasound, Minas Gerais, Brazil) for her valuable contribution in the design of the Figures in the section Online Resources.
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Electronic supplementary material
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Figure_1. A longitudinal scan of the chest wall showing the pleural surface in between and below the two ribs (PNG 1359 kb)
Figure_2. An oblique scan showing the maximal extension of the pleural surface without interposition of the ribs (PNG 1554 kb)
Figure_3. Anterior chest between the parasternal line (PSL) and the anterior axillary line (AAL). The scan 1 is performed longitudinally to examine the 4-5 anterior intercostal spaces (PNG 1509 kb)
Figure_4. Lateral chest between the anterior axillary line (AAL) and the posterior axillary line (PAL). The scan 2 is performed longitudinally to examine the 4-5 lateral intercostal spaces. The scan 3 is performed in oblique to examine the costophrenic angle to diagnose effusion (PNG 1131 kb)
Figure_5. Posterior chest between the scapula and the spine line (SL). The scan 4 is performed longitudinally to examine 6-7 posterior intercostal spaces. The scan 5 is performed in oblique to examine in steps the 3-4 intercostal spaces below the inferior margin of the scapula (PNG 1382 kb)
Figure_6. The “tilting” adjustment to optimize the visualization of the pleural surface and the lung artifacts. This regulation is particularly crucial in the dorsal scans (PNG 1820 kb)
Figure_7. CT image of the same confirmed COVID-19 case of the Video 20, showing the ground glass opacity corresponding to the light beam sign detected by LUS in the left lateral area of the chest (PNG 198 kb)
Figure_8. CT image of the same confirmed COVID-19 case of the Video 21, showing the ground glass opacity corresponding to the light beam sign detected by LUS in the left superior lateral area of the chest (JPG 214 kb)
Figure_9. Flow chart for hospital flooding of patients with acute respiratory failure. These are those patients complaining of fatigue and peripheral oxygen saturation <92-93% on room air without history of chronic cardiac and/or lung diseases. LUS: Lung Ultrasound; ED: Emergency Department; PCT: serum Procalcitonin; LC: Leukocyte Count; RT-PCR: nasal swab Reverse Transcriptase-Polymerase Chain Reaction for SARS-CoV-2; ICU: Intensive Care Unit Our proposal of the patient triage is based on a dedicated structural organization of the hospital, with availability of: 1) CT scan facility 24 hours a day; 2) isolation areas in the ED; 3) ICU, sub-intensive emergency ward and general ward dedicated to COVID-19; 4) intermediate wards were patients can be isolated in specific areas separated from other patients, waiting for the confirmation by RT-PCR; 5) general wards dedicated to negative patients with other diseases. LUS allows the diagnosis of COVID-19 pneumonia while swab RT-PCR allows confirmation of the SARS-CoV2 infection. Absence of signs of pneumonia at LUS cannot exclude that the patient carries the SARS-CoV2 anyway. General wards should be organized to maintain distance and test any admitted patient and also personnel to reduce the possibility of cross infections. (JPG 64kb)
Figure_10. Flow chart for hospital flooding of patients with mild symptoms and no signs of respiratory failure. LUS: Lung Ultrasound; ED: Emergency Department; PCT: serum Procalcitonin; LC: Leukocyte Count; RT-PCR: nasal swab Reverse Transcriptase-Polymerase Chain Reaction for SARS-CoV-2; ICU: Intensive Care Unit (JPG 65 kb)
Figure_11.Flow chart for hospital flooding of patients with exacerbation of symptoms of chronic cardiac or respiratory diseases. These are those patients with chronic heart failure, cor pulmonale, or any significant chronic respiratory disease. LUS: Lung Ultrasound; CT: Computed Tomography; ED: Emergency Department; RT-PCR: nasal swab Reverse Transcriptase-Polymerase Chain Reaction for SARS-CoV-2; ICU: Intensive Care Unit; PCT: serum Procalcitonin; LC: Leukocyte Count (JPG 47 kb)
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Volpicelli, G., Lamorte, A. & Villén, T. What’s new in lung ultrasound during the COVID-19 pandemic. Intensive Care Med 46, 1445–1448 (2020). https://doi.org/10.1007/s00134-020-06048-9