key: cord-1034046-6c9syvwa
authors: Pecho-Silva, Samuel; Navarro-Solsol, Ana Claudia; Taype-Rondan, Alvaro; Torres-Valencia, Javier; Arteaga-Livias, Kovy; Herriman, Daniel Albert; Acosta-Pinzas, Karim; Valenzuela-Rodriguez, German; Barboza, Joshuan J.; Panduro-Correa, Vicky
title: Pulmonary ultrasound in the diagnosis and monitorization of coronavirus disease (COVID-19): a systematic review: Pulmonary ultrasound for diagnosis of COVID-19
date: 2021-04-20
journal: Ultrasound Med Biol
DOI: 10.1016/j.ultrasmedbio.2021.04.011
sha: e39680b192feeaed37d01298f37e5c047bb7b744
doc_id: 1034046
cord_uid: 6c9syvwa

Systemize the evidence of pulmonary ultrasound (PU) use in diagnosis, monitorization or hospital discharge criteria for patients with COVID-19. Systematic review of evidence which utilized PU for diagnosis, monitorization, or as hospital discharge criteria for COVID-19 patients confirmed by RT-PCR between December 1st of 2019 and July 5th of 2020 compared with thoracic radiograph (TR), thoracic tomography (CT) and RT-PCR. Type of study, motives for PU, population, type of transducer and protocol, results of PU, and quantitative or qualitative correlation with TR and/or CT and/or RT-PCR were evaluated. Were evaluated 28 articles with 418 patients. Average age 50 years (SD 25.1 years), 395 adults and 23 children. 143 were women, 13 pregnant women. The most frequent result was diffuse, coalescent and confluent B-lines. The plural line was irregular, interrupted, or thickened. The presence of subpleural consolidation was noduliform, lobar, or multilobar. There was good qualitative correlation between TR and CT and a quantitative correlation with CT of r=0.65 (p<0.001). 44 patients were evaluated only with PU. PU is a useful tool for diagnosis, monitorization, and criteria for hospital discharge for patients with COVID-19.

Since the first cases were described in the province of Hubei in China the infection of coronavirus has become one of the most important infectious diseases of the century, and at the 20th of September almost 1 million deaths have been reported worldwide (Arteaga-Livias and Rodriguez-Morales 2020). Due to being a new disease, many questions of clinical characteristics, diagnosis, and treatment still remain (Dhama et al. 2020; Pecho-Silva et al. 2020 ).

The tools available for diagnosis and monitoring are important to ensure correct clinical decisions and a better comprehension of the evolution of the disease, as well as the possibility of complication of a patient with mild to moderate disease (Henriquez-Marquez et al. 2020) . Diverse authors coincide in that pulmonary ultrasound (PU) can be used in diverse stages of the disease caused by coronavirus 2019 , including triage of asymptomatic patients, diagnosis, monitoring and follow-up, evaluation of response to treatment, aid in the decision to remove the patient from the mechanical ventilator and as a criterion for patient discharge (Gargani et al. 2020; Kristensen et al. 2014; Soldati et al. 2020) .

PU would also have an additional advantage over chest x-ray (CXR) and chest tomography (CT), as it is a procedure that can be performed with portable equipment, thereby minimizing patient mobilization and the number of healthcare personnel required, thus reducing the number of professionals exposed to a possible contagion (Convissar et al. 2020; Pecho-Silva 2020; Smith et al. 2020 ).

Some articles have been published about the use of PU in COVID-19, as well as reviews with less than 60 patients (Convissar et al. 2020; Smith et al. 2020 ). The number of articles published has increased rapidly, therefore it is imperative to have up-to-date data on this topic to help decision-making.

This review aims to systemize the published evidence on the use of PU in the diagnosis, follow-up and as a criterion for discharge of patients with COVID-19, and to evaluate its correlation with other diagnostic procedures such as CXR, CT and tests of reverse transcription polymerase chain reaction (RT-PCR).

This study was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) checklist. The protocol is available in the Figshare repository (Taype-Rondan 2020). A systematic search was carried out in the following databases (between December 1, 2019 to July 5, 2020), with the following terms shown below: Pubmed: ("2019/12/01"[Date -Publication]:

"2020/07/05"[Date -Publication]) AND ([((lung or chest or pulmo* or thora*) and (ultraso* or sonog* or echography)) and (Covid* or SARS* or coronavirus*)]).

Scopus: [(TITLE-ABS-KEY ( *coronavirus OR sars* OR covid* ) AND TITLE-ABS-KEY ( ultraso* OR *sonography OR echography ) ) AND ( LIMIT-TO ( PUBYEAR , 2020 ) OR LIMIT-TO ( PUBYEAR , 2019 ) ) AND ( LIMIT-TO ( SUBJAREA , "MEDI" ) ) AND ( LIMIT-TO ( LANGUAGE , "English" ) OR LIMIT-TO ( LANGUAGE , "Spanish" ) )]. Google Schoolar: [((lung or chest or pulmo* or thora*) and (ultraso* or sonog* or echography)) and (Covid* or SARS* or coronavirus*)].

For this systematic review, all primary articles were included, including case series from more than one patient, as well as case reports (including letters to the editor); who have used the PU as part of the diagnostic evaluation and / or clinical followup and / or as a criterion for discharge of patients with COVID-19 confirmed by RT-PCR. Studies in which modifications had been made to the conventional PU technique were excluded.

The selection of articles was carried out independently by two investigators (SPS, ACNS). If there was no coincidence, a third investigator (JTV) decides to include or exclude the study. All the studies included in this systematic review had approval by the ethics committee.

The studies were rated for their quality according to the National Institutes of Health (NIH) Quality Assessment Tool for case series studies by two authors (KAL and VPC).

The data from each study was extracted into a Microsoft Excel database designed for this purpose. The data of country, type of study, reason for which the PU was performed, population, type of transducer and evaluation protocol used, findings in the PU, and the qualitative and / or quantitative correlation reported between PU and other imaging techniques was collected. (CXR or CT).

The search strategy yielded 949 results and 510 duplicates records were removed.

Of 439 records screened, 405 were excluded by title and abstract screening. Of 34 full-text articles assessed for elegibility, 6 articles were excluded, and 28 articles were included in qualitative analysis (Alkhafaji et al. 2020; Bar et al. 2020; Buonsenso et al. 2020a; Buonsenso et al. 2020b; Consoli et al. 2020; Denina et al. 2020; Duclos et al. 2020; Farrow et al. 2020; Feng et al. 2020; Huang et al. 2020 Inchingolo et al. 2020 Ji et al. 2020; Lomoro et al. 2020; Lu et al. 2020; Mongodi et al. 2020; Musolino et al. 2020; Nouvenne et al. 2020; Palmese et al. 2020; Peng et al. 2020; Poggiali et al. 2020; Reisinger and Koratala 2020; Shokoohi et al. 2020; Thomas et al. 2020; Tung-Chen 2020; Xing et al. 2020; Yang et al. 2020; Yassa et al. 2020; Yasukawa and Minami 2020; ) were included (Figure 1) . The studies were classified as the following: 2 retrospective cohort studies that included 150 patients, 1 prospective cohort with 31 patients, a cross-sectional study with 26 patients, 14 case series that included between 3 and 30 patients, and 10 case reports. Of the articles, 26 were written in English, 1 in German and 1 in Chinese.

The 28 articles included a total of 418 patients with COVID-19 confirmed by RT-PCR. One hundred fifty patients were described in two retrospective cohorts, 31 patients in one prospective cohort study, 26 patients in one cross-sectional study, 201 patients in fourteen case series studies, and 10 patients in ten case reports studies. PU was performed in all 28 articles as part of the diagnosis, in 20 for clinical follow-up, in 5 as part of a routine procedure, and in 5 as an additional criterion to decide whether to discharge the patient from hospital or discharge from the unit of intensive care. The age of the patients was reported by 22/28 articles: one study (Feng et al. 2020) included 5 neonates aged 1 to 18 days, and another 21 articles registered 18 children or adolescents between 1 to 17 years and 395

Adults. In 22/28 articles the sex of the patients was described, finding 203 men and 143 women (Alkhafaji et al. 2020; Bar et al. 2020; Buonsenso et al. 2020a; Consoli et al. 2020; Denina et al. 2020; Duclos et al. 2020; Farrow et al. 2020; Feng et al. 2020; Huang et al. 2020; Inchingolo et al. 2020; Ji et al. 2020; Mongodi et al. 2020; Musolino et al. 2020; Nouvenne et al. 2020; Palmese et al. 2020; Poggiali et al. 2020; Reisinger and Koratala 2020; Shokoohi et al. 2020; Thomas et al. 2020; Tung-Chen 2020; Xing et al. 2020; Yang et al. 2020; Yassa et al. 2020; Yasukawa and Minami 2020; ) (Table 1) .

Of the patients included, 13 were pregnant with an average gestation of 23.4 weeks (SD: 11.5 weeks) at the time of diagnosis (Buonsenso et al. 2020b; Inchingolo et al. 2020; Yassa et al. 2020) . It was reported that the 13 fetuses did not present alterations during gestation and four deliveries were reported with products without infection at birth.

In 20 of the 28 studies the PU was a bedside procedure, while the remaining 8 studies transferred the patients to a specific area for the procedure. Regarding the transducer used, 19 articles reported this variable, of which 17 used a linear or convex transducer (Bar et al. 2020; Buonsenso et al. 2020a; Consoli et al. 2020; Farrow et al. 2020; Huang et al. 2020; Inchingolo et al. 2020; Ji et al. 2020; Lomoro et al. 2020; Lu et al. 2020; Mongodi et al. 2020; Musolino et al. 2020; Reisinger and Koratala 2020; Shokoohi et al. 2020; Thomas et al. 2020 ; Tung-Chen 2020; Yang et al. 2020; Yassa et al. 2020; ) . In 15 of the 28 articles the ultrasound evaluation protocol used was mentioned. In 7 articles a protocol of 12 zones was used (Buonsenso et al. 2020a; Mongodi et al. 2020; Musolino et al. 2020; Peng et al. 2020; Shokoohi et al. 2020; Yang et al. 2020; , in 4 articles a protocol of 6 zones was used (Alkhafaji et al. 2020; Farrow et al. 2020; Reisinger and Koratala 2020; Yasukawa and Minami 2020) , in 1 article a protocol with 14 zones was used (Yassa et al. 2020) and in 3 articles a protocol of 8 zones was used (Bar et al. 2020; Nouvenne et al. 2020; Tung-Chen 2020) .

Two hundred seventy seven of 418 patients did not undergo CXR (Bar et al. 2020; Buonsenso et al. 2020b; Duclos et al. 2020; Huang et al. 2020; Ji et al. 2020; Lomoro et al. 2020; Lu et al. 2020; Musolino et al. 2020; Nouvenne et al. 2020; Palmese et al. 2020; Peng et al. 2020; Poggiali et al. 2020; Reisinger and Koratala 2020; Tung-Chen 2020; Xing et al. 2020; Yang et al. 2020; Yassa et al. 2020; Yasukawa and Minami 2020; ) , including 7 of the 13 pregnant women. 56 patients of the 418 did not undergo CT (Bar et al. 2020; Buonsenso et al. 2020b; Duclos et al. 2020; Huang et al. 2020; Ji et al. 2020; Lomoro et al. 2020; Lu et al. 2020; Musolino et al. 2020; Nouvenne et al. 2020; Palmese et al. 2020; Peng et al. 2020; Poggiali et al. 2020; Reisinger and Koratala 2020; Tung-Chen 2020; Xing et al. 2020; Yang et al. 2020; Yassa et al. 2020; Yasukawa and Minami 2020; ) including 10 of the 13 pregnant women. 44 patients out of the 418 underwent neither CXR nor CT, being evaluated only by PU and RT-PCR (Bar et al. 2020; Buonsenso et al. 2020b; Duclos et al. 2020; Huang et al. 2020; Ji et al. 2020; Lomoro et al. 2020; Lu et al. 2020; Musolino et al. 2020; Nouvenne et al. 2020; Palmese et al. 2020; Peng et al. 2020; Poggiali et al. 2020; Reisinger and Koratala 2020; Tung-Chen 2020; Xing et al. 2020; Yang et al. 2020; Yassa et al. 2020; Yasukawa and Minami 2020; ) . In the 5 articles that included these 44 patients, the authors did not describe a different clinical course from the rest of the patients evaluated with CXR and / or CT.

Due to the type of articles found in this systematic review, the global quantitative correlation of PU with CXR and / or CT could not be assessed, therefore we report the qualitative result described by the authors. Of the 14 articles that evaluated the qualitative correlation between the findings of PU and CXR, in 12 of them they considered it good and 2 (including the cohort of 84 patients) reported that PU was superior to CXR (Alkhafaji et al. 2020; Mongodi et al. 2020) . Likewise, of the 20 studies that evaluated the qualitative correlation between PU and CT, 18 considered it good and 2 reported that PU was superior to CT (Feng et al. 2020; Yang et al. 2020 ) (table 1). Only the cross-sectional article reported a quantitative correlation between PU and CT, indicating that it was good with r = 0.65 and p <0.001 (Nouvenne et al. 2020 ).

In total, considering all procedures performed in studies that used CXR or CT (even repeat examinations), we found that PU was performed 18 times more than that of CXR, and 12 times more than that of CT. The cohort of 84 patients reported that PU reduced the use of CXR and CT by 31.8% before the use of PU to 3.6% after the use of this procedure (Mongodi et al. 2020 ).

In table 2 the PU findings are shown. All articles (Alkhafaji et al. 2020; Bar et al. 2020; Buonsenso et al. 2020a; Buonsenso et al. 2020b; Consoli et al. 2020; Denina et al. 2020; Duclos et al. 2020; Farrow et al. 2020; Feng et al. 2020; Huang et al. 2020; Inchingolo et al. 2020; Ji et al. 2020; Lomoro et al. 2020; Lu et al. 2020; Mongodi et al. 2020; Musolino et al. 2020; Nouvenne et al. 2020; Palmese et al. 2020; Peng et al. 2020; Poggiali et al. 2020; Reisinger and Koratala 2020; Shokoohi et al. 2020; Thomas et al. 2020; Tung-Chen 2020; Xing et al. 2020; Yang et al. 2020; Yassa et al. 2020; Yasukawa and Minami 2020; ) report the presence of B-lines: coalescent, multifocal, diffuse, confluent or "white lung". The alteration of the pleural line was reported in 25 of 28 articles: irregular, thickened, interrupted.

The alteration of the pulmonary parenchyma was reported as: presence of lobar, multilobar or noduliform subpleural consolidations with bilateral and posterior distribution. The presence of dynamic air bronchogram was described in 4 studies (Consoli et al. 2020; Huang et al. 2020; Mongodi et al. 2020; Shokoohi et al. 2020 ).

An article did not describe the presence or absence of pulmonary alterations ). An article indicated that no alterations to pulmonary parenchyma was found (Reisinger and Koratala 2020) . Pleural effusion was reported in only one article (Denina et al. 2020) . The presence of pneumothorax was only reported in one article (Consoli et al. 2020) . 

The results of the PU are similar and consistent between the different articles including this systematic review and simultaneously concur with the results of the systematic revisions and narratives (Ai et al. 2020 ; Antúnez-Montes and Buonsenso 2020; Convissar et al. 2020; Fang et al. 2020; Fiala 2020; Fraile Gutiérrez et al. 2020; Mohamed et al. 2020; Ojha et al. 2020; Smith et al. 2020) and correlate in a qualitative manner with the results of the disease COVID-19 observed in CT (Ai et al. 2020; Fang et al. 2020; Ojha et al. 2020; Pan et al. 2020) and is summarized in Table 3 .

Our results show that PU has been used in various stages of the disease (diagnosis, follow-up and as an evaluation for discharge, and to observe the resolution of the lesions in a progressive manner) in an adequate manner and with benefits for the patient. We have included 418 patients, indicating that the use of PU continues to spread in patients with COVID-19, previous reviews have included fewer than 60 patients (Convissar et al. 2020; Smith et al. 2020 ) and a recent systematic review with meta-analysis included 122 patients (Mohamed et al. 2020) although More evidence is still required to define the usefulness of the PU in each of these stages.

The protocols of 12 zones are the most used in the articles reviewed (Buonsenso et al. 2020a; Huang et al. 2020; Mongodi et al. 2020; Musolino et al. 2020; Peng et al. 2020; Shokoohi et al. 2020; Yang et al. 2020; ) including the study of cohorts of 84 patients, followed by the protocols of 6 zones (Alkhafaji et al. 2020; Farrow et al. 2020; Reisinger and Koratala 2020; Yasukawa and Minami 2020) . However, these variants in the protocols used did not affect the presence or absence of pathological findings in PU or their way of being reported. It might be convenient to propose the use of the 12-zone protocol as it is the most widely used. Also, convex and linear transducers were the most used, which is important because most conventional ultrasound equipment have these transducers.

PU has other benefits, such as a greater availability compared to CT and RT-PCR, low cost per examination, ease of access, shorter time for the procedure, dynamic and repeated evaluation of pulmonary parenchyma, accessibility to bedridden patients, safety for pregnant women, ease of integration of telemedicine in zones which lack trained specialists, and immediate results unlike that of RT-PCR (Alkhafaji et al. 2020; Bar et al. 2020; Buonsenso et al. 2020a; Buonsenso et al. 2020b; Consoli et al. 2020; Convissar et al. 2020; Denina et al. 2020; Duclos et al. 2020; Farrow et al. 2020; Feng et al. 2020; Gargani et al. 2020; Huang et al. 2020; Inchingolo et al. 2020; Ippolito et al. 2020; Ji et al. 2020; Kristensen et al. 2014; Lomoro et al. 2020; Lu et al. 2020; Mongodi et al. 2020; Musolino et al. 2020; Nouvenne et al. 2020; Ojha et al. 2020; Palmese et al. 2020; Pan et al. 2020; Pecho-Silva 2020; Peng et al. 2020; Poggiali et al. 2020; Reisinger and Koratala 2020; Schiaffino et al. 2020; Shokoohi et al. 2020; Smith et al. 2020; Soldati et al. 2020; Thomas et al. 2020; Tung-Chen 2020; Xing et al. 2020; Yang et al. 2020; Yassa et al. 2020; Yasukawa and Minami 2020; ) .

Regarding the learning process, the authors of some included articles have mentioned that its implementation is short and therefore feasible (Ippolito et al. 2020; Lu et al. 2020; Mongodi et al. 2020; Ojha et al. 2020; Pan et al. 2020; Pecho-Silva 2020; Schiaffino et al. 2020; Shokoohi et al. 2020; Smith et al. 2020; . PU also has the benefit that the cleaning and disinfection of the equipment is much easier and faster than that of the CXR or CT equipment and the same disinfection protocols are used.

In addition, portable PU equipment is becoming less expensive and with higher resolution, and allowing the transmission of images via Wi-Fi or Bluetooth, so only a single healthcare personnel would have to approach the patient to perform the procedure while the rest can receive the images outside the patient's isolation room without exposing themselves to potential contagion (Antúnez-Montes and Buonsenso 2020; Buonsenso et al. 2020a; Fraile Gutiérrez et al. 2020; Gargani et al. 2020; Mohamed et al. 2020; Musolino et al. 2020; Shokoohi et al. 2020; Tung-Chen 2020) . Up to now, no contraindications to the use of the PU or any complications from its use have been described.

So far, the PU is a useful tool for diagnosis, monitoring, and criteria for hospital and ICU discharge for patients with COVID-19. Up to now, no contraindications to the use of the PU or any complications from its use have been described. The findings in PU are similar between the different authors and correlate qualitatively well with the tomographic findings and better than the X-ray findings in patients with Covid-19. The use of PU could replace in selected cases chest radiography and / or tomography in the diagnosis and follow-up of patients with Covid-19 (Convissar et al. 2020; Smith et al. 2020) .

This review has grouped the largest number of patients with covid-19 evaluated with PU until now. Findings in PU of multifocal, multilobar, subpleural, posterior alterations of the pleural line of the coalescent, irregular, interrupted, thickened type together with alterations of the pulmonary parenchyma of multilobar or lobar distribution, with dynamic air bronchogram, are frequent findings and consistent with Covid-19 and aid in diagnosis, follow-up, evaluation of response to treatment and as criteria for discharge from the intensive care unit or hospital. The PU could replace the chest-x ray and could reduce the exposed to ionizing radiation to the patient and also reducing the displacement of the patient from his unit and thus exposing less staff and other patients to the intranosocomial transmissibility of Covid-19.

 Use convex or linear transducers. The latter are preferable to study the detail of the pleural and subpleural alterations. 

Some of the limitations of this systematic review have to do with the quality of the evidence that comes from only two retrospective cohort studies, one from a prospective cohort and one from a cross-sectional one, and the remaining letters to the editor, case series and case reports. Another limitation is the different evaluation protocols used to carry out the PU. A final limitation would be that the PU does not allow the detection of lesions that are not subpleural or peripheral, however, this would also be of little relevance since COVID-19 lesions are usually subpleural or peripheral and therefore evaluable by the PU (Convissar et al. 2020; Mohamed et al. 2020; Poggiali et al. 2020; Smith et al. 2020; Soldati et al. 2020 ).

The studies found show that in the world more experience is accumulating on the use of PU in patients with COVID-19, even in pregnant women and children. In addition, they report adequate sensitivity and specificity for the diagnosis of COVID-19, and no articles have been published that have found that PU is not useful or that it is harmful to the patient. This suggests that PU is an advantageous tool. However, studies of higher methodological quality are required to corroborate the current findings. 

Correlation of Chest CT and RT-PCR Testing for Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 Cases

A case of lung ultrasound findings in a 73-year-old male with COVID-19

Routine use of Point-of-Care lung ultrasound during the COVID-19 pandemic

La comunicación científica y el acceso abierto en la contención de enfermedades: El caso del Coronavirus novel 2019 (2019-nCoV)

The association of lung ultrasound images with COVID-19 infection in an emergency room cohort

Point-of-Care Lung Ultrasound findings in novel coronavirus disease-19 pnemoniae: a case report and potential applications during COVID-19 outbreak

Clinical role of lung ultrasound for diagnosis and monitoring of COVID-19 pneumonia in pregnant women

2019 novel coronavirus (COVID-19) pneumonia complications: the importance of lung ultrasound

Application of Lung Ultrasound During the COVID-19 Pandemic: A Narrative Review

Lung Ultrasound in Children With COVID-19

Coronavirus Disease 2019-COVID-19

No dose" lung ultrasound correlation with "low dose" CT scan for early diagnosis of SARS-CoV-2 pneumonia

Sensitivity of Chest CT for COVID-19: Comparison to RT-PCR

Early Multi-organ Point-of-Care Ultrasound Evaluation of Respiratory Distress During SARS-CoV-2 Outbreak: Case Report

Ultrasound in COVID-19: a timeline of ultrasound findings in relation to CT

Ultrasound in the management of the critically ill patient with SARS-CoV-2 infection (COVID-19): narrative review

Why, when, and how to use lung ultrasound during the COVID-19 pandemic: enthusiasm and caution

Prevención e identificación temprana de casos sospechosos COVID-19 en el primer nivel de atención en Centro América

A Preliminary Study on the Ultrasonic Manifestations of Peripulmonary Lesions of Non-Critical Novel Coronavirus Pneumonia (COVID-19)

The diagnosis of pneumonia in a pregnant woman with coronavirus disease 2019 using maternal lung ultrasound

Diagnostic impact of bedside chest X-ray features of 2019 novel coronavirus in the routine admission at the emergency department: case series from Lombardy region

Serial bedside lung ultrasonography in a critically ill COVID-19 patient

Ultrasonography for clinical decision-making and intervention in airway management: from the mouth to the lungs and pleurae

COVID-19 pneumonia manifestations at the admission on chest ultrasound, radiographs, and CT: single-center study and comprehensive radiologic literature review

A Clinical Study of Noninvasive Assessment of Lung Lesions in Patients with Coronavirus Disease-19 (COVID-19) by Bedside Ultrasound

Frequency of Abnormalities Detected by Point-of-Care Lung Ultrasound in Symptomatic COVID-19 Patients: Systematic Review and Meta-Analysis

Lung Ultrasound in Patients with Acute Respiratory Failure Reduces Conventional Imaging and Health Care Provider Exposure to COVID-19

Ultrasound Study Team for Pediatric COVID-19 (ROMULUS COVID Team). Lung Ultrasound in Children with COVID-19: Preliminary Findings

Lung Ultrasound in COVID-19 Pneumonia: Correlations with Chest CT on Hospital admission

CT in coronavirus disease 2019 (COVID-19): a systematic review of chest CT findings in 4410 adult patients

Daily Evaluation of COVID-19 Patients Primarily Based on Lung Ultrasound: In Times of Emergency, It's Time to Change Some Paradigms

Time Course of Lung Changes at Chest CT during Recovery from Coronavirus Disease 2019 (COVID-19)

Rol del ultrasonido pulmonar en el diagnóstico de la neumonía por SARS-CoV-2: ¿Alternativa a la escasez de tomógrafos?

Complicaciones extrapulmonares de la enfermedad por COVID-19

Chinese Critical Care Ultrasound Study Group (CCUSG). Findings of lung ultrasonography of novel corona virus pneumonia during the 2019-2020 epidemic

Can Lung US Help Critical Care Clinicians in the Early Diagnosis of Novel Coronavirus (COVID-19) Pneumonia?

Lung ultrasound: a valuable tool for the assessment of dialysis patients with COVID-19

Diagnostic Performance of Chest X-Ray for COVID-19 Pneumonia During the SARS-CoV-2 Pandemic in Lombardy, Italy

Lung ultrasound monitoring in patients with COVID-19 on home isolation

Point-of-care lung ultrasound in patients with COVID-19 -a narrative review

Is There a Role for Lung Ultrasound During the COVID-19 Pandemic?

Protocol systematic review PU. figshare

Lung ultrasound findings in a 64-year-old woman with COVID-19

Lung ultrasound in the monitoring of COVID-19 infection

Lung ultrasound findings in patients with COVID-19 pneumonia

Lung ultrasonography versus chest CT in COVID-19 pneumonia: a two-centered retrospective comparison study from China

Lung Ultrasound Can Influence the Clinical Treatment of Pregnant Women With COVID-19

Point-of-Care Lung Ultrasound Findings in Patients with COVID-19 Pneumonia

Sources of funding: This research has not received specific funding from public sector agencies, the commercial sector or non-profit organizations.

 Table 1