Vertical Artifacts as Lung Ultrasound Signs: Trick or Trap? Part 2- An Accademia di Ecografia Toracica Position Paper on B-Lines and Sonographic Interstitial Syndrome.

Although during the last few years the lung ultrasound (LUS) technique has progressed substantially, several artifacts, which are currently observed in clinical practice, still need a solid explanation of the physical phenomena involved in their origin. This is particularly true for vertical artifacts, conventionally known as B-lines, and for their use in clinical practice. A wider consensus and a deeper understanding of the nature of these artifactual phenomena will lead to a better classification and a shared nomenclature, and, ultimately, result in a more objective correlation between anatomo-pathological data and clinical scenarios. The objective of this review is to collect and document the different signs and artifacts described in the history of chest ultrasound, with a particular focus on vertical artifacts (B-lines) and sonographic interstitial syndrome (SIS). By reviewing the possible physical and anatomical interpretation of the signs and artifacts proposed in the literature, this work also aims to bring order to the available studies and to present the AdET (Accademia di Ecografia Toracica) viewpoint in terms of nomenclature and clinical approach to the SIS.

New International Guidelines and Consensus on the Use of Lung Ultrasound.

Following the innovations and new discoveries of the last 10 years in the field of lung ultrasound (LUS), a multidisciplinary panel of international LUS experts from six countries and from different fields (clinical and technical) reviewed and updated the original international consensus for point-of-care LUS, dated 2012. As a result, a total of 20 statements have been produced. Each statement is complemented by guidelines and future developments proposals. The statements are furthermore classified based on their nature as technical (5), clinical (11), educational (3), and safety (1) statements.

Are pocket sized ultrasound devices sufficient in the evaluation of lung ultrasound patterns and aeration scoring in pulmonary ICU patients?

Lung ultrasound (LUS) is a practical diagnostic tool for several lung pathologies. Pocket sized USG devices (PSUDs) are more affordable, accessible, practical, and learning to use them is easier than standard ultrasound devices (SUDs). Their capability in image quality have been found as comparable with standard USG machines. Studies have been showing that these devices can be useful as much as SUDs in the evaluation of heart, abdomen, vascular structures, diaphragm and optic nerve. The aim of this study is to compare PSUD with a standard ultrasound devices (SUD) in the evaluation of LUS patterns such as alveolar, interstitial syndromes and lung aeration score (LAS). Study performed in an University Hospital Pulmonary ICU. All patients older than 18 years old were included in this study. The sector probe of SUD (Vivid-Q) and PSUD (Vscan) were used for investigation of A lines, interstitial (B lines), alveolar syndromes (consolidation, hepatisation, air bronchograms) and pleural effusion. 33 patients were included in the study. When PSUD was compared with SUD in terms of total B2 count, and LAS in the right, left and both lung, there was an agreement without proportional bias according to Bland Altman test. There was also good inter class correlation coefficient value as greater than 0.8 and 0.7 between two physicians in terms of counting of total B1, B2, total B lines and calculating of total LAS for SUD and PSUD respectively. PSUDs is a reliable and valid method for evaluation of LUS patterns like SUDs.

B-Lines for the assessment of extravascular lung water: Just focused or semi-quantitative?

BACKGROUND: B-lines as typical artefacts of lung ultrasound are considered as surrogate measurement for extravascular lung water. However, B-lines develop in the sub-pleural space and do not allow assessment of the whole lung. Here, we present data from the first observational multi-centre study focusing on the correlation between a B-lines score and extravascular lung water in critically ill patients suffering from a variety of diseases. PATIENTS AND METHODS: In 184 adult patients, 443 measurements were obtained. B-lines were counted and expressed in a score which was compared to extravascular lung water, measured by single-indicator transpulmonary thermodilution. Appropriate correlation coefficients were calculated and receiver operating characteristics (ROC-) curves were plotted. RESULTS: Overall, B-lines score was correlated with body weight-indexed extravascular lung water characterized by r = .59. The subgroup analysis revealed a correlation coefficient in patients without an infection of r = .44, in those with a pulmonary infection of r = .75 and in those with an abdominal infection of r = .23, respectively. Using ROC-analysis the sensitivity and specificity of B-lines for detecting an increased extravascular lung water (>10 mL/kg) was 63% and 79%, respectively. In patients with a P/F ratio <200 mm Hg, sensitivity and specificity to predict an increased extravascular lung water was 71% and 93%, respectively. CONCLUSIONS: Assessment of B-lines does not accurately reflect actual extravascular lung water. In presence of an impaired oxygenation, B-lines may reliably indicate increased extravascular lung water as cause of the oxygenation disorders.

Our Italian experience using lung ultrasound for identification, grading and serial follow-up of severity of lung involvement for management of patients with COVID-19.

Lung ultrasound (LU) has rapidly become a tool for assessment of patients stricken by the novel coronavirus 2019 (COVID-19). Over the past two and a half months (January, February, and first half of March 2020) we have used this modality for identification of lung involvement along with pulmonary severity in patients with suspected or documented COVID-19 infection. Use of LU has helped us in clinical decision making and reduced the use of both chest x-rays and computed tomography (CT).

[Lung ultrasound in patients with SARS-CoV-2 infection]. / Lungenultraschall bei Patienten mit SARS-CoV-2-Infektion.

After taking a patient's history and physical examination, lung ultrasound can immediately reveal numerous causes and complications in patients suffering from respiratory tract infection and/or dyspnea. It can thus facilitate decisions on further diagnostic and first therapeutic procedures, even in patients with a SARS-CoV­2 infection who present to the emergency room. This review article highlights the typical findings of lung ultrasound in patients with COVID-19 and discusses its value compared to other imaging methods.

Abnormal lung ultrasound pattern during labor: A prospective cohort pilot study.

PURPOSE: Lung ultrasound (LUS) examination is used to evaluate patients with acute respiratory failure. The physiological LUS pattern during labor in healthy parturients has not been well described. The aim of this study was to evaluate the LUS pattern in a cohort of healthy women during uncomplicated labor. METHODS: We used the 8-point LUS assessment protocol and investigated lung sliding, A-lines, B-lines, interstitial syndrome, lung consolidation, and pleural effusion according to the International Consensus Document with two additional supradiaphragmatic projections. All patients were screened twice; once during the first stage of labor and again within 2 hours after delivery. RESULTS: We included 24 patients in this study from February 2014 to August 2015. A total of 480 LUS records were retained for further analysis. Overall, 16 of 24 patients (67%) had at least one positive region (three or more B-lines) during the peridelivery LUS evaluation. Interstitial syndrome was detected in five patients (21%). There were no differences in A-line (P = 0.38) or B-line (P = 0.68) prevalence between LUS examinations before and after delivery. CONCLUSIONS: Women in uncomplicated labor can present abnormal LUS findings, which may affect the interpretation of LUS results in patients with respiratory deterioration. Further studies should address this topic in larger cohort of patients.

Evaluating Extravascular Lung Water in Sepsis: Three Lung-Ultrasound Techniques Compared against Transpulmonary Thermodilution.

BACKGROUND: Excessive extravascular lung water (EVLW) is associated with increased morbidity and mortality. We compared three lung-ultrasound (L-US) techniques against the reference-standard transpulmonary thermodilution (TPTD) technique to access EVLW. MATERIALS AND METHODS: This was a prospective, single-blind, cross-sectional study. Forty-four septic patients were enrolled. EVLW index was measured by the TPTD method, and an index of ≥10 mL/kg was considered diagnostic of pulmonary edema. EVLW index was then compared to three established bedside L-US protocols that evaluate sonographic B-lines: (1) a 28-zone protocol (total B-line score [TBS]) (2) a scanning 8-region examination, and (3) a 4-point examination. RESULTS: Eighty-nine comparisons were obtained. A statistically significant positive correlation was found between L-US TBS and an EVLW index ≥10 mL/kg (r = 0.668,P < 0.001). The 28-zone protocol score ≥39 has a sensitivity of 81.6% and a specificity of 76.5% to define EVLW index ≥10 mL/kg. In contrast, the positive 4-point examination and scanning 8-regions showed low sensitivity (23.7% and 50.0%, respectively) but high specificity (96.1% and 88.2%, respectively). Ten patients with a total of 21 comparisons met criteria for acute respiratory distress syndrome (ARDS). In this subgroup, only the TBS had statistically significant positive correlation to EVLW (r = 0.488,P = 0.025). CONCLUSION: L-US is feasible in patients with severe sepsis. In addition, L-US 28-zone protocol demonstrated high specificity and better sensitivity than abbreviated 4- and 8-zone protocols. In ARDS, the L-US 28-zone protocol was more accurate than the 4- and 8-zone protocols in predicting EVLW. Consideration of limitations of the latter protocols may prevent clinicians from reaching premature conclusions regarding the prediction of EVLW. TRIAL REGISTRATION: ISRCTN11419081. Registered 4 February 2015 retrospectively.

Sonography of the chest using linear-array versus sector transducers: Correlation with auscultation, chest radiography, and computed tomography.

PURPOSE: The primary purpose of our study was to compare the efficacies of two sonographic (US) probes, a high-frequency linear-array probe and a lower-frequency phased-array sector probe in the diagnosis of basic thoracic pathologies. The secondary purpose was to compare the diagnostic performance of thoracic US with auscultation and chest radiography (CXR) using thoracic CT as a gold standard. METHODS: In total, 55 consecutive patients scheduled for thoracic CT were enrolled in this prospective study. Four pathologic entities were evaluated: pneumothorax, pleural effusion, consolidation, and interstitial syndrome. A portable US scanner was used with a 5-10-MHz linear-array probe and a 1-5-MHz phased-array sector probe. The first probe used was chosen randomly. US, CXR, and auscultation results were compared with the CT results. RESULTS: The linear-array probe had the highest performance in the identification of pneumothorax (83% sensitivity, 100% specificity, and 99% diagnostic accuracy) and pleural effusion (100% sensitivity, 97% specificity, and 98% diagnostic accuracy); the sector probe had the highest performance in the identification of consolidation (89% sensitivity, 100% specificity, and 95% diagnostic accuracy) and interstitial syndrome (94% sensitivity, 93% specificity, and 94% diagnostic accuracy). For all pathologies, the performance of US was superior to those of CXR and auscultation. CONCLUSIONS: The linear probe is superior to the sector probe for identifying pleural pathologies, whereas the sector probe is superior to the linear probe for identifying parenchymal pathologies. Thoracic US has better diagnostic performance than CXR and auscultation for the diagnosis of common pathologic conditions of the chest. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:383-389, 2016.

Intraoperative lung ultrasound: A clinicodynamic perspective.

In the era of evidence-based medicine, ultrasonography has emerged as an important and indispensable tool in clinical practice in various specialties including critical care. Lung ultrasound (LUS) has a wide potential in various surgical and clinical situations for timely and easy detection of an impending crisis such as pulmonary edema, endobronchial tube migration, pneumothorax, atelectasis, pleural effusion, and various other causes of desaturation before it clinically ensues to critical level. Although ultrasonography is frequently used in nerve blocks, airway handling, and vascular access, LUS for routine intraoperative monitoring and in crisis management still necessitates recognition. After reviewing the various articles regarding the use of LUS in critical care, we found, that LUS can be used in various intraoperative circumstances similar to Intensive Care Unit with some limitations. Except for few attempts in the intraoperative detection of pneumothorax, LUS is hardly used but has wider perspective for routine and crisis management in real-time. If anesthesiologists add LUS in their routine monitoring armamentarium, it can assist to move a step ahead in the dynamic management of critically ill and high-risk patients.

Lung Ultrasound Reproducibly Outperforms Computed Tomography in the Detection of Extravascular Lung Water in Patients Undergoing Haemodialysis.

BACKGROUND: Lung ultrasound (LUS) is increasingly used as an extension of physical examination, informing clinical diagnosis, and decision making. There is particular interest in the assessment of patients with pulmonary congestion and extravascular lung water, although gaps remain in the evidence base underpinning this practice as a result of the limited evaluation of its inter-rater reliability and comparison with more established radiologic tests. METHODS: 30 patients undergoing haemodialysis were prospectively recruited to an observational cohort study (NCT01949402). Patients underwent standardised LUS assessment before, during and after haemodialysis; their total LUS B-line score was generated, alongside a binary label of whether appearances were consistent with an interstitial syndrome. LUS video clips were recorded and independently scored by two blinded expert clinician sonographers. Low-dose non-contrast thoracic CT, pre- and post dialysis, was used as a "gold standard" radiologic comparison. RESULTS: LUS detected a progressive reduction in B-line scores in almost all patients undergoing haemodialysis, correlating with the volume of fluid removed once individuals with no or minimal B-lines upon pre-dialysis examination were discounted. When comparing CT scans pre- and post dialysis, radiologic evidence of the change in fluid status was only identified in a single patient. CONCLUSIONS: This is the first study to demonstrate that LUS detects changes in extravascular lung water caused by changing fluid status during haemodialysis using a blinded outcome assessment and that LUS appears to be more sensitive than CT for this purpose. Further research is needed to better understand the role of LUS in this and similar patient populations, with the aim of improving clinical care and outcomes.

Radiographic lung congestion scores in dogs with acute congestive heart failure caused by myxomatous mitral valve disease.

BACKGROUND: In humans, lung congestion scores are predictive of recurrence of acute congestive heart failure (CHF) and are superior to cardiac biomarkers in predicting survival. OBJECTIVES: The primary aim of this retrospective study was to determine if a modified lung congestion score (LCS) in dogs diagnosed with acute CHF because of myxomatous mitral valve disease was associated with time until recurrence or death. ANIMALS: Complete medical records were available for a total of 94 dogs between 2010 and 2019, but only 35 dogs fulfilled the criteria for inclusion. METHODS: This retrospective study used descriptive statistics to describe the cumulative and corrected LCS. Correlations were used to examine the association of the corrected LCS and time until recurrence or death, selected echocardiographic variables, and timing of furosemide administration. RESULTS: The mean LCS was 8.4 (SD 3.3) and corrected LCS was 0.48 (SD 0.19). The pattern was predominantly symmetric (40% of dogs) and focal (caudal) but more commonly right-sided when asymmetric (40% vs 20%). The median number of days after initial diagnosis of acute CHF to readmission and death was 150 days (range 4-572), and 266 days (range 5-965), respectively. No significant association between the dog's corrected LCS and number of days until readmission (r = .173, P = .42) nor survival (r = .109, P = .56) was found. There was a negative significant correlation (r = -.71, P < .001) between the time interval of furosemide administration and corrected LCS.

Use of Point-of-Care Ultrasound by Non-Physicians to Assess Respiratory Distress in the Out-of-Hospital Environment: A Scoping Review.

BACKGROUND: The use of ultrasound in the out-of-hospital environment is increasingly feasible. The potential uses for point-of-care ultrasound (POCUS) by paramedics are many, but have historically been limited to traumatic indications. This study utilized a scoping review methodology to map the evidence for the use of POCUS by paramedics to assess respiratory distress and to gain a broader understanding of the topic. METHODS: Databases Ovid MEDLINE, EMBASE, CINAHL Plus, and PUBMED were searched from January 1, 1990 through April 14, 2021. Google Scholar was searched, and reference lists of relevant papers were examined to identify additional studies. Articles were included if they reported on out-of-hospital POCUS performed by non-physicians for non-traumatic respiratory distress. RESULTS: A total of 591 unique articles were identified, of which seven articles met the inclusion criteria. The articles reported various different scan protocols and, with one exception, suffered from low enrolments and low participation. Most articles reported that non-physician-performed ultrasound was feasible. Articles reported moderate to high levels of agreement between paramedics and expert reviewers for scan interpretation in most studies. CONCLUSION: Paramedics and emergency medical technicians (EMTs) have demonstrated the feasibility of lung ultrasound in the out-of-hospital environment. Further research should investigate the utility of standardized education and scanning protocols in paramedic-performed lung ultrasound for the differentiation of respiratory distress and the implications for patient outcomes.

Optimizing Lung Ultrasound: The Effect of Depth, Gain and Focal Position on Sonographic B-Lines.

Ultrasonographic B-lines are artifacts present in alveolar-interstitial syndromes. We prospectively investigated optimal depth, gain, focal position and transducer type for B-line visualization and image quality. B-Lines were assessed at a single rib interspace with curvilinear and linear transducers. Video clips were acquired by changing parameters: depth (6, 12, 18 and 24 cm for curvilinear transducer, 4 and 8 cm for linear transducer), gain (10%, 50% and 90%) and focal position (at the pleural line or half the scanning depth). Clips were scored for B-lines and image quality. Five hundred sixteen clips were obtained and analyzed. The curvilinear transducer improved B-line visualization (63% vs. 37%, p < 0.0001), with higher image quality (3.52 ± 0.71 vs. 3.31 ± 0.86, p = 0.0047) compared with the linear transducer. B-Lines were better visualized at higher gains (curvilinear: gain of 50% vs. 10%, odds ratio = 7.04, 95% confidence interval: 4.03-12.3; gain of 90% vs. 10%, odds ratio = 9.48, 95% confidence interval: 5.28-17.0) and with the focal point at the pleural line (odds ratio = 1.64, 95% confidence interval: 1.02-2.63). Image quality was highest at 50% gain (p = 0.02) but decreased at 90% gain (p < 0.0001) and with the focal point at the pleural line (p < 0.0001). Image quality was highest at depths of 12-18 cm. B-Lines are best visualized using a curvilinear transducer with at least 50% gain and focal position at the pleural line. Gain less than 90% and image depth between 12 and 18 cm improve image quality.

Perioperative lung ultrasound pattern changes in patients undergoing gynecological procedures - a prospective observational study.

OBJECTIVES: General anesthesia and positive pressure ventilation are associated with perioperative pulmonary complications. Lung ultrasound (LUS) is a method used to evaluate lung parenchyma. The purpose of this study was to evaluate LUS patterns in a cohort of women undergoing gynecological surgery with uncomplicated general anesthesia. MATERIAL AND METHODS: Patients were assessed according to the 8-zone LUS assessment protocol used to detect lung sliding, A-lines, B-lines, interstitial syndrome and lung consolidation. Each patient was screened at specific time intervals: before induction of anesthesia, at induction, 30 and 60 minutes after induction and within two hours after recovery. RESULTS: A total of 99 patients undergoing gynecological surgery with uneventful anesthesia from November 2017 to November 2018 were included in this study. A total of 426 LUS records were retained for further analysis. Overall, no significant changes to patients' A-line appearance were detected, regardless of the time of assessment. There was, however, an increase in the number of B-lines at the screening times of 30 and 60 minutes after induction, as compared to initial assessments (p = 0.011 and p < 0.001 respectively), and an increase in the number of positive regions (≥ 3 B-lines) at 30 and 60 minutes after induction and after recovery, as compared to initial assessment (p < 0.001; p < 0.001 and p = 0.001 respectively). CONCLUSIONS: An uneventful anesthesia may predispose to abnormal LUS findings and should be considered while interpreting of LUS results in cases with perioperative pulmonary complications.

Diagnosis Accuracy of Lung Ultrasound for ARF in Critically Ill Patients: A Systematic Review and Meta-Analysis.

Background: Acute respiratory failure (ARF) is a commonly distressing condition in critically ill patients. Its early recognition and treatment may improve clinical outcomes. Mounting evidence suggests that lung ultrasound (LUS) could be an alternative to chest X-ray (CXR) or computed tomography (CT) for the diagnosis of ARF in critically ill patients. This meta-analysis aimed to determine whether LUS can be an alternative tool used to investigate the cause of ARF or thoracic pathologies associated with the diagnosis of ARF in critically ill patients. Method: A systematic literature search of the PubMed, Web of Science, Embase, and Cochrane Library databases was conducted from inception to March 2020. Two researchers independently screened studies investigating the accuracy of LUS with CXR or CT for adult critically ill patients with ARF. Data with baseline, true positives, false positives, false negatives, and true negatives were extracted. The study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The pooled sensitivity and specificity were obtained using a bivariate model. Results: Eleven studies, including 1,232 patients, were included in the meta-analysis. Most studies were of low quality. LUS had a pooled sensitivity of 92% (95% confidence interval [CI]: 85-96) and a pooled specificity of 98% (95% CI: 94-99). The area under the summary receiver operating characteristic curve was 98% (95% CI: 97-99). The sensitivity and specificity of LUS to identify different pathological types of ARF were investigated. For consolidation (1,040 patients), LUS had a sensitivity of 89% and a specificity of 97%. For pleural effusion (279 patients), LUS had a pooled sensitivity of 95% and a specificity of 99%. For acute interstitial syndrome (174 patients), LUS had a pooled sensitivity of 95% and a specificity of 91%. Conclusions: LUS is an adjuvant tool that has a moderate sensitivity and high specificity for the diagnosis of ARF in critically ill patients. Systematic Review Registration: The study protocol was registered with PROSPERO (CRD42020211493).

Lung Ultrasound: A Diagnostic Leading Tool for SARS-CoV-2 Pneumonia: A Narrative Review.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide causing a global pandemic. In this context, lung ultrasound (LUS) has played an important role due to its high diagnostic sensitivity, low costs, simplicity of execution and radiation safeness. Despite computed tomography (CT) being the imaging gold standard, lung ultrasound point of care exam is essential in every situation where CT is not readily available nor applicable. The aim of our review is to highlight the considerable versatility of LUS in diagnosis, framing the therapeutic route and follow-up for SARS-CoV-2 interstitial syndrome.

Lung Ultrasound Is Often, but Not Always, Normal in Healthy Subjects: Considerations for COVID-19 Pandemic.

BACKGROUND: Lung ultrasound (LU) is becoming an increasingly important diagnostic tool in detecting lung involvement in Corona Virus Disease 2019 (COVID-19). The aim of this study was to ascertain the likelihood of finding LU abnormalities; mimicking lung involvement; in COVID-19 negative healthy individuals. METHODS: We performed LU on 265 healthcare workers; not presenting COVID-19 major symptoms and in good health; during the course of a serological screening program for COVID-19 in our General Hospital. LU results were reported as total Lung Ultrasound Score (LUS) using a 12-zone method of reporting. RESULTS: 250/265 subjects were included in the COVID-19 negative group. LU was not completely normal (LUS ≠ 0) in 65/250 COVID-19 negative subjects (26%) and in 12/15 (80%) poorly symptomatic COVID-19 positive subjects; with a multifocal pattern in 12.7% vs. 66.7% of cases respectively. Age and COVID-19 positivity were independent predictors of total LUS. A total LUS ≥ 2 had a sensitivity of 66.67% and a specificity of 85.60% in detecting COVID-19 positivity. CONCLUSIONS: A slightly altered LU can be quite frequent in healthy COVID-19 negative subjects. LU can have a role in confirming but not screening COVID-19 poorly symptomatic cases.

Lung Ultrasound for Pulmonary Contusions.

Lung ultrasound (LUS) has high sensitivity for the rapid and reliable diagnosis of pulmonary contusions (PC) in patients who have sustained trauma. LUS diagnosis of PC exceeds that of thoracic radiographs in multiple animal and human studies. The sonographer should understand potential caveats and confounding variables for proper diagnosis of PC with LUS. LUS does not replace conventional radiography or computed tomography, especially in the polytrauma patient. LUS should be used concurrently with other point-of-care ultrasound trauma protocols to rapidly optimize patient assessment before movement to the radiology suite.