Body mass index and B-lines on lung ultrasonography in chronic and acute heart failure

Transfer Learning-Based B-Line Assessment of Lung Ultrasound for Acute Heart Failure

OBJECTIVE

B-lines assessed by lung ultrasound (LUS) outperform physical exam, chest radiograph, and biomarkers for the associated diagnosis of acute heart failure (AHF) in the emergent setting. The use of LUS is however limited to trained professionals and suffers from interpretation variability. The objective was to utilize transfer learning to create an AI-enabled software that can aid novice users to automate LUS B-line interpretation.

METHODS

Data from an observational AHF LUS study provided standardized cine clips for AI model development and evaluation. A total of 49,952 LUS frames from 30 patients were hand scored and trained on a convolutional neural network (CNN) to interpret B-lines at the frame level. A random independent evaluation set of 476 LUS clips from 60 unique patients assessed model performance. The AI models scored the clips on both a binary and ordinal 0-4 multiclass assessment.

RESULTS

A multiclassification AI algorithm had the best performance at the binary level when applied to the independent evaluation set, AUC of 0.967 (95% CI 0.965-0.970) for detecting pathologic conditions. When compared to expert blinded reviewer, the 0-4 multiclassification AI algorithm scale had a reported linear weighted kappa of 0.839 (95% CI 0.804-0.871).

CONCLUSIONS

The multiclassification AI algorithm is a robust and well performing model at both binary and ordinal multiclass B-line evaluation. This algorithm has the potential to be integrated into clinical workflows to assist users with quantitative and objective B-line assessment for evaluation of AHF.

The Importance of Lung Ultrasound and IGFBP7 (Insulin-like Growth Factor Binding Protein 7) Assessment in Diagnosing Patients with Heart Failure

Background: In daily practice, there are problems with adequately diagnosing the cause of dyspnea in patients with heart failure with preserved and mildly reduced ejection fractions (HFpEF and HFmrEF). This study aimed to assess the usefulness of lung ultrasound in diagnosing HFpEF and HFmrEF and determine its correlation with IGFBP7 (insulin-like growth factor binding protein 7), NTproBNP (N-terminal pro-B-type natriuretic peptide), and echocardiographic markers. Methods: The research was conducted on 143 patients hospitalized between 2018 and 2020, admitted due to dyspnea, and diagnosed with HFpEF and HFmrEF. Venous blood was collected from all participants to obtain basic biochemical parameters, NTproBNP, and IGFBP7. Moreover, all participants underwent echocardiography and transthoracic lung ultrasound. Two years after hospitalization a follow-up telephone visit was performed. Results: The number of B-lines in the LUS ≥ 16 was determined with a sensitivity of-73% and specificity of-62%, indicating exacerbation of heart failure symptoms on admission. The number of B-lines ≥ 14 on admission was determined as a cut-off point, indicating an increased risk of death during the 2-year follow-up period. The factors that significantly impacted mortality in the study patient population were age and the difference between the number of B-lines on ultrasound at admission and at hospital discharge. IGFBP7 levels had no significant effect on the duration of hospitalization, risk of rehospitalization, or mortality during follow-up. Conclusions: Lung ultrasonography provides additional diagnostic value in patients with HFpEF or HFmrEF and exacerbation of heart failure symptoms. The number of B-lines ≥ 14 may indicate an increased risk of death.

Lung Ultrasound to Assess Pulmonary Congestion in Patients with Acute Exacerbation of COPD

Purpose

Heart failure (HF) often coexists with chronic obstructive pulmonary disease (COPD) and is associated with worse outcomes. We aimed to assess the feasibility of detecting vertical artifacts (B-lines) on lung ultrasound (LUS) to identify concurrent HF in patients hospitalized with acute exacerbation of COPD (AECOPD). Second, we wanted to assess the association between B-lines and the risk of rehospitalization for AECOPD or death.

Patients and Methods

In a prospective cohort study, 123 patients with AECOPD underwent 8-zone bedside LUS within 24h after admission. A positive LUS was defined by ≥3 B-lines in ≥2 zones bilaterally. The ability to detect concurrent HF (adjudicated by a cardiologist committee) and association with events were evaluated by logistic- and Cox regression models.

Results

Forty-eight of 123 patients with AECOPD (age 75±9 years, 57[46%] men) had concurrent HF. Sixteen (13%) patients had positive LUS, and the prevalence of positive LUS was similar between patients with and without concurrent HF (8[17%] vs 8[11%], respectively, p=0.34). The number of B-lines was higher in concurrent HF: median 10(IQR 6-16) vs 7(IQR 5-12), p=0.03. The sensitivity and specificity for a positive LUS to detect concurrent HF were 17% and 89%, respectively. Positive LUS was not associated with rehospitalization and mortality: Adjusted HR: 0.93(0.49-1.75), p=0.81.

Conclusion

LUS did not detect concurrent HF or predict risk in patients with AECOPD.

Novice-performed point-of-care ultrasound for home-based imaging

Patient-performed point-of-care ultrasound (POCUS) may be feasible for use in home-based healthcare. We investigated whether novice users can obtain lung ultrasound (LUS) images via self-scanning with similar interpretability and quality as experts. Adult participants with no prior medical or POCUS training, who were capable of viewing PowerPoint slides in their home and who could hold a probe to their chest were recruited. After training, volunteers self-performed 8-zone LUS and saved images using a hand-held POCUS device in their own home. Each 8-zone LUS scan was repeated by POCUS experts. Clips were independently viewed and scored by POCUS experts blinded to performing sonographers. Quality and interpretability scores of novice- and expert-obtained LUS images were compared. Thirty volunteers with average age of 42.8 years (Standard Deviation (SD) 15.8), and average body mass index of 23.7 (SD 3.1) were recruited. Quality of novice and expert scans did not differ (median score 2.6, interquartile range (IQR) 2.3-2.9 vs. 2.8, IQR 2.3-3.0, respectively p = 0.09). Individual zone quality also did not differ (P > 0.05). Interpretability of LUS was similar between expert and novice scanners (median 7 zones interpretable, IQR 6-8, for both groups, p = 0.42). Interpretability of novice-obtained scans did not differ from expert scans (median 7 out of 8 zones, IQR 6-8, p = 0.42). Novice-users can self-obtain interpretable, expert-quality LUS clips with minimal training. Patient-performed LUS may be feasible for outpatient home monitoring.

Prevalence and Dynamic Changes in Lung Ultrasound Findings among Adults with Uncomplicated Malaria and Controls in the Amazon Basin, Brazil

Malaria patients are at risk of cardiopulmonary complications but diagnosis and management can be difficult in resource-limited settings. B-lines on lung ultrasound (LUS) mark changes in lung density; however, little is known about their role in malaria. We aimed to examine the prevalence of B-lines in adults with malaria at baseline and follow-up compared with controls in the Amazon Basin. We also examined the relationship between B-lines and left ventricular ejection fraction. We performed eight-zone LUS, echocardiography, and blood smears in 94 adults (mean age 40 years, 54% men) with uncomplicated malaria and 449 controls without heart failure, renal insufficiency or lung disease (mean age 41 years, 38% men). Examinations of adults with malaria were repeated after antimalarial treatment, corresponding to a median of 30 days (interquartile range [IQR] 27-39). Adults with malaria suffered from Plasmodium vivax (N = 70, median 2,823 [IQR 598-7,698] parasites/μL) or P. falciparum (N = 24, median 1,148 [IQR 480-3,128] parasites/μL). At baseline, adults with malaria more frequently had ≥ 3 B-lines (summed across eight zones) compared with controls (30% versus 2%, P value < 0.001), indicating higher lung density. When examinations were repeated, only 6% of adults with malaria had ≥ 3 B-lines at follow-up, which was significant lower compared with baseline (median reduction 3 B-line; P value < 0.001). B-lines were not significantly associated with left ventricular ejection fraction in adults with malaria. In conclusion, B-lines detected by LUS were more frequent in adults with uncomplicated malaria compared with controls and decreased after completed antimalarial treatment.

Lung Congestion Severity in Kidney Transplant Recipients Is Not Affected by Arteriovenous Fistula Function

Lung ultrasound is a bedside technique for the assessment of pulmonary congestion. The study aims to assess the severity of lung congestion in kidney transplant recipients (KTR) in relation to arteriovenous fistula (AVF) patency. One hundred fifty-seven patients at least 12 months after kidney transplantation were recruited to participate in a cross-sectional study. Apart from routine visits, lung ultrasound at 28 typical points was performed. The patients were assigned to either AVF+ or AVF− groups. The mean number of lung ultrasound B-lines (USBLs) was 5.14 ± 4.96 with no differences between groups: 5.5 ± 5.0 in AVF+ and 4.8 ± 4.9 in AVF−, p = 0.35. The number and proportion of patients with no congestion (0–5 USBLs), mild congestion (6–15 USBLs), and moderate congestion (16–30 USBLs) were as follows: 101 (64.7%), 49 (31.4%), and 6 (3.8%), respectively. In multivariate analysis, only symptoms (OR 5.90; CI 2.43,14.3; p = 0.0001), body mass index (BMI) (OR 1.09; CI 1.03,1.17; p = 0.0046), and serum cholesterol level (OR 0.994; CI 0.998,1.000; p = 0.0452) contributed significantly to the severity of lung congestion. Lung ultrasound is a valuable tool for the evaluation of KTR. Functioning AVF in KTR is not the major factor affecting the severity of pulmonary congestion.

Implementation of lung ultrasound in the triage of pregnant women during the SARS-CoV-2 pandemics

Lung ultrasound (US) has been shown that it is able to detect interstitial lung disease, subpleural consolidations and acute respiratory distress syndrome in clinical and physical studies that assess its role in upper respiratory infections. It is used worldwide in the coronavirus disease 2019 (COVID-19) outbreak and the effectiveness has been assessed in several studies. Fast diagnosis of COVID-19 is essential in deciding for patient isolation, clinical care and reducing transmission. Imaging the lung and pleura by ultrasound is efficient, cost-effective, and safe and it is recognized as rapid, repeatable, and reliable. Obstetricians are already using the US and are quite proficient in doing so. During the pandemic, performing lung US (LUS) right after the fetal assessment until reverse transcription polymerase chain reaction results are obtained, particularly in settings that have a centralized testing center, was found feasible for the prediction of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The use of LUS is efficient in the triage and monitoring of pregnant women. Clinicians dealing with pregnant women should consider LUS as the first-line diagnostic tool in pregnant women during the SARS-CoV-2 pandemic.

A-lines and B-lines in patients with acute heart failure

AIMS

Lung ultrasound (LUS) relies on detecting artefacts, including A-lines and B-lines, when assessing dyspnoeic patients. A-lines are horizontal artefacts and characterize normal lung, whereas multiple vertical B-lines are associated with increased lung density. We sought to assess the prevalence of A-lines and B-lines in patients with acute heart failure (AHF) and examine their clinical correlates and their relationship with outcomes.

METHODS AND RESULTS

In a prospective cohort study of adults with AHF, eight-zone LUS and echocardiography were performed early during the hospitalization and pre-discharge at an imaging depth of 18 cm. A- and B-lines were analysed separately off-line, blinded to clinical and outcome data. Of 164 patients [median age 71 years, 61% men, mean ejection fraction (EF) 40%], the sum of A-lines at baseline ranged from 0 to 19 and B-line number from 0 to 36. One hundred and fifty-six patients (95%) had co-existing A-lines and B-lines at baseline. Lower body mass index and lower chest wall thickness were associated with a higher number of A-lines (P trend < 0.001 for both). In contrast to B-lines, there was no significant change in the number of A-lines from baseline to discharge (median 6 vs. 5, P = 0.80). While B-lines were associated with 90-day HF readmission or death, A-lines were not [HR 1.67, 95% confidence interval (CI) 1.11-2.51 vs. HR 0.97, 95% CI 0.65-1.43].

CONCLUSIONS

A-lines and B-lines on LUS co-exist in the vast majority of hospitalized patients with AHF. In contrast to B-lines, A-lines were not associated with adverse outcomes.

Diagnostic accuracy of lung ultrasound for SARS-CoV-2: a retrospective cohort study

Background

As medical infrastructures are strained by SARS-CoV-2, rapid and accurate screening tools are essential. In portions of the world, reverse transcription polymerase chain reaction (RT-PCR) testing remains slow and in limited supply, and computed tomography is expensive, inefficient, and involves exposure to ionizing radiation. Multiple studies evaluating the efficiency of lung point-of-care ultrasound (POCUS) have been published recently, but include relatively small cohorts and often focus on characteristics associated with severe illness rather than screening efficacy. This study utilizes a retrospective cohort to evaluate the test characteristics (sensitivity, specificity, likelihood ratios, predictive values) of lung POCUS in the diagnosis of SARS-CoV-2, and to determine lung score cutoffs that maximize performance for use as a screening tool.

Results

Lung POCUS examinations had sensitivity 86%, specificity 71.6%, NPV 81.7%, and PPV 77.7%. The Lung Ultrasound Score had an area under the curve of 0.84 (95% CI 0.78, 0.90). When including only complete examinations visualizing 12 lung fields, lung POCUS had sensitivity 90.9% and specificity 75.6%, with NPV 87.2% and PPV 82.0% and an area under the curve of 0.89 (95% CI 0.83, 0.96). Lung POCUS was less accurate in patients with a history of interstitial lung disease, severe emphysema, and heart failure.

Conclusions

When applied in the appropriate patient population, lung POCUS is an inexpensive and reliable tool for rapid screening and diagnosis of SARS-CoV-2 in symptomatic patients with influenza-like illness. Adoption of lung POCUS screening for SARS-CoV-2 may identify patients who do not require additional testing and reduce the need for RT-PCR testing in resource-limited environments and during surge periods.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13089-021-00217-7.

Assessing congestion in acute heart failure using cardiac and lung ultrasound - a review

Introduction: Acute heart failure (AHF) is one of the leading causes of hospital admissions and is characterized by systemic and pulmonary congestion, which often precedes the overt clinical signs and symptoms. Echocardiography in the management of chronic HF is well described; however, there are less evidence regarding echocardiography and lung ultrasound (LUS) in the acute setting.Areas covered: We have summarized current evidence regarding the use of echocardiography and LUS for assessing congestion in patients with AHF. We discuss the value and reliability of handheld/pocketsize ultrasound devices in AHF.Expert opinion: Echocardiography is an essential tool for the diagnostic work up in patients with AHF. No individual parameter reliably detects congestion, thus the physician must integrate several measurements from the right and left heart. Novel methods and advances in cardiac imaging and clinical chemistry make it possible to detect congestion at an early stage. LUS is particularly helpful in assessing congestion, and it has demonstrated diagnostic, therapeutic, and prognostic value in AHF. LUS is relatively easy to learn and allows for quick assessment of the presence of pulmonary congestion and pleural effusion. We recommend integration of LUS for routine management of patients with AHF.

Prognostic value of lung ultrasound in chronic stable ambulatory heart failure patients

INTRODUCTION AND OBJECTIVES

The role of lung ultrasound (LUS) in acute heart failure (HF) has been widely studied, but little is known about its usefulness in chronic HF. This study assessed the prognostic value of LUS in a cohort of chronic HF stable ambulatory patients.

METHODS

We included consecutive outpatients who attended a scheduled follow-up visit in a HF clinic. LUS was performed in situ. The operators were blinded to clinical data and examined 8 thoracic areas. The sum of B-lines across all lung zones and the quartiles of this addition were used for the analyses. Linear regression and Cox regression analyses were performed. The main clinical outcomes were a composite of all-cause death or hospitalization for HF and mortality from any cause.

RESULTS

A total of 577 individuals were included (72% men; 69± 12 years). The mean number of B-lines was 5±6. During a mean follow-up of 31±7 months, 157 patients experienced the main clinical outcome and 111 died. Having ≥ 8 B-lines (Q4) doubled the risk of experiencing the composite primary event (P <.001) and increased the risk of death from any cause by 2.6-fold (P <.001). On multivariate analysis, the total sum of B-lines remained independent predictive factor of the composite endpoint (HR, 1.04; 95%CI, 1.02-1.06; P=.002) and of all-cause death (HR, 1.04; 95%CI, 1.02-1.07; P=.001), independently of whether or not N-terminal pro-B-type natriuretic peptide (NT-proBNP) was included in the model (P=.01 and P=.008, respectively), with a 3% to 4% increased risk for each 1-line addition.

CONCLUSIONS

LUS identified patients with stable chronic HF at high risk of death or HF hospitalization.

Ultrasound indices of congestion in patients with acute heart failure according to body mass index

BACKGROUND

The inverse relationship between body mass index (BMI) and natriuretic peptide levels complicates the diagnosis of heart failure (HF) in obese patients. Assessment of congestion with ultrasound could facilitate HF diagnosis but it is unclear if any relationship exists amongst BMI, inferior vena cava (IVC) diameter and the number of B-lines.

METHODS

We performed a comprehensive echocardiographic evaluation within 24 h from hospital admission in patients with HF, including lung B-lines and IVC diameter, and studied their relationship with BMI and outcome.

RESULTS

216 patients (median age 81 (77-86) years) were enrolled. Median number of B-lines was 31 (IQR 26-38), median IVC diameter was 23 (22-25) mm and median BNP 991 (727-1601) pg/mL. BMI was inversely correlated with B-lines (r = - 0.50, p < 0.001), but not with IVC diameter (r = - 0.04, p = 0.58). Compared to overweight patients (BMI 25-29.9 kg/m2; n = 100) or with a normal BMI (BMI < 25 kg/m2; n = 59), obese patients (BMI ≥ 30 kg/m2; n = 57) had lower B-lines [28 (24-33) vs 30 (26-35), and vs 38 (32-42), respectively; p < 0.001] but similar IVC diameter. During the first 60 days of follow-up, there were 53 primary events: 29 patients died and 24 had a HF-related hospitalisation. B-lines and IVC diameter were independently associated with an increased risk. However, B-lines were less likely to predict outcome in the subgroup of patients with a BMI ≥ 30 kg/m².

CONCLUSIONS

Assessment of IVC diameter or B-lines in patients admitted with AHF identifies those at greater risk of death or HF readmission. However, assessment of B-lines might be influenced by BMI.

Body mass index and B-lines on lung ultrasonography in chronic and acute heart failure

AIMS

Increased body mass index (BMI) is common in heart failure (HF) patients and is associated with lower levels of N-terminal pro-brain natriuretic peptide (NT-proBNP). We evaluated the influence of BMI on lung ultrasonography (LUS) findings indicative of pulmonary congestion (i.e. B-lines) in patients with chronic and acute HF (AHF).

METHODS AND RESULTS

We analysed ambulatory chronic HF (n = 118) and hospitalized AHF (n = 177) patients (mean age 70 years, 64% men, mean BMI 29 kg/m² , mean ejection fraction 42%) undergoing echocardiography and LUS in eight chest zones. B-lines and chest wall thickness (skin to pleura) on ultrasound were quantified offline and blinded to clinical findings. NT-proBNP was available in AHF patients (n = 167). In chronic HF, B-line number decreased by 18% per 5 unit increase in BMI [95% confidence interval (CI) -35% to +5%, P = 0.11]. In AHF, the number of B-lines decreased by 12% per 5 unit increase in BMI (95% CI -19% to -5%, P = 0.001), whereas NT-proBNP concentration decreased by 28% per 5 unit increase in BMI (95% CI -40% to -16%, P < 0.001). For AHF, B-line number declined to a lesser degree than NT-proBNP concentration with increasing BMI (P = 0.020), and >6 B-lines were observed in half of AHF patients with severe obesity. There was an inverse relationship between B-line number and chest wall thickness, and this association varied by chest region.

CONCLUSIONS

Despite an inverse relationship between B-lines and BMI, B-lines declined to a lesser degree than NT-proBNP with increasing BMI. These data suggest that LUS may be useful in patients with HF despite obesity.