Lung Ultrasound B-lines Occurrence in Relation to Left Ventricular Function and Hydration Status in Hemodialysis Patients

A nephrology trainee can define the fluid status through lung ultrasonography and inferior vena cava measurements in hemodialysis patients: an observational study in a single center

AIMS

The determination of ideal weight in hemodialysis patients remains a common problem. The use of Lung Ultrasound (LUS) is an emerging method of assessing the hydric status of hemodialysis patients. LUS combined with Inferior Vena Cava (IVC) ultrasonography can define the fluid status in hemodialysis patients.

METHODS

This study included 68 hemodialysis patients from the Dialysis Unit of Papageorgiou General Hospital in Thessaloniki. The patients underwent lung and IVC ultrasound 30 min before and after the end of the dialysis session by a nephrology trainee. Patients' ideal weight was modified based on daily clinical practice rather than ultrasound findings. The presence of B lines and ultrasound findings of the IVC were evaluated.

RESULTS

The average B line score was 11.53 ± 5.02 before dialysis and became 5.57 ± 3.14 after the session. The average diameter of the IVC was 14.266 ± 0.846 mm before dialysis and 12.328 ± 0.879 mm after the session. The patients were categorized based on the magnitude of overhydration and the findings were evaluated. In addition, findings after the session showed a statistically significant correlation between the b line score and the diameter of the IVC adjusted for the body surface area. (p = 0.009 < 0.05).

CONCLUSIONS

A high rate of hyperhydration was detected before the dialysis session (25%). While it is the first study conducted by a nephrology trainee highlighting that it is a feasible technique. Intervention studies should be carried out in the future to draw more precise conclusions.

The use of lung ultrasound in evaluation of extravascular lung water in hemodialysis patients: Systematic review and meta-analysis

RATIONALE AND OBJECTIVES

Determining dry weight is crucial for optimizing hemodialysis, influencing efficacy, cardiovascular outcomes, and overall survival. Traditional clinical assessment methods for dry weight, relying on factors such as blood pressure and edema, frequently lack reliability. Lung ultrasound stands out as a promising tool for assessing volume status, given its non-invasiveness and reproducibility. This study aims to explore the role of Lung ultrasound in evaluating the impact of hemodialysis and ultrafiltration on extravascular lung water, with a specific focus on changes in B-lines post-hemodialysis compared to pre-hemodialysis.

MATERIALS AND METHODS

The research encompassed searches across PubMed, WOS, and Scopus databases for studies related to lung ultrasound and hemodialysis. A meta-analysis was then performed to determine the mean differences in various parameters before compared to after, hemodialysis, including the number of B-lines, indexed end-inspiratory and end-expiratory inferior vena cava diameters, inferior vena cava collapsibility index, weight, blood pressure, and serum levels of NT-pro-BNP.

RESULTS

Our meta-analysis, included 33 studies with 2301 hemodialysis patients, revealed a significant decrease in the number of B-lines post-hemodialysis (mean difference = 8.30, 95% CI [3.55 to 13.05]). Furthermore, there was a noteworthy reduction in inspiratory and expiratory inferior vena cava diameters post-hemodialysis (mean difference = 2.32, 95% CI [0.31 to 4.33]; mean difference = 4.05, 95% CI [2.44 to 5.65], respectively). Additionally, a significant positive correlation was observed between B-lines and the maximum inferior vena cava diameter both pre- and post-hemodialysis (correlation coefficient = 0.39; correlation coefficient = 0.32, respectively).

CONCLUSION

These findings indicate the effectiveness of lung ultrasound in detection of volume overload and assessment of response to ultrafiltration in hemodialysis patients.

Lung Ultrasound and Bioelectrical Impedance Analysis for Fluid Status Assessing Patients Undergoing Maintenance Hemodialysis

Background

Volume overload is a fatal complication for people undergoing hemodialysis. Therefore, regulating a patient's "dry weight" based on their fluid status is imperative. Clinical experiences are too subjective to accurately judge a patient's fluid status, but techniques have emerged for improved fluid control in the two decades. Specifically, lung ultrasonography (LUS) uses a unique aspect of ultrasound images, the B-lines, to evaluate extravascular lung water, which has increasingly attracted attention. However, the role of B-line quantification in predicting short-mid-term death and/or cardiovascular complications is unclear.

Methods

Patients undergoing MHD at the hemodialysis center of Zhejiang Provincial People's Hospital from October 1, 2020, to February 28, 2021, were examined using LUS and a bioelectrical impedance analysis before and after dialysis, and related clinical data were collected. All patients were followed up for one year after the examination, and deaths and first cardiovascular events (e.g., stroke, myocardial infarction, and heart failure) during this period were recorded.

Results

98 patients were enrolled and divided into three groups in relation to their mild (<16 B-lines), moderate (16-30 B-lines), or severe (>30 B-lines) hypervolemia, defined by the number of B-lines. The long-term survival rate was significantly lower in the severe group than in the mild and moderate groups. LUS and bioelectrical impedance-related parameters (e.g., extracellular water-to-water ratio) were closely related to cardiac ultrasound parameters (left ventricular ejection fraction) (P < 0.001). The optimal B-line cutoff value on LUS for predicting fluid overload (defined clinically) in patients on hemodialysis was 11.5 lines (AUC = 0.840, 95% confidence interval 0.735-0.945, P < 0.001), and the diagnostic sensitivity and specificity were both 76.5%. During the one-year follow-up period, ten deaths and six cardiovascular events occurred. The survival rate was significantly lower in the severe group than in the mild group (log-rank test χ2 = 10.050, P=0.002) but did not differ between the severe and moderate groups (χ2 = 2.629, P=0.105).

Conclusion

LUS is a cheap, noninvasive, simple, and repeatable volume-monitoring method that can assist with individualized fluid volume management in patients undergoing MHD. LUS results may also help to predict the short-mid-term survival rate of patients to a certain extent.

Volume Status Assessment by Lung Ultrasound in End-Stage Kidney Disease: A Systematic Review

Purpose of review

Lung ultrasound is a noninvasive bedside technique that can accurately assess pulmonary congestion by evaluating extravascular lung water. This technique is expanding and is easily available. Our primary outcome was to compare the efficacy of volume status assessment by lung ultrasound with clinical evaluation, echocardiography, bioimpedance, or biomarkers. The secondary outcomes were all-cause mortality and cardiovascular events.

Sources of information

We conducted a MEDLINE literature search for observational and randomized studies with lung ultrasound in patients on maintenance dialysis.

Methods

From a total of 2363 articles, we included 28 studies (25 observational and 3 randomized). The correlation coefficients were pooled for each variable of interest using the generic inverse variance method with a random effects model. Among the clinical parameters, New York Heart Association Functional Classification of Heart Failure status and lung auscultation showed the highest correlation with the number of B-lines on ultrasound, with a pooled r correlation coefficient of .57 and .36, respectively. Among echocardiographic parameters, left ventricular ejection fraction and inferior vena cava index had the strongest correlation with the number of B-lines, with a pooled r coefficient of .35 and .31, respectively. Three randomized studies compared a lung ultrasound-guided approach with standard of care on hard clinical endpoints. Although patients in the lung ultrasound group achieved better decongestion and blood pressure control, there was no difference between the 2 management strategies with respect to death from any cause or major adverse cardiovascular events.

Key findings

Lung ultrasound may be considered for the identification of patients with subclinical volume overload. Trials did not show differences in clinically important outcomes. The number of studies was small and many were of suboptimal quality.

Limitations

The included studies were heterogeneous and of relatively limited quality.

Association of Lung Ultrasound B-Lines with Left Ventricular Diastolic Function in Clinically Euvolemic Haemodialysis Patients

INTRODUCTION

Left ventricular diastolic dysfunction (LVDD) frequently occurs in haemodialysis patients and is associated with adverse outcomes. Lung ultrasound (LUS) has been recently proposed for the quantification of extravascular lung water through assessment of B-lines. LUS findings and their relationship with LVDD in clinically euvolemic haemodialysis patients were investigated in this study.

METHODS

Echocardiography and LUS examinations were performed on each patient. Multivariate linear regression and forward stepwise logistic regression were performed to determine the relationship between B-lines and LVDD. A receiver operating characteristic (ROC) curve with area under the curve (AUC) was calculated to determine the accuracy of B-lines for evaluating LVDD.

RESULTS

A total of 119 patients were enrolled. The number of B-lines was statistically related to echocardiographic parameters (LAVI, LVEDVI, E/A, and E/e') of diastolic function, while the relationship between B-lines and LVEF disappeared after adjusting for potential confounding factors. Additionally, compared with the mild B-line group (B-lines: <14), the moderate (B-lines: 14-30) and severe B-line groups (B-lines: >30) were associated with an increased risk of LVDD (OR 24.344, 95% CI 4.854-122.084, p < 0.001, and OR 94.552, 95% CI 9.617-929.022, p < 0.001, respectively). Furthermore, the AUC of the ROC curve for B-lines predicting LVDD was 0.845, and the cut-off of B-lines was 14.5 (sensitivity 64.91%, specificity 93.55%).

CONCLUSION

LUS B-lines were closely associated with left ventricular diastolic function in clinically euvolemic haemodialysis patients. Moreover, our findings suggested a B-line ≥14.5 as a reliable cut-off value for identifying patients with LVDD. LUS B-lines may be used as a novel indicator for evaluating LVDD.

Lung Ultrasound Estimates the Overhydration and Benefits Blood Pressure Control in Normal or Mild Symptomatic Hemodialysis Patients

Introduction

Lung ultrasound (LUS) is used for dry weight guidance by assessment of pulmonary congestion in hemodialysis (HD) patients. The aim of this study was to estimate amounts of accumulated fluid by total LUS scores (TLUSS), which were scarcely reported in HD patients who were normal or had a mild functional abnormality. In addition, the correlations between the LUS score of each area and TLUSS were determined to suggest fewer specific areas valuable to shorten the examination time of LUS.

Methods

This cohort study was conducted in adult HD patients who have New York Heart Association Classes I-II. LUS and multifrequency bioimpedance (BIA) were performed at baseline and the individual prescribed dry weight was set. Then each LUS was conducted at 28 areas of bilateral intercostal spaces and calculated as TLUSS weekly for eight weeks in which dry weight was adjusted. The second BIA was also measured at week eight. The difference of pre-HD weight and target weight (weight gain; WG) represented the amount of fluid accumulation.

Results

Twenty patients with a mean age of 62.2±14.0 years were enrolled. One hundred and sixty-six LUS were performed in which forty episodes of them were simultaneously measured with BIA. Optimum dry weight adjusted by TLUSS which benefited in mean reductions of blood pressure, and cardiothoracic ratios. WG amounts were significantly correlated with TLUSS (r=0.38), and with extracellular fluid (r=0.35) and overhydration fluid (r=0.39) assessed by BIA. Estimations of mean fluid overload were 2.18 (TLUSS ≤15), 2.72 (TLUSS 16-24), 3.17 (TLUSS 25-33), 3.65 (TLUSS 34-38) and 5.03 (TLUSS ≥39) in liters. The cut-off points of sum scores of 12 specific lung areas represented the none-mild were <8, moderate at 8-16, and severe pulmonary congestions were >16.

Conclusion

TLUSS estimated accumulated fluid useful for volume and blood pressure controls. Performance of LUS in 12 specific lung areas may reduce spending time and support routine uses of LUS in clinical practice.

Detecting and Treating Lung Congestion with Kidney Failure

Fluid overload is a common complication in patients with CKD, particularly patients with kidney failure, a population with a very high risk for pulmonary edema. Lung ultrasound is now a well-validated technique that allows for reliable estimates of lung water in clinical practice. Several studies in patients with kidney failure documented a high prevalence of asymptomatic lung congestion of moderate to severe degree in this population, and this alteration was only weakly related with fluid excess as measured by bioimpedance spectroscopy. Furthermore, in these studies, lung congestion correlated in a dose-dependent fashion with death risk. In the Lung Water by Ultra-Sound Guided Treatment to Prevent Death and Cardiovascular Complications in High Risk Kidney Failure Patients with Cardiomyopathy (LUST) trial, a treatment strategy guided by lung ultrasound safely relieved lung congestion but failed to significantly reduce the risk for a combined end point including death, nonfatal myocardial infarction, and decompensated heart failure. However, in line with three trials in patients with heart failure, a post hoc analysis of the LUST trial showed that the use of lung ultrasound reduces the risk for repeated episodes of acute heart failure and repeated cardiovascular events. Given the high cardiovascular risk of pulmonary edema in patients with predialysis CKD, defining the epidemiology of lung congestion in this population is a public health priority. Specific trials in this population and additional trials in patients with kidney failure will establish whether targeting lung congestion at an asymptomatic phase may improve the severe cardiovascular prognosis of both patients predialysis and patients on dialysis.

Recommendations for Lung Ultrasound in Internal Medicine

A growing amount of evidence prompts us to update the first version of recommendations for lung ultrasound in internal medicine (POLLUS-IM) that was published in 2018. The recommendations were established in several stages, consisting of: literature review, assessment of literature data quality (with the application of QUADAS, QUADAS-2 and GRADE criteria) and expert evaluation carried out consistently with the modified Delphi method (three rounds of on-line discussions, followed by a secret ballot by the panel of experts after each completed discussion). Publications to be analyzed were selected from the following databases: Pubmed, Medline, OVID, and Embase. New reports published as of October 2019 were added to the existing POLLUS-IM database used for the original publication of 2018. Altogether, 528 publications were systematically reviewed, including 253 new reports published between September 2017 and October 2019. The new recommendations concern the following conditions and issues: pneumonia, heart failure, monitoring dialyzed patients' hydration status, assessment of pleural effusion, pulmonary embolism and diaphragm function assessment. POLLUS-IM 2020 recommendations were established primarily for clinicians who utilize lung ultrasound in their everyday clinical work.