Extravascular Lung Water Assessment by Ultrasound to Guide Dry Weight Changes: Ready for Prime Time?

Scanning more corresponds to more accuracy in hemodialysis patients: 28-zone protocol's superior findings from an observational study

AIMS

Hypervolemia remains a problem in hemodialysis patients and is associated with hypertension, cardiovascular events and mortality. Lung Ultrasound (LUS) is a technique that detects hypervolemia via 4 different protocols depending on the number of sites checked on the chest wall. It has not been established which protocol should be preferred in the literature.

METHODS

This study included 68 hemodialysis patients from one Dialysis Unit. All the patients underwent LUS with every single protocol 30 min before and after the end of the middle-week dialysis session by a nephrology trainee. Patients' ideal weight was modified based on daily clinical practice rather than ultrasound findings.

RESULTS

Seventeen patients (25%) had ultrasound findings compatible with hypervolemia before the dialysis session, while eleven patients (16.2%) had still pulmonary congestion after the end of the session. These findings were similar to the number of patients considered hyperhydrated based on clinical criteria (10 patients). The rest protocols (8-zone, 6-zone and 4-zone protocol) considered fewer patients as hypervolemic.

CONCLUSIONS

The 28-zone protocol can effectively detect hypervolemia and even classify the degree of it, although It is a time-consuming method. However, the other protocols can detect the hypervolemia in hemodialysis patients only when severe lung congestion exists. Their usefulness is limited in daily clinical practice in hemodialysis patients. More studies should be carried out for further and more reliable conclusions.

Quantitative Lung Ultrasonography for the Nephrologist: Applications in Dialysis and Heart Failure

Volume overload, and its attendant increase in acute care utilization and cardiovascular morbidity and mortality, represents a critical challenge for the practicing nephrologist. This is particularly true among patients with ESKD on HD, where predialysis volume overload and intradialytic and postdialytic hypovolemia account for almost a third of all cost for the Medicare dialysis benefit. Quantitative lung ultrasound is a tool for assessing the extent of extravascular lung water that outperforms physical exam and plain chest radiography. B-lines are vertical hyperechoic artifacts present in patients with increased extravascular lung water. B-lines have been shown to decrease dynamically during the hemodialysis treatment in proportion to ultrafiltration volume. Among patients with chronic heart failure, titration of diuretics on the basis of the extent of pulmonary congestion noted on lung ultrasonography has been shown to decrease recurrent acute care utilization. Early data from randomized controlled trials of lung ultrasound-guided ultrafiltration therapy among patients with ESKD on HD have shown promise for potential reduction in recurrent episodes of decompensated heart failure and cardiovascular events. Ultimately, lung ultrasound may predict those who are ultrafiltration tolerant and could be used to decrease acute care utilization and, thus, cost in this population.

Ultrasonographic Assessment of Extravascular Lung Water in Hospitalized Patients Requiring Hemodialysis: A Prospective Observational Study

INTRODUCTION

Sonographic technologies can estimate extravascular lung water (EVLW) in hemodialysis (HD) patients. This study investigated the suitability of a handheld scanner in contrast to a portable scanner for quantifying EVLW in hospitalized patients requiring HD.

METHODS

In this prospective study, 54 hospitalized HD patients were enrolled. Bedside lung ultrasound was performed within 30 min before and after dialysis using handheld (phased array transducer, 1.7-3.8 MHz) and portable (curved probe, 5-2 MHz) ultrasound devices. Eight lung zones were scanned for total B-lines number (TBLN). The maximum diameter of inferior vena cava (IVC) was measured. We performed Passing-Bablok regression, Deming regression, Bland-Altman, and logistic regression analysis.

RESULTS

The 2 devices did not differ in measuring TBLN and IVC (p > 0.05), showing a high correlation (r = 0.92 and r = 0.51, respectively). Passing-Bablok regression had a slope of 1.11 and an intercept of 0 for TBLN, and the slope of Deming regression was 1.02 within the CI bands of 0.94 and 1.11 in the full cohort. TBLN was logarithmically transformed for Bland-Altman analysis, showing a bias of 0.06 (TBLN = 1.2) between devices. The slope and intercept of the Deming regression in IVC measurements were 0.77 and 0.46, respectively; Bland-Altman plot showed a bias of -0.07. Compared with predialysis, TBLN significantly (p < 0.001) decreased after dialysis, while IVC was unchanged (p = 0.16). Univariate analysis showed that cardiovascular disease (odds ratio [OR] 8.94 [2.13-61.96], p = 0.002), smoking history (OR 5.75 [1.8-20.46], p = 0.003), and right pleural effusion (OR 5.0 [1.2-25.99], p = 0.03) were strong predictors of EVLW indicated by TBLN ≥ 4.

CONCLUSION

The lung and IVC findings obtained from handheld and portable ultrasound scanners are comparable and concordant. Cardiovascular disease and smoking history were strong predictors of EVLW. The use of TBLN to assess EVLW in hospitalized HD patients is feasible. Further studies are needed to determine if TBLN can help guide volume removal in HD patients.

Lung ultrasound methods for assessing fluid volume change and monitoring dry weight in pediatric hemodialysis patients

BACKGROUND

The value of lung ultrasound in adult hemodialysis has been confirmed. The determination of dry weight in children remains challenging. This study explores the usefulness of lung ultrasound in assessing fluid volume change and the possibility of pulmonary ultrasound as a method to monitor dry weight in pediatric dialysis patients.

METHODS

This was a prospective observational study. We compared the predialysis and postdialysis B-line scores of the dry-weight group and non-dry-weight group. Changes in body weight and B-line scores were recorded during the dialytic period and interdialytic period, and the correlation was analyzed. Lung ultrasound was performed after the dialysis session every Friday, and B-line score < 10 was considered to indicate that there was no volume overload; the weight was recorded as the target weight.

RESULTS

Fourteen patients were included. A total of 78 ultrasound assessments were performed: 30 in the dry-weight group and 48 in the non-dry-weight group. The B-line scores decreased after dialysis in all patients (p < 0.001). Thirty-three assessments were performed in the interdialytic period, and 40 assessments in the dialytic period were performed within 1 week. Linear regression showed that changes in B-line number were directly and positively correlated with interdialytic weight gain (r = 0.517, p = 0.002) and dialytic weight loss (r = 0.558, p < 0.001). The weight of the children increased gradually without volume overload in two patients during follow-up.

CONCLUSION

Lung ultrasound can assess the fluid volume change of pediatric dialysis patients in real time. Lung ultrasound could be a valuable method for monitoring dry weight in pediatric dialysis patients.