#SCM16: Lung Ultrasound for the Renal Doctor

Peguero SCM16 headshotDr. Alfredo Peguero (AP), from James A. Haley VA Hospital in Tampa, Florida, discusses his abstract for the National Kidney Foundation’s 2016 Spring Clinical Meetings (SCM16), Ultrasonography to Evaluate Pulmonary Edema Resolution With Blood Pressure Control in a Hemodialysis Patient, with Dr. Kenar Jhaveri, AJKD Blog Editor.

AJKDblog: Why don’t you tell us a little about your research and abstract being presented at the NKF 2016 Spring Meetings?

AP: Like many other nephrologists, I found the evaluation of extracellular volume in patients to be challenging. The current methods are not completely accurate or reliable, making it hard to precisely determine the “dry weight” of patients with end-stage renal disease (ESRD).

The clinical situation is more delicate when the patient presents with clinical signs of active heart failure. The main goal is to normalize interstitial volume, which is normally indicated by the presence of edema or inspiratory rates. The jugular venous distention frequently is not a reliable sign in the dialysis population due to the high prevalence of pulmonary hypertension, internal jugular vein structural abnormalities, and/or obesity.

The use of lung ultrasonography to evaluate pulmonary interstitial syndrome is emerging as a promising tool in the diagnosis and management of patients with ESRD. Recently, it has been demonstrated in patients on hemodialysis (HD) that moderate to severe increases in ultrasonographic signs of pulmonary interstitial syndrome correlate with mortality at two years. Moreover, 38% of HD patients with moderate to severe ultrasonographic signs were classified as New York Heart Association class I or asymptomatic. The presence of ultrasonic B-lines correlate with mortality and physical functioning in the ESRD population. In our opinion, sonographic assessment of the lungs is more reliable than auscultation in the evaluation of pulmonary congestion. In addition, the B-lines, when related to heart failure, are very dynamic, and proper treatment results in their disappearance.

Ultrafiltration does not always improve the dyspnea or pulmonary congestion in the dialysis population. A small but sizable (15%) percentage of hypertensive patients increase their blood pressure during dialysis or ultrafiltration sessions. If these HD patients have systolic and/or diastolic dysfunction, the increase in the afterload may induce an increase in the end-diastolic pressure. This increases venous and pulmonary interstitial pressures leading to an accumulation of lung interstitial fluid. This is counteracted by the systemic fluid removal through ultrafiltration. Visual evaluation and rapid resolution of this pulmonary edema was captured by assessment of the decrease in sonographic B-lines. As an additional observation, the resolution of dyspnea was concomitant with the resolution of the sonographic findings but not to the auscultatory means. The conclusion of our observational study is that serial sonographic assessments may be supplemental to the physical exam in the evaluation of dyspnea and the management of pulmonary edema/congestion in ESRD patients. In addition, this case supports pharmacologic afterload reduction as having a more immediate effect on resolving pulmonary interstitial lung water than ultrafiltration alone, which can paradoxically lead to an increase in lung water due to afterload increase from physiologic responses to vascular volume reduction.

AJKDblog: Can you explain to us the findings on lung ultrasound that help diagnose pulmonary edema?

AP: In the presence of interstitial lung water, the ultrasound beam is reflected or echoed by the subpleural interlobular septa, which is thickened by lung edema. The reflection of the beam generates reverberation artifacts in the form of laser rays or comet tails called B-lines.

To distinguish these B-lines from other conditions like pneumonia, atelectasis, pulmonary fibrosis or acute respiratory distress syndrome, is essential to know that their presence is bilateral and homogenous as well as present in dependent areas with an absence of peripleural lesions or other lung signs.

AJKDblog: Where do you and your group go from here?

Our group is planning to evaluate prospectively the concept of “dry lung” by quantification of B-lines in dialysis patients before and after adjusting ultrafiltration therapy and correlate it with functional physical performing measures, hospitalizations, and survival.

All Spring Clinical Meeting abstracts are available in the May issue of AJKD.

Check out more AJKDblog coverage of the NKF’s 2016 Spring Clinical Meetings (#SCM16)!

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