Lung ultrasound during hemodialysis: the role in the assessment of volume status

• Published in: International urology and nephrology 2014, Vol.46 (1), p.169-174
• Main Authors: Vitturi, Nicola, Dugo, Mauro, Soattin, Marta, Simoni, Francesco, Maresca, Luisa, Zagatti, Riccardo, Maresca, Maria Cristina
• Format: Article
• Language: English
• Subjects: Aged; Body Composition; Body Water - diagnostic imaging; Electric Impedance; Female; Humans; Lung - diagnostic imaging; Male; Medicine; Medicine & Public Health; Middle Aged; Nephrology; Nephrology - Original Paper; Renal Dialysis; Ultrasonography; Urology; Vena Cava, Inferior - diagnostic imaging
• ISSN: 0301-1623; 1573-2584
• DOI: 10.1007/s11255-013-0500-5

Objective Fluid balance is important in patients undergoing hemodialysis. “Dry” weight is usually estimated clinically, and also, bioimpedance is considered reliable. Ultrasonography of inferior vena cava (IVC) estimates central venous pressure, and lung ultrasound evaluates extravascular (counting B-lines artifact) lung water. Our study was aimed to clarify their usefulness in the assessment of volume status during hemodialysis. Methods A total of 71 consecutive patients undergoing hemodialysis underwent lung and IVC ultrasound and bioimpedance spectroscopy immediately before and after dialysis. Results There was a significant reduction in the number of B-lines (3.13 vs 1.41) and in IVC diameters (end-expiratory diameter 1.71 vs 1.37; end-inspiratory diameter 1.19 vs 0.95) during dialysis. The reduction in B-lines correlated with weight reduction during dialysis ( p 0.007); none of the parameters concerning the IVC correlated with fluid removal. At the end of the dialysis session, the total number of B-lines correlated with bioimpedance residual weight ( p 0.002). Discussion The reduction in B-lines correlated with fluid loss due to hemodialysis, despite the small pre-dialysis number, confirming that lung ultrasound can identify even modest variations in extravascular lung water. IVC ultrasound, which reflects the intravascular filling grade, might not be sensitive enough to detect rapid volume decrease. Clinically estimated dry weight had a poor correlation with both bioimpedance and ultrasound techniques. Post-dialysis B-lines number correlates with residual weight assessed with bioimpedance, suggesting a role for ultrasound in managing hemodialysis patients.