Can the assessment of ultrasound lung water in haemodialysis patients be simplified?

Abstract

Lung ultrasound (US) reliably estimates lung water and it is increasingly applied in clinical practice in dialysis patients. A semi-quantitative US score summing up the US-B lines (an equivalent of B lines in the standard chest X-ray) at 28 sites in the intercostal spaces (Jambrik et al. Usefulness of ultrasound lung comets as a non-radiologic sign of extravascular lung water. Am J Cardiol 2004; 93: 1265-1270) is the most used score. We compared the prognostic performance for death, and cardiovascular (CV) events of the 28-sites US score with a score restricted to eight sites in a cohort of 303 haemodialysis (HD) patients. The 8- and the 28-sites scores were highly inter-related (Spearman's ρ = 0.93, P < 0.001), and their concordance index was fairly good (k = 0.79, 95% confidence interval 0.74-0.84). During a mean follow-up of 3 years, 112 patients died, and 129 experienced a CV event. At univariate and multivariate analysis, both scores were associated with mortality (P ≤ 0.01) and CV events (P ≤ 0.05). The explained variances (R2) for death and CV events of the 28-sites score in multivariate models including major risk factors for these outcomes in the end-stage kidney disease (ESKD) population were 3.9 and 2.2%, and those of the 8-sites score were 3.1 and 2.4%, respectively. The median time needed to perform the examination was 3.05 min [interquartile range (IQR) 2.22-5.00 min] for the 28-sites score and 1.35 min (IQR 1.16-2.00 min) for the 8-sites score. The 8-sites score is tightly related to the classical Jambrik 28-sites score and this score holds an almost identical predictive power to the reference score. Even though the 28-sites score can be completed just in ∼3 min, the 8-sites score requires only ∼1.30 min, and it is, therefore, better suited for application in everyday clinical practice in HD units.