Use of lung ultrasound to assess volume status and its association with physical examination in patients with chronic kidney disease

Abstract

Introduction Defining the optimal hydration status in patients with chronic kidney disease (CKD) is challenging, and the quest for an objective accurate method continues. Lung ultrasound (LUS) is a well-validated technique to estimate volume status. Previous studies examining the relationship between LUS and physical examination demonstrated conflicting results. We aimed to evaluate the correlation between LUS results and physical examination for assessing volume status in patients with CKD, and to compare different LUS protocols. Methods A prospective, single center trial correlating physical examination findings to LUS results in different CKD groups, including non-dialysis and dialysis patients. Hemodialysis patients were tested twice, before and after dialysis, to compare results with ultrafiltration volume. Different LUS protocols were performed and compared, including 16, 12 and 8-zones measurements. Results We recruited 175 participants. A strong positive correlation was demonstrated between 16 and 12-zone protocols (r = 0.91 (P < 0.001)) and between 12 and 8-zone protocols (r = 0.951, P < 0.001). Correlation was significant in various CKD groups. While blood pressure did not correlate with LUS score, there was a significant correlation between LUS and other components of the physical examination including lung crackles (OR = 1.15 (95%CI 1.096–1.22), P < 0.01), pleural effusion (OR = 1.15 (95%CI 1.09–2.13), P < 0.01) and peripheral edema (r = 0.24, P < 0.001). Ultrafiltration volume did not correlate significantly with change in LUS scores pre and post dialysis (r = 0.169, P = 0.065). Conclusion Most components of physical examination findings correlated with extravascular lung water assessment on LUS in CKD patients. The use of a simplified pragmatic LUS protocol may facilitate LUS use in clinical practice.