Role of Lung Ultrasound in the Assessment of Hydration Status of Chronic Haemodialysis Patients

Abstract

Background: Fluid overload is frequent in Haemodialysis (HD) and is one of the major factors of cardiovascular morbidity and mortality for chronic HD patients. The main challenge with chronic haemodialysis patients is indeed the maintenance of a normal extracellular volume through dry weight determination. Our study aimed at assessing the role of lung ultrasound in the detection of B-lines for the determination of hydration status in chronic HD patients. Methods: We conducted a cross-sectional study including 31 patients undergoing chronic HD treatment for at least 3 months, in the Yaounde University Teaching Hospital dialysis unit. Lung ultrasonography and clinical examinations were performed immediately before dialysis, and 30 minutes after dialysis. Differences between clinical and ultrasound variables before and after dialysis were measured to assess the effects of dialysis. Association between categorical variables was assessed with the Chi-squared test or Fischer test, and Rho’s Spearman coefficient for quantitative variables. Results: There was a reduction in the median of B-lines score after dialysis [12 (7 - 26) versus 8 (5 - 13)], clinical score [2 (1 - 3) versus 0 (-1 - 2)], mean of systolic blood pressure (164.74 ± 26.50 versus 158.48 ± 27.89), frequency of dyspnoea in patients (32.3% versus 6.5%); and raising of the frequency of cramps in patients (0% versus 19.4%) and all statistically significant (p ≤ 0.031). B-lines score before and after dialysis was associated with dyspnoea and raised jugular venous pressure (p < 0.05). B-lines score before dialysis was correlated with B-lines score after dialysis (r = 0.805; p < 0.001), B-lines reduction (r = 0.862; p < 0.001), and clinical score (r = 0.49; p = 0.005). Reduction of B-lines score was not correlated with weight loss. Conclusion: Lung ultrasound for the detection of B-lines reflects the variation of extracellular volume during dialysis and can even capture pulmonary oedema at a pre-clinical stage. It is then a reliable and sensible method for assessing extravascular lung water and thus hydration status of haemodialysis patients. It could constitute a better alternative for an objective and accurate definition of dry weight, specifically in the African and Cameroonian context, with its assets being low cost, availability, and easiness to perform in a large population of HD patients. We, therefore, recommend further multicentric studies in order to design a standardized protocol of ultrasound follow-up for all chronic HD patients’ hydration status assessments.