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 haemodialysis 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 haemodialysed patients. Methods We conducted a cross sectional study including 31 patients undergoing chronic HD treatment for at least 3 months, in Yaounde University Teaching Hospital dialysis unit. Lung ultrasonography and clinical examinations were performed immediately before dialysis, and 30 minutes after dialysis. Differences between variables before and after dialysis were measured to assess dialysis’s effect. Association between categorical variables was assessed with Chi-squared test or Fischer test, and Rho’s Spearman coefficient for quantitative variables. Results There were reduction in 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 frequency of cramps in patients (0% versus 19.4%), 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 detection of B-lines reflects variation of extracellular volume during dialysis and can even capture pulmonary oedema at pre-clinical stage. It is then a reliable and sensible method in assessing hydration status. It could constitute a better alternative in objective and accurate definition of dry weight, specifically in the African and Cameroonian context, with its assets at low cost, its availability, its easiness to perform in large population of haemodialysis patients.