Utility of Bedside Lung Ultrasound in the Assessment of Volume Status in Patients on Chronic Haemodialysis

Abstract

Aim: The estimation of the ‘dry weight’ in a patient on haemodialysis with end-stage renal disease is an important clinical challenge to date. Physical examination has its limitations in the precise assessment of volume status. The monitoring of blood volume, natriuretic peptides, and bioimpedance spectroscopy are explored as a guide for the ultrafiltration process during haemodialysis (HD) therapy. Unfortunately, none of these methods has shown promising results when used in isolation and has serious limitations. The point-of-care lung ultrasonography has emerged recently as an adjunct to physical examination as a non-invasive, radiation-free technique to estimate extravascular lung water. In this study, the authors aimed to compare the volume status assessment in end-stage renal disease patients on HD using conventional clinical methods, bio-electrical impedance, and chest ultrasound (US). Materials and Methods: A prospective cohort study was conducted on 34 patients undergoing regular HD in the Department of Nephrology dialysis centre at the University College of Medical Sciences Guru Teg Bahadur Hospital, Delhi, India, a multi-speciality tertiary care centre. Parameters included to assess the dry weight of patients were bio-impedance spectroscopy and chest US, measured in two phases: 30 minutes before and 10–60 minutes following the HD session. Results: A total of 100 assessments were done on 34 patients over 6 months. The mean pre-HD extracellular water was 17.52±2.69 L and post-HD was 16.38±2.46 L, showing a significant reduction (<0.001). The bioimpedance analysis showed that 44% of the volume status assessments had fluid overload (≥1.1 L), even when the patients were considered to be in a state of clinical euvolemia, while 79% of the assessments had a Comet Score of ≥3 suggesting a fluid overload state. Most assessments showed a significant reduction in the number of B-lines (i.e., 62% [Comet Score of between 0–2]). The mean post-HD Comet Score was 1.73±1.36 (37%). Conclusion: Chest US to assess Comet Score is highly correlated with the clinical signs and symptoms. Lung Comet Scores can also be highly correlated with ultrafiltration volume, and thus can be used as a good marker for achieving dry weight in dialysis patients.