Bedside Lung Ultrasound in the Assessment of Volume Status in Chronic Hemodialysis Patients

Abstract

BACKGROUND: Dry weight of patient with chronic kidney disease on hemodialysis is usually assessed by using clinical parameters (BP; edema etc); Biochemical parameters (BNP; ANP); Bioimpedance Spectroscopy and IVC diameter-collapsibility on ultrasound. Sonographic B-lines; also known as lung comets; have been shown to correlate with the presence of extravascular lung water. Our study aims to assess the usefulness of ultrasound chest for assessment of volume status in patients on maintenance hemodialysis. AIM OF THE STUDY: To compare the efficacy of body fluid volume status and lung water assessment by clinical methods; Ultrasound chest and Bioimpedance Spectroscopy in chronic kidney disease patients on hemodialysis. METHODS: A cross-sectional study was conducted at hemodialysis center in Department of Nephrology at Christian Medical College and Hospital; Ludhiana over a period of 6 months. Lung ultrasound using MicroMaxx Ultrasound System with a 6 Mhz vascular probe and Bioimpedance spectroscopy using Bodystat QuadScan 4000 was performed for each patient. A longitudinal ultrasound scan with patient in supine position; from second to the fourth intercostal space of the left hemi-thorax and second to fifth intercostal space of the right hemi-thorax in parasternal; midclavicular; anterior axillary and midaxillary lines of each side making a total of 28 sectors was performed before and after dialysis. The comet score was determined by calculating the total B-lines found in each examined site. Bioimpedance spectroscopy was also performed and total body water (TBW); intracellular water (ICW); extracellular water (ECW); residual fluid overload (ECW pre HD-ECW post HD) was recorded for each patient. RESULTS: We conducted 100 assessments on 34 patients presenting to the hospital for maintenance hemodialysis. The mean age of the study population was 54.3 + 11 years with a sex ratio (M/F) of 6:1. Mean systolic blood pressure was 141.1 + 19 mmHg and diastolic blood pressure was 83 + 9.3 mmHg with 3 episodes of intradialytic hypotension. The mean dry weight was 59.8 + 10 Kg and weight gain by clinical assessment was 2.1 + 1.5 Kg. Residual fluid overload on Bio impedance spectroscopy was 1.11 ± 0.85 litre. Comet score assessed by chest ultrasound had a mean of 4.54 + 2.53 before dialysis and 1.73 ± 1.36 after dialysis. The residual fluid overload on Bio impedance spectroscopy and lung ultrasound comet score after dialysis had a significant correlation (p value <0.0001). Of the 100 assessments; 40% had fluid overload after dialysis with Bio impedance and 35% had lung congestion on ultrasound chest even after achieving euvolemia according to the dry weight assessed clinically. CONCLUSIONS: Our observations strongly support the use of bedside lung ultrasound in estimating volume overload and monitoring the response to therapy in patients on dialysis. It can therefore help in decreasing the subjective errors of volume status assessment by clinical methods.