Introduction: Volume assessment in end-stage kidney disease patients on hemodialysis (HD) remains inadequate by existing methods: clinical examination, bioimpedance spectroscopy, measurement of inferior vena cava diameter by ultrasound (IVCD), and plasma B-type natriuretic peptide (NT-pro BNP). This study aims to compare the performance of lung ultrasound against existing methods for volume assessment in a HD cohort. Methods: Two nephrologists independently performed 28-point lung ultrasound immediately before and after midweek HD in 50 patients. Lung congestion was classified into mild, moderate, and severe categories based on lung ultrasound findings. Clinical examination for crepitations and oedema, change in hydration status (ΔHS) measured by bioimpedance spectroscopy, NT-pro BNP, IVCD during inspiration (IVCDimin), expiration (IVCDimax), and inferior vena cava collapsibility index were also assessed before and after midweek HD. Findings: In all, 61% of patients with normohydration status by bioimpedance spectroscopy had moderate or severe lung congestion on lung ultrasound. There were significant correlations between predialysis lung ultrasound, and NT-pro BNP (r = 0.432, P = 0.004), ΔHS (r = 0.447, P < 0.001), and IVCD parameters (P < 0.05). Some correlations weakened postdialysis (ΔHS [r = 0.322, P = 0.01] and IVCDimax [r = 0.307, P = 0.03]), whereas NT-pro BNP and ΔHS paradoxically increased in 28% and 30% of the cohort, respectively. On receiver operator curve analysis, most methods of volume assessment had limited discriminatory power to detect mild lung congestion. Discussion: Lung ultrasound demonstrates some comparability with existing volume assessment methods in Asian dialysis patients. However, it appears more effective at detecting subclinical pulmonary congestion, and tracking fluid changes real-time compared to bioimpedance spectroscopy and NT-pro BNP.
Background and Aims In recent years, point-of-care ultrasonography (POCUS) with lung ultrasonography (LUS) and inferior vena cava diameter (IVCD) measurements have attracted growing attention due to their capacity to estimate volume status in end-stage kidney disease (ESKD). There have been concerns about inter-operator reproducibility in POCUS, particularly the new user’s ability to distinguish varying lung pathologies on LUS accurately. For instance, lung diseases with thickening of subpleural structures, such as pulmonary fibrosis, can mimic LUS B-lines. B-lines are artefacts produced by extravascular lung water, which is summated into a B-line score (BLS). This study aims to investigate the ease of learning, and the inter-operator reproducibility of LUS and IVCD in an Asian haemodialysis (HD) cohort, in users with no prior ultrasound experience. Method A subgroup of 14 HD patients from the observational study by Teng et al comparing LUS and IVCD with other fluid assessment methods in a HD cohort, underwent LUS and IVCD pre- and post-HD with 2 operators in separate settings. LUS was performed via a 28-point protocol, while IVCD was measured in both inspiration (IVCDmin) and expiration (IVCDmax). IVCDi was calculated by indexing IVCD to body surface area. Study details are available elsewhere. One operator was a Nephrologist experienced in ultrasonography who had done 150 previous studies, whilst the second operator was a Resident who had no prior exposure to POCUS. The Resident underwent 4 hours of instructional teaching including theory sessions, simulation and image interpretation. Images acquired by the Resident during the study were audited for interpretative accuracy, such as the ability to diagnose lung pathology accurately. The Resident was required to review the clinical presentations of all patients before making ultrasound diagnoses. Results 392 lung images and 56 IVC images were acquired for 14 HD patients. 100% of patients’ clinical notes were reviewed prior to making ultrasound diagnosis. >98% of the diagnoses were correctly made, and only in 1 patient (7 lung images; case of bronchiectasis), was the ultrasonographic diagnosis incorrectly made of B-lines, although B-lines were seen in other lung fields in the same patient. There was excellent inter-operator variability for BLS (r = 0.983, p < 0.001). There was moderate agreement between both operators in terms of BLS and by BLS categories (k = 0.586, p = 0.015 and k = 0.521, p = 0.010). In 14 independent LUS studies, only 1 reading demonstrated interobserver difference exceeding 1.96 standard deviation (SD). There was also excellent inter-operator variability for IVCDimax (r = 0.994, p < 0.001) and IVCDimin. In 14 independent IVCDimax readings, 2 readings demonstrated interobserver difference exceeding 1.96 SD. Conclusion Point-of-care ultrasonography for volume assessment is able to demonstrate good inter-operator reproducibility and is easy for new users to learn. There is hence potential for more widespread incorporation of these volume assessment tools into community dialysis centres. POCUS has traditionally been performed by medical professionals, but in light of the relative ease of learning curve, it may be possible for allied healthcare professionals to acquire skills in POCUS.
Background and Aims At present, there are no precise and quantitative clinical indices for assessing fluid status in haemodialysis (HD). Existing modalities such as plasma B-type natriuretic peptide (NT-pro BNP), measurement of inferior vena cava diameter (IVCD) by ultrasound or bioimpedance spectroscopy (BIS) have limitations and do not always give quantitative measurements to guide dry weight titration. Lung ultrasonography (LUS) has emerged as a novel real-time technique to assess extravascular lung water (EVLW) on HD. Current studies comparing the above techniques often lack standardized dialysis days and timepoints for sampling volume assessment methods. This study aims to compare the performance of LUS against existing methods (NT-pro BNP, IVCD, BIS) of volume assessment in an Asian HD cohort, using a standardised protocol for sampling. The secondary aim was to measure the turnover time required for performing each volume assessment method. Method This was a prospective study of 50 chronic HD patients in a single dialysis unit. In this cohort, 34 (68%) had diabetes, and 43 (86%) were on at least 1 antihypertensive. Patients aged more than 21 years, on thrice weekly dialysis with a high flux dialyser for more than 3 months with residual urine output less then 500 ml per day were recruited. NT-pro BNP, IVCD and BIS were sampled immediately pre- and post- midweek dialysis. 28-intercostal space LUS was performed by a Nephrologist with appropriate certification immediately pre- and 30 minutes after midweek dialysis. EVLW produces lung artefacts (B-lines), which is summated into a B-line score (BLS). We also measured the time required, from performing each volume assessment methodology, to the point of result acquisition. Results Pre-HD, lung congestion was classified as mild (BLS ≤ 15) in 6 patients (12%), moderate (BLS 15 – 30) in 12 patients (24%) and severe (BLS > 30) in 32 patients (64%). Median BLS reduced from 46.5 (22.5 – 77.0) pre-HD to 15.5 (9.9 – 21.5) post-HD. There was a linear correlation between changes in BLS and ultrafiltration on HD, with UF 500ml approximately equal to 8.2 B-lines. There were significant but weak to moderate correlations between pre-HD LUS and BIS (r = 0.457, p = 0.004), IVCD indexed to body surface area during expiration (IVCDimax) (r = 0.371, p = 0.026) and NT-pro BNP (r = 0.406, p = 0.004). Post-HD, correlations between LUS and IVCDimax remained similar (r = 0.353, p = 0.02), but weakened with BIS (r = 0.329, p = 0.021) and became non-significant with NT-pro BNP. This was related to a paradoxical increment in NT-pro BNP and BIS overhydration values post-HD, in up to 40% of the cohort. Separately, the mean execution time for the various volume measurements were LUS: 6 ± 0.2 minutes, BIS: 5.9 ± 0.4 minutes, IVCD: 4.1 ± 0.3 minutes and the laboratory turnaround time to obtain a NT-pro BNP result was 125 ± 10.6 minutes. Conclusion LUS was able to demonstrate a linear correlation with UF volume, and may be more effective then NT-pro BNP or BIS at real-time assessment of fluid changes post-HD. The execution of LUS was no more time-consuming then BIS. LUS is hence likely to be a useful clinical tool for dry weight titration in HD patients.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.