THE UTILITY OF BEDSIDE CLINICAL ASSESSMENT OF INTRAVASCULAR VOLUME STATUS WITH HAND CARRIED ULTRASOUND DEVICES IN HEMODIALYSIS CLINICS

Abstract

In Canada, the majority of end stage renal disease (ESRD) patients undergo conventional facility based hemodialysis. Despite technological advancements, conventional hemodialysis is associated with significant patient morbidity and mortality related to fluid imbalances. Inaccurate hemodialysis prescriptions calculated from clinical estimates of intravascular volume status (IVS) may serve as a major contributor to patient morbidity. Previous studies have demonstrated improved patient outcomes by adjusting hemodialysis prescriptions based on echocardiographic volume assessments. However, implementation of this platform in practice remains impractical, warranting further research in order to assess whether Hand-Carried Ultrasound (HCU) provides similar benefits in chronic hemodialysis patients. The primary objective of this study is to investigate the utility of inferior vena cava (IVC) measurements using HCU as an imaging modality to accurately assess IVS in hemodialysis patients. The potential impact would be a portable, cost-efficient, and accurate measurement of patient volume status in order to improve hemodialysis prescriptions and fluid homeostasis. This prospective study involved ESRD patients on hemodialysis at a single tertiary care centre. IVC diameter (IVCdi) and collapsibility index (IVCci) were measured at three hemodialysis sessions for each patient. At each dialysis session, pre-, mid-, and post-dialysis values were collected. IVC parameters were compared to clinical indices of volume status including blood pressure, patient symptoms, and ultrafiltration. A total of 29 patients were included in this study (19 males, mean age 63±16 years). The mean IVC diameter for the pre-dialysis, mid-dialysis, and post-dialysis time points was 1.65±0.40 cm, 1.29 ± 0.33 cm, and 1.39±0.32 cm, respectively (p<0.05). The IVCdi decreased in size from the pre-dialysis to mid-dialysis time points and subsequently increased at the post-dialysis measurement (Figure 1). A subset of 5 patients came back for an additional scan two hours after their dialysis session ended; their IVC diameters continued to increase in size toward pre-dialysis levels. A comparison of IVCdi measurements and clinical indices demonstrated a significant correlation only between post-dialytic IVCdi and post-dialytic symptoms. IVCci did not correlate with blood pressure, volume removal, or patient symptoms at any of the three time points. IVC indices by HCU did not correlate with changes in systolic blood pressure, ultrafiltration, or patient symptoms. These clinical determinants of volume status are inherently inaccurate and do not disprove the validity of HCU in volume assessments. Further studies are warranted to evaluate the benefit of HCU guided hemodialysis prescriptions on patient morbidity and mortality.