Does the intravascular volume status in haemodialysis patients measured by inferior vena cava ultrasound correlate with bioimpedance spectroscopy?

Aims and objectives To evaluate the accuracy of traditional clinical predialytic fluid assessment by renal nurses and the efficacy of 2 additional fluid assessment methods focussing on the potential preventative effect for intradialytic hypotension (IDH). Background Predialytic fluid assessment remains a daily challenge for renal nurses, when aiming for adverse event free haemodialysis treatments. Adding further objective parameters obtained through noninvasive methods into pre- and intradialytic fluid assessment could potentially improve health outcomes for haemodialysis patients. Design Comparative, observational study of three fluid assessment methods on their reliability on volume status and correlation to clinical outcomes. Methods Clinical predialytic nursing fluid assessments in 30 haemodialysis patients were compared with additional initial bioimpedance spectroscopy (BIS) measurements, and 3 serial intradialytic ultrasound scans of the inferior vena cava (IVC-US) performed by a second renal nurse concurrently during the same session. A retrospective data analysis compared all measurements in each individual for the predictive value for IDH. A STROBE checklist for observational cohort studies was used for the reporting of results. Results Seven subjects experienced episodes of symptomatic intradialytic hypotension (S-IDH), which would have been anticipated by IVC-US or by BIS in 5 patients (71%). Using an algorithm to predict IDH would have provided a sensitivity of 100% and specificity of 95%. Conclusion Both additional fluid assessment methods would have provided critical information before and during each haemodialysis session. Therefore, we consider them as being potentially effective for the prevention of intradialytic hypotension, with IVC-US being similar to BIS. Relevance to clinical practice Traditional clinical nursing fluid assessment methods in haemodialysis patients do not provide sufficient information to prevent episodes of IDH. Additional objective fluid assessment methods are useful and likely to lead to improved health outcomes in HD patients when applied by renal nurses. A combination of IVC-US, MAP and BIS has potential to reduce the risk of IDH events in HD patients significantly.