Effect of absolute blood volume measurement guided fluid management on the incidence of intradialytic hypotension associated events: a randomised controlled trial

Abstract Background Ultrafiltration to target weight during haemodialysis is complicated by intradialytic hypotension associated adverse events (IHAAE) in 10-30% of dialysis treatments. IHAAE are caused by critical reductions in absolute blood volume (ABV), due to the interaction of ultrafiltration, refill and compensatory mechanisms. Non-randomised studies suggested that ABV-guided treatment, using an indicator dilution technique employing the blood volume monitor on the dialysis machine, could reduce the incidence of IHAAE. Methods We performed an open label randomised controlled trial. Patients were randomly assigned to adjustment of target weight guided by ABV measurements or standard care. Primary outcome was change in the incidence of IHAAE from baseline, defined as the percentage of treatment episodes in a four-week period where the patient had a systolic blood pressure <90 mmHg or symptoms of impending hypotension. ABV measurements were compared to anthropomorphometric estimation and the gold standard using isotope dilution. Results Fifty-six patients were randomised, of whom 29 were allocated to ABV-guided treatment and 27 to standard care. Overall baseline incidence of IHAAE was 26.0%. ABV-guided treatment significantly reduced the incidence of IHAAE compared to standard care, with a mean change from baseline of -9.6% (95% CI: -17.3; -1.8%) versus +2.4% (-2.3; +7.2%). The adjusted difference between the groups was 10.5% (1.3; 19.8%, p = 0.026). ABV measurement had moderate agreement with other methods to estimate blood volume. The sensitivity for the previously suggested threshold of a post-dialysis normalised blood volume of 65 ml/kg was observed to be 74% in this study. Conclusions ABV-guided volume management significantly reduced IHAAE compared to standard care. The clinical relevance of the previously suggested threshold of 65 ml/kg cannot be firmly concluded on the basis of our results. If confirmed in a larger trial, this intervention could potentially change dialysis practice and impact patient care in a clinically meaningful way.