A novel system to continuously estimate intradialytic blood pressure in real time

Background Intradialytic hypotension (IDH) is a common complication of haemodialysis that is associated with adverse patient outcomes. We have developed a new non-invasive approach to continuously estimate systolic blood pressure (SBP) in real time during haemodialysis using pressure wave sensors in the extracorporeal circuit. We sought to compare the performance of our continuous real-time SBP estimator against brachial cuff SBP measurements. Methods Single-centre, observational study conducted in 21 participants receiving haemodialysis with a functioning arteriovenous fistula, studied throughout two 4-h haemodialysis sessions. Time-averaged real-time SBP estimator values from the 5-s period immediately prior to each cuff measurement were compared with matched brachial cuff SBP values. Results Mean age was 71 +/- 11 years and median dialysis vintage was 20.0 months (interquartile range 12.5-63.5). Across 522 SBP comparison data points, mean brachial cuff SBP and real-time SBP estimate were 121.8 +/- 27.1 mmHg and 123.7 +/- 27.9 mmHg, respectively. Brachial cuff SBP and real-time SBP estimate were significantly associated (r = 0.825; P < .001). There was a low absolute mean difference between the brachial cuff SBP and the real-time SBP estimate of -1.9 +/- 16 mmHg, and no evidence of systematic bias between measurements. Across all comparison points, 95% of estimator values were within 30% of the matched brachial cuff value, and 66% within 10% of the cuff value. Conclusions A blood pressure estimator that runs in real time during haemodialysis using pressure wave sensors in the extracorporeal circuit and avoiding additional sensor-burden on patients has good performance in tracking intradialytic SBP when compared against brachial cuff measurements, supporting its further development and larger scale testing.