PS-BPC03-6: USING A SIMPLE FIXED-RATIO BASED ALGORITHM MINIMIZES VARIABILITY IN OSCILLOMETRIC BLOOD PRESSURE DERIVATION IN PATIENTS WITH CHRONIC KIDNEY DISEASE

Abstract

Objective: Oscillometric device accuracy may be decreased, and variability may be increased, in patients with chronic kidney disease. The objective of this study was to compare three oscillometric algorithms to identify which minimizes oscillometric blood pressure variability in chronic kidney disease. Design & Methods: Sixty patients with chronic kidney disease were studied. Thirty were on hemodialysis (HD group) and thirty had stage 3 chronic kidney disease (Stage 3 CKD). Baseline demographics and medical comorbidities were recorded. The mean of 3 readings from the Omron HEM 907XL device was used to provide a control (reference) blood pressure. Three oscillometric waveforms were also collected using a computer-based system, processed, and used to derive blood pressure by each of three algorithms: 1. simple fixed-ratio; 2. initial binning according to mean arterial pressure and then application of different fixed ratios within each bin (binning method); and 3. binning plus linear regression to incorporate the influence of additional oscillometric waveform characteristics (binning regression method). The mean of three blood pressure determinations from each algorithm was calculated and compared to the Omron mean, with variability assessed by calculating the standard deviation of the difference compared to the Omron. Results: Mean age in the overall group (± SD) was 65.6 ± 13.7 years (HD 63.4 ± 16.3 years; Stage 3 CKD 65.9 ± 10.7 years), percent female in the overall group was 42% (HD 37%; Stage 3 CKD 47%), and mean arm circumference overall was 31.5 ± 4.7 cm (HD 30.8 ± 4.4 cm; Stage 3 CKD 32.2 ± 5.0 cm. Hypertension was present in 82% of participants (HD 80%; Stage 3 CKD 83%). Mean Omron blood pressure was 136.9 ± 25.4/72.7 ± 15.8 mmHg. Compared to the Omron, the systolic/diastolic results for each algorithm were 134.4 ± 20.5/75.0 ± 12.9 for fixed ratio, 128.5 ± 19.8/71.4 ± 12.0 for binning, and 127.7 ± 18.7/70.2 ± 8.8 for binning regression (Table 1). Conclusions: An oscillometric algorithm based on simple fixed-ratio minimized variability in patients with chronic kidney disease. Manufacturers of devices designed for blood pressure measurement in this population should consider incorporating this approach into their algorithm-based blood pressure derivation.