Repeatability of central aortic blood pressures measured non-invasively using radial artery applanation tonometry and peripheral pulse wave analysis

Objective. To estimate the repeatability of radial pulse wave analysis (PWA) in measuring central systolic and diastolic blood pressures (cSBP/ cDBP), pulse pressure (cPP), augmentation pressure (cAP) and pulse pressure amplification (PPA). Methods. After 15 min supine rest, 20 ambulant patients (aged 27-82 years; four female) underwent four SphygmoCor PWA measurements on a single occasion. Two nurses independently undertook two measurements in alternate order, blind to their colleague's measurements. Analysis was by Bland-Altman limits of agreement (LOA). Results. Heart rate and brachial blood pressure (BP) were stable during assessment. Based on the average of two PWA measurements between-observer differences (LOA, mean difference +/- 2SD) were small (cSBP 1.5 +/- 10.9 mmHg; cDBP 0.4 +/- 5.2 mmHg; cAP 0.5 +/- 4.5 mmHg; cPP 1.1 +/- 10.5 mmHg; PPA 20.5% +/- 5.6%). Between-observer differences were much greater for single/ initial PWA measurement (cSBP 3.6 +/- 15.9 mmHg; cDBP 2.8 +/- 8.8 mmHg; cAP 0.7 +/- 5.8 mmHg; cPP 0.8 +/- 13.6 mmHg; PPA 21.2 +/- 9.4%). Within- observer LOA were very similar for both nurse A (cSBP 24.2 +/- 14.1 mmHg; cDBP 24.6 +/- 13.1 mmHg; cAP 20.4 +/- 4.4 mmHg; cPP 0.5 +/- 11.0 mmHg; PPA 0.7% +/- 9.0%) and nurse B (cSBP 0.0 +/- 12.1 mmHg; cDBP 0.2 +/- 8.5 mmHg; cAP 20.1 +/- 4.4 mmHg; cPP 20.2 +/- 11.9 mmHg; PPA 20.7% +/- 10.6%). Conclusion. Non-invasive assessment of central aortic pressures using PWA on a single occasion is highly repeatable in ambulant patients even when used by relatively inexperienced staff.