Reliability of oscillometric central blood pressure and wave reflection readings: effects of posture and fasting.

Objective: Oscillometric pulse wave analysis devices have recently emerged, presenting suitable options for investigating central hemodynamic properties in clinical practice. This study sought to examine whether the between-day reliability of central SBP (cSBP) and systemic arterial wave reflection (augmentation index, AIx) readings exceed the criterion for acceptable reliability or are affected by posture (supine and seated) and fasting state.

Methods: Twenty healthy adults (50% female, 27.9 years, 24.2 kg/m) were tested on six different mornings: 3 days fasted and 3 days nonfasted. On each occasion, participants were tested in supine and seated postures. Oscillometric pressure waveforms were recorded on left upper arm.

Results: For cSBP, there was nonsignificant main effect for fasting state (P = 0.819) but there was a main effect for posture (P = 0.002). Conversely, for AIx, there was nonsignificant main effect for posture (P = 0.537) but there was a large main effect for fasting state (P = < 0.001). The criterion intraclass correlation coefficient value of 0.75 was exceeded for both variables when participants were assessed under the combined supine-fasted condition. For cSBP, the reliability coefficient was lowest (best) when supine fasted (6.8 mmHg) and greatest (worst) when seated nonfasted (8.6 mmHg). For AIx, the reliability coefficient was lower for the supine (11.4-11.7%) compared with the seated (14.0-15.2%) posture.

Conclusion: Findings from this study suggest that oscillometric assessments of central hemodynamic variables exceed the criterion for acceptable reliability and are most reliable when participants are evaluated while supine and fasted.