P2.12: Non-Invasive Estimates of Cardiac Output: Comparison of a Novel Pulse Waveform Analysis Method with Inert Gas Re-Breathing

Objectives Non-invasive, cuff-based systems are currently available for the assessment of central haemodynamic parameters. The aim of the current study was to compare measurements of cardiac output (CO) derived from pulse waveform analysis (Vicorder) with an inert gas re-breathing method (Innocor) in response to postural change, (study 1) and mild exercise. (study 2). Methods Study 1 included 27 subjects, mean age 35±9 years. Haemodynamic indices were measured after 10 minutes each of supine rest, standing and further supine rest. Study 2 included 30 subjects, mean age 35±8 years. Haemodynamic indices were measured after resting on an upright cycle ergometer, and during the final minute of 5 minutes of steady-state cycling at 20rpm and 35rpm, corresponding to 12 and 20 watts respectively. Results Overall, values of CO and SV were significantly correlated between devices (r = 0.42, p = 0.001, CO) and (r = 0.27, p = 0.001, SV). There was reasonable agreement between devices with a mean difference (±SD) in CO of 0.8±2.7 L/minute (supine) 0.7±2.5 L/minute (standing) and 0.7±1.3 (final supine). Similarly, in study 2, the mean differences were 0.4±3.6 L/minute (resting), 0.2±4.3 L/minute and 0.8±3.5 L/minute cycling at 20rpm and 35rpm respectively. The direction and magnitude of the changes in CO detected with each device were similar ( Figures 1 & 2 ). Conclusions The Vicorder and Innocor devices produce similar estimates of CO at rest and detect similar changes in CO in response to physiological challenges. Moreover, the Vicorder is a simple-to-use, cost-effective device that may be considered for comprehensive haemodynamic monitoring. Figure 1 Figure 2