Non-invasive Assessment of Cardiac Output by Brachial Cuff Technique; Comparison to the Open Circuit Acetylene Washin Method

Cardiac output (CO) assessment as a basic hemodynamic parameter has been of interest in exercise physiology, cardiology and anesthesiology. Non-invasive techniques available are technically challenging, and thus difficult to use outside of the clinical or laboratory setting. We propose a novel method of non-invasive CO assessment using a single upper arm cuff. The method uses the arterial pressure pulse wave signal acquired from the brachial artery during 20 second intervals of suprasystolic occlusion. This method was evaluated on a cohort of 12 healthy individuals (age of 27.7±5.4 years, 50% male) and compared to an established method for non-invasive CO assessment, the open circuit acetylene method (OpCirc) at rest, and during low- to - moderate intensity exercise. CO increased from rest to exercise (rest: 7.4±0.8 vs. 7.2±0.8; low: 9.8±1.8 vs. 9.9±2.0; moderate: 14.1±2.8 vs. 14.8±3.2 l/min) as assessed by the cuff-occlusion and OpCirc techniques, respectively. The average error of experimental technique compared to OpCirc was -0.25±1.02 l/min, Pearson's correlation coefficient of 0.96 (resting + exercise), and 0.21±0.42 l/min with Pearson's correlation coefficient of 0.87 (rest only). Bland-Altman analysis demonstrated good agreement between methods (within 95% boundaries) the reproducibility coefficient (RPC) = 0.84 l/min with R²=0.75 at rest and RPC=2 l/min with R²=0.92 at rest and during exercise, respectively. In comparison with an established method to quantify cardiac output, the cuff-occlusion method provides similar measures at rest and with light to moderate exercise. Thus we believe this method has the potential to be used as a new noninvasive method for use during exercise.

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