Beat to Beat Cardiac Output from the Arterial Pressure Pulse Contour

Comparison of noninvasive cardiac output measurements using the Nexfin monitoring device and the esophageal Doppler

“…This technology was first introduced by Peñaz in 1973 and has achieved significant development in the past 40 years [24]. Nexfin calculates beat-to-beat SV by dividing the area under the SBP curve (measured at 200 Hz) by the aortic input impedance, Z in , similar to the method described by Wesseling et al and Westerhof et al [25,26]. The value of Z in is determined from a three-element Windkessel model [27] in which the nonlinear effect of mean arterial pressure (MAP) and the influence of the patient's age, height, weight, and gender on aortic mechanical properties are incorporated.…”

Normovolaemia defined by central blood volume and venous oxygen saturation

“…Previously, pulse contour methods were just linear and integrated the systolic area of the arterial pulse wave, sometimes with a correction for heart rate. 80 However, the elastic behaviour of the thoracic human aorta varies non-linearly with the changing distending pressure, 81 which is not accounted for by the early pulse contour methods. The Modelflow method, 82 as implemented in the Finometer (Finapres Medicdal System, Amsterdam, The Netherlands), computes an aortic flow waveform from either finger or intra-arterial pressure by simulating a non-linear three-element model of the aortic input impedance.…”

Continuous cardiac output monitoring via arterial pressure waveform analysis following severe hemorrhagic shock in dogs*

“…Arterial pulse contour analysis has been investigated as a noninvasive method for beat-to-beat determination of cardiac output since the early 20th century (6). Various mathematical models and algorithms have attempted to correlate the area under the arterial pressure wave and stroke volume (SV) (7)(8)(9). Although logical, this approach has been problematic due to technical difficulties associated with accurately analyzing arterial pressure waveforms.…”