Cardiac Output Monitoring via an Automatic Arm Cuff Device: Potential in Surgical Patients

Pulse contour devices estimate cardiac output (CO) by analysis of an invasive blood pressure (BP) waveform. However, arterial catheters are only employed in the highest risk patients. By contrast, automatic arm cuff devices are used for non-invasive BP monitoring in numerous hospital patients. Furthermore, these devices directly measure cuff pressure oscillations, which are directly related to pulsatile blood volume rather than BP. The hypothesis of this study was that automatic arm cuff devices can offer an effective means to monitor CO. A custom-built cuff device was employed to measure cuff pressure and make a unique measurement of the volume of air pumped into and out of the cuff during linear deflation. Cuff device measurements, an invasive BP waveform via a radial artery catheter, and reference CO via pulmonary artery catheter-bolus thermodilution were obtained during major interventions from 24 liver transplant and 10 cardiac surgery patients. A basic analysis was applied to estimate CO in L/min as the product of heart rate, the maximum cuff pressure oscillation amplitude, the compliance of the cuff-arm system derived from the measured cuff volume-pressure relationship, and the body to arm surface area ratio derived using anthropometric information. This arm cuff-based method yielded a correlation of 0.60 and concordance rate of 83% against the reference CO. For comparison, classic pulse contour analysis of the invasive BP waveform produced a correlation of 0.62 and concordance rate of 81%. These initial findings indicate the potential for CO monitoring via a non-invasive automatic arm cuff device in surgical patients.