Validation of a continuous cardiac output measurement using arterial pressure waveforms

Introduction

Intermittent bolus thermodilution cardiac output (ICO) and continuous cardiac output (CCO) measurements with pulmonary artery catheters (PAC) are the most commonly preferred methods of cardiac output (CO) measurement for guiding hemodynamic therapy in the clinical setting. A novel arterial pressure cardiac output (APCO) measurement method requires only access to a radial or femoral artery via a standard arterial catheter and does not require use of venous access or injection of a dilution medium for calibration.

Hypothesis/methods

We hypothesize that APCO, which measures CO via arterial pressure analysis, is reliable when compared with ICO. We compared a prototype APCO system (FloTrac™; Edwards Lifesciences, Irvine, CA, USA) with PAC (Swan–Ganz^®; Edwards Lifesciences, Irvine, CA, USA) routinely used in clinical practice. APCO, ICO, and CCO data were collected from a total of 36 patients (29 cardiac surgery, seven ICU) from three centers (two USA, one France). Average age was 64.1 (± 14.4) years, and 72.2% of the patients were male. Grouped measurements (252 data points) for APCO, ICO and CCO were analyzed for bias, precision and correlation via Bland–Altman analysis.

Results

Bland–Altman analysis of the differences between CCO and ICO and between APCO and ICO (Fig. 1) were conducted. The analysis yielded a mean bias and precision (± one standard deviation) of 0.8 ± 1.1 and 0.2 ± 1.3 l/min, respectively. APCO trends correlated with ICO in 98% of all data points collected.

Figure 1

Bland–Altman analysis of the differences between arterial pressure cardiac output (APCO) and intermittent bolus thermodilution cardiac output (ICO).

Conclusions

Data show that the APCO method of CCO measurement is reliable and correlates well with ICO measurements when used in critically ill patients. The development of an accurate, less invasive, simple method of measuring CO may contribute to the expansion of CO monitoring to critically ill patients who currently are not monitored with a PAC.