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Accuracy of Continuous Cardiac Output Monitoring by Pulse Contour Analysis in Patients with Septic Shock: A Comparison with Continuous Pulsed Thermodilution
Ulrich Haas, M.D.; Pirkko Hettrich; Harald Bauer, M.D.; Eike Martin, M.D.; Bernd W. Böttiger, M.D.
Department of Anesthesiology, University of Heidelberg, Heidelberg, Germany
Introduction: Accurate hemodynamic assessment is crucial for the optimization and guidance of therapy in patients with septic shock. Pulmonary artery thermodilution measurements have long been considered the only practical and reliable method of clinical cardiac output monitoring. A recent innovation uses pulse contour analysis to achieve continuous cardiac output monitoring in a less invasive manner. However, there have been no studies up to now to evaluate this method in septic patients. We, therefore, studied the accuracy and precision of continous pulse contour cardiac output (PCCO) compared to the continuous thermodilution technique (CCO) in patients with septic shock.

Methods: After approval by the institutional ethics committee, 10 patients (mean 59±19 years) with septic shock (definition according to the criteria of the ACCP/SCCM consensus conference1) were prospectively studied. All patients were deeply sedated, mechanically ventilated in a pressure-controlled mode and required continuous norepinephrine (>0.1 μg·kg-1·min-1) infusion. CCO measurements were obtained from a pulmonary artery catheter (CCOmboV/CEDV; 7.5 F; Baxter Healthcare Corporation, Irvine, CA) connected to the Vigilance CCO system. PCCO values were obtained from a 4 F arterial thermodilution catheter (PV 8015; PiCCO monitoting Kit; Pulsion, Munich, Germany) connected to the monitor to analyse the arterial pulse pressure curve (Pulsion, Munich, Germany). The PCCO was initially calibrated with the mean value of triple transpulmonary thermodilution cardiac output measurements at the onset of application. CCO and PCCO measurements were performed simultaneously. Statistical analysis was performed using Bland/Altmann's bias and precision. Bias was calculated as the mean difference between CCO and PCCO.

Results: Cardiac output measurements yielded 157 data pairs (range: 4.1–14.0 L/min). The number of measurements per patient ranged from 8 to 32 (mean 15±4). Over all time points, CCO versus PCCO showed a bias of –0.7 L/min and a precision of ± 2.1 L/min.

Conclusions: In the present study, PCCO has been demonstrated to show clinically acceptable levels of accuracy and precision when compared to CCO in patients with septic shock. Therefore, in patients with septic shock, continuous cardiac output measurement (and calculation of derived hemodynamic variables like systemic vascular resistance) can be accurately achieved by PCCO in a less invasive manner.

References: 1. Crit Care Med 1992;20:864-874

Anesthesiology 2002; 96: A584