Monitoring cardiac output using the femoral and radial arterial pressure waveform.

This study was performed to determine the interchangeability of femoral artery pressure and radial artery pressure measurements as the input for the PiCCO system (Pulsion Medical Systems, Munich, Germany). We studied 15 intensive care patients following cardiac surgery. Five-second averages of the cardiac output derived from the femoral artery pressure (COfem) were compared to 5-s averages derived from the radial artery pressure (COrad). One patient was excluded due to problems in the pattern recognition of the arterial pressure signal. In the remaining 14 patients, 14 734 comparative cardiac output values were analysed. The mean sample time was 88 min, range [30-119 min]. Mean (SD) COfem was 6.24 (1.1) l.min(-1) and mean COrad 6.23 (1.1) l.min(-1). Bland-Altman analysis showed an excellent agreement with a bias of - 0.01 l.min(-1), and limits of agreement from 0.60 to - 0.62 l.min(-1). If changes in CO were > 0.5 l.min(-1), the direction of changes in COfem and COrad were equal in 97% of instances. We conclude that femoral artery pressure and radial artery pressure are interchangeable as inputs for the PiCCO device.

Pulmonary artery thermodilution cardiac output vs. transpulmonary thermodilution cardiac output in two patients with intrathoracic pathology.

In two adult patients, one with a severe hemorrhage and one with a partial anomalous pulmonary vein, cardiac output (CO) measurements were performed simultaneously by means of the bolus transpulmonary thermodilution technique (COao) and continuous pulmonary artery thermodilution method (CCOpa). In both cases, the methods revealed clinically significant different cardiac output values based upon the site of measurement and the underlying pathology. The assessment of cardiac output (CO) is considered an important part of cardiovascular monitoring of the critically ill patient. Cardiac output is most commonly determined intermittently by the bolus thermodilution technique with a pulmonary artery catheter (COpa). As continuous monitoring of CO is preferable to this intermittent technique, two major techniques have been proposed. Firstly, a nearly continuous thermodilution method (CCOpa) using a heating filament mounted on a pulmonary artery catheter (Baxter Edwards Laboratories, Irvine, CA), with a clinically acceptable accuracy compared with the intermittent bolus technique. Based on these results we assumed CCOpa equivalent to real CO during hemodynamically stable conditions, and secondly, a continuous cardiac output system based on pulse contour analysis (PCCO), such as the PiCCO system (Pulsion Medical System, Munchen, Germany). To calibrate this device, which uses a derivation of the algorithm of Wesseling and colleagues, an independently obtained value of CO by the transpulmonary thermodilution method (COao) is used. Clinical validation studies in patients without underlying intrathoracic pathology, comparing transpulmonary COao with the pulmonary technique (COpa), mostly yielded good agreement.