Measurement of rate of pressure development (dP/dtmax) based on femoral artery pressure waveforms: comparison with left ventricular dP/dtmax
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KeywordsFemoral Artery Calcium Chloride Pressure Development Pressure Waveform Left Ventricular Cavity
Recently, calculation of the rate of pressure development (dP/dtmax) has been incorporated in the pulse contour cardiac output (PCCO) software technology (Pulsion Medical Systems, Munich, Germany).
Until now its measurement necessitated the presence of an intraventricular pressure catheter. Since dP/dtmax represents a relative load-independent measure of left ventricular function, its availability using standard invasive monitoring technology may provide additional information on the patient's cardiac function. The present study assessed the reliability of PCCO dP/dtmax under different experimental conditions.
In 40 coronary surgery patients a high-fidelity pressure catheter was positioned in the left ventricular cavity and a 5-F thermistor-tipped catheter (Pulsiocath PV2015L13) in the femoral artery. Studies were performed before initiation of cardiopulmonary bypass. PCCO dP/dtmax was compared with dP/dtmax measured in the left ventricle under the following experimental conditions: increase in cardiac load obtained by leg elevation, and increase in blood pressure obtained by injection of calcium chloride.
A weak correlation was observed between absolute dP/dtmax values measured by both systems (leg elevation: r = 0.36, P = 0.001; calcium: r = 0.52, P < 0.001) (Bland–Altman bias ± standard deviation: leg elevation: 81 ± 213; calcium: 93 ± 243). However, when changes in dP/dtmax with leg elevation and with calcium administration were analyzed, a close correlation was observed between both measurements (leg elevation: r = 0.9, P < 0.001; calcium: r = 0.58, P < 0.001) (Bland–Altman bias + standard deviation: leg elevation: 8 ± 30; calcium: 19± 99).
The changes in PCCO dP/dtmax with a physiological or pharmacological intervention closely correlated with the changes in left ventricular dP/dtmax. These findings suggest that PCCO dP/dtmax analysis may provide a valuable tool to guide cardiac treatment. Further studies will have to elucidate whether these findings also hold for other interventions.