The Effects of Vasodilation on Cardiac Output Measured by PiCCO

Objectives: The purpose of this study was to investigate the effects of vasodilation on cardiac output (CO) measured by pulse contour method using PiCCO (Pulsion Medical Systems AG, Munich, Germany) in comparison with CO by the thermodilution method. Design: A prospective observational study. Settings: An operating room in a university hospital. Participants: Twenty patients scheduled for off-pump coronary artery bypass grafting. Interventions: After anesthesia induction with midazolam, fentanyl, and vecuronium, the PiCCO catheter and pulmonary artery catheter were inserted. Before the initiation of surgery, progressively higher infusions of prostaglandin E1 (PGE1) were administered for vasodilation. Measurements and Main Results: CO was measured before PGE1 (control); at PGE1 0.01, 0.02, and 0.04 μg/kg/min; and 15 minutes after stopping PGE1 infusion. Systemic vascular resistances (SVRs) at PGE1 0.02 and 0.04 μg/kg/min were significantly lower than the control value. The correlation coefficient (R²) at each point, percentage error, and limits of agreement (bias ± 2 standard deviation of bias) were 0.89, 17, -0.21 ± 0.53 before PGE1; 0.72, 27, -0.31 ± 0.93 at 0.01 μg/kg/min; 0.53, 40, -0.62 ± 1.41 at 0.02 μg/kg/min; 0.57, 34, -0.61 ± 1.26 at 0.04 μg/kg/min; and 0.97, 21, -0.14 ± 0.69 L/min 15 minutes after the end of infusion, respectively. Conclusions: PiCCO may not be an alternative to thermodilution measurement without recalibration when SVR decreases by infusion of PGE1 ≥0.02 μg/kg/min.