ESICM LIVES 2016: part three

Comparison between picco and pac methods to evaluate the cardiac index during veno-venous extracorporeal membrane oxygenation. A prospective observational study Introduction: Cardiac index (CI) monitoring in patients with severe acute respiratory distress syndrome (ARDS) is important to optimize organ perfusion, avoiding pulmonary fluid-overload. CI can be measured using both pulmonary artery catheter (PAC) method and less invasive transpulmonary thermodilution-based PiCCO system. However, the accuracy of PiCCO during extracorporeal membrane oxygenation (ECMO) is still unconfirmed. Objectives: To compare the effectiveness of PAC and PiCCO methods to measure CI during venovenous ECMO. Methods: Data were collected in two patients treated with femorofemoral veno-venous ECMO for severe ARDS. In both cases, continuous cardiac output PAC catheters (Edwards Lifesciences, CA) were placed in the internal jugular veins, while PiCCO catheters (Pulsion Medical Systems, DE) were introduced in the brachial arteries. With extracorporeal blood flows in the range of 3-4 L/min and mean arterial blood pressure >70 mmHg, CI determinations were performed twice daily in both patients (at 10.00 AM and at 6.00 PM) simultaneously with PAC and PiCCO systems (CIPAC and CIPiCCO). Mean values between three thermodilutions were recorded for each measurement. Statistics were performed according to the regression linear analysis and the Bland-Altman method. Significance was assumed at a p-value < 0.05. Results: A total of 13 parallel CI measurements were recorded over three days (one patient underwent three determinations on day 3). CIPAC ranged from 2.4 to 4.8 L/min/m2 and CIPiCCO from 2.4 to 6.2 L/ min/m2. Linear regression analysis between CIPAC and CIPiCCO revealed R2 = 0.78, p < 0.0001 (Figure 74). From Bland-Altman analysis, the mean differences (m) and SD between CIPAC and CIPiCCO resulted in m= 0.193 L/min/m2 and SD = 0.557 L/min/m2 (Figure 75). Conclusions: We observed a strong correlation between CIPAC and CIPiCCO (R = 0.89) during veno-venous ECMO, but also a small CI overestimation (0.193 L/min/m2; 95%CI: −0.89 - 1.28) of PiCCO over PAC. Due to the wide confidential interval, it follows that PiCCO system can not be considered accurate, at least during ECMO. Further investigations are needed to confirm this preliminary observation.