Low flow extracorporeal veno‐venous CO2 removal (ECCO2R) therapy is used to remove CO2 while reducing ventilation intensity. However, the use of this technique is limited because efficiency of CO2 removal and potential beneficial effects on pulmonary hemodynamics are not precisely established. Moreover, this technique requires anticoagulation that may induce severe complications in critically ill patients. Therefore, our study aimed at determining precise efficiency of CO2 extraction and its effects on right ventricular (RV) afterload, and comparing regional anticoagulation with citrate to systemic heparin anticoagulation during ECCO2R. This study was performed in an experimental model of severe hypercapnic acidosis performed in two groups of three pigs. In the first group (heparin group), pigs were anticoagulated with a standard protocol of unfractionated heparin while citrate was used for ECCO2R device anticoagulation in the second group (citrate group). After sedation, analgesia and endotracheal intubation, pigs were connected to a volume‐cycled ventilator. Severe hypercapnic acidosis was obtained by reducing tidal volume by 60%. ECCO2R was started in both groups when arterial pH was lower than 7.2. Pump Assisted Lung Protection (PALP, Maquet, Rastatt, Germany) system was used to remove CO2. CO2 extraction, arterial pH, PaCO2 as well as systemic and pulmonary hemodynamic were continuously followed. Mean arterial pH was normalized to 7.37 ± 1.4 at an extracorporeal blood flow of 400 mL/min, coming from 7.11 ± 1.3. RV end‐systolic pressure increased by over 30% during acute hypercapnic acidosis and was normalized in parallel with CO2 removal. CO2 extraction was not significantly increased in citrate group as compared to heparin group. Mean ionized calcium and MAP were significantly lower in the citrate group than in the heparin group during ECCO2R (1.03 ± 0.20 vs. 1.33 ± 0.19 and 57 ± 14 vs. 68 ± 15 mm Hg, respectively). ECCO2R was highly efficient to normalize pH and PaCO2 and to reduce RV afterload resulting from hypercapnic acidosis. Regional anticoagulation with citrate solution was as effective as standard heparin anticoagulation but did not improve CO2 removal and lead to more hypocalcemia and hypotension.
The Extracorporeal CO 2 removal device (ECCO 2 RD) is used in clinics to treat patients suffering from respiratory failures like acute respiratory distress syndrome (ARDS) or chronic obstructive pulmonary disease (COPD). The aim of this device is to decarboxylate blood externally with low blood flow. A mathematical model is proposed to describe protective ventilation, ARDS and an extracorporeal CO 2 removal therapy (ECCO 2 RT). The simulations are compared with experimental data carried out on 10 pigs. The results show a good agreement between the mathematical simulations and the experimental data, which provides a nice validation of the model. This model is thus able to predict the decrease of PCO 2 during ECCO 2 RT for different blood flows across the extracorporeal lung support.
Venoarterial extracorporeal life support (VA-ECLS) is used in ICUs (intensive care units) for the most extreme presentations of acute and severe cardiogenic shock, and one of the main issues the clinicians have to deal with is the weaning from VA-ECLS. In this study, a patient-specific model of the cardiovascular system connected to a VA-ECLS is built to improve the understanding of this complex system. Pig experiments are performed to validate the model, and the results are quite promising since the mean difference between experimental data and simulation is smaller than 5% for all the hemodynamic quantities. It is also a major objective of this paper to provide a proof-of-concept analysis that model-based approaches could improve the weaning strategy for VA-ECLS therapy.
Abstract-Extracorporeal CO 2 Removal device is used in clinics when a patient suffers from a pulmonary insufficiency like Acute Respiratory Distress Syndrome and allows to decarboxylate blood externally. In this work, a model of the respiratory system coupled with such a device is proposed to analyze the decrease of CO 2 partial pressure in blood. To validate the model, some parameters are estimated thanks to experimental data. Metabolism is a crucial parameter and we show that its time evolution must be taken into account in order to have correct CO 2 partial pressure simulations in arteries and in veins.
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