Currently, artificial-membrane lungs consist of thousands of hollow fiber membranes where blood flows around the fibers and gas flows inside the fibers, achieving diffusive gas exchange. At both ends of the fibers, the interspaces between the hollow fiber membranes and the plastic housing are filled with glue to separate the gas from the blood phase. During a uniaxial centrifugation process, the glue forms the “potting.” The shape of the cured potting is then determined by the centrifugation process, limiting design possibilities and leading to unfavorable stagnation zones associated with blood clotting. In this study, a new multiaxial centrifugation process was developed, expanding the possible shapes of the potting and allowing for completely new module designs with potentially superior blood flow guidance within the potting margins. Two-phase simulations of the process in conceptual artificial lungs were performed to explore the possibilities of a biaxial centrifugation process and determine suitable parameter sets. A corresponding biaxial centrifugation setup was built to prove feasibility and experimentally validate four conceptual designs, resulting in good agreement with the simulations. In summary, this study shows the feasibility of a multiaxial centrifugation process allowing greater variety in potting shapes, eliminating inefficient stagnation zones and more favorable blood flow conditions in artificial lungs. Graphic abstract
Background: RESP score and PRESERVE score have been validated for veno-venous Extracorporeal Membrane Oxygenation in severe ARDS to assume individual mortality risk. ARDS patients with low-flow Extracorporeal Carbon Dioxide Removal, especially pumpless Extracorporeal Lung Assist, have also a high mortality rate, but there are no validated specific or general outcome scores. This retrospective study tested whether these established specific risk scores can be validated for pumpless Extracorporeal Lung Assist in ARDS patients in comparison to a general organ dysfunction score, the SOFA score. Methods: In a retrospective single center cohort study we calculated and evaluated RESP, PRESERVE, and SOFA score for 73 ARDS patients with pumpless Extracorporeal Lung Assist treated between 2002 and 2016 using the XENIOS iLA Membrane Ventilator. Six patients had a mild, 40 a moderate and 27 a severe ARDS according to the Berlin criteria. Demographic data and hospital mortality as well as ventilator settings, hemodynamic parameters, and blood gas measurement before and during extracorporeal therapy were recorded. Results: Pumpless Extracorporeal Lung Assist of mechanical ventilated ARDS patients resulted in an optimized lung protective ventilation, significant reduction of P aCO2 , and compensation of acidosis. Scoring showed a mean score of alive versus deceased patients of 3 ± 1 versus − 1 ± 1 for RESP (p < 0.01), 3 ± 0 versus 6 ± 0 for PRESERVE (p < 0.05) and 8 ± 1 versus 10 ± 1 for SOFA (p < 0.05). Using receiver operating characteristic curves, area under the curve (AUC) was 0.78 (95% confidence interval (CI) 0.67-0.89, p < 0.01) for RESP score, 0.80 (95% CI 0.70-0.90, p < 0.0001) for PRESERVE score and 0.66 (95% CI 0.53-0.79, p < 0.05) for SOFA score. Conclusions: RESP and PRESERVE scores were superior to SOFA, as non-specific critical care score. Although scores were developed for veno-venous ECMO, we could validate RESP and PRESERVE score for pumpless Extracorporeal Lung Assist. In conclusion, RESP and PRESERVE score are suitable to estimate mortality risk of ARDS patients with an arterio-venous pumpless Extracorporeal Carbon Dioxide Removal.
Purpose-Currently used cannulae for extracorporeal carbon dioxide removal (ECCO 2 R) are associated with complications such as thrombosis and distal limb ischemia, especially for long-term use. We hypothesize that the risk of these complications is reducible by attaching hemodynamically optimized grafts to the patient's vessels. In this study, as a first step towards a long-term stable ECCO 2 R connection, we investigated the feasibility of a venovenous connection to the common iliac veins. To ensure its applicability, the drainage of reinfused blood (recirculation) and high wall shear stress (WSS) must be avoided. Methods-A reference model was selected for computational fluid dynamics, on the basis of the analysis of imaging data. Initially, a sensitivity analysis regarding recirculation was conducted using as variables: blood flow, the distance of drainage and return to the iliocaval junction, as well as the diameter and position of the grafts. Subsequently, the connection was optimized regarding recirculation and the WSS was evaluated. We validated the simulations in a silicone model traversed by dyed fluid. Results-The simulations were in good agreement with the validation measurements (mean deviation 1.64%). The recirculation ranged from 32.1 to 0%. The maximum WSS did not exceed 5.57 Pa. The position and diameter of the return graft show the highest influence on recirculation. A correlation was ascertained between recirculation and WSS. Overall, an inflow jet directed at a vessel wall entails not only high WSS, but also a flow separation and thereby an increased recirculation. Therefore, return grafts aligned to the vena cava are crucial. Conclusion-In conclusion, a connection without recirculation could be feasible and therefore provides a promising option for a long-term ECCO 2 R connection.
Carbon monoxide (CO) poisoning is the leading cause of poisoning-related deaths globally. The currently available therapy options are normobaric oxygen (NBO) and hyperbaric oxygen (HBO). While NBO lacks in efficacy, HBO is not available in all areas and countries. We present a novel method, extracorporeal hyperoxygenation therapy (EHT), for the treatment of CO poisoning that eliminates the CO by treating blood extracorporeally at elevated oxygen partial pressure. In this study, we proof the principle of the method in vitro using procine blood: Firstly, we investigated the difference in the CO elimination of a hollow fibre membrane oxygenator and a specifically designed batch oxygenator based on the bubble oxygenator principle at elevated pressures (1, 3 bar). Secondly, the batch oxygenator was redesigned and tested for a broader range of pressures (1, 3, 5, 7 bar) and temperatures (23, 30, 37 °C). So far, the shortest measured carboxyhemoglobin half-life in the blood was 21.32 min. In conclusion, EHT has the potential to provide an easily available and effective method for the treatment of CO poisoning.
Background: RESP score and PRESERVE score have been validated for veno-venous Extracorporeal Membrane Oxygenation in severe ARDS to assume individual mortality risk. ARDS patients with low-flow Extracorporeal Carbon Dioxide Removal, especially pumpless Extracorporeal Lung Assist, have also a high mortality rate, but there are no validated specific or general outcome scores. Methods: In a retrospective single center cohort study we calculated and evaluated RESP, PRESERVE, and SOFA score for 73 ARDS patients with pumpless Extracorporeal Lung Assist. Additionally, demographic data and hospital mortality as well as ventilator settings, hemodynamic parameters, and blood gas measurement before and during extracorporeal therapy were recorded. Results: Pumpless Extracorporeal Lung Assist of mechanical ventilated ARDS patients resulted in an optimized lung protective ventilation, significant reduction of PaCO2, and compensation of acidosis. Scoring showed a mean score of alive versus deceased patients of 3 ± 1 versus -1 ± 1 for RESP (p < 0.01), 3 ± 0 versus 6 ± 0 for PRESERVE (p < 0.05) and 8 ± 1 versus 10 ± 1 for SOFA (p < 0.05). Using receiver operating characteristic curves, area under the curve (AUC) was 0.78 (95 % confidence interval (CI) 0.67 – 0.89, p < 0.01) for RESP score, 0.80 (95 % CI 0.70 – 0.90, p < 0.0001) for PRESERVE score and 0.66 (95 % CI 0.53 – 0.79, p < 0.05) for SOFA score. Conclusions: RESP and PRESERVE scores were superior to SOFA, as non-specific critical care score. Although scores were developed for veno-venous ECMO, we could validate RESP and PRESERVE score for pumpless Extracorporeal Lung Assist. In conclusion, RESP and PRESERVE score are suitable to estimate mortality risk of ARDS patients with an arterio-venous pumpless Extracorporeal Carbon Dioxide Removal.
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