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924 result(s) for "Kühn, Christian"
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Comparison of anticoagulation strategies for veno-venous ECMO support in acute respiratory failure
Background Extracorporeal membrane oxygenation (ECMO) support in acute respiratory failure may be lifesaving, but bleeding and thromboembolic complications are common. The optimal anticoagulation strategy balancing these factors remains to be determined. This retrospective study compared two institutional anticoagulation management strategies focussing on oxygenator changes and both bleeding and thromboembolic events. Methods We conducted a retrospective observational cohort study between 04/2015 and 02/2020 in two ECMO referral centres in Germany in patients receiving veno-venous (VV)-ECMO support for acute respiratory failure for > 24 h. One centre routinely applied low-dose heparinization aiming for a partial thromboplastin time (PTT) of 35–40 s and the other routinely used a high-dose therapeutic heparinization strategy aiming for an activated clotting time (ACT) of 140–180 s. We assessed number of and time to ECMO oxygenator changes, 15-day freedom from oxygenator change, major bleeding events, thromboembolic events, 30-day ICU mortality, activated clotting time and partial thromboplastin time and administration of blood products. Primary outcome was the occurrence of oxygenator changes depending on heparinization strategy; main secondary outcomes were the occurrence of severe bleeding events and occurrence of thromboembolic events. The transfusion strategy was more liberal in the low-dose centre. Results Of 375 screened patients receiving VV-ECMO support, 218 were included in the analysis (117 high-dose group; 101 low-dose group). Disease severity measured by SAPS II score was 46 (IQR 36–57) versus 47 (IQR 37–55) and ECMO runtime was 8 (IQR 5–12) versus 11 (IQR 7–17) days ( P  = 0.003). There were 14 oxygenator changes in the high-dose group versus 48 in the low-dose group. Freedom from oxygenator change at 15 days was 73% versus 55% (adjusted HR 3.34 [95% confidence interval 1.2–9.4]; P  = 0.023). Severe bleeding events occurred in 23 (19.7%) versus 14 (13.9%) patients ( P  = 0.256) and thromboembolic events occurred in 8 (6.8%) versus 19 (19%) patients ( P  = 0.007). Mortality at 30 days was 33.3% versus 30.7% ( P  = 0.11). Conclusions In this retrospective study, ECMO management with high-dose heparinization was associated with lower rates of oxygenator changes and thromboembolic events when compared to a low-dose heparinization strategy. Prospective, randomized trials are needed to determine the optimal anticoagulation strategy in patients receiving ECMO support.
Normothermic perfusion of donor lungs for preservation and assessment with the Organ Care System Lung before bilateral transplantation: a pilot study of 12 patients
Cold flush and static cold storage is the standard preservation technique for donor lungs before transplantations. Several research groups have assessed normothermic perfusion of donor lungs but all devices investigated were non-portable. We report first-in-man experience of the portable Organ Care System (OCS) Lung device for concomitant preservation, assessment, and transport of donor lungs. Between Feb 18, and July 1, 2011, 12 patients were transplanted at two academic lung transplantation centres in Hanover, Germany and Madrid, Spain. Lungs were perfused with low-potassium dextran solution, explanted, immediately connected to the OCS Lung, perfused with Steen's solution supplemented with two red-cell concentrates. We assessed donor and recipient characteristics and monitored extended criteria donor lung scores; primary graft dysfunction scores at 0, 24, 48, and 72 h; time on mechanical ventilation after surgery; length of stays in hospital and the intensive-care unit after surgery; blood gases; and survival of grafts and patients. Eight donors were female and four were male (mean age 44·5 years, range 14–72). Seven recipients were female and five were male (mean age 50·0 years, range 31–59). The preharvest donor ratio of partial pressure of oxyen (PaO2) to fractional concentration of oxygen in inspired air (FIO2) was 463·9 (SD 91·4). The final ratio of PaO2 to FIO2 measured with the OCS Lung was 471·58 (127·9). The difference between these ratios was not significant (p=0·72). All grafts and patients survived to 30 days; all recipients recovered and were discharged from hospital. Lungs can be safely preserved with the OCS Lung, resulting in complete organ use and successful transplantation in our series of high-risk recipients. In November, 2011, we began recruitment for a prospective, randomised, multicentre trial (INSPIRE) to compare preservation with OCS Lung with standard cold storage. TransMedics and German Federal Ministry of Education and Research.
Key characteristics impacting survival of COVID-19 extracorporeal membrane oxygenation
Background Severe COVID-19 induced acute respiratory distress syndrome (ARDS) often requires extracorporeal membrane oxygenation (ECMO). Recent German health insurance data revealed low ICU survival rates. Patient characteristics and experience of the ECMO center may determine intensive care unit (ICU) survival. The current study aimed to identify factors affecting ICU survival of COVID-19 ECMO patients. Methods 673 COVID-19 ARDS ECMO patients treated in 26 centers between January 1st 2020 and March 22nd 2021 were included. Data on clinical characteristics, adjunct therapies, complications, and outcome were documented. Block wise logistic regression analysis was applied to identify variables associated with ICU-survival. Results Most patients were between 50 and 70 years of age. PaO 2 /FiO 2 ratio prior to ECMO was 72 mmHg (IQR: 58–99). ICU survival was 31.4%. Survival was significantly lower during the 2nd wave of the COVID-19 pandemic. A subgroup of 284 (42%) patients fulfilling modified EOLIA criteria had a higher survival (38%) ( p  = 0.0014, OR 0.64 (CI 0.41–0.99)). Survival differed between low, intermediate, and high-volume centers with 20%, 30%, and 38%, respectively ( p  = 0.0024). Treatment in high volume centers resulted in an odds ratio of 0.55 (CI 0.28–1.02) compared to low volume centers. Additional factors associated with survival were younger age, shorter time between intubation and ECMO initiation, BMI > 35 (compared to < 25), absence of renal replacement therapy or major bleeding/thromboembolic events. Conclusions Structural and patient-related factors, including age, comorbidities and ECMO case volume, determined the survival of COVID-19 ECMO. These factors combined with a more liberal ECMO indication during the 2nd wave may explain the reasonably overall low survival rate. Careful selection of patients and treatment in high volume ECMO centers was associated with higher odds of ICU survival. Trial registration Registered in the German Clinical Trials Register (study ID: DRKS00022964, retrospectively registered, September 7th 2020, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00022964 . Graphical abstract
Use of extracorporeal membrane oxygenation for eCPR in the emergency room in patients with refractory out-of-hospital cardiac arrest
Out-of-hospital cardiac arrest (OHCA) refractory to conventional high-quality cardiopulmonary resuscitation (CPR) may be rescued by extracorporeal CPR (eCPR) using veno-arterial extracorporeal membrane oxygenation (V-A ECMO). Even when trying to identify eCPR candidates based on criteria assumed to be associated with a favourable neurological outcome, reported survival rates are frequently below 10%. All patients undergoing implantation of V-A ECMO for eCPR between January 2018 and December 2019 (N = 40) were analysed (age 53±13 years; 75% male). Patients with refractory OHCA and potentially favourable circumstances (initial shockable rhythm, witnessed arrest, bystander CPR, absence of limiting comorbidities, age <75 years) were transported under mechanical chest compression. Candidates for eCPR should have a pH [greater than or equal to]6.9, arterial lactate [less than or equal to]15 mmol/L and time-to-ECMO should be [less than or equal to]60 minutes. Overall 30-day survival was 12.5%, with 3 of 5 survivors having a favourable neurological outcome (cerebral performance category (CPC) 1 or 2), representing 7.5% of the total eCPR population. No patient selected for eCPR met all pre-defined criteria (median of unfavourable criteria: 3). Importantly, time-to-ECMO most often (39/40) exceeded 60 minutes (mean 102 ±32 min.), and lactate was >15mmol/L in 30 out of 40 patients. Moreover, 22 out of 40 patients had a non-shockable rhythm on the first ECG. Despite our intention to select patients with potentially advantageous circumstances to achieve acceptable eCPR outcomes, the imminent deadly consequence of withholding eCPR obviously prompted individual physicians to perform the procedure also in presumably more unfavourable settings, resulting in similar mortality rates of eCPR as reported before.
Blood cytokine expression correlates with early multi-organ damage in a mouse model of moderate hypothermia with circulatory arrest using cardiopulmonary bypass
Cardiopulmonary bypass (CPB) with moderate hypothermic cardiac arrest (MHCA) is essential for prolonged complex procedures in cardiac surgery and is associated with postoperative complications. Although cytokine release provoked through MHCA under CPB plays a pivotal role in postoperative organ damage, the pathomechanisms are unclear. Here, we investigated the cytokine release pattern and histological organ damage after MHCA using a recently described mouse CPB model. Eight BALB/c mice underwent 60 minutes of circulatory arrest under CPB, were successively rewarmed and reperfused. Blood cytokine concentrations and liver and kidney function parameters were measured and histological changes to these organs were compared to control animals. Our results showed a marked increase in proinflammatory cytokines and histological changes in the kidney, lung, and liver after CPB. Furthermore, clinical chemistry showed signs of hemolysis and acute kidney injury. These results suggest early onset of solid organ injury which correlates with increased leukocyte infiltration. A better understanding of the interplay between pro-inflammatory cytokine activation and solid organ injury in this model of CBP with MHCA will inform strategies to reduce organ damage during cardiac surgeries in the clinic.
Untersuchungen zur Kinetik von Reaktionen zwischen OH-Radikalen und oxygenierten Kohlenwasserstoffen mittels laserinduzierter Fluoreszenzspektroskopie
Im Rahmen der vorliegenden Arbeit wurden die Reaktionen der Ester Methylformiat (MeFo) und Dimethylcarbonat (DMC) inklusive deuterierter Isotopologe mit Hydroxylradikalen (OH-Radikalen) reaktionskinetisch untersucht. MeFo und DMC werden gegenwärtig als potentielle regenerative Kraftstoffe diskutiert. Die Reaktion der untersuchten Spezies mit den OH-Radikalen zählt zu den wichtigsten Reaktionen dieser Spezies in der Atmosphären- und Verbrennungschemie. Es wurden Experimente mit gepulster Laserphotolyse in Kombination mit laserinduzierter Fluoreszenz unter Bedingungen durchgeführt, welche bei Verbrennungsprozessen und in der Atmosphäre von Relevanz sind. Es wurden die bimolekularen Geschwindigkeitskonstanten und die Arrhenius-Ausdrücke bestimmt und mit Werten aus der Literatur verglichen. Zudem wird der Reaktionsmechanismus unter Einbeziehung quantenchemischer Rechnungen diskutiert. Des Weiteren wurde Formaldehyd als Reaktionsprodukt der Reaktion von Ethylen mit OH-Radikalen laserspektroskopisch untersucht und ein Referenzsystem zur Ausbeutebestimmung von Formaldehyd auf seine Anwendbarkeit getestet. Die Untersuchungen der vorliegenden Arbeit können somit einen Beitrag zum Verständnis der chemisch-kinetischen Prozesse bei den untersuchten Reaktionen leisten.
Towards Biohybrid Lung Development: Establishment of a Porcine In Vitro Model
Lung transplantation (LTx) is the only curative therapy option for patients with end-stage lung diseases, though only available for chosen patients. To provide an alternative treatment option to LTx, we aim for the development of an implantable biohybrid lung (BHL) based on hollow fiber membrane (HFM) technology used in extracorporeal membrane oxygenators. Crucial for long-lasting BHL durability is complete hemocompatibility of all blood contacting surfaces, which can be achieved by their endothelialization. In continuation to successful in vitro investigations using human endothelial cells (ECs), indicating general feasibility, the appropriate porcine in vivo model needs to be prepared and established to fill the translational data gap prior to patient’s application. Therefore, isolation of porcine ECs from carotid arteries (pCECs) was established. Following, pCECs were used for HFM endothelialization and examined under static and dynamic conditions using cell medium or heparinized blood, to assess their proliferation capacity, flow resistance and activation state, especially under clinically relevant conditions. Additionally, comparative hemocompatibility tests between native and endothelialized HFMs were performed. Overall, pure pCECs formed a viable and confluent monolayer, which resisted applied flow conditions, in particular due to physiological extracellular matrix synthesis. Additionally, pCECs remained the non-inflammatory and anti-thrombogenic status, significantly improving the hemocompatibility of endothelialized HFMs. Finally, as relevant for reliable porcine to human translation, pCECs behaved in the same way as human ECs. Concluding, generated in vitro data justify further steps towards pre-clinical BHL examination, in particular BHL application to porcine lung injury models, reflecting the clinical scenario with end-stage lung-diseased patients.
Biohybrid lung Development: Towards Complete Endothelialization of an Assembled Extracorporeal Membrane Oxygenator
Towards the establishment of a long-term lung-assist device to be used both as a bridge and as an alternative to lung transplantation according to final destination therapy, we develop the biohybrid lung (BHL) on the technical basis of contemporary extracorporeal membrane oxygenation (ECMO). Here, to overcome the significant drawbacks of ECMO, in particular the missing hemocompatibility of the artificial surfaces, all blood-contacting areas need to be endothelialized sufficiently. In continuation of our recent accomplishments, demonstrating the feasibility of establishing a physiological acting endothelial cell (EC) monolayer on the hollow fiber membranes (HFMs) of the ECMO in vitro, the next step towards BHL translation is the endothelialization of the complete oxygenator, consisting of HFMs and the surrounding housing. Therefore, we assessed EC seeding inside our model oxygenator (MOx), which simulated the conditions in the assembled HFM oxygenators in order to identify the most important factors influencing efficient endothelialization, such as cell seeding density, cell distribution, incubation time and culture medium consumption. Overall, upon adjusting the concentration of infused ECs to 15.2 × 104/cm2 and ensuring optimal dispersion of cells in the MOx, viable and confluent EC monolayers formed on all relevant surfaces within 24 h, even though they comprised different polymers, i.e., the fibronectin-coated HFMs and the polysulfone MOx housing. Periodic medium change ensured monolayer survival and negligible apoptosis rates comparable to the reference within the assembled system. By means of these results, revealing essential implications for BHL development, their clinical translation is coming one step closer to reality.
Lung Transplantation following Emergency Pneumonectomy in a Polytraumatized 18-Year-Old
Introduction. On rare occasions, a pneumonectomy needs to be performed after a severe polytrauma. Statistically, this procedure increases the mortality rate to 50%. One option to reduce this high rate could be an organ transplantation if a matching organ can be found. However, the current literature lacks any documentation of such a case. One reason for this stems from the fact that regulations for organ transplantation are very restricted and rarely allow exceptions. In addition, the chance for survival of polytraumatized patients in need of organs in the acute phase of the therapy is often quite unsure. Case Presentation. In this paper, we present the case of an 18-year-old patient who was involved in a serious motorcycle accident. His injury severity score was 29, but he suffered from severe bleeding in his lung which made a pneumonectomy necessary. The procedure led to a severe deterioration of his overall condition. An ECMO therapy was initiated, which effectively only slowed the aggravation. Therefore, he was transferred to our clinic where he was stabilized temporarily. A few days later, his situation turned worse. Since he had no other chance of survival, he was scheduled for a lung transplantation and was assigned an organ. After the transplantation, he stabilized quickly and recovered almost completely. Discussion. In this report, we want to show that an exception to the rules for organ transplantation might make sense on rare occasions. However, to increase the chance for any success, patients must be transferred to highly specialized clinics capable of treating patients with severe conditions. This might be the only chance for those patients to survive.