Predictors associated with mortality of extracorporeal life support therapy for acute heart failure: single-center experience with 679 patients.

Background: Extracorporeal life support (ECLS) therapy is increasingly used for cardiac and respiratory support postcardiotomy, refractory cardiogenic shock and cardiopulmonary resuscitation. This study aims to describe in-hospital mortality of patients requiring ECLS, identify independent predictors associated with mortality and analyze changes of mortality over time. Methods: This retrospective study includes all adult ECLS cases at the University Hospital Zurich, a designated ECLS center in Switzerland, in the period 2007 to 2019. Results: ECLS therapy was required in 679 patients (median age 60 years, 27.5% female). In-hospital mortality was 55.5%. Cubic spline interpolation did not detect evidence for a change in mortality over the whole period of 13 years. In-hospital mortality significantly varied between ECLS indications: 70.7% (152/215) for postcardiotomy, 67.9% (108/159) for cardiopulmonary resuscitation, 47.0% (110/234) for refractory cardiogenic shock, and 9.9% (7/71) for lung transplantation and expansive thoracic surgery (P<0.001). Logistic regression modelling showed excellent discrimination in the receiver operating characteristic (ROC) area under the curve (AUC) of 0.89 [95% confidence interval (CI): 0.87-0.92] and identified significant mortality predictors: age, simplified acute physiology score (SAPS) II, as well as new liver failure and each allogenic blood transfusion unit given per day. ECLS after cardiopulmonary resuscitation was associated with significantly higher mortality compared to ECLS for refractory cardiogenic shock. Conclusions: In-hospital mortality of patients treated with ECLS therapy is high. Outcomes have not changed significantly in the observed period. We identified age, SAPS II, new liver failure and each allogenic blood transfusion unit given per day as independent mortality predictors. Knowledge of predictors strongly associated with in-hospital mortality may affect future decisions about ECLS indications and the respective management to use this elaborate therapy more effectively.

Comparing the effectiveness of augmented reality-based and conventional instructions during single ECMO cannulation training.

PURPOSE: Effective training of extracorporeal membrane oxygenation (ECMO) cannulation is key to fighting the persistently high mortality rate of ECMO interventions. Though augmented reality (AR) is a promising technology for improving information display, only a small percentage of AR projects have addressed training procedures. The present study investigates the potential benefits of AR-based, contextual instructions for ECMO cannulation training as compared to instructions used during conventional training at a university hospital. METHODOLOGY: An AR step-by-step guide was developed for the Microsoft HoloLens 2 that combines text, images, and videos from the conventional training program with simple 3D models. A study was conducted with 21 medical students performing two surgical procedures on a simulator. Participants were divided into two groups, with one group using the conventional instructions for the first procedure and AR instructions for the second and the other group using instructions in reverse order. Training times, a detailed error protocol, and a standardized user experience questionnaire (UEQ) were evaluated. RESULTS: AR-based execution was associated with slightly higher training times and with significantly fewer errors for the more complex second procedure ([Formula: see text], Mann-Whitney U). These differences in errors were most present for knowledge-related errors, resulting in a 66% reduction in the number of errors. AR instructions also led to significantly better ratings on 5 out of the 6 scales used in the UEQ, pointing to higher perceived clarify of information, information acquisition speed, and stimulation. CONCLUSION: The results extend previous research on AR instructions to ECMO cannulation training, indicating its high potential to improve training outcomes as a result of better information acquisition by participants during task execution. Future work should investigate how better performance in a single training session relates to better performance in the long run.

Outcome Prediction in Patients with Severe COVID-19 Requiring Extracorporeal Membrane Oxygenation-A Retrospective International Multicenter Study.

The role of veno-venous extracorporeal membrane oxygenation therapy (V-V ECMO) in severe COVID-19 acute respiratory distress syndrome (ARDS) is still under debate and conclusive data from large cohorts are scarce. Furthermore, criteria for the selection of patients that benefit most from this highly invasive and resource-demanding therapy are yet to be defined. In this study, we assess survival in an international multicenter cohort of COVID-19 patients treated with V-V ECMO and evaluate the performance of several clinical scores to predict 30-day survival. METHODS: This is an investigator-initiated retrospective non-interventional international multicenter registry study (NCT04405973, first registered 28 May 2020). In 127 patients treated with V-V ECMO at 15 centers in Germany, Switzerland, Italy, Belgium, and the United States, we calculated the Sequential Organ Failure Assessment (SOFA) Score, Simplified Acute Physiology Score II (SAPS II), Acute Physiology And Chronic Health Evaluation II (APACHE II) Score, Respiratory Extracorporeal Membrane Oxygenation Survival Prediction (RESP) Score, Predicting Death for Severe ARDS on V­V ECMO (PRESERVE) Score, and 30-day survival. RESULTS: In our study cohort which enrolled 127 patients, overall 30-day survival was 54%. Median SOFA, SAPS II, APACHE II, RESP, and PRESERVE were 9, 36, 17, 1, and 4, respectively. The prognostic accuracy for all these scores (area under the receiver operating characteristic-AUROC) ranged between 0.548 and 0.605. CONCLUSIONS: The use of scores for the prediction of mortality cannot be recommended for treatment decisions in severe COVID-19 ARDS undergoing V-V ECMO; nevertheless, scoring results below or above a specific cut-off value may be considered as an additional tool in the evaluation of prognosis. Survival rates in this cohort of COVID-19 patients treated with V­V ECMO were slightly lower than those reported in non-COVID-19 ARDS patients treated with V-V ECMO.

Initiation of an inter-hospital extracorporeal membrane oxygenation transfer programme for critically ill patients with coronavirus disease 2019: bringing extracorporeal membrane oxygenation support to peripheral hospitals.

OBJECTIVES: Extracorporeal membrane oxygenation (ECMO) is a resource-intensive, highly specialized and expensive therapy that is often reserved for high-volume centres. In recent years, we established an inter-hospital ECMO transfer programme that enables ECMO implants in peripheral hospitals. During the pandemic, the programme was expanded to include ECMO support in selected critically ill patients with coronavirus disease 2019 (COVID-19). METHODS: This retrospective single-centre study reports the technical details and challenges encountered during our initial experience with ECMO implants in peripheral hospitals for patients with COVID-19. RESULTS: During March and April 2020, our team at the University Hospital of Zurich performed 3 out-of-centre ECMO implants at different peripheral hospitals. The implants were performed without any complications. The patients were transported by ambulance or helicopter. Good preparation and selection of the required supplies are the keys to success. The implant should be performed by a well-trained, seasoned ECMO team, because options are limited in most peripheral hospitals. CONCLUSIONS: Out-of-centre ECMO implants in well-selected patients with COVID-19 is feasible and safe if a well-established organization is available and if the implantation is done by an experienced and regularly trained team.

Hyperoxia in portal vein causes enhanced vasoconstriction in arterial vascular bed.

Long-term perfusion of liver grafts outside of the body may enable repair of poor-quality livers that are currently declined for transplantation, mitigating the global shortage of donor livers. In current ex vivo liver perfusion protocols, hyperoxic blood (arterial blood) is commonly delivered in the portal vein (PV). We perfused porcine livers for one week and investigated the effect of and mechanisms behind hyperoxia in the PV on hepatic arterial resistance. Applying PV hyperoxia in porcine livers (n = 5, arterial PV group), we observed an increased need for vasodilator Nitroprussiat (285 ± 162 ml/week) to maintain the reference hepatic artery flow of 0.25 l/min during ex vivo perfusion. With physiologic oxygenation (venous blood) in the PV the need for vasodilator could be reduced to 41 ± 34 ml/week (p = 0.011; n = 5, venous PV group). This phenomenon has not been reported previously, owing to the fact that such experiments are not feasible practically in vivo. We investigated the mechanism of the variation in HA resistance in response to blood oxygen saturation with a focus on the release of vasoactive substances, such as Endothelin 1 (ET-1) and nitric oxide (NO), at the protein and mRNA levels. However, no difference was found between groups for ET-1 and NO release. We propose direct oxygen sensing of endothelial cells and/or increased NO break down rate with hyperoxia as possible explanations for enhanced HA resistance.

Effect of blood viscosity on the performance of virtually wall-less venous cannulas.

AIM: This study was designed to quantify the influence of blood as test medium compared to water in cannula bench performance assessment. METHODS: An in vitro circuit was set-up with silicone tubing between two reservoirs. The test medium was pumped from the lower reservoir by centrifugal pump to the upper reservoir. The test-cannula was inserted in a silicone tube connected between the lower reservoir and the centrifugal pump. Flow rate and pump inlet-pressure were measured for wall-less versus thin-wall cannula using a centrifugal pump in a dynamic bench-test for an afterload of 40-60 mmHg using two media: blood 10 g/dL and 5.6 g/dL and water 0 g/dL. RESULTS: The wall-less cannula showed significantly higher flows rates as compared to the thin-wall cannula (control), with both hemoglobin concentrations and water. Indeed, for a target volume of 200-250 mL of blood (Hg 10 g/dL) in the upper reservoir, the cannula outlet pressure (P) was -14 ± 14 mmHg versus -18 ± 11 mmHg for the wall-less and control respectively; the cannula outlet flow rate (Q) was 3.91 ± 0.41 versus 3.67 ± 0.45 L/min, respectively. At the same target volume but with a Hg of 5.7 g/dL, P was -16 ± 12 mmHg versus -19 ± 12 mmHg and Q was 4 ± 0.1 versus 4 ± 0.4 L/min for the wall-less cannula and control respectively. Likewise, P and Q values with water were -1 mmHg versus -0.67 ± 0.58 mmHg and 4.17 ± 0.45 L/min versus 4.08 ± 0.47 L/min for the wall-less and control respectively. CONCLUSION: Walls-less cannula showed 5.6% less pump inlet-pressure differences calculated between blood and water, as compared to that of thin-wall cannula (-21 times). Flow differences were 6% and 10% for the walls-less and thin-wall cannula respectively. We conclude that testing the cannula performance with water is a good scenario and can overestimate the flow by a 10%. However, superiority for wall-less is preserved with both water and blood.

Outcome of inter-hospital transfer of patients on extracorporeal membrane oxygenation in Switzerland.

AIMS OF THE STUDY: An extracorporeal membrane oxygenation system (ECMO), as a bridge to either recovery, a ventricular assist device (VAD), or heart or lung transplantation, may be the only lifesaving option for critically ill patients suffering from refractory cardiac, respiratory or combined cardiopulmonary failure. As peripheral hospitals may not offer ECMO treatment, tertiary care centres provide specialised ECMO teams for on-site implantation and subsequent patient transfer on ECMO to the tertiary hospital. This study reports the results of the largest ECMO transportation programme in Switzerland and describes its feasibility and safety. METHODS: Patients transported on ECMO by our mobile ECMO team to our tertiary centre between 1 September 2009 and 31 December, 2016 underwent retrospective analysis. Implantation was performed by our specialised ECMO team (primary transport) or by the medical staff of the referring hospital (secondary transport) with subsequent transfer to our institution. Type of ECMO, transport data, patient baseline characteristics, operative variables and postoperative outcomes including complications and mortality were collected from medical records. RESULTS: Fifty-eight patients were included (three patients excluded: one repatriation, two with incomplete medical records). Thirty-five patients (60%) received veno-venous, 22 (38%) veno-arterial and one patient (2%) veno-venoarterial ECMO. Forty-nine (84%) patients underwent primary and nine (16%) secondary transport. Thirty-five (60%) patients were transferred by helicopter and 23 (40%) by ambulance, with median distances of 38.1 (13–225) km and 21 (3-71) km respectively. No clinical or technical complications occurred during transportation. During hospitalisation, three patients had ECMO-associated complications (two compartment syndrome of lower limb, one haemothorax after central ECMO upgrade). Median days on ECMO was 8 (<1–49) and median days in hospital was 17 (<1–122). ECMO weaning was successful in 41 patients (71%), on-transport survival was 100%, 40 patients survived to discharge (69%), and overall survival was 67% (39 patients) at a median follow-up of 58 days (<1–1441). Cumulative survival was significantly affected by cardiogenic shock vs. ARDS (p = 0.001), veno-arterial and veno-venoarterial vs. veno-venous ECMO (p = 0.001) and after secondary vs. primary transport (p <0.001). The ECMO weaning rate was significantly lower after secondary transfer (22%, two patients, both vaECMO) vs. primary transfer (80%, p = 0.002, 39 patients of which 35 (71%) had vvECMO). CONCLUSIONS: The first results of our ECMO transportation programme show its feasibility, safety and efficacy without on-site implant or on-transport complications or mortality. The favourable early survival may justify the large effort with respect to logistics, costs and manpower. With rising awareness, referring centres may increasingly consider this lifesaving option at an early stage, which may further improve outcomes.

New, optimized, dual-lumen cannula for veno-venous ECMO.

OBJECTIVE: The present study was designed to assess in vivo a new, optimized, virtually wall-less, dual-lumen, bi-caval cannula for veno-venous ECMO in comparison to a commercially available cannula. METHODS: Veno-venous extracorporeal membrane oxygenation (ECMO) was carried out in a bovine study (n=5, bodyweight 75±5kg). Following systemic heparinization, ECMO was established in a trans-jugular fashion through a calibrated 23F orifice, using a new, optimized, virtually wall-less, dual-lumen, bi-caval 24F cannula (Smartcanula LLC, Lausanne, Switzerland) versus a commercially available 23F bi-caval, dual-lumen control cannula (Avalon Elite®, Maquet, Rastatt, Germany) in a veno-venous ECMO setup. Veno-venous ECMO was initiated at 500 revolutions per minute (RPM) and increased by incremental steps of 500 RPM up to 2500 RPM. Catheter outlet pressure, catheter inlet pressure, oxygen saturation and pump flow were recorded at each stage. RESULTS: Mean flow accounted for 0.37±0.04 L/min for wall-less versus 0.29± 0.07 L/min for control at 500 RPM, 0.97±0.12 versus 0.67±0.06 at 1000 RPM, 1.60±0.14 versus 1.16±0.08 at 1500 RPM, 2.31±0.13 versus 1.52±0.13 for 2000 RPM and 3.02±0.5 versus 2.11±0.18 (p<0.004). The mean venous suction required was 19±8 mmHg for wall-less versus 20±3 mmHg for control at 500 RPM, 7±3 versus 9±4 for 1000 RPM, -11±10 versus -12±8 at 1500 RPM, -39±15 versus -49±10 for 2000 RPM and -60±28 versus -94±7 for 2500 RPM. The mean venous injection pressure accounted for 29±7 mmHg for wall-less versus 27±5 mmHg for control at 500 RPM, 50±6 versus 61±7 at 1000 RPM, 89±10 versus 99±17 for 1500 RPM, 142±14 versus 161±9 at 2000 RPM and 211±41 versus 252 ±3 for 2500 RPM. CONCLUSION: Compared to the commercially available control cannula, the new, optimized, virtually wall-less, dual-lumen, bi-caval 24F cannula allows for significantly higher blood flows, requires less suction and results in lower injection pressures in vivo.

Clinical Experience in Minimally Invasive Cardiac Surgery With Virtually Wall-Less Venous Cannulas.

OBJECTIVE: Inadequate peripheral venous drainage during minimally invasive cardiac surgery (MICS) is a challenge and cannot always be solved with increased vacuum or increased centrifugal pump speed. The present study was designed to assess the benefit of virtually wall-less transfemoral venous cannulas during MICS. METHODS: Transfemoral venous cannulation with virtually wall-less cannulas (3/8″ 24F 530-630-mm ST) was performed in 10 consecutive patients (59 ± 10 years, 8 males, 2 females) undergoing MICS for mitral (6), aortic (3), and other (4) procedures (combinations possible). Before transfemoral insertion of wall-less cannulas, a guidewire was positioned in the superior vena cava under echocardiographic control. The wall-less cannula was then fed over the wire and connected to a minimal extracorporeal system. Vacuum assist was used to reach a target flow of 2.4 l/min per m with augmented venous drainage at less than -80 mm Hg. RESULTS: Wall-less venous cannulas measuring either 630 mm (n = 8) in length or 530 mm (n = 2) were successfully implanted in all patients. For a body size of 173 ± 11 cm and a body weight of 78 ± 26 kg, the calculated body surface area was 1.94 ± 0.32 m. As a result, the estimated target flow was 4.66 ± 0.78 l/min, whereas the achieved flow accounted for 4.98 ± 0.69 l/min (107% of target) at a vacuum level of 21.3 ± 16.4 mm Hg. Excellent exposure and "dry" intracardiac surgical field resulted. CONCLUSIONS: The performance of virtually wall-less venous cannulas designed for augmented peripheral venous drainage was tested in MICS and provided excellent flows at minimal vacuum levels, confirming an increased performance over traditional thin wall cannulas. Superior results can be expected for routine use.

Reemergence of Mycobacterium chimaera in Heater-Cooler Units despite Intensified Cleaning and Disinfection Protocol.

Invasive Mycobacterium chimaera infections after open-heart surgery have been reported internationally. These devastating infections result from aerosols generated by contaminated heater-cooler units used with extracorporeal circulation during surgery. Despite intensified cleaning and disinfection, surveillance samples from factory-new units acquired during 2014 grew nontuberculous mycobacteria after a median of 174 days.

Retrograde Autologous Priming as a Safe and Easy Method to Reduce Hemodilution and Transfusion Requirements during Cardiac Surgery.

BACKGROUND: During the last decades many efforts have been made to reduce transfusion requirements and adverse clinical effects during cardiopulmonary bypass (CPB). The minimal extracorporeal circulation (MECC) system and the technique of retrograde autologous priming (RAP) of a conventional CPB circuit have been associated with decreased hemodilution. Our study aimed to compare conventional CPB (cCPB), RAP, and the ROCsafe MECC (Terumo Europe N.V., Leuven, Belgium) system in elective coronary artery bypass patients. PATIENTS AND METHODS: Data were retrospectively collected on three cohorts of 30 adult CPB patients. Patients were operated using cCPB, RAP, and the ROCsafe MECC system. RESULTS: The three groups were comparable in demographic data. The priming volume in the ROCsafe and RAP group was significantly less compared with the conventional priming group (p <0.05). The mean time of extracorporeal circulation and aortic cross-clamp time (p <0.05) were significantly shorter in the ROCsafe group. The levels of hemoglobin (Hb) and hematocrit (Hct) during CPB and postoperatively showed significant differences between the three groups (p < 0.05) and resulted in significantly higher blood transfusion requirements (p < 0.05). Lactate, serum creatinine, troponin, and creatine kinase-myocardial band (CK-MB) levels did not differ significantly among the three groups (p >0.05). There was also no statistically significant difference in ventilation time, intensive care unit (ICU) stay, overall hospital stay, and postoperative complications (p >0.05). CONCLUSION: In conclusion, RAP is compared with cCPB and MECC a safe and low-cost technique in reducing the priming volume of the CPB system, causes less hemodilution, and reduces the need for intra- and postoperative blood transfusion.