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Concept: Extracorporeal membrane oxygenation

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BACKGROUND: Preoperative extracorporeal membrane oxygenation (ECMO) is a risk factor for poor outcome and currently considered a contraindication to lung transplantation. The lung allocation score system was introduced in May 2005 and prioritizes lung allocation to those with the greatest respiratory impairment. The purpose of this study is to determine whether ECMO as a bridge to lung transplantation is an acceptable option to support those in respiratory failure until donor lungs become available in the lung allocation score era. METHOD: A retrospective review of 715 consecutive lung transplants performed between May 2005 and September 2011 was conducted using a prospectively collected institutional registry database. Twenty-four lung transplants (3.4%) were performed in the 31 patients with attempted pretransplant ECMO; 7 patients who received ECMO patients did not survive or were deemed unfit for transplantation. These patients were compared with a control group of 691 patients who did not receive pretransplant ECMO. RESULTS: The duration of pretransplant ECMO was 171 ± 242 hours (median, 91 hours). Venovenous ECMO was used for respiratory failure in 15 patients, whereas venoarterial ECMO was used for circulatory collapse due to pulmonary hypertension in 9 patients. Patients in the retransplant ECMO group were younger (46 ± 15 years vs 57 ± 14 years, P < .01) compared with the control group, with no difference in recipient gender (male/female: 10/14 vs 380/311), donor age (33 ± 14 years vs 36 ± 15 years), or donor gender (male/female: 10/14 vs 352/339). Emphysema was less common (1, 4% vs 260, 38%, P < .01), and cystic fibrosis (5, 21% vs 72, 10%, P = .09), redo lung transplant (3, 13% vs 28, 4%, P = .08), and bronchiectasis (2, 8% vs 6, 1%, P = .03) were more common in the pretransplant ECMO group. Patients in the pretransplant ECMO group had a significantly higher lung allocation score (87 ± 9 vs 44 ± 15, P < .01). All patients in the pretransplant ECMO group underwent double lung transplants on pump (cardiopulmonary bypass/ECMO), and single lung transplants were performed in 171 patients (25%) and pump was used in 243 patients (35%) in the control group. The cardiopulmonary bypass time was longer in the pretransplant ECMO group (277 ± 69 minutes vs 225 ± 89 minutes, P = .02), with no difference in ischemic time (343 ± 93 minutes vs 330 ± 98 minutes, P = .54). Cadaveric lobar lung transplants were performed because of the urgency to overcome size mismatch with an oversized donor more frequently in 25% (n = 6, no mortality with the longest follow-up at 6 years) of patients in the pretransplant ECMO group versus 0.3% (n = 2) of patients in the control group (P < .01). Post-transplant ECMO was used for primary graft dysfunction in 13 patients (54%) in the pretransplant ECMO group and 41 patients (6%) in the control group (P < .01). The median hospital stay was 46 days in the pretransplant ECMO group versus 27 days in the control group (P = .16). The actuarial survivals after lung transplants at 1, 3, 6, 12, and 24 months were 96%, 88%, 83%, 74%, and 74%, respectively, in the pretransplant ECMO group, and 97%, 94%, 90%, 83%, and 74%, respectively, in the control group (P = .787). CONCLUSIONS: Although the incidence of primary graft dysfunction requiring post-transplant ECMO is higher and the hospital stay is longer in patients receiving pretransplant ECMO, the graft survival is good (2-year survival, 74%). ECMO is efficacious as a bridge to lung transplantation with good post-lung transplant outcomes.

Concepts: Pulmonology, Cystic fibrosis, Organ transplant, Pulmonary hypertension, Lung transplantation, Extracorporeal, Extracorporeal membrane oxygenation, Lung allocation score

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Objective:To analyze operative repair, extracorporeal membrane oxygenation (ECMO) and survival rates based on highest pre-ductal oxygen saturation (Pre-O(2)SAT) in a large infant cohort reported to Congenital Diaphragmatic Hernia Study Group Registry between 2000 and 2010.Study Design:Analyzed data included gestational age, birth weight, defect side and size, repair, ECMO use, survival and highest reported PaO(2) and Pre-O(2)SAT in first 24 h of life. We excluded 614 infants due to severe anomaly. Pre-O(2)SAT data were available for 1672 infants.Result:Among infants with highest Pre-O(2)SAT value <85%, survival (24/105=23%) and repair (55/105=52%) rates were significantly decreased compared with infants with higher values. Survival increased to 44% for infants with highest Pre-O(2)SAT<85% who underwent operative repair. Of these, 83% (20/24) required ECMO support compared with 15% (144/961) of survivors with Pre-O(2)SAT>99% (P<0.001). The lowest reported Pre-O(2)SAT with survival was 32% and for survival without ECMO was 52%.Conclusion:A reported highest Pre-O(2)SAT<85% in the first 24 h of life was not uniformly fatal; but survival of infants with Pre-O(2)SAT<85% was associated with high ECMO use and prolonged hospitalization.

Concepts: Pregnancy, Fetus, Life, Obstetrics, Pediatrics, Extracorporeal, Extracorporeal membrane oxygenation, Congenital diaphragmatic hernia

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Rationale: Increasing use of extracorporeal membrane oxygenation (ECMO) for acute respiratory failure may increase resource requirements and hospital costs. Better prediction of survival in these patients may improve resource utilisation, allow risk-adjusted comparison of center-specific outcomes and help clinicians to target patients most likely to benefit from ECMO. Objectives: To create a model for predicting hospital survival at initiation of ECMO for respiratory failure. Methods: Adult patients with severe acute respiratory failure treated by ECMO from 2000 to 2012 were extracted from the Extracorporeal Life Support Organization (ELSO) international registry. Multivariable logistic regression was used to create the Respiratory ECMO Survival Prediction score (RESP-score) using bootstrapping methodology with internal and external validation. Main results: Of the 2355 patients included in the study, 1338 patients (57%) were discharged alive from hospital. The RESP-score was developed using pre-ECMO variables independently associated with hospital survival on logistic regression which included: age, immunocompromised status, duration of mechanical ventilation prior to ECMO, diagnosis, central nervous system dysfunction, acute associated non-pulmonary infection, neuro-muscular blockade agents or nitric oxide use, bicarbonate infusion, cardiac arrest, PaCO2 and peak inspiratory pressure. The ROC curve analysis of the RESP score was c=0.74, 95% Confidence Interval (0.72 - 0.76). External validation, performed on 140 patients, exhibited excellent discrimination (c=0.92 [95%CI 0.89 - 0.97]). Conclusions: The RESP-score is a relevant and validated tool to predict survival for patients receiving ECMO for respiratory failure.

Concepts: Central nervous system, Nervous system, Regression analysis, Intensive care medicine, Prediction, Prediction interval, Extracorporeal, Extracorporeal membrane oxygenation

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The use of extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation was reported for the first time more than three decades ago; nevertheless, its use in lung transplantation was largely abandoned because of poor patient survival and frequent complications. The outcomes of patients bridged to lung transplantation using ECMO have substantially improved in the last 5 years. Recent advances in extracorporeal life support technology now allow patients with end-stage lung disease to be successfully supported for prolonged periods of time, preventing the use of mechanical ventilation and facilitating physical rehabilitation and ambulation while the patients awaits lung transplantation. This review briefly describes the evolution of ECMO use in lung transplantation and summarizes the available technology and current approaches to provide ECMO support.

Concepts: Pulmonology, Medical terms, Patient, Intensive care medicine, Medical equipment, Extracorporeal, Extracorporeal membrane oxygenation, Perfusionist

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We report our experience with the Levitronix CentriMag (Levitronix LLC, Waltham, MA) in the setting of venoarterial extracorporeal membrane oxygenation (ECMO) system support as treatment for postcardiotomy cardiogenic shock. Between January 2007 and August 2011, 14 consecutive adult patients received CentriMag ECMO support after cardiac surgery procedures at our institution. There were nine males (64.3%) and the mean age was 53.1 ± 14.3 years (range: 25-70 years). Cardiac surgery included: n = 6, aortic and/or mitral valve replacement; n = 5, coronary artery bypass grafting (CABG); and n = 3, Bentall procedures. The CentriMag ECMO support was installed centrally in eight patients and peripherally in six. Median duration of support was 5 days (range: 1-55 days). Seven patients were weaned from ECMO (50%), whereas six patients died while on support mainly because of multiple organ failure (42.9%). One patient died on ECMO support after transfer to the referral hub center while waiting for heart transplantation (Htx). Six (42.8%) patients were successfully discharged home. Levitronix CentriMag in ECMO configuration proved to be effective in managing postcardiotomy cardiogenic shock and the results are encouraging. The system was easy to install and manage.

Concepts: Atherosclerosis, Cardiology, Heart, Artery, Coronary circulation, Coronary artery bypass surgery, Mitral valve, Extracorporeal membrane oxygenation

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Extracorporeal life support for acute respiratory failure has increased as a result of technological advancements and promising results from recent studies as compared to historical trials.

Concepts: Intensive care medicine, Extracorporeal membrane oxygenation, Prehistory

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We present a 16-year-old male with severe acute respiratory and renal failure as a result of Goodpasture syndrome, requiring venovenous extracorporeal membrane oxygenation (VV-ECMO) for pulmonary haemorrhage. The patient received no systemic anticoagulation for 25 of 26 ECMO days (20 days consecutively) and suffered no coagulation-related adverse events. The patient had a subtherapeutic anticoagulation profile according to recommended ECMO guidelines during most of this time. The patient made a full recovery without respiratory compromise, ECMO circuit failure, thrombotic events or the need for ongoing haemodialysis.

Concepts: Present, Time, Chronic kidney disease, Nephrology, Intensive care medicine, Glomerulonephritis, Extracorporeal, Extracorporeal membrane oxygenation

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Mechanical ventilation (MV) remains the cornerstone of acute respiratory distress syndrome (ARDS) management. It guarantees sufficient alveolar ventilation, high FiO2 concentration, and high positive end-expiratory pressure levels. However, experimental and clinical studies have accumulated, demonstrating that MV also contributes to the high mortality observed in patients with ARDS by creating ventilator-induced lung injury. Under these circumstances, extracorporeal lung support (ECLS) may be beneficial in two distinct clinical settings: to rescue patients from the high risk for death associated with severe hypoxemia, hypercapnia, or both not responding to maximized conventional MV, and to replace MV and minimize/abolish the harmful effects of ventilator-induced lung injury. High extracorporeal blood flow venovenous extracorporeal membrane oxygenation (ECMO) may therefore rescue the sickest patients with ARDS from the high risk for death associated with severe hypoxemia, hypercapnia, or both not responding to maximized conventional MV. Successful venovenous ECMO treatment in patients with extremely severe H1N1-associated ARDS and positive results of the CESAR trial have led to an exponential use of the technology in recent years. Alternatively, lower-flow extracorporeal CO2 removal devices may be used to reduce the intensity of MV (by reducing Vt from 6 to 3-4 ml/kg) and to minimize or even abolish the harmful effects of ventilator-induced lung injury if used as an alternative to conventional MV in nonintubated, nonsedated, and spontaneously breathing patients. Although conceptually very attractive, the use of ECLS in patients with ARDS remains controversial, and high-quality research is needed to further advance our knowledge in the field.

Concepts: Pulmonology, Pneumonia, Intensive care medicine, Acute respiratory distress syndrome, Mechanical ventilation, Pulmonary contusion, Extracorporeal, Extracorporeal membrane oxygenation

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In patients under extracorporeal membrane oxygenation (ECMO) support requiring renal replacement therapy or plasmapheresis, connecting such extracorporeal therapy device to the ECMO circuit provides many advantages compared with central venous catheterization. However, high pressures of the ECMO circuit limit the usefulness of this technique. We propose a new approach to connect extracorporeal therapy lines to the ECMO circuit. Inlet line is connected to the oxygenator, and outlet line is connected either to the femoral artery antegrade perfusion cannula in case of venoarterial ECMO or to the lateral vent of the return cannula in case of venovenous ECMO. We report the successful management of 21 patients using this connection, with much longer hemofilter average lifetime than previously reported.

Concepts: Cardiopulmonary bypass, Medical equipment, Extracorporeal, Extracorporeal membrane oxygenation

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Extracorporeal membrane oxygenation (ECMO) for cardiopulmonary support of critically ill patients is used frequently in the pediatric population. ECMO is burdened by complications, including thrombosis and hemorrhage. Here we demonstrate the focused location of clots, their histological composition, and the relationship of in situ thrombus to local hemodynamics in ECMO circuits.Pediatric ECMO circuits from Children’s Healthcare of Atlanta, Emory University (Atlanta, GA) were obtained following removal from extracorporeal support over a 2.5-year period (n=50). All clots and material deposited within the circuit were recorded. Location of clot was compared with local hemodynamics.Most clots were adherent to the junctions made by the tubing and connectors, as opposed to being randomly disturbed throughout the circuit tubing (p<0.05). Loose, non-adherent clots were also found at the entry side of oxygenators. The clots co-located directly with zones of low shear rate. Histology revealed a fibrinous composition, consistent with coagulation potentiated by low shear.Centrifugal pump circuits (n=16) had more clots than roller pump (n=34) circuits (p<0.05). In addition, all centrifugal pumps had clots that formed at the top of the pump shaft.The ECMO circuits from our single-center study demonstrate the concentrated location of fibrin clots at low shear zones created by tubing connector junctions (TCJs). Type of pump also influences the frequency of clot formation. Since the mechanism of the majority of ECMO circuit thrombosis is low-shear and fibrin driven, optimization of hemodynamics and anticoagulation regimen may reduce clot formation and bleeding.

Concepts: Blood, Coagulation, Fibrin, Warfarin, Hemostasis, Thrombus, Extracorporeal membrane oxygenation, The Circuit