Extracorporeal Membrane Oxygenation in the Adult

Silicon Micropore-Based Parallel Plate Membrane Oxygenator

Extracorporeal membrane oxygenation (ECMO) is a life support system that circulates the blood through an oxygenating system to temporarily (days to months) support heart or lung function during cardiopulmonary failure until organ recovery or replacement. Currently, the need for high levels of systemic anticoagulation and the risk for bleeding are main drawbacks of ECMO that can be addressed with a redesigned ECMO system. Our lab has developed an approach using microelectromechanical systems (MEMS) fabrication techniques to create novel gas exchange membranes consisting of a rigid silicon micropore membrane (SμM) support structure bonded to a thin film of gas-permeable polydimethylsiloxane (PDMS). This study details the fabrication process to create silicon membranes with highly uniform micropores that have a high level of pattern fidelity. The oxygen transport across these membranes was tested in a simple water-based bench-top set-up as well in a porcine in vivo model. It was determined that the mass transfer coefficient for the system using SµM-PDMS membranes was 3.03 ± 0.42 mL O₂ min^-1 m^-2 cm Hg^-1 with pure water and 1.71 ± 1.03 mL O₂ min^-1 m^-2 cm Hg^-1 with blood. An analytic model to predict gas transport was developed using data from the bench-top experiments and validated with in vivo testing. This was a proof of concept study showing adequate oxygen transport across a parallel plate SµM-PDMS membrane when used as a membrane oxygenator. This work establishes the tools and the equipoise to develop future generations of silicon micropore membrane oxygenators.

Bleeding Complications Associated With Percutaneous Tracheostomy Insertion in Patients Supported With Venovenous Extracorporeal Membrane Oxygen Support: A 10-Year Institutional Experience

OBJECTIVES

To evaluate the bleeding complications associated with percutaneous tracheostomy while a patient is receiving venovenous extracorporeal membrane oxygen (VV ECMO) support.

DESIGN

Retrospective, observational analysis.

SETTING

Single-center, tertiary, academic institution.

PARTICIPANTS

All consecutive patients on VV ECMO over a 10 year-period undergoing percutaneous tracheostomy.

INTERVENTIONS

Percutaneous tracheostomy.

MEASUREMENTS AND MAIN RESULTS

Fifty percutaneous tracheostomies were performed in patients requiring VV ECMO support over the 10-year period. The authors observed a 40% incidence of bleeding, with 32% of these incidences characterized as minor (self-limiting, localized stomal ooze) and 8% characterized as significant (necessitating surgical control and frequent packing or accompanied by a decrease in hemoglobin >20%).

CONCLUSIONS

Bleeding is associated with percutaneous tracheostomy and is self-limiting in the majority of patients.

Pre-ECMO coagulopathy does not increase the occurrence of hemorrhage during extracorporeal support

INTRODUCTION AND METHODS

Observational retrospective cohort study to evaluate the association between precannulation coagulopathy and the occurrence of hemorrhage during extracorporeal membrane oxygenation (ECMO) in neonatal and pediatric patients at a tertiary children's hospital.

RESULTS

Of 241 patients supported with ECMO between January 2009 and December 2014, 175 (72.6%) had precannulation coagulation laboratory data and were included in the study. Of the eligible patients, 84 (48%) were identified as coagulopathic and 91 (52%) were noncoagulopathic. In the coagulopathic group, sepsis (27.3%) was the most common diagnosis leading to ECMO. Over half of the patients in both groups (55.9% of the coagulopathic and 52.7% of the noncoagulopathic group) developed hemorrhagic complications during ECMO support. The most frequent bleeding sites for both groups were the cannulation site (24%), the chest tube site (17%), and intracranial (10%). Pre-ECMO coagulopathy was not associated with higher incidence of hemorrhage during extracorporeal support (p = 0.76).

CONCLUSIONS

Pre-ECMO coagulopathy was frequent in our cohort but did not increase the occurrence of hemorrhage during extracorporeal support. Although the identification of factors associated with hemorrhage is key to safely managing ECMO anticoagulation, the implication of precannulation coagulopathy seems to be minimal.

Extracorporeal Life Support: Four Decades and Counting

Extracorporeal membrane oxygenation (ECMO) or extracorporeal life support (ECLS) is a form of heart lung bypass that is used to support neonates, pediatrics, and adult patients with cardiorespiratory failure for days or weeks till organ recovery or transplantation. Venoarterial (VA) and venovenous (VV) ECLS are the most common modes of support. ECLS circuit components and monitoring have been evolving over the last 40 years. The technology is safer, simpler, and more durable with fewer complications. The use of neonatal respiratory ECLS use has been declining over the last two decades, while adult respiratory ECLS is growing especially since the H1N1 influenza pandemic in 2009. This review provides an overview of ECLS evolution over the last four decades, its use in neonatal, pediatric and adults, description of basic principles, circuit components, complications, and outcomes as well as a quick look into the future.

Anticoagulation practices and the prevalence of major bleeding, thromboembolic events, and mortality in venoarterial extracorporeal membrane oxygenation: A systematic review and meta-analysis

PURPOSE

The purpose was to evaluate the safety of anticoagulation in venoarterial extracorporeal membrane oxygenation (VA-ECMO).

DESIGN

We performed a systematic review and meta-analysis using multiple electronic databases. Studies were from 1977 to September 27, 2016. We evaluated the effect of anticoagulation in VA-ECMO on outcomes including major bleeding, thromboembolic events, and in-hospital mortality using a random effects model meta-analysis.

RESULTS

Twenty-six studies (1496 patients) were included. Ten studies only had patients with postcardiotomy shock, 4 studies only included extracorporeal cardiopulmonary resuscitation patients, and 10 studies had a mixture of patients. Most studies (n=17) were low quality with a Newcastle-Ottawa Scale score ≤5. The summary prevalence of major bleeding was 27% (95% confidence interval [CI], 18%-35%), with considerable between-study heterogeneity (I²=91%). Major bleeding requiring reoperation was the most common bleeding event. The summary prevalence of thromboembolic events was 8% (95% CI, 4%-13%; I²=83%). Limb ischemia, circuit-related clotting, and stroke were the most commonly reported events. The summary prevalence for in-hospital mortality was 59% (95% CI, 52%-67%; I²=78%).

CONCLUSIONS

The optimal targets and strategies for anticoagulation in VA-ECMO are unclear. Evaluation of major bleeding and thromboembolic events is limited by study quality and between-study heterogeneity. Clinical trials are needed to investigate the optimal anticoagulation strategy.

Considerations for analgosedation and antithrombotic management during extracorporeal life support

Despite the immense growth in extracorporeal life support (ECLS) technology and experience, opportunity remains to better characterize the pharmacotherapeutic considerations during ECLS. Analgosedation can be particularly challenging in the ECLS population due to in drug-circuit interactions that may lead to decreased systemic concentrations and pharmacodynamic effect. ECLS also requires the use of antithrombotic agents to mitigate the prothrombotic state created by the artificial surface in the ECLS circuit. There are a number of coagulation monitoring tests available. However, optimal monitoring and management in ECLS has not been established. Heparin continues to be the anticoagulant of choice for most ECLS centers, however, there is growing interest in the use of parenteral direct thrombin inhibitors (DTI) in this population. Advances in understanding pharmacotherapeutic management have not kept up with the technological advances in this population. More investigation is warranted to gain a greater understanding of the pharmacotherapeutic implications, facilitate standardized evidence-based practices, and improve patient centered outcomes.

Elective Use of Veno-venous Extracorporeal Membrane Oxygenation and High-flow Nasal Oxygen for Resection of Subtotal Malignant Distal Airway Obstruction

We describe the use of peripheral veno-venous extracorporeal membrane oxygenation (VV ECMO) and high-flow nasal oxygen as procedural support in a patient undergoing debulking of a malignant tumour of the lower airway. Due to the significant risk of complete airway obstruction upon induction of anaesthesia, ECMO was established while the patient was awake, and was maintained without systemic anticoagulation to minimise the risk of intraoperative bleeding. This case illustrates that ECMO support with high-flow nasal oxygen can be considered as part of the algorithm for airway management during surgery for subtotal lower airway obstruction, as it may be the only viable option for maintaining adequate gas exchange.

State of the Art: Bridging to lung transplantation using artificial organ support technologies

Lung transplantation increasingly is being performed in recipients of higher risk and acuity. A subset of these patients has severely abnormal gas exchange and/or right ventricular dysfunction, such that artificial organ support strategies are required to bridge patients to lung transplantation. We review the rationales and currently used and potential strategies for bridging to lung transplantation and characterize bridging outcomes. Based on physiologic reasoning and a study of the existing literature, we provide a working strategy for bridging to lung transplantation.

Extracorporeal Membrane Oxygenation for Hemodynamic Support of Ventricular Tachycardia Ablation

Background—

We report the experience in a cohort of consecutive patients receiving extracorporeal membrane oxygenation during catheter ablation of unstable ventricular tachycardia (VT) at our center.

Methods and Results—

From 2010 to 2015, extracorporeal membrane oxygenation was initiated in 64 patients (average age: 63±15 years; left ventricular ejection fraction in 27±9%; cardiogenic shock in 23%, and electrical storm in 62% of patients) undergoing 74 unstable VT catheter ablation procedures. At least one VT was terminated in 81% of procedures with baseline inducible VT, and VT noninducibility was achieved in 69%. Acute heart failure occurred in 5 patients: 3 underwent emergency heart transplantation, 1 had left ventricular assist device (LVAD) implantation, and 1 patient eventually died because of subsequent mesenteric ischemia. All other patients were discharged alive. After a median follow-up of 21 months (13–28 months), VT recurrence was 33%; overall survival was 56 out of 64 patients (88%). Extracorporeal membrane oxygenation–supported ablation was the bridge to LVAD in 6.9% and to heart transplantation in 3.5% of patients. VT recurrence was related to ablation success (after 180 days of follow up: 19% when VT was noninducible, 42% if nonclinical VT was inducible, 75% when clinical VT was inducible, and 75% in untested patients, P <0.001). Incidence of all-cause death, heart transplantation, and LVAD was independently related to ablation outcome (at 180 days of follow-up: 9% when noninducibility was achieved, 50% in case of inducible VT, and 75% in untested patients, P <0.001). At multivariable analyses, noninducibility (hazard ratio 0.198; P =0.001) and left ventricular ejection fraction (hazard ratio 0.916; P =0.008) correlated with all-cause death, LVAD, and heart transplantation.

Conclusions—

Ablation of unstable VTs can be safely supported by extracorporeal membrane oxygenation, which allows rhythm stabilization with low procedure mortality, bridging decompensated patients to permanent LVAD or heart transplantation. Successful ablation is associated with better outcomes than unsuccessful ablation.

The inflammatory response to extracorporeal membrane oxygenation (ECMO): a review of the pathophysiology

Extracorporeal membrane oxygenation (ECMO) is a technology capable of providing short-term mechanical support to the heart, lungs or both. Over the last decade, the number of centres offering ECMO has grown rapidly. At the same time, the indications for its use have also been broadened. In part, this trend has been supported by advances in circuit design and in cannulation techniques. Despite the widespread adoption of extracorporeal life support techniques, the use of ECMO remains associated with significant morbidity and mortality. A complication witnessed during ECMO is the inflammatory response to extracorporeal circulation. This reaction shares similarities with the systemic inflammatory response syndrome (SIRS) and has been well-documented in relation to cardiopulmonary bypass. The exposure of a patient’s blood to the non-endothelialised surface of the ECMO circuit results in the widespread activation of the innate immune system; if unchecked this may result in inflammation and organ injury. Here, we review the pathophysiology of the inflammatory response to ECMO, highlighting the complex interactions between arms of the innate immune response, the endothelium and coagulation. An understanding of the processes involved may guide the design of therapies and strategies aimed at ameliorating inflammation during ECMO. Likewise, an appreciation of the potentially deleterious inflammatory effects of ECMO may assist those weighing the risks and benefits of therapy.

Current Limitations of the Assessment of Haemostasis in Adult Extracorporeal Membrane Oxygenation Patients and the Role of Point-of-Care Testing

Haemostatic perturbations are commonly seen in extracorporeal membrane oxygenation (ECMO) patients and remain a clinical challenge, contributing significantly to morbidity and mortality. The approach to anticoagulation monitoring and the management of bleeding varies considerably across ECMO centres. Routine laboratory tests have their limitations in terms of turnaround time and specificity of information provided. Newer point-of-care testing (POCT) for coagulation may overcome these issues, as it provides information about the entire coagulation pathway from clot initiation to lysis. It is also possible to obtain qualitative information on platelet function from these tests. Furthermore, the ability to incorporate these results into a goal-directed algorithm to manage bleeding with targeted transfusion strategies appears particularly attractive and cost effective. Further studies are required to evaluate the utility of POCT to optimise bleeding and anticoagulation management in these complex patients.

Thromboelastometry guided fibrinogen replacement therapy in cardiac surgery: a retrospective observational study

This retrospective, observational study compared the impact of a point-of-care rotational thromboelastometry (ROTEM^®) method versus conventional bleeding management in terms of postoperative (24-h) blood loss, intraoperative and postoperative (24-h) transfusion requirement and length of stay in the postoperative intensive care unit (ICU) in patients undergoing cardiac surgery. Forty consecutive patients undergoing cardiac surgery under ROTEM^®-guided hemostatic management were enrolled; the control population included 40 selected patients undergoing similar interventions without ROTEM^® monitoring. Significantly more patients in the thromboelastometry group versus the control group received fibrinogen (45 vs 10 %; p < 0.0001), while fewer received a transfusion (40 vs 72.5 %; p < 0.0033). Compared with control group patients, those in the thromboelastometry group had less postoperative bleeding (285 vs 393 mL; p < 0.0001), a shorter time from cardiopulmonary bypass discontinuation to skin suture (79.3 vs 92.6 min; p = 0.0043) and a shorter stay in the ICU (43.7 vs 52.5 h; p = 0.0002). In our preliminary experience, ROTEM^®-guided bleeding management was superior to conventional management of bleeding in patients undergoing complex cardiac surgery with cardiopulmonary bypass in terms of reduced postoperative blood loss, transfusion requirement, and length of ICU stay.

Adult venovenous extracorporeal membrane oxygenation for severe respiratory failure: Current status and future perspectives

Extracorporeal membrane oxygenation (ECMO) for severe acute respiratory failure was proposed more than 40 years ago. Despite the publication of the ARDSNet study and adoption of lung protective ventilation, the mortality for acute respiratory failure due to acute respiratory distress syndrome has continued to remain high. This technology has evolved over the past couple of decades and has been noted to be safe and successful, especially during the worldwide H1N1 influenza pandemic with good survival rates. The primary indications for ECMO in acute respiratory failure include severe refractory hypoxemic and hypercarbic respiratory failure in spite of maximum lung protective ventilatory support. Various triage criteria have been described and published. Contraindications exist when application of ECMO may be futile or technically impossible. Knowledge and appreciation of the circuit, cannulae, and the physiology of gas exchange with ECMO are necessary to ensure lung rest, efficiency of oxygenation, and ventilation as well as troubleshooting problems. Anticoagulation is a major concern with ECMO, and the evidence is evolving with respect to diagnostic testing and use of anticoagulants. Clinical management of the patient includes comprehensive critical care addressing sedation and neurologic issues, ensuring lung recruitment, diuresis, early enteral nutrition, treatment and surveillance of infections, and multisystem organ support. Newer technology that delinks oxygenation and ventilation by extracorporeal carbon dioxide removal may lead to ultra-lung protective ventilation, avoidance of endotracheal intubation in some situations, and ambulatory therapies as a bridge to lung transplantation. Risks, complications, and long-term outcomes and resources need to be considered and weighed in before widespread application. Ethical challenges are a reality and a multidisciplinary approach that should be adopted for every case in consideration.

Antithrombin Administration During Intravenous Heparin Anticoagulation in the Intensive Care Unit: A Single-Center Matched Retrospective Cohort Study

Unfractionated heparin (UFH) is a frequently utilized indirect anticoagulant that induces therapeutic effect by enhancing antithrombin (AT)-mediated procoagulant enzyme inhibition. In suspected heparin resistance (HR) during cardiopulmonary bypass, AT activity may be decreased and AT supplementation helps restore UFH responsiveness. The benefit of AT supplementation in HR over longer durations of UFH therapy is unclear. The objective of this study was to describe and evaluate the use of AT III concentrate in the intensive care units (ICUs) at our institution for improving UFH therapy response over 72 hours. A total of 44 critically ill patients were included in the analysis-22 patients received at least 1 dose of AT and 22 patients received no AT. Thirty (68.2%) of the 44 patients were receiving mechanical circulatory support. Baseline characteristics were similar between groups. The average AT activity prior to AT supplementation was 57.9% in the treatment group, and the median cumulative dose of AT was 786.5 U (9.26 U/kg) per patient. There were no significant differences observed in proportion of time spent in therapeutic range (31.9% vs 35.2%, P = .65), time to therapeutic goal (16.5 vs 15.5 hours, P = .97), or patients who experienced a bleeding event (5 vs 5, P = .99) between groups. In conclusion, AT supplementation had minimal impact on anticoagulant response in this cohort of ICU patients with mild to moderate HR receiving a prolonged UFH infusion. Additional research is needed to define AT activity targets and to standardize AT supplementation practices in patients receiving prolonged heparin infusion.

Pediatric Patient Blood Management Programs: Not Just Transfusing Little Adults

Red blood cell transfusions are a common life-saving intervention for neonates and children with anemia, but transfusion decisions, indications, and doses in neonates and children are different from those of adults. Patient blood management (PBM) programs are designed to assist clinicians with appropriately transfusing patients. Although PBM programs are well recognized and appreciated in the adult setting, they are quite far from standard of care in the pediatric patient population. Adult PBM standards cannot be uniformly applied to children, and there currently is significant variation in transfusion practices. Because transfusing unnecessarily can expose children to increased risk without benefit, it is important to design PBM programs to standardize transfusion decisions. This article assesses the key elements necessary for a successful pediatric PBM program, systematically explores various possible pediatric specific blood conservation strategies and the current available literature supporting them, and outlines the gaps in the evidence suggesting need for further/improved research. Pediatric PBM programs are critically important initiatives that not only involve a cooperative effort between pediatric surgery, anesthesia, perfusion, critical care, and transfusion medicine services but also need operational support from administration, clinical leadership, finance, and the hospital information technology personnel. These programs also expand the scope for high-quality collaborative research. A key component of pediatric PBM programs is monitoring pediatric blood utilization and assessing adherence to transfusion guidelines. Data suggest that restrictive transfusion strategies should be used for neonates and children similar to adults, but further research is needed to assess the best oxygenation requirements, hemoglobin threshold, and transfusion strategy for patients with active bleeding, hemodynamic instability, unstable cardiac disease, and cyanotic cardiac disease. Perioperative blood management strategies include minimizing blood draws, restricting transfusions, intraoperative cell salvage, acute normovolemic hemodilution, antifibrinolytic agents, and using point-of-care tests to guide transfusion decisions. However, further research is needed for the use of intravenous iron, erythropoiesis-stimulating agents, and possible use of whole blood and pathogen inactivation. There are numerous areas where newly formed collaborations could be used to investigate pediatric transfusion, and these studies would provide critical data to support vital pediatric PBM programs to optimize neonatal and pediatric care.

Significantly reduced adsorption and activation of blood components in a membrane oxygenator system coated with crosslinkable zwitterionic copolymer

A crosslinkable zwitterionic copolymer PMBT was coated onto the surfaces of polypropylene hollow fiber membrane (PP-HFM) oxygenator and its connecting tubes. The PMBT copolymer coating on the oxygenator circuit formed a cell outer membrane mimetic surface with excellent stability. The hemocompatibility of the PMBT copolymer coated PP-HFM oxygenator circuit was evaluated by animal extracorporeal circulation. The concentrations of clotting components fibrinogen and platelet in the blood were almost unchanged during the circulation through the PMBT copolymer coated oxygenator circuits. By contrast, the concentrations of fibrinogen and platelet were significantly reduced to 52% and 56% respectively in the uncoated oxygenator group due to adsorption and thrombogenesis of the blood during 2h circulation. Moreover, concentration of activation marker beta-thromboglobulin for platelet in the blood was remarkably lower in the PMBT group than the uncoated control group (p<0.01). All the results strongly supported that the hemocompatibility of the PP-HFM oxygenator circuit could be improved significantly by coating a stable and densely assembled zwitterionic polymer film. This simple, stable and highly effective cell membrane mimetic coating strategy may be applicable in developing advanced oxygenator systems and other artificial organs.

STATEMENT OF SIGNIFICANCE

Although a number of studies have reported the fabrication of zwitterionic phosphorylcholine coated oxygenators to resist the adsorption and activation of blood components and eliminate heparin-induced thrombocytopenia, none of them have fabricated stable and densely assembled film, especially with crosslinkable amphiphilic random copolymer described in our manuscript. The novel features of our work include.

The occurrence of pressure damage in the oral cavity caused by endotracheal tubes

The aim of this observational study was to investigate the occurrence of pressure damage caused by endotracheal tubes (ETT) when the tube is repositioned from one corner of the mouth to the other every third day. For the assessment of oral condition and the eventual damage caused by ETT, a modified version of the Oral Assessment Guide (OAG) was used. The oral condition was assessed once per day in all adult patients who were orally intubated with a tube for over 24 hours. Thirty-eight patients were included in the study. Most patients ( n = 33, 86.8%) had no pressure damage. Five patients (13.2%) had pressure damage on the oral mucosa and lip caused by endotracheal tubes. The group with damage to the oral mucosa was treated with noradrenaline, had bleeding problems and clotting disorders and had significantly more intubated and study days. The assessment of the oral mucosa according to the OAG reflected the worsening oral condition in the group with pressure damage. Endotracheal tubes may need to be repositioned more often than every third day to avoid pressure damage in patients with a high risk of complications, and individually tailored care may need to be implemented.

ECMO Rescue Therapy in Diffuse Alveolar Haemorrhage: A Case Report with Review of Literature

Extracorporeal Membrane Oxygenation (ECMO) has evolved as a treatment option for patients having potentially reversible severe respiratory failure who are deteriorating on conventional ventilation. During ECMO, systemic anticoagulation is needed to maintain patency of the circuit. Therefore, ongoing haemorrhage remains a relative contra-indication to ECMO as it can further increase the bleeding. There is only limited evidence available for the use of ECMO in patients with alveolar haemorrhage. Most of these patients did not receive any anticoagulation during ECMO. We describe our experience with a patient who received intravenous anticoagulation during ECMO for refractory hypoxemic respiratory failure due to Diffuse Alveolar Haemorrhage (DAH) associated with Granulomatosis polyangitis (Wegner's GPA). ECMO sustained life by maintaining gas exchange support and provided the time for the immunotherapy to be effective. We report the successful use of anticoagulation during ECMO in a patient with DAH.

Extracorporeal Membrane Oxygenation-What the Nephrologist Needs to Know

Extracorporeal membrane oxygenation (ECMO) use in adults is rapidly increasing in its use for both cardiac and respiratory failure. ECMO exists in 2 primary configurations: veno-venous ECMO, used in the setting of isolated respiratory failure, and veno-arterial ECMO, which can be used in respiratory failure but is mandatory in the setting of cardiac failure. Acute kidney injury occurs frequently in patients on ECMO, and renal replacement therapy is often required. Continuous forms of renal replacement therapy predominate, but there is a high degree of variation in clinical practice among ECMO centers internationally. No consensus exists regarding the optimal technique, but the use of continuous renal replacement machines has been shown to be safe and effective in patients on ECMO. An understanding of the basic principles and functionality of ECMO is important for both acid-base and fluid management in the intensive care unit.

Venovenous extracorporeal membrane oxygenation for acute respiratory failure : A clinical review from an international group of experts

Despite expensive life-sustaining interventions delivered in the ICU, mortality and morbidity in patients with acute respiratory failure (ARF) remain unacceptably high. Extracorporeal membrane oxygenation (ECMO) has emerged as a promising intervention that may provide more efficacious supportive care to these patients. Improvements in technology have made ECMO safer and easier to use, allowing for the potential of more widespread application in patients with ARF. A greater appreciation of the complications associated with the placement of an artificial airway and mechanical ventilation has led clinicians and researchers to seek viable alternatives to providing supportive care in these patients. Thus, this review will summarize the current knowledge regarding the use of venovenous (VV)-ECMO for ARF and describe some of the recent controversies in the field, such as mechanical ventilation, anticoagulation and transfusion therapy, and ethical concerns in patients supported with VV-ECMO.

[A case of adenovirus infection complicated by gram-negative polymicrobial sepsis: A clinical and morphological observation]

Among respiratory infections, adenovirus infection (ADVI), in the presence of which there may be severe pneumonia that frequently results in a fatal outcome, occupies particular attention. ADVI in patients without immunodeficiency is usually mild and shows a limited extent of injury. At the same time the disease in immunocompromised individuals may be severe, presenting with viremia, evolving sepsis, and high death rates. The paper gives a characteristic example of severe ADVI and its fatal outcome.

Predicting Transfusion Requirements During Extracorporeal Membrane Oxygenation

OBJECTIVE

Patients requiring extracorporeal membrane oxygenation (ECMO) have a well-known bleeding risk and the potential for experiencing possibly fatal thromboembolic complications. Risk factors and predictors of transfusion requirements during ECMO support remain uncertain. The authors hypothesized that compromised organ function immediately before ECMO support will influence transfusion requirements.

DESIGN

A prospective observational study.

SETTING

A tertiary, single-institutional university hospital.

PARTICIPANTS

The study included 40 adult patients requiring ECMO for intractable cardiac and respiratory failure between July 2010 and December 2012. Blood samples were taken before initiation of ECMO (baseline), after 24 and 48 hours on ECMO, and 24 hours after termination of ECMO.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Independent of veno-arterial or veno-venous support, 26% of patients required≥2 packed red blood cells per day (PRBC/d) and 74% of patients required<2 PRBC/d during ECMO. Requirements of≥2 PRBC/d during ECMO support were associated with higher creatinine levels and lower prothrombin times (PT, %) at baseline and with impaired platelet function after 24 hours on ECMO. Platelet function, activated by thrombin receptor-activating peptide stimulation, decreased by 30% to 40% over time on ECMO. Receiver operating characteristic curve analysis showed cut-off values for creatinine of 1.49 mg/dL (sensitivity 70%, specificity 70%; area under the curve [AUC] 0.76, 95% confidence interval [CI] 0.58-0.94), for PT of 48% (sensitivity 80%, specificity 59%; AUC 0.69, 95% CI 0.50-0.87), and for thrombin receptor-activating peptide (TRAP) 32 U (sensitivity 90%, specificity 68%; AUC 0.76, 95% CI 0.59-0.93).

CONCLUSIONS

The results of this study demonstrated that increased creatinine levels and lower PT before ECMO and secondary impaired platelet function significantly increased transfusion requirement.

Discordance between ROTEM® clotting time and conventional tests during unfractionated heparin–based anticoagulation in intensive care patients on extracorporeal membrane oxygenation

We hypothesised that ROTEM® (Basel, Switzerland) INTEM® (ROTEM, Basel, Switzerland) clotting time (CT) would have good agreement with activated partial thromboplastin time (aPTT) in determining whether a dose adjustment should be made to the unfractionated heparin (UFH) infusion in patients on extracorporeal membrane oxygenation. All patients treated with extracorporeal membrane oxygenation over a five-year period were included for data analysis. Retrospective analysis was performed of prospectively collected data points, wherein aPTT, activated CT and ROTEM was performed simultaneously to monitor UFH–based anticoagulation. Two hundred data points were available for analysis. Turnaround time was shortest for activated CT followed by ROTEM and aPTT. Despite achieving therapeutic aPTT targets, the majority (>50%) of INTEM CT results were within normal limits. The aPTT and INTEM CT results correlated weakly (r=0.31, 95% confidence interval [0.17, 0.43]) and there was no agreement between the directional changes of aPTT and INTEM CT results on successive days (χ2 = 2.33, P=0.17). Due to relative insensitivity, INTEM CT–guided UFH titration was estimated to result in a 289% increase in incidence of up-titration, over aPTT–guided titration. The INTEM CT results (r=0.36, 95% confidence interval [0.23, 0.48]) correlated weakly with UFH infusion rates. The UFH infusion rate only explained 13% variability in INTEM CT values. While haemorrhagic complications were frequent, no major clotting complications were encountered. Our results demonstrated that aPTT and INTEM CT do not provide equivalent information to guide UFH infusion rate titration during extracorporeal membrane oxygenation. Our study suggests caution regarding the use of ROTEM for guiding UFH–based anticoagulation as it may lead to excessive UFH exposure.

Safe anticoagulation when heart and lungs are "on vacation"

Circulation and oxygenation of blood outside the body is commonly required during complex surgical interventions involving coronary pulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO). Both CPB and ECMO are life-supporting procedures utilizing a heart-lung machine, which subjects the blood to unphysiological conditions, potentially promoting undesirable blood coagulation. Traditionally, thrombotic complications from CPB and ECMO are resolved by heparin, an inexpensive broad spectrum anticoagulant that prevents blood clotting, but often results in bleeding. Despite hemostatic support therapy and constant monitoring, the lives of patients undergoing CPB and ECMO are often threatened by uncontrolled bleeding. There is an urgent need for novel strategies which provide safe anti-coagulation alternatives during CPB and ECMO procedures. Several non-traditional approaches, including nitric oxide donors as well as various protease and contact activation inhibitors, have been investigated and shown some success. More recently, Larsson et al. isolated a recombinant fully human (3F7) antibody inhibiting Factor XIIa. The antibody was shown to be both an efficacious and safe alternative to heparin. Below we will examine this study in more detail and offer considerations for translation of this novel concept to the clinic.

Results of extracorporeal life support implementation in routine clinical practice: single center experience

Aim

To describe our experience in the clinical application of extracorporeal life support (ECLS) and analyze whether ECLS leads to acceptable clinical outcomes in patients with cardiac failure.

Methods

Data from clinical database of University Hospital Center Zagreb, Croatia, on 75 patients undergoing ECLS support from 2009 to 2014 due to cardiac failure were retrospectively analyzed. Outcomes were defined as procedural and clinical outcomes. ECLS as a primary procedure and ECLS as a postcardiotomy procedure due to inability to wean from cardiopulmonary bypass were analyzed.

Results

ECLS was used in 75 adult patients, and in 24 (32%) of those procedural success was noted. ECLS was implemented as a primary procedure in 36 patients and as a postcardiotomy procedure in 39 patients. Nine out of 39 (23.08%) patients had postcardiotomy ECLS after heart transplantation. Bleeding complications occurred in 30 (40%) patients, both in primary (11/36 patients) and postcardiotomy group (19/39 patients). ECLS was established by peripheral approach in 46 patients and by central cannulation in 27 patients. In 2 patients, combined cannulation was performed, with an inflow cannula placed into the right atrium and an outflow cannula placed into the femoral artery. Eleven patients treated with peripheral approach had ischemic complications.

Conclusion

ECLS is a useful tool in the treatment of patients with refractory cardiac failure and its results are encouraging in patients who otherwise have an unfavorable prognosis.

Identification of acquired coagulation disorders and effects of target-controlled coagulation factor substitution on the incidence and severity of spontaneous intracranial bleeding during veno-venous ECMO therapy

Introduction:

Intracranial haemorrhage is a redoubtable complication during extracorporeal membrane oxygenation (ECMO) therapy. The underlying mechanisms of haemorrhagic diathesis are still not completely understood. This study was performed to evaluate a coagulation protocol for the regular analysis of acquired coagulation disorders and the systematic substitution of coagulation factors to reach predefined target values. We hypothesised that using this strategy would lead to the identification of acquired bleeding disorders which cannot be monitored with standard coagulation tests and that substitution of the respective factors in a target-controlled approach could have an impact on the incidence and severity of intracranial haemorrhage.

Methods:

A protocol for the analysis of acquired coagulation disorders and the subsequent administration of associated factor concentrates was introduced. Previously, coagulation management was mainly based on clinical bleeding signs as the trigger for the administration of blood products. In this investigation, nineteen consecutive patients before (control group) and twenty consecutive patients after the implementation of the protocol (intervention group) have been included in the study.

Results:

Eighty-eight percent of the patients developed factor XIII deficiency, 79% acquired von Willebrand syndrome, 40% fibrinogen deficiency and 54% of the patients showed a decline in platelet count >20% within the first 24 hours of ECMO therapy. In 6 out of 19 (31%) patients in the control group and in 2 patients out of 20 (10%) in the intervention group, intracranial haemorrhage was detected. Whilst 5 of 6 patients in the control group died because of fatal bleeding, both of the patients in the intervention group recovered with a favourable neurologic outcome.

Conclusions:

Veno-venous ECMO therapy leads to thrombocytopenia, factor XIII and fibrinogen deficiency as well as acquired von Willebrand syndrome. The implementation of a coagulation protocol including a standardized determination and target-controlled substitution of coagulation factors may have a beneficial impact on the incidence and severity of intracranial haemorrhage.

Hollow fiber membrane modification with functional zwitterionic macromolecules for improved thromboresistance in artificial lungs

Respiratory assist devices seek optimized performance in terms of gas transfer efficiency and thromboresistance to minimize device size and reduce complications associated with inadequate blood biocompatibility. The exchange of gas with blood occurs at the surface of the hollow fiber membranes (HFMs) used in these devices. In this study, three zwitterionic macromolecules were attached to HFM surfaces to putatively improve thromboresistance: (1) carboxyl-functionalized zwitterionic phosphorylcholine (PC) and (2) sulfobetaine (SB) macromolecules (mPC or mSB-COOH) prepared by a simple thiol-ene radical polymerization and (3) a low-molecular weight sulfobetaine (SB)-co-methacrylic acid (MA) block copolymer (SBMAb-COOH) prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. Each macromolecule type was covalently immobilized on an aminated commercial HFM (Celg-A) by a condensation reaction, and HFM surface composition changes were analyzed by X-ray photoelectron spectroscopy. Thrombotic deposition on the HFMs was investigated after contact with ovine blood in vitro. The removal of CO2 by the HFMs was also evaluated using a model respiratory assistance device. The HFMs conjugated with zwitterionic macromolecules (Celg-mPC, Celg-mSB, and Celg-SBMAb) showed expected increases in phosphorus or sulfur surface content. Celg-mPC and Celg-SBMAb experienced rates of platelet deposition significantly lower than those of unmodified (Celg-A, >95% reduction) and heparin-coated (>88% reduction) control HFMs. Smaller reductions were seen with Celg-mSB. The CO2 removal rate for Celg-SBMAb HFMs remained comparable to that of Celg-A. In contrast, the rate of removal of CO2 for heparin-coated HFMs was significantly reduced. The results demonstrate a promising approach to modifying HFMs using zwitterionic macromolecules for artificial lung devices with improved thromboresistance without degradation of gas transfer.

Incidence of Platelet Dysfunction by Thromboelastography-Platelet Mapping in Children Supported with ECMO: A Pilot Retrospective Study

BACKGROUND

Bleeding complications are common and decrease the odds of survival in children supported with extracorporeal membrane oxygenation (ECMO). The role of platelet dysfunction on ECMO-induced coagulopathy and resultant bleeding complications is not well understood. The primary objective of this pilot study was to determine the incidence and magnitude of platelet dysfunction according to thromboelastography (TEG(®))-platelet mapping (PM) testing.

METHODS

Retrospective chart review of children <18 years old who required ECMO at a tertiary level hospital. We collected TEG(®)-PM and conventional coagulation tests data. We also collected demographic, medications, blood products administered, and clinical outcome data. We defined severe platelet dysfunction as <50% aggregation in response to an agonist.

RESULTS

We identified 24 out of 46 children on ECMO, who had TEG(®)-PM performed during the study period. We found the incidence of severe bleeding was 42% and mortality was 54% in our study cohort. In all samples measured, severe qualitative platelet dysfunction was more common for adenosine diphosphate (ADP)-mediated aggregation (92%) compared to arachidonic acid (AA)-mediated aggregation (75%) (p = 0.001). Also, ADP-mediated percent of platelet aggregation was significant lower than AA-mediated platelet aggregation [15% (interquartile range, IQR 2.8-48) vs. 49% (IQR 22-82.5), p < 0.001]. There was no difference in kaolin-activated heparinase TEG(®) parameters between the bleeding group and the non-bleeding group. Only absolute platelet count and TEG(®)-PM had increased predictive value on receiver operating characteristics analyses for severe bleeding and mortality compared to activated clotting time.

CONCLUSION

We found frequent and severe qualitative platelet dysfunction on TEG(®)-PM testing in children on ECMO. Larger studies are needed to determine if the assessment of qualitative platelet function by TEG(®)-PM can improve prediction of bleeding complications for children on ECMO.

Extracorporeal membrane oxygenation-hemostatic complications

The use of extracorporeal membrane oxygenation (ECMO) support for cardiac and respiratory failure has increased in recent years. Improvements in ECMO oxygenator and pump technologies have aided this increase in utilization. Additionally, reports of successful outcomes in supporting patients with respiratory failure during the 2009 H1N1 pandemic and reports of ECMO during cardiopulmonary resuscitation have led to increased uptake of ECMO. Patients requiring ECMO are a heterogenous group of critically ill patients with cardiac and respiratory failure. Bleeding and thrombotic complications remain a leading cause of morbidity and mortality in patients on ECMO. In this review, we describe the mechanisms and management of hemostatic, thrombotic and hemolytic complications during ECMO support.

Venovenous extracorporeal life support for posttraumatic respiratory distress syndrome in adults: the risk of major hemorrhages

Background

The aim of this retrospective study is to investigate the therapeutic benefits and the bleeding risks of venovenous extracorporeal life support (VV-ECLS) when used for adult posttraumatic respiratory distress syndrome (posttraumatic ARDS).

Materials and methods

Twenty adult trauma patients (median age: 38 years, median injury severity score: 35) treated with VV-ECLS in a level I trauma center between January 2004 and June 2013 were enrolled in this study. The indication of VV-ECLS for posttraumatic ARDS was refractory hypoxemia (P_aO₂/F_iO₂ ratio ≤ 70 mmHg) under advanced mechanical ventilation. To minimize potential complications, a protocol-guided VV-ECLS was adopted.

Results

Sixteen patients were weaned off VV-ECLS, and of these patients fourteen survived. Medians of the trauma-to-ECLS time, the pre-ECLS mechanical ventilation, and the ECLS duration in all patients were 64, 45, and 144 hours respectively. The median P_aO₂/F_iO₂ ratio was improved significantly soon after VV-ECLS, from 56 to 106 mmHg (p < 0.001). However, seven major hemorrhages occurred during VV-ECLS, of which three were lethal. The multivariate analysis revealed that the occurrence of major hemorrhages during VV-ECLS was independently related to the trauma-to-ECLS time < 24 hours (OR: 20; p = 0.02; 95% CI: 2–239; c-index: 0.81).

Conclusions

Despite an effective respiratory support, VV-ECLS should be cautiously administered to patients who develop advanced ARDS soon after major trauma.

Electronic supplementary material

The online version of this article (doi:10.1186/s13049-014-0056-0) contains supplementary material, which is available to authorized users.

A 2014 Update on Coagulation Management for Cardiopulmonary Bypass

Coagulopathy after cardiac surgery with cardiopulmonary bypass is a serious complication that may result in massive bleeding requiring transfusion of significant amounts of blood products, plasma, and platelets. In addition to increased patient morbidity and mortality it is associated with longer hospital stay and increased resource utilization. The current review discusses aspects in cardiopulmonary bypass–induced coagulopathy with emphasis on point-of-care testing and individualized “goal-directed” therapy in patients who develop excessive bleeding after cardiac surgery.