Extracorporeal life support

Platelet Adhesion and Activation in an ECMO Thrombosis-on-a-Chip Model

Use of extracorporeal membrane oxygenation (ECMO) for cardiorespiratory failure remains complicated by blood clot formation (thrombosis), triggered by biomaterial surfaces and flow conditions. Thrombosis may result in ECMO circuit changes, cause red blood cell hemolysis, and thromboembolic events. Medical device thrombosis is potentiated by the interplay between biomaterial properties, hemodynamic flow conditions and patient pathology, however, the contribution and importance of these factors are poorly understood because many in vitro models lack the capability to customize material and flow conditions to investigate thrombosis under clinically relevant medical device conditions. Therefore, an ECMO thrombosis-on-a-chip model is developed that enables highly customizable biomaterial and flow combinations to evaluate ECMO thrombosis in real-time with low blood volume. It is observed that low flow rates, decelerating conditions, and flow stasis significantly increased platelet adhesion, correlating with clinical thrombus formation. For the first time, it is found that tubing material, polyvinyl chloride, caused increased platelet P-selectin activation compared to connector material, polycarbonate. This ECMO thrombosis-on-a-chip model can be used to guide ECMO operation, inform medical device design, investigate embolism, occlusion and platelet activation mechanisms, and develop anti-thrombotic biomaterials to ultimately reduce medical device thrombosis, anti-thrombotic drug use and therefore bleeding complications, leading to safer blood-contacting medical devices.

Antithrombin III infusion improves anticoagulation in congenital diaphragmatic hernia patients on extracorporeal membrane oxygenation

PURPOSE

Achieving effective anticoagulation during neonatal extracorporeal membrane oxygenation (ECMO) without increasing the risk of hemorrhage remains challenging. The use of antithrombin III (AT-III) for this purpose has been examined, but studies have been limited to intermittent bolus dosing. We aimed to evaluate the efficacy and safety of an institutionally developed AT-III continuous infusion protocol in neonates receiving ECMO for the treatment of congenital diaphragmatic hernia (CDH).

METHODS

In this single center, retrospective study, all neonates with a CDH who received ECMO support during the study period were included. Data on anticoagulation labs and therapy, life-threatening bleeding, and circuit changes were analyzed.

RESULTS

Eleven patients were divided into two groups: patients with AT-III continuous infusion (n = 5) and without (n = 6). There were no differences in the gestational age (p = 0.29), sex (p = 1.00), ECMO duration (p = 0.59), or initial AT-III levels (p = 0.76) between groups. Patients in the AT-III infusion group had on average 18.5% higher AT-III levels (p < 0.0001). Patients receiving continuous AT-III infusions spent a significantly higher percentage of ECMO time within the therapeutic range, measured using anti-Factor Xa levels (64.9±4.2% vs. 29.1±8.57%, p = 0.008), and required fewer changes to the heparin infusion rate (6.48±0.88 vs 2.38±0.36 changes/day changes/day, p = 0.005). Multivariate analysis revealed continuous infusion of AT-III did not increase the rate of intracranial or surgical bleeding (p = 0.27).

CONCLUSION

AT-III as a continuous infusion in CDH neonates on ECMO provides a decreased need to modify heparin infusion and more consistent therapeutic anticoagulation without increasing the risk of life-threatening bleeding.

Percutaneous Decannulation for Venoarterial Extracorporeal Membrane Oxygenation Using a Perclose ProGlide Closure Device and a Balloon Catheter Without On-Site Cardiac Surgical Backup

Surgical decannulation for venoarterial extracorporeal membrane oxygenation (VA-ECMO) is recommended as a standard weaning strategy considering large-sized cannulas (14-22 French) are inserted in VA-ECMO. However, we should be aware of complications such as bleeding and infection when removing an arterial cannula, especially in facilities without on-site cardiac surgical backup. Percutaneous closure devices for femoral arterial access sites are currently approved for the decannulation of a 10-French or smaller sheath. We reported a case of successful weaning off from ECMO using a combination method of a balloon catheter and a Perclose ProGlide closure device. We successfully removed the arterial cannula using this technique for four ECMO-treated patients without vascular complications or blood transfusion. Percutaneous decannulation by this method could reduce the procedural time and adverse events and be safely performed even in facilities without on-site cardiac surgical backup.

An Accelerated Thrombosis Model for Computational Fluid Dynamics Simulations in Rotary Blood Pumps

Purpose

Thrombosis ranks among the major complications in blood-carrying medical devices and a better understanding to influence the design related contribution to thrombosis is desirable. Over the past years many computational models of thrombosis have been developed. However, numerically cheap models able to predict localized thrombus risk in complex geometries are still lacking. The aim of the study was to develop and test a computationally efficient model for thrombus risk prediction in rotary blood pumps.

Methods

We used a two-stage approach to calculate thrombus risk. The first stage involves the computation of velocity and pressure fields by computational fluid dynamic simulations. At the second stage, platelet activation by mechanical and chemical stimuli was determined through species transport with an Eulerian approach. The model was compared with existing clinical data on thrombus deposition within the HeartMate II. Furthermore, an operating point and model parameter sensitivity analysis was performed.

Results

Our model shows good correlation (R² > 0.93) with clinical data and identifies the bearing and outlet stator region of the HeartMate II as the location most prone to thrombus formation. The calculation of thrombus risk requires an additional 10–20 core hours of computation time.

Conclusion

The concentration of activated platelets can be used as a surrogate and computationally low-cost marker to determine potential risk regions of thrombus deposition in a blood pump. Relative comparisons of thrombus risk are possible even considering the intrinsic uncertainty in model parameters and operating conditions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13239-021-00606-y.

Venovenous extracorporeal membrane oxygenation-assisted tracheobronchial surgery: a retrospective analysis and literature review

Background

Airway management in tracheobronchial surgeries, especially carinal resection and reconstruction, remains one of the greatest challenges to thoracic surgeons. This study investigated the safety and effectiveness of venovenous extracorporeal membrane oxygenation (VV-ECMO) for respiratory support during tracheobronchial surgeries.

Methods

The data of patients who underwent VV-ECMO-assisted tracheobronchial surgeries at the Shanghai Chest Hospital from August 2006 to August 2021 were retrospectively reviewed. The clinicopathological, perioperative, and follow-up outcomes were analyzed.

Results

A total of 7 patients (4 males and 3 females) with a median age of 56 years (range, 11–70 years) were included in the study. The following tracheobronchial surgeries were conducted: carinal resection and reconstruction with complete pulmonary parenchyma preservation (n=4), left main bronchus and hemi-carinal sleeve resection (n=1), right upper sleeve lobectomy and hemi-carinal resection (n=1), and tracheal resection and reconstruction (n=1). The mean time on VV-ECMO was 167.7±65.8 min, and the mean operative time was 192.4±55.0 min. The average estimated blood loss was 271.4±125.4 mL. No perioperative death or reimplantation of VV-ECMO occurred. Postoperative complications were observed in 2 patients, including 1 case of respiratory failure due to preoperative severe chronic obstructive pulmonary disease (COPD) and 1 case of chylothorax. The median hospital stay was 11 days (range, 7–46 days). The median follow-up time was 30 months (range, 21–33 months). All the patients remained alive, and no postoperative readmission occurred during the follow-up period.

Conclusions

VV-ECMO is a safe and feasible ventilation mode when intraoperative oxygen saturation cannot be well maintained during tracheobronchial surgery.

Near-fatal Panton-Valentine leukocidin-positive Staphylococcus aureus pneumonia, shock and complicated extracorporeal membrane oxygenation cannulation: A case report

BACKGROUND

Panton-Valentine leukocidin (PVL) is an exotoxin secreted by Staphylococcus aureus (S. aureus), responsible for skin and soft tissue infections. As a cause of severe necrotising pneumonia, it is associated with a high mortality rate. A rare entity, the epidemiology of PVL S. aureus (PVL-SA) pneumonia as a complication of influenza coinfection, particularly in young adults, is incompletely understood.

CASE SUMMARY

An adolescent girl presented with haemoptysis and respiratory distress, deteriorated rapidly, with acute respiratory distress syndrome (ARDS) and profound shock requiring extensive, prolonged resuscitation, emergency critical care and venovenous extracorporeal membrane oxygenation (ECMO). Cardiac arrest and a rare complication of ECMO cannulation necessitated intra-procedure extracorporeal cardiopulmonary resuscitation, i.e., venoarterial ECMO. Coordinated infectious disease, microbiology and Public Health England engagement identified causative agents as PVL-SA and influenza A/H3N2 from bronchial aspirates within hours. Despite further complications of critical illness, the patient made an excellent recovery with normal cognitive function. The coordinated approach of numerous multidisciplinary specialists, nursing staff, infection control, specialist cardiorespiratory support, hospital services, both adult and paediatric and Public Health are testimony to what can be achieved to save life against expectation, against the odds. The case serves as a reminder of the deadly nature of PVL-SA when associated with influenza and describes a rare complication of ECMO cannulation.

CONCLUSION

PVL-SA can cause severe ARDS and profound shock, with influenza infection. A timely coordinated multispecialty approach can be lifesaving.

Hemostasis, coagulation and thrombin in venoarterial and venovenous extracorporeal membrane oxygenation: the HECTIC study

Extracorporeal membrane oxygenation (ECMO) support has a high incidence of both bleeding and thrombotic complications. Despite clear differences in patient characteristics and pathologies between veno-venous (VV) and veno-arterial (VA) ECMO support, anticoagulation practices are often the same across modalities. Moreover, there is very little data on their respective coagulation profiles and comparisons of thrombin generation in these patients. This study compares the coagulation profile and thrombin generation between patients supported with either VV and VA ECMO. A prospective cohort study of patients undergoing VA and VV ECMO at an Intensive care department of a university hospital and ECMO referral centre. In addition to routine coagulation testing and heparin monitoring per unit protocol, thromboelastography (TEG), multiplate aggregometry (MEA), calibrated automated thrombinography (CAT) and von-Willebrand’s activity (antigen and activity ratio) were sampled second-daily for 1 week, then weekly thereafter. VA patients had significantly lower platelets counts, fibrinogen, anti-thrombin and clot strength with higher d-dimer levels than VV patients, consistent with a more pronounced consumptive coagulopathy. Thrombin generation was higher in VA than VV patients, and the heparin dose required to suppress thrombin generation was lower in VA patients. There were no significant differences in total bleeding or thrombotic event rates between VV and VA patients when adjusted for days on extracorporeal support. VA patients received a lower median daily heparin dose 8500 IU [IQR 2500–24000] versus VV 28,800 IU [IQR 17,300–40,800.00]; < 0.001. Twenty-eight patients (72%) survived to hospital discharge; comprising 53% of VA patients and 77% of VV patients. Significant differences between the coagulation profiles of VA and VV patients exist, and anticoagulation strategies for patients of these modalities should be different. Further research into the development of tailored anticoagulation strategies that include the mode of ECMO support need to be completed.

Thrombolysis in Children: A Case Report and Review of the Literature

Thromboembolism (TE), including venous thromboembolism (VTE), arterial TE, arterial ischemic stroke (AIS), and myocardial infarction (MI), is considered a relatively rare complication in the pediatric population. Yet, the incidence is rising, especially in hospitalized children. The vast majority of pediatric TE occurs in the setting of at least one identifiable risk factor. Most recently, acute COVID-19 and multisystem inflammatory syndrome in children (MIS-C) have demonstrated an increased risk for TE development. The mainstay for the management pediatric TE has been anticoagulation. Thrombolytic therapy is employed more frequently in adult patients with ample data supporting its use. The data for thrombolysis in pediatric patients is more limited, but the utilization of this therapy is becoming more commonplace in tertiary care pediatric hospitals. Understanding the data on thrombolysis use in pediatric TE and the involved risks is critical before initiating one of these therapies. In this paper, we present the case of an adolescent male with acute fulminant myocarditis and cardiogenic shock likely secondary to MIS-C requiring extracorporeal life support (ECLS) who developed an extensive thrombus burden that was successfully resolved utilizing four simultaneous catheter-directed thrombolysis (CDT) infusions in addition to a review of the literature on the use of thrombolytic therapy in children.

The role of antibiotic pharmacokinetic studies performed post-licensing

Post-licensing pharmacometric studies can provide a better understanding of the pharmacokinetic (PK) alterations in special patient populations and may lead to better clinical outcomes. Some patient populations exhibit markedly different pathophysiology to general ward patients or healthy individuals. This may be developmental (paediatric patients), a manifestation of an underlying disease pathology (patients with obesity or haematological malignancies) or due to medical interventions (critically ill patients receiving extracorporeal therapies). This paper outlines the factors that affect the PK of special patient populations and describes some novel methods of antimicrobial administration that may increase antimicrobial concentrations at the site of infection and improve treatment of severe infection.

Comparison of Diazeniumdiolated Dialkylhexanediamines as Nitric Oxide Release Agents on Nonthrombogenicity in an Extracorporeal Circulation Model

When blood from a patient is circulated through extracorporeal circuits (ECCs), such as in cardiopulmonary bypass or extracorporeal life support, platelets in the blood are activated and form a thrombus. This is prevented clinically with a range of different systemic anticoagulation agents (e.g., heparin); however, this increases a patient's risk of hemorrhage. Previous work with nitric oxide (NO) releasing materials using the combined diazeniumdiolated diamine, N-N-di-N'-butyl-1,6-hexanediamine (DBHD), and a polymer-linked thrombin inhibitor, argatroban (AG), showed significant nonthrombogenicity in ECCs using a 4 h rabbit model. Herein, we evaluated if diazeniumdiolated N-N-di-N'-propyl-1,6-hexanediamine (DPHDN₂O₂), which has a slightly lower degree of lipophilicity compared to DBHDN₂O₂, would provide similar nonthrombogenicity as the AG/DBHDN₂O₂-polymer-coated circuits. While DPHDN₂O₂ releases NO at a higher flux rate than DBHDN₂O₂ when coated (within CarboSil polymer) on the inner wall of polyvinyl chloride tubing, neither coated circuit significantly affected animal hemodynamics. Both diazeniumdiolated diamines, in combination with immobilized AG or alone, significantly reduced thrombus formation similarly in the 4 h rabbit model (vs uncoated control): AG/DBHDN₂O₂: 0.12 ± 0.03 cm²; DBHDN₂O₂: 2.57 ± 0.82 cm²; AG/DPHDN₂O₂: 0.68 ± 0.22 cm²; DPHDN₂O₂: 1.87 + 1.26 cm²; uncoated control: 6.95 ± 0.82 cm². AG/DPHDN₂O₂ was no different than AG/DBHDN₂O in preserving platelet count and function. In addition, AG did not leach into the systemic circulation as the total clotting times were insignificantly different from the baseline values (AG/DPHDN₂O₂: 12.7 + 0.5 s (n = 3); AG/DBHDN₂O₂: 12.3 + 0.7 s (n = 3); baseline: 13.9 + 0.3 s (n = 13)). Based on these results, both DPHDN₂O₂ and DPHDN₂O₂ are good candidates as NO donor molecules for creating nonthrombogenic polymer coatings for ECCs.

Cannula position and Bernoulli effect contribute to leg malperfusion during extracorporeal life support with femoral arterial cannulation-an in silico simulation study†

OBJECTIVES

Limb ischaemia during extracorporeal life support (ECLS) using femoral artery cannulation is frequently observed even in patients with regular vessel diameters and without peripheral arterial occlusive disease. We investigated underlying pathomechanisms using a virtual fluid-mechanical simulation of the human circulation.

METHODS

A life-sized model of the human aorta and major vascular branches was virtualized using 3-dimensional segmentation software (Mimics, Materialise). Steady-state simulation of different grades of cardiac output (0-100%) was performed using Computational Fluid Dynamics (CFX, ANSYS). A straight cannula [virtualized 16 Fr (5.3 mm)] was inserted into the model via the left common femoral artery. The ECLS flow was varied between 1 and 5 l/min. The pressure boundary conditions at the arterial outlets were selected to demonstrate the downstream vascular system. Qualitative and quantitative analyses concerning flow velocity and direction were carried out in various regions of the model.

RESULTS

During all simulated stages of reduced cardiac output and subsequently adapted ECLS support, retrograde blood flow originating from the ECLS cannula was observed from the cannulation site up to the aortic bifurcation. Analysis of pressure showed induction of zones of negative pressure close to the cannula tip, consistent with the Bernoulli principle. Depending on cannula position and ECLS flow rate, this resulted in negative flow from the ipsilateral superficial femoral artery or the contralateral internal iliac artery. The antegrade flow to the non-cannulated side was generally greater than that to the cannulated side.

CONCLUSIONS

The cannula position and ECLS flow rate both influence lower limb perfusion during femoral ECLS. Therefore, efforts to optimize the cannula position and to avoid limb malperfusion, including placement of a distal perfusion cannula, should be undertaken in patients treated with ECLS.

Cost-utility of extracorporeal cardiopulmonary resuscitation in patients with cardiac arrest

BACKGROUND

Extracorporeal cardiopulmonary resuscitation (ECPR) is a resource-intensive tool that provides haemodynamic and respiratory support in patients who have suffered cardiac arrest. In this study, we investigated the cost-utility of ECPR (cost/QALY) in cardiac arrest patients treated at our institution.

METHODS

We performed a retrospective review of patients who received ECPR following cardiac arrest between 2012 and 2018. All medical care-associated charges with ECPR and subsequent hospital admission were recorded. The quality-of-life of survivors was assessed with the Health Utilities Index Mark II. The cost-utility of ECPR was calculated with cost and quality-of-life data.

RESULTS

ECPR was used in 32 patients (15/32 in-hospital, 47%) with a median age of 55.0 years (IQR 46.3-63.3 years), 59% male and 66% African American. The median duration of ECPR support was 2.1 days (IQR 0.9-3.8 days). Survival to hospital discharge was 16%. The median score of the Health Utilities Index Mark II at discharge for the survivors was 0.44 (IQR 0.32-0.52). The median operating cost for patients undergoing ECMO was $125,683 per patient (IQR $49,751-$206,341 per patient). The calculated cost-utility for ECPR was $56,156/QALY gained.

CONCLUSIONS

The calculated cost-utility is within the threshold considered cost-effective in the United States (<$150,000/QALY gained). These results are comparable to the cost-effectiveness of heart transplantation for end-stage heart failure. Larger studies are needed to assess the cost-utility of ECPR and to identify whether other factors, such as patient characteristics, affect the cost-utility benefit.

Clinical complications during veno-arterial extracorporeal membrane oxigenation in post-cardiotomy and non post-cardiotomy shock: still the achille's heel

Extracorporeal membrane oxygenation (ECMO) is life-saving for potentially reversible heart failure and respiratory injuries not responsive to conventional therapies. Technological innovations have produced over the years significant improvements in ECMO devices (pump, cannula design and oxygenator) and have allowed a better risk/benefit profile. Alongside with recognized advantages in the treatment of very sick patients, ECMO remains an invasive procedure for mechanical circulatory support (MCS) and it is associated with complications that strongly influence the prognosis. Current review was designed to provide a comprehensive outline on ECMO complications, analyzing risk factors and strategies of management, focusing on adult population undergoing veno-arterial ECMO (VA-ECMO) therapy.

Veno-Arterial Extracorporeal Membrane Oxygenation Support in Patients Undergoing Aortic Surgery

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is an option for mechanical support for patients with postcardiotomy cardiogenic shock (PCS). However, the use of VA-ECMO in patients suffering from aortic disease with PCS has not been greatly reported. This is a retrospective review of adult patients undergoing aortic surgery who received VA-ECMO support to treat refractory PCS from August 2009 to May 2016. A total of 36 patients who underwent aortic surgery with VA-ECMO support for refractory PCS were included. Preoperative, perioperative, and postoperative variables were assessed and analyzed for possible correlation with in-hospital mortality. After a mean duration of 3.6 ± 2.9 days, 24 patients (67%) were weaned off VA-ECMO, and 18 patients (50%) were discharged from the hospital. The overall in-hospital mortality was 50%. The main cause of death was multiple organ dysfunction. The survivors had a lower level of preoperative creatine kinase-MB (CK-MB), a higher rate of antegrade cannulation, and a lower lactate level at 12 h, respectively. Relevant factors for in-hospital mortality were retrograde-flow cannulation (odds ratio [OR], 2.49), peak lactate levels greater than 20 mmol/L (OR, 5.0), and preoperative CK-MB greater than 100 IU/L (OR, 6.40). Antegrade cannulation may provide better perfusion and should be emphasized to improve outcomes. Additionally, levels of peak serum lactate and preoperative CK-MB may be relevant factors for in-hospital mortality in aortic patients with PCS.

Mechanical Circulatory Support in Acute Decompensated Heart Failure and Shock

An array of interventional therapeutics is available in the modern era, with uses depending on acute or chronic situations. This article focuses on support in acute decompensated heart failure and cardiogenic shock, including intra-aortic balloon pumps, continuous aortic flow augmentation, and extra-corporeal membrane oxygenation.

Mechanical circulatory support is associated with loss of platelet receptors glycoprotein Ibα and glycoprotein VI

Essentials Relationship of acquired von Willebrand disease (VWD) and platelet dysfunction is explored. Patients with ventricular assist devices and on extracorporeal membrane oxygenation are investigated. Acquired VWD and platelet receptor shedding is demonstrated in the majority of patients. Loss of platelet adhesion receptors glycoprotein (GP) Ibα and GPVI may increase bleeding risk.

SUMMARY

Background Ventricular assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) are associated with bleeding that is not fully explained by anticoagulant or antiplatelet use. Exposure of platelets to elevated shear in vitro leads to increased shedding. Objectives To investigate whether loss of platelet receptors occurs in vivo, and the relationship with acquired von Willebrand syndrome (AVWS). Methods Platelet counts, coagulation tests and von Willebrand factor (VWF) analyses were performed on samples from 21 continuous flow VAD (CF-VAD), 20 ECMO, 12 heart failure and seven aortic stenosis patients. Levels of platelet receptors were measured by flow cytometry or ELISA. Results The loss of high molecular weight VWF multimers was observed in 18 of 19 CF-VAD and 14 of 20 ECMO patients, consistent with AVWS. Platelet receptor shedding was demonstrated by elevated soluble glycoprotein (GP) VI levels in plasma and significantly reduced surface GPIbα and GPVI levels in CF-VAD and ECMO patients as compared with healthy donors. Platelet receptor levels were also significantly reduced in heart failure patients. Conclusions These data link AVWS and increased platelet receptor shedding in patients with CF-VADs or ECMO for the first time. Loss of the platelet surface receptors GPIbα and GPVI in heart failure, CF-VAD and ECMO patients may contribute to ablated platelet adhesion/activation, and limit thrombus formation under high/pathologic shear conditions.

Attenuation of thrombosis and bacterial infection using dual function nitric oxide releasing central venous catheters in a 9day rabbit model

Two major problems with implanted catheters are clotting and infection. Nitric oxide (NO) is an endogenous vasodilator as well as natural inhibitor of platelet adhesion/activation and an antimicrobial agent, and NO-releasing polymers are expected to have similar properties. Here, NO-releasing central venous catheters (CVCs) are fabricated using Elast-eon™ E2As polymer with both diazeniumdiolated dibutylhexanediamine (DBHD/NONO) and poly(lactic-co-glycolic acid) (PLGA) additives, where the NO release can be modulated and optimized via the hydrolysis rate of the PLGA. It is observed that using a 10% w/w additive of a PLGA with ester end group provides the most controlled NO release from the CVCs over a 14d period. The optimized DBHD/NONO-based catheters are non-hemolytic (hemolytic index of 0%) and noncytotoxic (grade 0). After 9d of catheter implantation in the jugular veins of rabbits, the NO-releasing CVCs have a significantly reduced thrombus area (7 times smaller) and a 95% reduction in bacterial adhesion. These results show the promise of DBHD/NONO-based NO releasing materials as a solution to achieve extended NO release for longer term prevention of clotting and infection associated with intravascular catheters.

STATEMENT OF SIGNIFICANCE

Clotting and infection are significant complications associated with central venous catheters (CVCs). While nitric oxide (NO) releasing materials have been shown to reduce platelet activation and bacterial infection in vitro and in short-term animal models, longer-term success of NO-releasing materials to further study their clinical potential has not been extensively evaluated to date. In this study, we evaluate diazeniumdiolate based NO-releasing CVCs over a 9d period in a rabbit model. The explanted NO-releasing CVCs were found to have significantly reduced thrombus area and bacterial adhesion. These NO-releasing coatings can improve the hemocompatibility and bactericidal activity of intravascular catheters, as well as other medical devices (e.g., urinary catheters, vascular grafts).

Adverse effects of extracorporeal carbon dioxide removal (ECCO2R) for acute respiratory failure: a systematic review protocol

BACKGROUND

The extracorporeal membrane carbon dioxide removal (ECCO2R) system is primarily designed for the purpose of removing CO2 from the body for patients with potentially reversible severe acute hypercapnic respiratory failure or being considered for lung transplantation. Systematic reviews have focused on the effectiveness of ECCO2R. To the author's best knowledge, this is the first systematic review to focus on the adverse effects of this procedure.

METHODS

We will conduct a systematic review of procedure-related adverse effects of ECCO2R systems. A high sensitivity search strategy will be employed in Cochrane Library, MEDLINE, EMBASE, Web of Science and product regulatory databases and ongoing trial registers to identify citations. Reference lists of relevant studies and grey literature will also be searched. Screening of the results will be performed by two reviewers independently using pre-defined inclusion and exclusion criteria. Clinical trials and observational studies will be included. Data will be extracted using a purposefully developed extraction form. Appropriateness for statistical pooling of the results will be determined and carried out if heterogeneity is low to moderate. The GRADE framework will be employed to grade the overall quality of the evidence.

DISCUSSION

In the UK, the current access to the use of ECCO2R is possible only with special arrangements for clinical governance, consent and for audit or research. Current evidence on ECCO2R suggests that there are a number of well-recognised complications which vary greatly across studies. This systematic review will consolidate the existing knowledge on adverse effects resulting from the use of ECCO2R.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015023503 .

Improved hemocompatibility of silicone rubber extracorporeal tubing via solvent swelling-impregnation of S-nitroso-N-acetylpenicillamine (SNAP) and evaluation in rabbit thrombogenicity model

Blood-contacting devices, including extracorporeal circulation (ECC) circuits, can suffer from complications due to platelet activation and thrombus formation. Development of nitric oxide (NO) releasing polymers is one method to improve hemocompatibility, taking advantage of the ability of low levels of NO to prevent platelet activation/adhesion. In this study a novel solvent swelling method is used to load the walls of silicone rubber tubing with the NO donor S-nitroso-N-acetylpenicillamine (SNAP). This SNAP-silicone rubber tubing exhibits an NO flux of ca. 1×10(-10)molcm(-2)min(-1), which mimics the range of NO release from the normal endothelium, which is stable for at least 4h. Images of the tubing before and after swelling, obtained via scanning electron microscopy, demonstrate that this swelling method has little effect on the surface properties of the tubing. The SNAP-loaded silicone rubber and silicone rubber control tubing are used to fabricate ECC circuits that are evaluated in a rabbit model of thrombogenicity. After 4h of blood flow, the SNAP-loaded silicone rubber circuits were able to preserve the blood platelet count at 64% of baseline (vs. 12% for silicone rubber control). A 67% reduction in the degree of thrombus formation within the thrombogenicity chamber was also observed. This study demonstrates the ability to improve the hemocompatibility of existing/commercial silicone rubber tubing via a simple solvent swelling-impregnation technique, which may also be applicable to other silicone-based blood-contacting devices.

STATEMENT OF SIGNIFICANCE

Localized nitric oxide (NO) release can be achieved from biomedical grade polymers doped with S-nitroso-N-acetylpenicillamine (SNAP). Despite the promising in vitro and in vivo biocompatibility results reported for these NO releasing polymers, many of these materials may face challenges in being translated to clinical applications, especially in the areas of polymer processing and manufacturing. In this study, we report a solvent swelling-impregnation technique to incorporate SNAP into extracorporeal circuit (ECC) tubing. These NO-releasing ECCs were able to attenuate the activation of platelets and maintain their functionality, while significantly reducing the extent of thrombus formation during 4h blood flow in the rabbit model of thrombogenicity.

Extracorporeal Membrane Oxygenation as a Bridge for Heart Failure and Cardiogenic Shock

Heart failure (HF) can be defined as cardiac structural or functional abnormality leading to a series of symptoms due to deficiency of oxygen delivery. In the clinical practice, acute heart failure (AHF) is usually performed as cardiogenic shock (CS), pulmonary edema, and single or double ventricle congestive heart failure. CS refers to depressed or insufficient cardiac output (CO) attributable to myocardial infarction, fulminant myocarditis, acute circulatory failure attributable to intractable arrhythmias or the exacerbation of chronic heart failure, postcardiotomy low CO syndrome, and so forth. Epidemiological studies have shown that CS has higher in-hospital mortality in patients with AHF. Besides, we call the induced, sustained circulatory failure even after administration of high doses of inotropes and vasopressors refractory cardiogenic shock. In handling these cases, mechanical circulatory support devices are usually needed. In this review, we discuss the current application status and clinical points in utilizing extracorporeal membrane oxygenation (ECMO).

The Complex Relationship of Extracorporeal Membrane Oxygenation and Acute Kidney Injury: Causation or Association?

Extracorporeal membrane oxygenation (ECMO) is a modified cardiopulmonary bypass (CPB) circuit capable of providing prolonged cardiorespiratory support. Recent advancement in ECMO technology has resulted in increased utilisation and clinical application. It can be used as a bridge-to-recovery, bridge-to-bridge, bridge-to-transplant, or bridge-to-decision. ECMO can restitute physiology in critically ill patients, which may minimise the risk of progressive multiorgan dysfunction. Alternatively, iatrogenic complications of ECMO clearly contribute to worse outcomes. These factors affect the risk : benefit ratio of ECMO which ultimately influence commencement/timing of ECMO. The complex interplay of pre-ECMO, ECMO, and post-ECMO pathophysiological processes are responsible for the substantial increased incidence of ECMO-associated acute kidney injury (EAKI). The development of EAKI significantly contributes to morbidity and mortality; however, there is a lack of evidence defining a potential benefit or causative link between ECMO and AKI. This area warrants investigation as further research will delineate the mechanisms involved and subsequent strategies to minimise the risk of EAKI. This review summarizes the current literature of ECMO and AKI, considers the possible benefits and risks of ECMO on renal function, outlines the related pathophysiology, highlights relevant investigative tools, and ultimately suggests an approach for future research into this under investigated area of critical care.

A Survey of Physicians' Attitudes toward Decision-Making Authority for Initiating and Withdrawing VA-ECMO: Results and Ethical Implications for Shared Decision Making

OBJECTIVE

Although patients exercise greater autonomy than in the past, and shared decision making is promoted as the preferred model for doctor-patient engagement, tensions still exist in clinical practice about the primary locus of decision-making authority for complex, scarce, and resource-intensive medical therapies: patients and their surrogates, or physicians. We assessed physicians' attitudes toward decisional authority for adult venoarterial extracorporeal membrane oxygenation (VA-ECMO), hypothesizing they would favor a medical locus.

DESIGN, SETTING, PARTICIPANTS

A survey of resident/fellow physicians and internal medicine attendings at an academic medical center, May to August 2013.

MEASUREMENTS

We used a 24-item, internet-based survey assessing physician-respondents' demographic characteristics, knowledge, and attitudes regarding decisional authority for adult VA-ECMO. Qualitative narratives were also collected.

MAIN RESULTS

A total of 179 physicians completed the survey (15 percent response rate); 48 percent attendings and 52 percent residents/fellows. Only 32 percent of the respondents indicated that a surrogate's consent should be required to discontinue VA-ECMO; 56 percent felt that physicians should have the right to discontinue VA-ECMO over a surrogate's objection. Those who self-reported as "knowledgeable" about VA-ECMO, compared to those who did not, more frequently replied that there should not be presumed consent for VA-ECMO (47.6 percent versus 33.3 percent, p = 0.007), that physicians should have the right to discontinue VA-ECMO over a surrogate's objection (76.2 percent versus 50 percent, p = 0.02) and that, given its cost, the use of VA-ECMO should be restricted (81.0 percent versus 54.4 percent, p = 0.005).

CONCLUSIONS

Surveyed physicians, especially those who self-reported as knowledgeable about VA-ECMO and/or were specialists in pulmonary/critical care, favored a medical locus of decisional authority for VA-ECMO. VA-ECMO is complex, and the data may (1) reflect physicians' hesitance to cede authority to presumably less knowledgeable patients and surrogates, (2) stem from a stewardship of resources perspective, and/or (3) point to practical efforts to avoid futility and utility disputes. Whether these results indicate a more widespread reversion to paternalism or a more circumscribed usurping of decisional authority occasioned by VA-ECMO necessitates further study.

Chronic mould exposure as a risk factor for severe community acquired pneumonia in a patient requiring extra corporeal membrane oxygenation

A previously fit and well man developed acute respiratory failure due to environmental mould exposure from living in damp rental accommodation. Despite aggressive intensive care management he rapidly deteriorated and required respiratory and cardiac Extracorporeal Membrane Oxygenation. We hypothesize that poor domiciliary conditions may make an underestimated contribution to community respiratory disease. These conditions may present as acute and severe illness with non-typical pathogens identified.

U.S. and International In-Hospital Costs of Extracorporeal Membrane Oxygenation: a Systematic Review

CONTEXT

The in-hospital costs of extracorporeal membrane oxygenation (ECMO) have not been well established.

OBJECTIVE

To evaluate the in-hospital costs of ECMO technology in both US and non-US settings for all patient types.

DATA SOURCES

Systematic review of English-language articles, using the PubMed, Embase, Web of Science and EconLit databases. Searches consisted of the terms 'ECMO' AND 'health expenditures' or 'resource use' or 'costs' or 'cost analysis' or 'cost(-)effectiveness' or 'cost(-)benefit' or 'cost(-)utility' or 'economic(-)evaluation' or 'economic' or 'QALY' or 'cost per quality-adjusted life year'.

STUDY SELECTION

Only full scientific research articles were included. The exclusion criteria included papers that focused on pumpless ECMO, simulation training or decision support systems; papers that did not include human subjects or were not written in English; papers that did not mention ECMO, costs, economics or resource utilization; and papers that included only outside-hospital, infrastructure capital or device capital costs.

DATA EXTRACTION

Data extraction was completed by one author, using predefined criteria.

RESULTS

From the database searches, 1371 results were returned, 226 records underwent a full review and 18 studies were included in the final review. Three papers studied adult populations, two studied adult and paediatric populations, five studied only paediatric populations, one studied a paediatric and neonatal population, and the remaining seven exclusively examined ECMO in neonatal populations. The sample sizes ranged from 8 to 8753 patients. ECMO for respiratory conditions was the most common diagnosis category, followed by congenital diaphragmatic hernia (CDH) and then cardiac conditions. Most papers (n = 14) used retrospective cost collection. Only eight papers stated the perspective of the cost analysis. The results show a large variation in the cost of ECMO over multiple cost categories (e.g., range of total in-hospital costs of treatment: USD 42,554-537,554 [in 2013 values]). In the U.S.A., the reported costs of ECMO were highest for CDH repair, followed by cardiac conditions, and lowest for respiratory conditions. The US charges were highest for cardiac conditions. Outside the U.S.A., the ECMO cost was highest for cardiac conditions, followed by respiratory conditions, and lowest for CDH repair. No non-US studies reported charges.

CONCLUSION

The current literature shows that a large variation exists in the in-hospital cost estimates for ECMO. Further research is needed to understand how the diagnosis, setting and other factors relate to this variation in the cost of this technology. Reliable costing methodologies and cost information will be critical to inform policymakers and stakeholders wishing to maximize the value of advanced medical technologies such as ECMO.

Prospective observational study of hemostatic alterations during adult extracorporeal membrane oxygenation (ECMO) using point-of-care thromboelastometry and platelet aggregometry

OBJECTIVES

To characterize the longitudinal hemostatic profile during adult ECMO using point-of-care tests (POCT) for coagulation and to compare these parameters to standard laboratory tests. In addition, the clinicians' responses during bleeding episodes using available information were compared to a POCT-based response.

DESIGN

Prospective observational cohort study.

SETTING

ECMO-referral center in a university teaching hospital.

PARTICIPANTS

Ten critically ill adult ECMO patients.

INTERVENTIONS

Daily laboratory coagulation profile, transfusion history and near-daily thromboelastometry (ROTEM®) and platelet aggregometry (Multiplate®).

MAIN RESULTS

Six male and four female patients, seven with VA- and three with VV-ECMO were studied over 110 days. Seventy-five thromboelastometry (TEM) and 36 platelet aggregometry (MEA) results were analyzed. A majority of TEM values were within the normal range, except for FIBTEM (majority high), which remained consistent over long (>5 days) ECMO runs. In MEA there were low values, particularly in the adenosine diphosphate- and ristocetin-induced assay, implying possibly a vWF-factor or GpIb-receptor defect. There was correlation between laboratory and POCT as well as good correlation between the clot firmness after 10 minutes (A10) and the maximum clot firmness in ROTEM, suggesting that reliable information can be obtained within 15 minutes. Twenty-two bleeding episodes were observed in five patients. When comparing the clinicians' response to a transfusion algorithm based on POCT, there was a concordance in less than 20% of episodes.

CONCLUSIONS

POCT for coagulation can provide specific, reliable, and timely information during bleeding episodes and the use of targeted therapy algorithms could improve outcomes and reduce costs.

Reduction in Thrombosis and Bacterial Adhesion with 7 Day Implantation of S-Nitroso-N-acetylpenicillamine (SNAP)-Doped Elast-eon E2As Catheters in Sheep

Thrombosis and infection are two common problems associated with blood-contacting medical devices such as catheters. Nitric oxide (NO) is known to be a potent antimicrobial agent as well as an inhibitor of platelet activation and adhesion. Healthy endothelial cells that line the inner walls of all blood vessels exhibit a NO flux of 0.5~4×10^-10 mol cm^-2 min^-1 that helps prevent thrombosis. Materials with a NO flux that is equivalent to this level are expected to exhibit similar anti-thrombotic properties. In this study, NO-releasing catheters were fabricated by incorporating S-nitroso-N-acetylpenicillamine (SNAP) in the Elast-eon E2As polymer. The SNAP/E2As catheters release physiological levels of NO for up to 20 d, as measured by chemiluminescence. Furthermore, SNAP is stable in the E2As polymer, retaining 89% of the initial SNAP after ethylene oxide (EO) sterilization. The SNAP/E2As and E2As control catheters were implanted in sheep veins for 7 d to examine the effect on thrombosis and bacterial adhesion. The SNAP/E2As catheters reduced the thrombus area when compared to the control (1.56 ± 0.76 and 5.06 ± 1.44 cm², respectively). A 90% reduction in bacterial adhesion was also observed for the SNAP/E2As catheters as compared to the controls. The results suggest that the SNAP/E2As polymer has the potential to improve the hemocompatibility and bactericidal activity of intravascular catheters, as well as other blood-contacting medical devices (e.g., vascular grafts, extracorporeal circuits).

Extracorporeal membrane oxygenation in adults: a brief review and ethical considerations for nonspecialist health providers and hospitalists

Given the pace, distribution, and uptake of technological innovation, patients experiencing respiratory failure, heart failure, or cardiac arrest are, with greater frequency, being treated with extracorporeal membrane oxygenation (ECMO). Although most hospitalists will not be responsible for ordering or managing ECMO, in-hospital healthcare providers continue to be a vital source of patient referral and, accordingly, need to understand the rudiments of these technologies so as to co-manage patients, counsel families, and help ensure that the provision of ECMO is consistent with patient preferences and appropriate goals of care. In an effort to prepare hospitalists for these clinical responsibilities, we review the history and technology behind modern-day ECMO, including venoarterial extracorporeal membrane oxygenation (VA-ECMO) and venovenous extracorporeal membrane oxygenation. Building upon that foundation, we further highlight special ethical considerations that may arise in VA-ECMO, and present an ethically grounded approach to the initiation, continuation, and discontinuation of treatment.

Development and hemocompatibility testing of nitric oxide releasing polymers using a rabbit model of thrombogenicity

Hemocompatibility is the goal for any biomaterial contained in extracorporeal life supporting medical devices. The hallmarks for hemocompatibility include nonthrombogenicity, platelet preservation, and maintained platelet function. Both in vitro and in vivo assays testing for compatibility of the blood/biomaterial interface have been used over the last several decades to ascertain if the biomaterial used in medical tubing and devices will require systemic anticoagulation for viability. Over the last 50 years systemic anticoagulation with heparin has been the gold standard in maintaining effective extracorporeal life supporting. However, the biomaterial that maintains effective ECLS without the use of any systemic anticoagulant has remained elusive. In this review, the in vivo 4-h rabbit thrombogenicity model genesis will be described with emphasis on biomaterials that may require no systemic anticoagulation for extracorporeal life supporting longevity. These novel biomaterials may improve extracorporeal circulation hemocompatibility by preserving near resting physiology of the major blood components, the platelets and monocytes. The rabbit extracorporeal circulation model provides a complete assessment of biomaterial interactions with the intrinsic coagulation players, the circulating platelet and monocytes. This total picture of blood/biomaterial interaction suggests that this rabbit thrombogenicity model could provide a standardization for biomaterial hemocompatibility testing.

Age-based difference in activation markers of coagulation and fibrinolysis in extracorporeal membrane oxygenation

OBJECTIVE

Coagulation system activation in extracorporeal membrane oxygenation results in hemostatic derangements. Thrombin generation markers like prothrombin fragment 1+2 and thrombin-antithrombin complex are sensitive markers of hypercoagulability. Plasmin-antiplasmin complex is a sensitive marker for fibrinolysis. D-dimers reflect thrombin generation and fibrinolysis. The aim was to identify the extent of hemostasis activation during extracorporeal membrane oxygenation by measuring thrombin-antithrombin complex, prothrombin fragment 1+2, plasmin-antiplasmin complex, and D-dimer.

DESIGN

Prospective cohort study.

SETTING

Tertiary care academic center.

PATIENTS

Children placed on extracorporeal membrane oxygenation from April 2011 to January 2013.

INTERVENTIONS

Prothrombin fragment 1+2, thrombin-antithrombin complex, plasmin-antiplasmin complex, and D-dimer were measured on days 1 and 5 of extracorporeal membrane oxygenation.

MEASUREMENTS AND MAIN RESULTS

Data presented as median (interquartile range); nonparametric tests were done using SPSS. Twenty-nine children (52% < 30 d old [neonates], median extracorporeal membrane oxygenation length 151 hr) were studied. Complications included thrombosis in 14%, bleeding in 45%, and thrombosis and bleeding together in 10%. Thrombin-antithrombin complex, prothrombin fragment 1+2, plasmin-antiplasmin complex, and D-dimer levels were high on day 1 and remained increased on extracorporeal membrane oxygenation. In neonates, all levels were higher on day 5 compared with day 1: thrombin-antithrombin complex (55.6 μg/L [30.7-76.0] vs 18.7 μg/L [10.9-34.6]; p = 0.03), prothrombin fragment 1+2 (2,038 pmol/L [1,093-4,018.5] vs 377.5 pmol/L [334.3-1,103.0]; p = 0.00), plasmin-antiplasmin complex (2,160 μg/L [786-3,090] vs 398 μg/L [296.8-990.8]; p = 0.00), and D-dimer (3.0 μg/mL [1.9-11.5] vs 1.5 μg/mL [0.6-2.9]; p = 0.01). Thrombin-antithrombin complex, prothrombin fragment 1+2, plasmin-antiplasmin complex, and D-dimer levels did not correlate with anti-Xa activity or heparin dose. In bleeders older than 30 days, plasmin-antiplasmin complex stayed elevated on day 5, but in patients with no bleeding complications, plasmin-antiplasmin level showed a declining trend. In neonates, plasmin-antiplasmin levels increased over the course of extracorporeal membrane oxygenation irrespective of bleeding.

CONCLUSION

Despite our best efforts at adequate anticoagulation with unfractionated heparin, neonates showed persistent increase in coagulation activation on extracorporeal membrane oxygenation. Fibrinolysis activation may contribute to bleeding in patients older than 30 days. Different anticoagulation protocols should be individualized based on age.

Monitoring of the adult patient on venoarterial extracorporeal membrane oxygenation

Venoarterial extracorporeal membrane oxygenation (VA ECMO) provides mechanical support to the patient with cardiac or cardiopulmonary failure. This paper reviews the physiology of VA ECMO including the determinants of ECMO flow and gas exchange. The efficacy of this therapy may be determined by assessing patient hemodynamics and device flow, overall gas exchange support, markers of adequate oxygen delivery, and pulsatility of the arterial blood pressure waveform.

Hemocompatibility Comparison of Biomedical Grade Polymers Using Rabbit Thrombogenicity Model for Preparing Nonthrombogenic Nitric Oxide Releasing Surfaces

Nitric oxide (NO) is an endogenous vasodilator as well as natural inhibitor of platelet adhesion/activation. Nitric oxide releasing (NOrel) materials can be prepared by doping an NO donor species, such as diazeniumdiolated dibutylhexanediamine (DBHD/N₂O₂), within a polymer coating. The inherent hemocompatibility properties of the base polymer can also influence the efficiency of such NO release coatings. In this study, four biomedical grade polymers were evaluated in a 4 h rabbit model of thrombogenicity for their effects on extracorporeal circuit thrombus formation and circulating platelet count. At the end of 4 h, Elast-Eon E2As was found to preserve 58% of baseline platelets versus 48, 40, and 47% for PVC/DOS, Tecophilic SP-60D-60, and Tecoflex SG80A, respectively. Elast-Eon also had significantly lower clot area of 5.2 cm² compared to 6.7, 6.1, and 6.9 cm² for PVC/DOS, SP-60D-60, and SG80A, respectively. Based on the results obtained for the base polymer comparison study, DBHD/N₂O₂-doped E2As was evaluated in short-term (4 h) rabbit studies to observe the NO effects on prevention of clotting and preservation of platelet function. Platelet preservation for this optimal NO release formulation was 97% of baseline after 4 h, and clot area was 0.9 cm² compared to 5.2 cm² for controls, demonstrating that combining E2As with NO release provides a truly advanced hemocompatible polymer coating for extracorporeal circuits and potentially other blood contacting applications.

Safety and efficacy of recombinant activated factor VII for refractory hemorrhage in pediatric patients on extracorporeal membrane oxygenation: a single center review

Background:

Medically refractory hemorrhage in patients on ECMO (extracorporeal membrane oxygenation) support can have catastrophic complications. Recombinant-Activated Factor VII (rFVIIa; NovoSeven®) may provide lifesaving hemostasis; however, there are reports of catastrophic thrombosis related to its administration.

Objective:

This review attempts to add safety and efficacy data to existing literature regarding the use of rFVIIa for refractory hemorrhage in pediatric patients on ECMO support.

Design/Methods:

A retrospective chart review was performed for all pediatric patients on ECMO who received rFVIIa for refractory hemorrhage from 2004 to 2009. Data was extracted for each refractory bleeding event, including patient blood loss and transfused blood products in the 6 hours before the first dose, between rFVIIa doses and in the 6 hours after the final dose. For purposes of data collection, a hemorrhagic event was defined as new onset hemorrhage or a hemorrhage occurring at least 12 hours after the most recent dose of rFVIIa.

Results:

In total, seven patients aged 1 month to 15 years received rFVIIa for 14 different hemorrhagic events. There was no significant difference in blood loss or blood product transfusion associated with rFVIIa administration. There was one patient-related and one ECMO-related complication temporally associated with rFVIIa administration: decreased ECMO circuit oxygenator efficiency and the development of an intra-gastric clot requiring surgical evacuation.

Conclusion:

These data suggest limited efficacy for rFVIIa use for refractory hemorrhage in pediatric patients on ECMO support. There were two non-catastrophic complications temporally associated with its administration.

A review of emergency cardiopulmonary bypass for severe poisoning by cardiotoxic drugs

Cardiovascular collapse remains a leading cause of death in severe acute drug intoxication. Commonly prescribed medications such as antidysrhythmics, calcium channel antagonists, and beta adrenergic receptor antagonists can cause refractory cardiovascular collapse in massive overdose. Emergency cardiopulmonary bypass (ECPB), a modality originating in cardiac surgery, is a rescue technique that has been successfully implemented in the treatment of refractory cardiogenic shock and cardiac arrest unresponsive to traditional medical interventions. More recently a growing number of animal studies, case reports, and case series have documented its use in refractory hemodynamic collapse in poisoned patients. This article will review current ECPB techniques and explore its growing role in the treatment of severely hemodynamically compromised poisoned patients.

Pre-clinical evaluation of the infant Jarvik 2000 heart in a neonate piglet model

BACKGROUND

The infant Jarvik 2000 heart is a very small, hermetically sealed, intracorporeal, axial-flow ventricular assist device (VAD) designed for circulatory support in neonates and infants. The anatomic fit, short-term biocompatibility and hemodynamic performance of the device were evaluated in a neonate piglet model.

METHODS

The infant Jarvik 2000 heart with two different blade profiles (low- or high-flow blade design) was tested in 6 piglets (8.8 ± 0.9 kg). Using a median sternotomy, the pump was placed in the left ventricle through the apex without cardiopulmonary bypass. An outflow graft was anastomosed to the ascending aorta. Hemodynamics and biocompatibility were studied for 6 hours.

RESULTS

All 6 pumps were implanted without complication. Optimal anatomic positioning was found with the pump body inserted 2.4 cm into the left ventricle. Hemodynamics demonstrated stability throughout the 6-hour duration. The pump flow increased from 0.27 to 0.95 liter/min at increasing speeds from 18 to 31 krpm for the low-flow blade design, whereas the pump flow increased from 0.54 liter/min to 1.12 liters/min at increasing speeds from 16 krpm to 31 krpm for the high-flow blade design. At higher speeds, >80% of flow could be supplied by the device. Blood chemistry and final pathology demonstrated no acute organ injury or thrombosis for either blade design.

CONCLUSIONS

The infant Jarvik 2000 heart is anatomically and biologically compatible with an short-term neonate piglet model. This in vivo study demonstrates the future feasibility of this device for clinical use.

Bivalirudin in pediatric patients maintained on extracorporeal life support

OBJECTIVE

Anticoagulation with heparin is standard of care for patients maintained on extracorporeal life support. Very limited evidence exists for the use of alternative anticoagulants during extracorporeal life support. Patients with heparin-induced thrombocytopenia, heparin resistance, and evidence of significant thrombosis while on heparin may be candidates for alternative anticoagulation. The objective of this analysis is to present evidence for the use of bivalirudin during extracorporeal life support in pediatric patients.

DESIGN

Case series.

SETTING

University of California, Davis Medical Center.

PATIENTS

Twelve critically ill, pediatric patients receiving bivalirudin for anticoagulation during extracorporeal life support.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Twelve patients meeting entry criteria received bivalirudin during the study period. The median patient age was 8 days (range, 1 d to 6 yr). Eight patients were neonates. Eight patients were male. Nine patients were supported with venoarterial extracorporeal life support. Median duration of extracorporeal life support was 226 hours (range, 111-913) and median time on bivalirudin was 92 hours (range, 60-230). Bivalirudin bolus doses were administered to select patients without bleeding complications. The maintenance dose that corresponded with initial target activated partial thromboplastin time ranged from 0.045 to 0.48 mg/kg/hr with a median rate of 0.16 mg/kg/hr. The median dose for days 1, 3, and 5 was 0.135, 0.175, and 0.267 mg/kg/hr, respectively. The correlation (r2) between dose adjustment and activated partial thromboplastin time response was 0.264.

CONCLUSIONS

This is the largest case series describing the use of a direct thrombin inhibitor in pediatric extracorporeal life support patients. The maintenance dose range reflected considerable inter-patient variability. There was an observed increase in dose requirements with time. Bivalirudin, with close monitoring, is a potential option for pediatric patients on extracorporeal life support who have developed heparin-induced thrombocytopenia, heparin resistance, or significant thrombosis while on heparin.

Recombinant factor VIIa for uncontrollable bleeding in patients with extracorporeal membrane oxygenation: report on 15 cases and literature review

Introduction

Bleeding is the most frequent complication in patients receiving venoarterial or venovenous extracorporeal membrane oxygenation (ECMO). Recombinant activated factor VII (rFVIIa) has been used in these patients with conflicting results. We describe our experience with rFVIIa for refractory bleeding in this setting and review the cases reported in the literature.

Methods

Clinical characteristics, demographics, bleeding, thrombotic complications, mortality, and rFVIIa administration were retrospectively collected for analysis from the electronic charts of the 15 patients in our intensive care unit who received rFVIIa while being given ECMO from January 2006 to March 2011.

Results

Fifteen patients received rFVIIa for persistent bleeding under venoarterial (n = 11) or venovenous (n = 4) ECMO. Bleeding dramatically decreased in 14 patients, without a major thrombotic event, except in one patient in whom a major stroke could not be ruled out. Two circuits were changed within the 48 hours after rFVIIa administration for clots in the membrane and decreased oxygenation but without massive clotting. The mortality rate was 60%.

Conclusions

rFVIIa use for intractable hemorrhaging in patients receiving ECMO controlled bleeding, without major thrombotic events, and with 60% dying. Hence, its use warrants discussion, and clinicians should be aware of the possibility of potentially life-threatening systemic thrombosis, emboli, or circuit clotting. Whether rFVIIa can save the lives of such patients remains to be determined.