Adsorption of Blood Components to Extracorporeal Membrane Oxygenation (ECMO) Surfaces in Humans: A Systematic Review.

The accumulation of blood proteins and cells on extracorporeal membrane oxygenation (ECMO) circuits has been proposed as a contributing factor to the coagulopathic state of many patients. This systematic review aims to summarize and discuss the existing knowledge of blood components binding to the ECMO circuits in human patients. A systematic review was conducted using the Medline, PubMed and Embase databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Seven studies were included in this review. Three studies identified a leukocyte adhesion, three studies observed von Willebrand factor accumulation and four studies identified bound platelets on the surface of the circuits. Other identified components included fibrin, albumin, hemoglobin, erythrocytes, progenitor cells, fibronectin and IgG. This systematic review demonstrates the limited state of knowledge when it comes to adsorption to the ECMO circuits in humans. Most of the studies lacked insight or detail into the mechanisms of binding and the interactions between different components bound to the ECMO circuits. Further research is required to comprehensively characterize surface adsorption to ECMO circuits in humans and to define the specific mechanisms of binding, enabling improvements that increase biocompatibility between the blood-circuit interface in this important clinical setting.

The Safe Addition of Nitric Oxide into the Sweep Gas of the Extracorporeal Circuit during Cardiopulmonary Bypass and Extracorporeal Life Support.

Low cardiac output syndrome and the systemic inflammatory response are consequences of the cardiac surgical perioperative course. The mechanisms responsible are multifactorial, but recent studies have shown that nitric oxide (NO) may be a key component in mitigating some of these processes. Following on from literature reports detailing the use of inhaled NO added to the gas phase of the extracorporeal circuit, we set about developing a technique to perform this addition safely and efficiently. In the setting of cardiopulmonary bypass, the technique was validated in a randomized prospective trial looking at 198 children. The benefits observed in this trial then stimulated the incorporation of NO into all extracorporeal life support (ECLS) circuits. This required additional hardware modifications all of which were able to be performed safely. Initial results from the first series of ECLS patients using NO also appear promising.

Safety of nitric oxide added to the ECMO circuit: a pilot study in children.

We describe our experience of 30 consecutive children supported with ECMO and receiving 20 ppm of nitric oxide in the oxygenator of the ECMO circuit. Administration of nitric oxide into the ECMO circuit is safe and could potentially mitigate ischaemia reperfusion injury and end-organ dysfunction of children requiring mechanical support.

Cerebral oxygen saturation and tissue hemoglobin concentration as predictive markers of early postoperative outcomes after pediatric cardiac surgery.

BACKGROUND: Near-infrared spectroscopy (NIRS) provides an assessment of cerebral oxygenation and tissue hemoglobin concentration. AIM: The aim of this study was to investigate whether the cerebral oxygenation and hemoglobin concentration measured with NIRS could predict outcomes after pediatric cardiac surgery. METHOD: We conducted a retrospective observational study in 399 patients who underwent pediatric cardiac surgery. Associations were determined between postoperative outcome and preoperative and postoperative cerebral tissue oxygenation index (TOI), postoperative normalized tissue hemoglobin index (nTHI), concentration changes in oxygenated hemoglobin (Δ[HbO2 ]) and deoxygenated hemoglobin (Δ[HHb]). RESULTS: Thirty-nine children had major postoperative morbidity and 12 died. Using Spearman's correlation analysis, postoperative lower TOI and higher Δ[HHb] were associated with longer stays in the Intensive Care Unit (ICU) (r = -0.48, P < 0.001, r = 0.31, P < 0.001, respectively) and longer duration of intubation (r = -0.48, P < 0.001, r = 0.31, P < 0.001, respectively) and higher probability of death determined by the Risk Adjusted Classification for Congenital Heart Surgery (RACHS-1) (r = -0.39, P < 0.001, r = 0.23, P < 0.001, respectively). In multivariate regression analysis, postoperative TOI was independently associated with major morbidity and mortality and Δ[HHb] was independently associated with major morbidity. In receiver operating characteristic analysis, postoperative TOI and Δ[HHb] predicted major morbidity (Area under the curve [AUC] = 0.72, 0.68, respectively) and mortality (AUC = 0.81, 0.69, respectively). CONCLUSION: Lower TOI or higher [HHb] at the end of surgery and higher RACHS-1 category predicted worse outcomes.

Device closure of paravalvular defects following transcatheter aortic valve replacement with the Edwards Sapien valve.

Paravalvular aortic insufficiency (AI) is observed in the majority of patients undergoing transcatheter aortic valve replacement (TAVR). While paravalvular AI is most commonly modest following TAVR, moderate or severe AI was seen in 10.5% and 6.8% of the PARTNER inoperable and high-risk cohorts at 1 year and has been reportedly associated with dyspnea and diminished survival. We report two cases of transcatheter heart valve (THV) associated paravalvular defects closed using catheter delivered devices. Both patients derived hemodynamic and symptomatic improvement from device closure. Additional research is warranted to define the adverse consequences of THV associated AI, indications for treatment, and risks associated with device closure of these defects.

Plasmin generation and fibrinolysis in pediatric patients undergoing cardiopulmonary bypass surgery.

This prospective, single-centre cohort study aimed to evaluate plasmin generation and fibrinolysis during and after cardiopulmonary bypass (CPB) surgery in a cohort of children up to 6 years of age. Blood samples were drawn at eight time points: after induction of anesthesia, before unfractionated heparin (UFH), after UFH, after initiation of bypass, before protamine, after protamine, after chest closure, and 6 h after chest closure. The study identified an increase in fibrinolysis during CPB and particularly up to 6 h afterward in children. This could be the mechanism for the significant bleeding events observed in this young population after CPB. This study establishes the foundation for future studies in this area, particularly those focusing on clinical outcomes after CPB surgery.

The quantitative and qualitative responses of platelets in pediatric patients undergoing cardiopulmonary bypass surgery.

This prospective, single-center study aimed to evaluate the platelet response during cardiopulmonary bypass (CPB) surgery in a large cohort of children up to 6 years of age. Blood samples were drawn at four time points: after induction of anesthesia, after initiation of the CPB, before protamine, and immediately after chest closure. The study recruited 60 children requiring CPB for surgical repair of congenital heart defects. The platelet count decreased throughout CPB surgery, but during the same period, platelet activity increased. The more pronounced decrease in platelet count observed in children younger than 1 year compared with that of children 1 to 6 years of age was not associated with an age-specific change in platelet activity. The overall increase in platelet function observed in this study could provide a mechanism that compensates for the decrease in platelet count. This study provides a new foundation for future studies investigating requirements of platelet supplementation in the setting of pediatric CPB surgery.

Percutaneous closure of a mitral perivalvular leak using three dimensional real time and color flow imaging.

The role of echocardiography, including three-dimensional (3D) echocardiography, during interventional procedures in the cardiac catheterization laboratory is continuing to expand as interventional cardiologists perform more catheter-based interventions. Echocardiography often complements angiographic imaging of cardiac structures and sometimes provides additional information not available by angiography and fluoroscopy. The closure of perivalvular leaks using catheter-based techniques is one of the areas in which 3D echocardiography can be helpful. This case report describes the use of 3D real-time and color flow imaging during the closure of a mitral perivalvular leak. Three-dimensional echocardiography was used to assess the leak prior to intervention and the success of the intervention at the completion of the case.

Design ground motions for seismic retrofit evaluation of large bridges in the Eastern U.S.

Beginning in the mid 1990's, the first seismic retrofit evaluation projects were carried out for large highway bridges in the eastern U.S. We summarize experiences gained from these projects. A major findings is, that while the seismicity rates are often low, and the seismic hazard is moderate, the seismic risk potential can be high in large cities with a large stock of aged structural inventory.First results indicate that retrofit of some portions of some of the investigated bridges would be desirable in order to meet considered seismic perfomance criteria.(AU)