Machine Perfusion Deters Ischemia-Related Derangement of a Rodent Free Flap: Development of a Model.

Introduction: Machine perfusion can enable isolated support of composite tissues, such as free flaps. The goal of perfusion in this setting is to preserve tissues prior to transplantation or provide transient support at the wound bed. This study aimed to establish a rodent model of machine perfusion in a fasciocutaneous-free flap to serve as an affordable testbed and determine the potential of the developed support protocol to deter ischemia-related metabolic derangement.

Epoxy silane sulfobetaine block copolymers for simple, aqueous thromboresistant coating on ambulatory assist lung devices.

Developing an ambulatory assist lung (AAL) for patients who need continuous extracorporeal membrane oxygenation has been associated with several design objectives, including the design of compact components, optimization of gas transfer efficiency, and reduced thrombogenicity. In an effort to address thrombogenicity concerns with currently utilized component biomaterials, a low molecular weight water soluble siloxane-functionalized zwitterionic sulfobetaine (SB-Si) block copolymer was coated on a full-scale AAL device set via a one pot aqueous circulation coating. All device parts including hollow fiber bundle, housing, tubing and cannular were successfully coated with increasing atomic compositions of the SB block copolymer and the coated surfaces showed a significant reduction of platelet deposition while gas exchange performance was sustained.

Subject-specific factors affecting particle residence time distribution of left atrial appendage in atrial fibrillation: A computational model-based study.

Background: Atrial fibrillation (AF) is a prevalent arrhythmia, that causes thrombus formation, ordinarily in the left atrial appendage (LAA). The conventional metric of stroke risk stratification, CHADS-VASc score, does not account for LAA morphology or hemodynamics. We showed in our previous study that residence time distribution (RTD) of blood-borne particles in the LAA and its associated calculated variables (i.

Design and In Vitro Evaluation of an Artificial Placenta Made From Hollow Fiber Membranes.

For infants born at the border of viability, care practices and morbimortality rates vary widely between centers. Trends show significant improvement, however, with increasing gestational age and weight. For periviable infants, the goal of critical care is to bridge patients to improved outcomes.

Improvement of a Mathematical Model to Predict CO Removal in Hollow Fiber Membrane Oxygenators.

The use of extracorporeal oxygenation and CO removal has gained clinical validity and popularity in recent years. These systems are composed of a pump to drive blood flow through the circuit and a hollow fiber membrane bundle through which gas exchange is achieved. Mathematical modeling of device design is utilized by researchers to improve device hemocompatibility and efficiency.

Effect of Hematocrit on the CO2 Removal Rate of Artificial Lungs.

Extracorporeal CO2 removal (ECCO2R) can permit lung protective or noninvasive ventilation strategies in patients with chronic obstructive pulmonary disease (COPD) and acute respiratory distress syndrome (ARDS). With evidence supporting ECCO2R growing, investigating factors which affect CO2 removal is necessary. Multiple factors are known to affect the CO2 removal rate (vCO2) which can complicate the interpretation of changes in vCO2; however, the effect of hematocrit on the vCO2 of artificial lungs has not been investigated.

Month-long Respiratory Support by a Wearable Pumping Artificial Lung in an Ovine Model.

Background: A wearable artificial lung could improve lung transplantation outcomes by easing implementation of physical rehabilitation during long-term pretransplant respiratory support. The Modular Extracorporeal Lung Assist System (ModELAS) is a compact pumping artificial lung currently under development. This study evaluated the long-term in vivo performance of the ModELAS during venovenous support in awake sheep.

In vivo testing of the low-flow CO removal application of a compact, platform respiratory device.

Background: Non-invasive and lung-protective ventilation techniques may improve outcomes for patients with an acute exacerbation of chronic obstructive pulmonary disease or moderate acute respiratory distress syndrome by reducing airway pressures. These less invasive techniques can fail due to hypercapnia and require transitioning patients to invasive mechanical ventilation. Extracorporeal CO removal devices remove CO independent of the lungs thereby controlling the hypercapnia and permitting non-invasive or lung-protective ventilation techniques.

Respiratory Dialysis-A Novel Low Bicarbonate Dialysate to Provide Extracorporeal CO2 Removal.

Objectives: We designed a novel respiratory dialysis system to remove CO2 from blood in the form of bicarbonate. We aimed to determine if our respiratory dialysis system removes CO2 at rates comparable to low-flow extracorporeal CO2 removal devices (blood flow < 500 mL/min) in a large animal model.

Design: Experimental study.

Blood Recirculation Enhances Oxygenation Efficiency of Artificial Lungs.

Ambulating patients on extracorporeal membrane oxygenation (ECMO) or extracorporeal CO2 removal (ECCO2R) improves outcomes. These systems would further simplify ambulation if made more compact. This study investigates blood recirculation to decrease device size by increasing efficiency.

Carbon dioxide removal using low bicarbonate dialysis in rodents.

Background: Extracorporeal carbon dioxide removal may be used to manage hypercapnia, but compared to dialysis, it's not widely available. A recent study showed that dialysis with low bicarbonate dialysates removes CO.

Objective: To show that bicarbonate dialysis removes CO in an animal model to validate findings and quantify the effect on arterial pH.

Acute In Vivo Evaluation of the Pittsburgh Pediatric Ambulatory Lung.

Respiratory failure is a significant problem within the pediatric population. A means of respiratory support that readily allows ambulation could improve treatment. The Pittsburgh Pediatric Ambulatory Lung (P-PAL) is being developed as a wearable pediatric pump-lung for long-term respiratory support and has previously demonstrated positive benchtop results.

A Proof of Concept Study, Demonstrating Extracorporeal Carbon Dioxide Removal Using Hemodialysis with a Low Bicarbonate Dialysate.

Extracorporeal carbon dioxide removal (ECCO2R) devices remove CO2 directly from blood, facilitating ultraprotective ventilation or even providing an alternative to mechanical ventilation. However, ECCO2R is not widely available, whereas dialysis is available in most intensive care units (ICUs). Prior attempts to provide ECCO2R with dialysis, by removing CO2 in the form of bicarbonate, have been plagued by metabolic acidosis.

Bench Validation of a Compact Low-Flow CO Removal Device.

Background: There is increasing evidence demonstrating the value of partial extracorporeal CO removal (ECCOR) for the treatment of hypercapnia in patients with acute exacerbations of chronic obstructive pulmonary disease and acute respiratory distress syndrome. Mechanical ventilation has traditionally been used to treat hypercapnia in these patients, however, it has been well-established that aggressive ventilator settings can lead to ventilator-induced lung injury. ECCOR removes CO independently of the lungs and has been used to permit lung protective ventilation to prevent ventilator-induced lung injury, prevent intubation, and aid in ventilator weaning.

Time course of red blood cell intracellular pH recovery following short-circuiting in relation to venous transit times in rainbow trout, Oncorhynchus mykiss.

Accumulating evidence is highlighting the importance of a system of enhanced hemoglobin-oxygen (Hb-O) unloading for cardiovascular O transport in teleosts. Adrenergically stimulated sodium-proton exchangers (β-NHE) create H gradients across the red blood cell (RBC) membrane that are short-circuited in the presence of plasma-accessible carbonic anhydrase (paCA) at the tissues; the result is a large arterial-venous pH shift that greatly enhances O unloading from pH-sensitive Hb. However, RBC intracellular pH (pH) must recover during venous transit (31-90 s) to enable O loading at the gills.

Effects of Hollow Fiber Membrane Oscillation on an Artificial Lung.

Gas transfer through hollow fiber membranes (HFMs) can be increased via fiber oscillation. Prior work, however, does not directly translate to present-day, full-scale artificial lungs. This in vitro study characterized the effects of HFM oscillations on oxygenation and hemolysis for a pediatric-sized HFM bundle.

Development of zwitterionic sulfobetaine block copolymer conjugation strategies for reduced platelet deposition in respiratory assist devices.

Respiratory assist devices, that utilize ∼2 m of hollow fiber membranes (HFMs) to achieve desired gas transfer rates, have been limited in their adoption due to such blood biocompatibility limitations. This study reports two techniques for the functionalization and subsequent conjugation of zwitterionic sulfobetaine (SB) block copolymers to polymethylpentene (PMP) HFM surfaces with the intention of reducing thrombus formation in respiratory assist devices. Amine or hydroxyl functionalization of PMP HFMs (PMP-A or PMP-H) was accomplished using plasma-enhanced chemical vapor deposition.

In Vivo 5 Day Animal Studies of a Compact, Wearable Pumping Artificial Lung.

Recent studies show improved outcomes in ambulated lung failure patients. Ambulation still remains a challenge in these patients. This necessitates development of more compact and less cumbersome respiratory support specifically designed to be wearable.

In Vitro Characterization of the Pittsburgh Pediatric Ambulatory Lung.

Acute and chronic respiratory failure are a significant source of pediatric morbidity and mortality. Current respiratory support options used to bridge children to lung recovery or transplantation typically render them bedridden and can worsen long-term patient outcomes. The Pittsburgh Pediatric Ambulatory Lung (P-PAL) is a wearable pediatric blood pump and oxygenator (0.

An extracorporeal carbon dioxide removal (ECCOR) device operating at hemodialysis blood flow rates.

Background: Extracorporeal carbon dioxide removal (ECCOR) systems have gained clinical appeal as supplemental therapy in the treatment of acute and chronic respiratory injuries with low tidal volume or non-invasive ventilation. We have developed an ultra-low-flow ECCOR device (ULFED) capable of operating at blood flows comparable to renal hemodialysis (250 mL/min). Comparable operating conditions allow use of minimally invasive dialysis cannulation strategies with potential for direct integration to existing dialysis circuitry.

Extracorporeal CO removal by hemodialysis: in vitro model and feasibility.

Background: Critically ill patients with acute respiratory distress syndrome and acute exacerbations of chronic obstructive pulmonary disease often develop hypercapnia and require mechanical ventilation. Extracorporeal carbon dioxide removal can manage hypercarbia by removing carbon dioxide directly from the bloodstream. Respiratory hemodialysis uses traditional hemodialysis to remove CO from the blood, mainly as bicarbonate.

In vitro and in vivo evaluation of a novel integrated wearable artificial lung.

Background: Conventional extracorporeal membrane oxygenation (ECMO) is cumbersome and is associated with high morbidity and mortality. We are currently developing the Pittsburgh Ambulatory Assist Lung (PAAL), which is designed to allow for ambulation of lung failure patients during bridge to transplant or recovery. In this study, we investigated the in vitro and acute in vivo performance of the PAAL.

Fiber Bundle Design for an Integrated Wearable Artificial Lung.

Mechanical ventilation (MV) and extracorporeal membrane oxygenation (ECMO) are the only viable treatment options for lung failure patients at the end-stage, including acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD). These treatments, however, are associated with high morbidity and mortality because of long wait times for lung transplant. Contemporary clinical literature has shown ambulation improves post-transplant outcomes in lung failure patients.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016.

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].