Showing papers by "Robert H. Bartlett published in 2013"

Extracorporeal membrane oxygenation circuitry.

Abstract: The extracorporeal membrane oxygenation circuit is made of a number of components that have been customized to provide adequate tissue oxygen delivery in patients with severe cardiac and/or respiratory failure for a prolonged period of time (days to weeks). A standard extracorporeal membrane oxygenation circuit consists of a mechanical blood pump, gas-exchange device, and a heat exchanger all connected together with circuit tubing. Extracorporeal membrane oxygenation circuits can vary from simple to complex and may include a variety of blood flow and pressure monitors, continuous oxyhemoglobin saturation monitors, circuit access sites, and a bridge connecting the venous access and arterial infusion limbs of the circuit. Significant technical advancements have been made in the equipment available for short- and long-term extracorporeal membrane oxygenation applications. Contemporary extracorporeal membrane oxygenation circuits have greater biocompatibility and allow for more prolonged cardiopulmonary support time while minimizing the procedure-related complications of bleeding, thrombosis, and other physiologic derangements, which were so common with the early application of extracorporeal membrane oxygenation. Modern era extracorporeal membrane oxygenation circuitry and components are simpler, safer, more compact, and can be used across a wide variety of patient sizes from neonates to adults.

In vitro and in vivo study of sustained nitric oxide release coating using diazeniumdiolate-doped poly(vinyl chloride) matrix with poly(lactide-co-glycolide) additive

Abstract: Nitric oxide (NO) is an endogenous vasodilator as well as natural inhibitor of platelet adhesion and activation that can be released from a NO donor species, such as diazeniumdiolated dibutylhexanediamine (DBHD/N2O2) within a polymer coating. In this study, various Food and Drug Administration approved poly(lactic-co-glycolic acid) (PLGA) species were evaluated as additives to promote a prolonged NO release from DBHD/N2O2 within a plasticized poly(vinyl chloride) (PVC) matrix. When using an ester-capped PLGA additive with a slow hydrolysis time, the resulting coatings continuously release between 7 and 18 × 10−10 mol cm−2 min−1 NO for 14 days at 37 °C in PBS buffer. The corresponding pH changes within the polymer films were visualized using pH sensitive indicators and are shown to correlate with the extended NO release pattern. The optimal combined diazeniumdiolate/PLGA-doped NO release (NOrel) PVC coating was evaluated in vitro and its effect on the hemodynamics was also studied within a 4 h in vivo extracorporeal circulation (ECC) rabbit model of thrombogenicity. Four out of 7 control circuits clotted within 3 h, whereas all the NOrel coated circuits were patent after 4 h. Platelet counts on the NOrel ECC were preserved (79 ± 11% compared to 54 ± 6% controls). The NOrel coatings showed a significant decrease in the thrombus area as compared to the controls. Results suggest that by using ester-capped PLGAs as additives to a conventional plasticized PVC material containing lipophilic diazeniumdiolates, the NO release can be prolonged for up to 2 weeks by controlling the pH within the organic phase of the coating.

Prolonged duration ECMO for ARDS: futility, native lung recovery, or transplantation?

Abstract: Extracorporeal membrane oxygenation (ECMO) is recommended as a treatment modality for severe acute respiratory distress syndrome (PaO2/FiO2 ≤ 100 mm Hg with positive end-expiratory pressure ≥ 5 cm H2O) as defined by the Berlin definition. The reported usual duration of ECMO in these patients is 7-10 days. However, increasing reports of prolonged duration ECMO (>14 days) for respiratory failure document survival rates of 50-70% with native lung recovery, and ECMO bridge to lung transplantation has been performed at many centers. At present, there are no established national criteria for when to consider futility or lung transplantation in adult patients requiring ECMO for acute respiratory failure. We report a case of prolonged duration venovenous-ECMO (1,347 hours, 56.13 days), with native lung recovery and discuss treatment strategies to optimize native lung recovery in ECMO patients. The lung may have unexpected regenerative capacity with native lung recovery after prolonged mechanical support, similar to acute kidney injury and native renal recovery. We recommend redefining irreversible lung injury and futility in ECMO.

Effect of air exposure and suction on blood cell activation and hemolysis in an in vitro cardiotomy suction model.

Abstract: Cardiopulmonary bypass (CPB) elicits a systemic inflammatory response. The cause may include surface-induced leukocyte activation and hemolysis. A study was designed to describe the effects of both suction and an air–blood interface independently and in combination on leukocyte and platelet activation, and hemolysis in an in vitro model. Fresh human blood was drawn and tested in four different conditions including control (A), 10 minutes of −600 mm Hg suction (B), 10 minutes of blood exposure to room air at 100 ml/min (C), and 10 minutes of simultaneous suction and air flow (D). Samples were analyzed by flow cytometry (platelets and leukocytes) and plasma-free hemoglobin (PFHb). Leukocyte CD11b expression and platelet P-selectin (CD62P) were analyzed by flow cytometry. In comparison with baseline, granulocytes were significantly activated by air (group C, p = 0.0029) and combination (group D, p = 0.0123) but not by suction alone (group B). Monocytes and platelets were not significantly activated in any group. The PFHb increased significantly in group C (p < 0.001) and group D (p < 0.001). This study suggests that the inflammatory response and associated hemolysis during CPB may be related to air exposure, which could be reduced by minimizing the air exposure of air to blood during cardiotomy suction. ASAIO Journal 2013; 59:474–479.

Fabrication and in vivo thrombogenicity testing of nitric oxide generating artificial lungs

Abstract: Hollow fiber artificial lungs are increasingly being used for long-term applications. However, clot formation limits their use to 1-2 weeks. This study investigated the effect of nitric oxide generating (NOgen) hollow fibers on artificial lung thrombogenicity. Silicone hollow fibers were fabricated to incorporate 50 nm copper particles as a catalyst for NO generation from the blood. Fibers with and without (control) these particles were incorporated into artificial lungs with a 0.1 m2 surface area and inserted in circuits coated tip-to-tip with the NOgen material. Circuits (N=5/each) were attached to rabbits in a pumpless, arterio-venous configuration and run for 4 hrs at an activated clotting time of 350-400s. Three control circuits clotted completely, while none of the NOgen circuits failed. Accordingly, blood flows were significantly higher in the NOgen group (95.9 ± 11.7, p < 0.01) compared to the controls (35.2 ± 19.7) (ml/min), and resistance was significantly higher in the control group after 4 hours (15.38 ± 9.65, p<0.001) than in NOgen (0.09 ± 0.03) (mmHg/mL/min). On the other hand, platelet counts and plasma fibrinogen concentration expressed as percent of baseline in control group (63.7 ± 5.7%, 77.2 ± 5.6% [p<0.05]) were greater than those in the NOgen group (60.4 ± 5.1%, 63.2 ± 3.7%). Plasma copper levels in the NOgen group were 2.8 times baseline at 4 hours (132.8 ± 4.5 μg/dl) and unchanged in the controls. This work demonstrates that NO generating gas exchange fibers could be a potentially effective way to control coagulation inside artificial lungs.

A simple, standard method to characterize pressure/flow performance of vascular access cannulas

Abstract: Vascular access cannulas for extracorporeal life support are characterized by French (Fr) size alone, which affords limited information on pressure (P) and flow (Q) performance, making their selection difficult. Previously, we developed an accurate metric of cannula performance, the M number, but its complexity and the need of a nomogram hindered its utility. We propose adoption of an easier and clinically useful metric to assess cannula performance: Q at 100 mm Hg P, the updated M number, or the "UM number." A circuit was created using a centrifugal pump, Tygon tubing, and a reservoir. A total of 74 cannulas (arterial, venous, and double lumen) ranging from 6 to 50 Fr size were studied. Glycerol solution with a viscosity of 3 cP was used to mimic blood. A Biopac system and ultrasonic flow probe was used to collect P/Q data across a cannula's performance range. The UM number describes the pressure-flow characteristics of any given cannula. It can be used to select access cannulas based on performance and to determine if flow matches expected flow during use.

Reducing time on for extra-corporeal membrane oxygenation for adults with H1N1 pneumonia with the use of the Volume Diffusive Respirator.

Abstract: Background The investigators compared a series of adult survivors of severe H1N1 pneumonia treated with extracorporeal membrane oxygenation (ECMO) with members of the Extracorporeal Life Support Organization registry for patients with H1N1 with regard to ventilator management while on ECMO. Methods Adults who survived ECMO were compared regarding time on ECMO for those treated with the Volume Diffusive Respirator (VDR) or with conventional “lung rest.” The VDR delivered 500 percussions/min, with tidal pressures of 24/12 cm H2O and a fraction of inspired oxygen of .4 at 15 beats/min. Results There were no differences between the study patients (n = 7) and the Extracorporeal Life Support Organization cohort (n = 150) regarding age, pre-ECMO ventilator days, pre-ECMO ratio of partial pressure of oxygen to fraction of inspired oxygen, or survival after lung recovery. Patients treated with VDR required ECMO support for a shorter duration (mean, 193.29 ± 35.71 vs 296.63 ± 18.17 hours; P = .029). Conclusions These data suggest that the VDR enhanced pulmonary recovery from severe H1N1 pneumonia in adults. Shorter times on ECMO may improve the risk/benefit and cost/benefit ratios associated with ECMO care.

Sustained nitric oxide release coating using diazeniumdiolate-doped polymer matrix with ester capped poly(lactic-co-glycolic acid) additive

Abstract: A polymeric composition includes a polymer matrix having a lipophilic discrete nitric oxide adduct and/or a polymeric nitric oxide adduct associated therewith, by covalent attachment to the polymer matrix and/or by dispersion within the polymer matrix, with the discrete nitric oxide adduct and/or the polymeric nitric oxide adduct being capable of releasing nitric oxide (NO). The polymeric composition further includes an ester capped poly(lactide-co-glycolide) (PLGA) additive to at least one of increase, prolong, and control NO release rates from the lipophilic discrete nitric oxide adduct and/or the polymeric nitric oxide adduct.

Long-term animal model of venovenous extracorporeal membrane oxygenation with atrial septal defect as a bridge to lung transplantation

Abstract: This study evaluated the effectiveness of an atrial septal defect (ASD) with venovenous extracorporeal membrane oxygenation (vv-ECMO) as a bridge to transplantation. Sheep (56 ± 3 kg; n = 7) underwent a right-sided thoracotomy to create the ASD (diameter = 1 cm) and place instrumentation and a pulmonary artery (PA) occluder. After recovery, animals were placed on ECMO, and the PA was constricted to generate a twofold rise in right ventricular (RV) systolic pressure. Sheep were then maintained for 60 hours on ECMO, and data were collected hourly. Five sheep survived 60 hours. One sheep died because of a circuit clot extending into the RV, and another died presumably because of an arrhythmia. Mean right ventricular pressure (mRVP) was 19 ± 3 mm Hg at baseline, averaged 27 ± 7 mm Hg over the experiment, but was not statistically significant (p = 0.27) due to one sheep without an increase. Cardiac output was 6.8 ± 1.2 L/min at baseline, averaged 6.0 ± 1.0 L/min during the experiment, and was statistically unchanged (p = 0.34). Average arterial oxygen saturation and PCO2 over the experiment were 96.8 ± 1.4% and 31.8 ± 3.4 mm Hg, respectively. In conclusion, an ASD combined with vv-ECMO maintains normal systemic hemodynamics and arterial blood gases during a long-term increase in RV afterload.

26: association of mortality with hospital-level extracorporeal membrane oxygenation patient volume

Abstract: Introduction: For neonates and children, hospital-level extracorporeal membrane oxygenation (ECMO) volume is associated with probability of mortality. No study has examined total hospital ECMO volume or examined ECMO volume-mortality associations among adult patients. Methods: This study was sponsor

cardiac surgery Outcome of pediatric patients treated with extracorporeal life support after

Abstract: Ann Thorac Surg 2003;76:1435-1441 Ohye, Robert H. Bartlett and Thomas J. Kulik Nikoleta S. Kolovos, Susan L. Bratton, Frank W. Moler, Edward L. Bove, Richard G.cardiac surgery Outcome of pediatric patients treated with extracorporeal life support afterhttp://ats.ctsnetjournals.org/cgi/content/full/76/5/1435 located on the World Wide Web at: The online version of this article, along with updated information and services, is