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Akif Ündar - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of two femoral arterial Cannulae with conventional non pulsatile and alternative pulsatile flow in a simulated adult ecls circuit
    Artificial Organs, 2019
    Co-Authors: Shigang Wang, Madison Force, Christoph Brehm, Allen R. Kunselman, Akif Ündar
    Abstract:

    The objective of this study is to evaluate the hemodynamic characteristics of two femoral arterial Cannulae in terms of circuit pressure, pressure drop, and hemodynamic energy transmission under non-pulsatile and pulsatile modes in a simulated adult extracorporeal life support (ECLS) system. The ECLS circuit consisted of i-cor diagonal pump and console (Xenios AG, Heilbronn, Germany), an iLA membrane ventilator (Xenios AG), an 18 Fr or 16 Fr femoral arterial cannula (Xenios AG), and a 23/25 Fr Estech remote access perfusion (RAP) femoral venous cannula (San Ramon, CA, USA). The circuit was primed with lactated Ringer's solution and packed red blood cells to achieve a hematocrit of 35%. All trials were conducted at room temperature with flow rates of 1-4 L/min (1 L/min increments). The pulsatile flow settings were set at pulsatile frequency of 75 bpm and pulsatile amplitudes of 1000-4000 rpm (1000 rpm increments). Flow and pressure data were collected using a custom data acquisition system. Total hemodynamic energy (THE) is calculated by multiplying the ratio between the area under the hemodynamic power curve (∫flow × pressure dt) and the area under the pump flow curve (∫flow dt) by 1332. The pressure drop across the arterial cannula increased with increasing flow rate and decreasing cannula size. The pressure drops of 18 Fr and 16 Fr Cannulae were 19.4-24.5 and 38.4-45.3 mm Hg at 1 L/min, 55.2-56.8 and 110.9-118.3 mm Hg at 2 L/min, 94.1-105.1 and 209.7-215.1 mm Hg at 3 L/min, and 169.2-172.6 and 376.4 mm Hg at 4 L/min, respectively. Pulsatile flow created more hemodynamic energy than non-pulsatile flow, especially at lower flow rates. The percentages of THE loss across 18 Fr and 16 Fr cannula were 16.0-18.7 and 27.5-30.8% at 1 L/min, 35.1-35.7 and 52.3-53.8% at 2 L/min, 48.3-50.3 and 67.3-68.4% at 3 L/min and 62.9-63.1 and 79.0% at 4 L/min. The hemodynamic performance of the arterial cannula should be evaluated before use in clinical practice. The pressure drops and percentages of THE loss across two Cannulae tested using human blood were higher compared to the manufacturer's data tested using water. The cannula size should be chosen to match the expected flow rate. In addition, this novel i-cor ECLS system can provide non-pulsatile and ECG-synchronized pulsatile flow without significantly increasing the cannula pressure drop and hemodynamic energy loss.

  • Hemodynamic Evaluation of Avalon Elite Bi-Caval Dual Lumen Cannulas and Femoral Arterial Cannulas.
    Artificial Organs, 2018
    Co-Authors: Shigang Wang, Madison Force, David A. Palanzo, Christoph Brehm, Allen R. Kunselman, Akif Ündar
    Abstract:

    : Translational research is a useful tool to provide scientific evidence for cannula selection during extracorporeal life support (ECLS). The objective of this study was to evaluate four Avalon Elite bi-caval dual lumen cannulas and nine femoral arterial cannulas in terms of flow range, circuit pressure, pressure drop, and hemodynamic energy transmission in a simulated adult ECLS model. A veno-venous ECLS circuit was used to evaluate four Avalon Elite bi-caval dual lumen cannulas (20, 23, 27, and 31 Fr), and a veno-arterial ECLS circuit was used to evaluate nine femoral arterial cannulas (15, 17, 19, 21, and 23 Fr). The two circuits included a Rotaflow centrifugal pump, a Quadrox-D adult oxygenator, and 3/8 in ID tubing for arterial and venous lines. The circuits were primed with lactated Ringer's solution and packed human red blood cells (hematocrit 40%). Trials were conducted at rotational speeds from 1000 to 5000 RPM (250 rpm increments) for each Avalon cannula, and at different flow rates (0.5-7 L/min) for each femoral arterial cannula. Real-time pressure and flow data were recorded for analysis. Small caliber cannulas created higher circuit pressures, higher pressure drops and higher M-numbers compared with large ones. The inflow side of Avalon dual lumen cannula had a significantly higher pressure drop than the outflow side (inflow vs. outflow: 20 Fr-100.2 vs. 49.2 mm Hg at 1.1 L/min, 23 Fr-93.7 vs. 41.4 mm Hg at 1.6 L/min, 27 Fr-102.3 vs. 42.8 mm Hg at 2.6 L/min, 31 Fr-98.1 vs. 44.7 mm Hg at 3.8 L/min). There was more hemodynamic energy lost in the veno-arterial ECLS circuit using small cannulas compared to larger ones (17 Fr vs. 19 Fr vs. 21 Fr at 4 L/min-Medtronic: 71.0 vs. 64.8 vs. 60.9%; Maquet: 71.4 vs. 65.6 vs. 62.0%). Medtronic femoral arterial cannulas had lower pressure drops (Medtronic vs. Maquet at 4 L/min: 17 Fr-121.7 vs. 125.0 mm Hg, 19 Fr-71.2 vs. 73.7 mm Hg, 21 Fr-42.9 vs. 47.4 mm Hg) and hemodynamic energy losses (Medtronic vs. Maquet at 4 L/min: 17 Fr-43.6 vs. 44.4%, 19 Fr-31.0 vs. 31.4%, 21 Fr-20.8 vs. 22.4%) at high flow rates when compared with the Maquet Cannulae. The results for this study provided valuable hemodynamic characteristics of all evaluated adult cannulas with human blood in order to guide ECLS cannula selection in clinical practice. Use of larger cannulas are suggested for VV- and VA-ECLS.

  • Characterization of neonatal aortic cannula jet flow regimes for improved cardiopulmonary bypass.
    2018
    Co-Authors: Prahlad G. Menon, Akif Ündar, Nikola C. Teslovich, Chia-yuan Chen, Kerem Pekkan
    Abstract:

    During pediatric and neonatal cardiopulmonary bypass (CPB), tiny aortic outflow Cannulae (2-3 mm inner diameter), with micro-scale blood-wetting features transport relatively large blood volumes (0.3 to 1.0 L/min) resulting in high blood flow velocities (2 to 5 m/s). These severe flow conditions are likely to complement platelet activation, release pro-inflammatory cytokines, and further result in vascular and blood damage. Hemodynamically efficient aortic outflow Cannulae are required to provide high blood volume flow rates at low exit force. In addition, optimal aortic insertion strategies are necessary in order to alleviate hemolytic risk, post-surgical neurological complications and developmental defects, by improving cerebral perfusion in the young patient. The methodology and results presented in this study serve as a baseline for design of superior aortic outflow Cannulae. In this study, direct numerical simulation (DNS) computational fluid dynamics (CFD) was employed to delineate baseline hemodynamic performance of jet wakes emanating from microCT scanned state-of-the-art pediatric cannula tips in a cuboidal test rig operating at physiologically relevant laminar and turbulent Reynolds numbers (Re: 650-2150 , steady inflow). Qualitative and quantitative validation of CFD simulated device-specific jet wakes was established using time-resolved flow visualization and particle image velocimetry (PIV). For the standard end-hole cannula tip design, blood damage indices were further numerically assessed in a subject-specific cross-clamped neonatal aorta model for different cannula insertion configurations. Based on these results, a novel diffuser type cannula tip is proposed for improved jet flow-control, decreased blood damage and exit force and increased permissible flow rates. This study also suggests that surgically relevant cannula orientation parameters such as outflow angle and insertion depth may be important for improved hemodynamic performance. The jet flow design paradigm demonstrated in this study represents a philosophical shift towards cannula flow control enabling favorable pressure-drop versus outflow rate characteristics.

  • in vitro hemodynamic evaluation of five 6 fr and 8 fr arterial Cannulae in simulated neonatal cardiopulmonary bypass circuits
    Artificial Organs, 2016
    Co-Authors: Shigang Wang, David A. Palanzo, Allen R. Kunselman, Akif Ündar
    Abstract:

    The objective of this study was to evaluate five small-bore arterial Cannulae (6Fr and 8Fr) in terms of pressure drop and hemodynamic performance in simulated neonatal cardiopulmonary bypass (CPB) circuits. The experimental circuits consisted of a Jostra HL-20 roller pump, a Terumo Capiox Baby FX05 oxygenator with integrated arterial filter, an arterial and a venous tubing (1/4, 3/16, or 1/8 in × 150 cm), and an arterial cannula (Medtronic Bio-Medicus 6Fr and 8Fr, Maquet 6Fr and 8Fr, or RMI Edwards 8Fr). The circuit was primed using lactated Ringer's solution and heparinized packed human red blood cells (hematocrit 30%). Trials were conducted at different flow rates (6Fr: 200-400 mL/min; 8Fr: 200-600 mL/min) and temperatures (35 and 28°C). Flow and pressure data were collected using a custom-based data acquisition system. Higher circuit pressure, circuit pressure drop, and hemodynamic energy loss across the circuit were recorded when using small-bore arterial cannula and small inner diameter arterial tubing in a neonatal CPB circuit. The maximum preoxygenator pressures reached 449.7 ± 1.0 mm Hg (Maquet 6Fr at 400 mL/min), and 395.7 ± 0.4 mm Hg (DLP 8Fr at 600 mL/min) when using 1/8 in ID arterial tubing at 28°C. Hypothermia further increased circuit pressure drop and hemodynamic energy loss. Compared with the others, the RMI 8Fr arterial cannula had significantly lower pressure drop and energy loss. Maquet 6Fr arterial cannula had a greater pressure drop than the DLP 6Fr. A small-bore arterial cannula and arterial tubing created high circuit pressure drop and hemodynamic energy loss. Appropriate arterial cannula and arterial tubing should be considered to match the expected flow rate. Larger cannula and tubing are recommended for neonatal CPB. Low-resistance neonatal arterial Cannulae need to be developed.

  • computational modeling of neonatal cardiopulmonary bypass hemodynamics with full circle of willis anatomy
    Artificial Organs, 2015
    Co-Authors: Senol Piskin, Kerem Pekkan, Akif Ündar
    Abstract:

    Cardiopulmonary bypass (CPB) procedure is employed to repair most congenital heart defects (CHD). Cannulation is a critical component of this procedure where the location and diameter of cannula controls the hemodynamic performance. State-of-the-art computational studies of neonatal CPB employed an isolated aortic arch region by truncating the three-dimensional (3D) patient-specific cerebral system. The present work expanded these studies where the 3D patient-specific MRI reconstruction of the cerebral system, including the Circle of Willis (CoW), is integrated with a hypoplastic neonatal aortic arch. The inlet of the arterial cannula is assigned a steady velocity boundary condition of the CPB pump, while all outlets are modeled as resistance boundary conditions, thus allowing acute comparisons between different cannula configurations. Three-dimensional (3D) flow simulations in the aortic arch model are performed at a Reynolds number of 2150 using an experimentally validated commercial solver. Results demonstrate that the inclusion of 3D CoW is essential to predict the accurate head-neck blood perfusion and therefore critical in deciding the neonatal aortic cannulation strategy preoperatively. Using this integrated model two CPB configurations are studied, where the cannulas were placed at innominate artery (IA) (IA-cannula configuration) and ductus arteriosus (DA) (DA-cannula configuration). Configuration change produced significant differences in flow splits and local hemodynamics of blood flow throughout the whole aortic arch, neck and cerebral arteries. Percent flow rate differences between the IA- and DA-cannula configurations are computed to be: 19%, for descending aorta, 198% for ascending aorta (perfusing coronary arteries), 91% for right anterior cerebral artery, and 68% for left anterior cerebral artery. Another important finding is the retrograde flow at vertebral arteries for IA-cannula configuration, but not for DA-cannula. These results may help to translate better neonatal arterial Cannulae design for minimizing cerebral complications during CPB procedures.

David A. Palanzo - One of the best experts on this subject based on the ideXlab platform.

  • Hemodynamic Evaluation of Avalon Elite Bi-Caval Dual Lumen Cannulas and Femoral Arterial Cannulas.
    Artificial Organs, 2018
    Co-Authors: Shigang Wang, Madison Force, David A. Palanzo, Christoph Brehm, Allen R. Kunselman, Akif Ündar
    Abstract:

    : Translational research is a useful tool to provide scientific evidence for cannula selection during extracorporeal life support (ECLS). The objective of this study was to evaluate four Avalon Elite bi-caval dual lumen cannulas and nine femoral arterial cannulas in terms of flow range, circuit pressure, pressure drop, and hemodynamic energy transmission in a simulated adult ECLS model. A veno-venous ECLS circuit was used to evaluate four Avalon Elite bi-caval dual lumen cannulas (20, 23, 27, and 31 Fr), and a veno-arterial ECLS circuit was used to evaluate nine femoral arterial cannulas (15, 17, 19, 21, and 23 Fr). The two circuits included a Rotaflow centrifugal pump, a Quadrox-D adult oxygenator, and 3/8 in ID tubing for arterial and venous lines. The circuits were primed with lactated Ringer's solution and packed human red blood cells (hematocrit 40%). Trials were conducted at rotational speeds from 1000 to 5000 RPM (250 rpm increments) for each Avalon cannula, and at different flow rates (0.5-7 L/min) for each femoral arterial cannula. Real-time pressure and flow data were recorded for analysis. Small caliber cannulas created higher circuit pressures, higher pressure drops and higher M-numbers compared with large ones. The inflow side of Avalon dual lumen cannula had a significantly higher pressure drop than the outflow side (inflow vs. outflow: 20 Fr-100.2 vs. 49.2 mm Hg at 1.1 L/min, 23 Fr-93.7 vs. 41.4 mm Hg at 1.6 L/min, 27 Fr-102.3 vs. 42.8 mm Hg at 2.6 L/min, 31 Fr-98.1 vs. 44.7 mm Hg at 3.8 L/min). There was more hemodynamic energy lost in the veno-arterial ECLS circuit using small cannulas compared to larger ones (17 Fr vs. 19 Fr vs. 21 Fr at 4 L/min-Medtronic: 71.0 vs. 64.8 vs. 60.9%; Maquet: 71.4 vs. 65.6 vs. 62.0%). Medtronic femoral arterial cannulas had lower pressure drops (Medtronic vs. Maquet at 4 L/min: 17 Fr-121.7 vs. 125.0 mm Hg, 19 Fr-71.2 vs. 73.7 mm Hg, 21 Fr-42.9 vs. 47.4 mm Hg) and hemodynamic energy losses (Medtronic vs. Maquet at 4 L/min: 17 Fr-43.6 vs. 44.4%, 19 Fr-31.0 vs. 31.4%, 21 Fr-20.8 vs. 22.4%) at high flow rates when compared with the Maquet Cannulae. The results for this study provided valuable hemodynamic characteristics of all evaluated adult cannulas with human blood in order to guide ECLS cannula selection in clinical practice. Use of larger cannulas are suggested for VV- and VA-ECLS.

  • in vitro hemodynamic evaluation of five 6 fr and 8 fr arterial Cannulae in simulated neonatal cardiopulmonary bypass circuits
    Artificial Organs, 2016
    Co-Authors: Shigang Wang, David A. Palanzo, Allen R. Kunselman, Akif Ündar
    Abstract:

    The objective of this study was to evaluate five small-bore arterial Cannulae (6Fr and 8Fr) in terms of pressure drop and hemodynamic performance in simulated neonatal cardiopulmonary bypass (CPB) circuits. The experimental circuits consisted of a Jostra HL-20 roller pump, a Terumo Capiox Baby FX05 oxygenator with integrated arterial filter, an arterial and a venous tubing (1/4, 3/16, or 1/8 in × 150 cm), and an arterial cannula (Medtronic Bio-Medicus 6Fr and 8Fr, Maquet 6Fr and 8Fr, or RMI Edwards 8Fr). The circuit was primed using lactated Ringer's solution and heparinized packed human red blood cells (hematocrit 30%). Trials were conducted at different flow rates (6Fr: 200-400 mL/min; 8Fr: 200-600 mL/min) and temperatures (35 and 28°C). Flow and pressure data were collected using a custom-based data acquisition system. Higher circuit pressure, circuit pressure drop, and hemodynamic energy loss across the circuit were recorded when using small-bore arterial cannula and small inner diameter arterial tubing in a neonatal CPB circuit. The maximum preoxygenator pressures reached 449.7 ± 1.0 mm Hg (Maquet 6Fr at 400 mL/min), and 395.7 ± 0.4 mm Hg (DLP 8Fr at 600 mL/min) when using 1/8 in ID arterial tubing at 28°C. Hypothermia further increased circuit pressure drop and hemodynamic energy loss. Compared with the others, the RMI 8Fr arterial cannula had significantly lower pressure drop and energy loss. Maquet 6Fr arterial cannula had a greater pressure drop than the DLP 6Fr. A small-bore arterial cannula and arterial tubing created high circuit pressure drop and hemodynamic energy loss. Appropriate arterial cannula and arterial tubing should be considered to match the expected flow rate. Larger cannula and tubing are recommended for neonatal CPB. Low-resistance neonatal arterial Cannulae need to be developed.

  • hemodynamic evaluation of the avalon elite bi caval dual lumen Cannulae
    Artificial Organs, 2011
    Co-Authors: Feng Qiu, David A. Palanzo, John L Myers, Larry D Baer, Akif Ündar
    Abstract:

    In previous studies, we have evaluated the hemodynamic properties of selected oxygenators, pumps (centrifugal and roller), and single lumen Cannulae. Because the dual lumen Cannulae are widely used in veno-venous extracorporeal life support (ECLS) and are receiving popularity due to their advantages over the single lumen Cannulae, we evaluated the flow ranges and pressure drops of three different sizes of Avalon Elite dual lumen Cannulae (13Fr, 16Fr, and 19Fr) in a simulated neonatal ECLS circuit primed with human blood. The experimental ECLS circuit was composed of a RotaFlow centrifugal pump, a Capiox BabyRX05 oxygenator, 3 ft of 1/4-in venous and arterial line tubing, an Avalon Elite dual lumen cannula, and a soft reservoir as a pseudo-right atrium. All experiments were conducted at 37°C using an HCU 30 heater-cooling unit and with human blood at a hematocrit of 36%. The blood pressure in the pseudo-right atrium was continuously monitored and maintained at 4-5 mm Hg. For each cannula, pump flow rates and pressures at both the arterial and venous sides were recorded at revolutions per minute (RPMs) from 1750 to 3750 in 250 intervals. For each RPM, six data sets were recorded for a total of 162 data sets. The total volume of the system was 300 mL. The flow range for the 13Fr, 16Fr, and 19Fr Cannulae were from 228 to 762 mL/min, 478 to 1254 mL/min, and 635 to 1754 mL/min, respectively. The pressure drops at the arterial side were higher than the venous side at all tested conditions except at 1750 rpm for the 19Fr cannula. The results of this study showed the flow ranges and the pressure drops of three different sized dual lumen Cannulae using human blood, which is more applicable in clinical settings compared with evaluations using water.

Shigang Wang - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of two femoral arterial Cannulae with conventional non pulsatile and alternative pulsatile flow in a simulated adult ecls circuit
    Artificial Organs, 2019
    Co-Authors: Shigang Wang, Madison Force, Christoph Brehm, Allen R. Kunselman, Akif Ündar
    Abstract:

    The objective of this study is to evaluate the hemodynamic characteristics of two femoral arterial Cannulae in terms of circuit pressure, pressure drop, and hemodynamic energy transmission under non-pulsatile and pulsatile modes in a simulated adult extracorporeal life support (ECLS) system. The ECLS circuit consisted of i-cor diagonal pump and console (Xenios AG, Heilbronn, Germany), an iLA membrane ventilator (Xenios AG), an 18 Fr or 16 Fr femoral arterial cannula (Xenios AG), and a 23/25 Fr Estech remote access perfusion (RAP) femoral venous cannula (San Ramon, CA, USA). The circuit was primed with lactated Ringer's solution and packed red blood cells to achieve a hematocrit of 35%. All trials were conducted at room temperature with flow rates of 1-4 L/min (1 L/min increments). The pulsatile flow settings were set at pulsatile frequency of 75 bpm and pulsatile amplitudes of 1000-4000 rpm (1000 rpm increments). Flow and pressure data were collected using a custom data acquisition system. Total hemodynamic energy (THE) is calculated by multiplying the ratio between the area under the hemodynamic power curve (∫flow × pressure dt) and the area under the pump flow curve (∫flow dt) by 1332. The pressure drop across the arterial cannula increased with increasing flow rate and decreasing cannula size. The pressure drops of 18 Fr and 16 Fr Cannulae were 19.4-24.5 and 38.4-45.3 mm Hg at 1 L/min, 55.2-56.8 and 110.9-118.3 mm Hg at 2 L/min, 94.1-105.1 and 209.7-215.1 mm Hg at 3 L/min, and 169.2-172.6 and 376.4 mm Hg at 4 L/min, respectively. Pulsatile flow created more hemodynamic energy than non-pulsatile flow, especially at lower flow rates. The percentages of THE loss across 18 Fr and 16 Fr cannula were 16.0-18.7 and 27.5-30.8% at 1 L/min, 35.1-35.7 and 52.3-53.8% at 2 L/min, 48.3-50.3 and 67.3-68.4% at 3 L/min and 62.9-63.1 and 79.0% at 4 L/min. The hemodynamic performance of the arterial cannula should be evaluated before use in clinical practice. The pressure drops and percentages of THE loss across two Cannulae tested using human blood were higher compared to the manufacturer's data tested using water. The cannula size should be chosen to match the expected flow rate. In addition, this novel i-cor ECLS system can provide non-pulsatile and ECG-synchronized pulsatile flow without significantly increasing the cannula pressure drop and hemodynamic energy loss.

  • Hemodynamic Evaluation of Avalon Elite Bi-Caval Dual Lumen Cannulas and Femoral Arterial Cannulas.
    Artificial Organs, 2018
    Co-Authors: Shigang Wang, Madison Force, David A. Palanzo, Christoph Brehm, Allen R. Kunselman, Akif Ündar
    Abstract:

    : Translational research is a useful tool to provide scientific evidence for cannula selection during extracorporeal life support (ECLS). The objective of this study was to evaluate four Avalon Elite bi-caval dual lumen cannulas and nine femoral arterial cannulas in terms of flow range, circuit pressure, pressure drop, and hemodynamic energy transmission in a simulated adult ECLS model. A veno-venous ECLS circuit was used to evaluate four Avalon Elite bi-caval dual lumen cannulas (20, 23, 27, and 31 Fr), and a veno-arterial ECLS circuit was used to evaluate nine femoral arterial cannulas (15, 17, 19, 21, and 23 Fr). The two circuits included a Rotaflow centrifugal pump, a Quadrox-D adult oxygenator, and 3/8 in ID tubing for arterial and venous lines. The circuits were primed with lactated Ringer's solution and packed human red blood cells (hematocrit 40%). Trials were conducted at rotational speeds from 1000 to 5000 RPM (250 rpm increments) for each Avalon cannula, and at different flow rates (0.5-7 L/min) for each femoral arterial cannula. Real-time pressure and flow data were recorded for analysis. Small caliber cannulas created higher circuit pressures, higher pressure drops and higher M-numbers compared with large ones. The inflow side of Avalon dual lumen cannula had a significantly higher pressure drop than the outflow side (inflow vs. outflow: 20 Fr-100.2 vs. 49.2 mm Hg at 1.1 L/min, 23 Fr-93.7 vs. 41.4 mm Hg at 1.6 L/min, 27 Fr-102.3 vs. 42.8 mm Hg at 2.6 L/min, 31 Fr-98.1 vs. 44.7 mm Hg at 3.8 L/min). There was more hemodynamic energy lost in the veno-arterial ECLS circuit using small cannulas compared to larger ones (17 Fr vs. 19 Fr vs. 21 Fr at 4 L/min-Medtronic: 71.0 vs. 64.8 vs. 60.9%; Maquet: 71.4 vs. 65.6 vs. 62.0%). Medtronic femoral arterial cannulas had lower pressure drops (Medtronic vs. Maquet at 4 L/min: 17 Fr-121.7 vs. 125.0 mm Hg, 19 Fr-71.2 vs. 73.7 mm Hg, 21 Fr-42.9 vs. 47.4 mm Hg) and hemodynamic energy losses (Medtronic vs. Maquet at 4 L/min: 17 Fr-43.6 vs. 44.4%, 19 Fr-31.0 vs. 31.4%, 21 Fr-20.8 vs. 22.4%) at high flow rates when compared with the Maquet Cannulae. The results for this study provided valuable hemodynamic characteristics of all evaluated adult cannulas with human blood in order to guide ECLS cannula selection in clinical practice. Use of larger cannulas are suggested for VV- and VA-ECLS.

  • in vitro hemodynamic evaluation of five 6 fr and 8 fr arterial Cannulae in simulated neonatal cardiopulmonary bypass circuits
    Artificial Organs, 2016
    Co-Authors: Shigang Wang, David A. Palanzo, Allen R. Kunselman, Akif Ündar
    Abstract:

    The objective of this study was to evaluate five small-bore arterial Cannulae (6Fr and 8Fr) in terms of pressure drop and hemodynamic performance in simulated neonatal cardiopulmonary bypass (CPB) circuits. The experimental circuits consisted of a Jostra HL-20 roller pump, a Terumo Capiox Baby FX05 oxygenator with integrated arterial filter, an arterial and a venous tubing (1/4, 3/16, or 1/8 in × 150 cm), and an arterial cannula (Medtronic Bio-Medicus 6Fr and 8Fr, Maquet 6Fr and 8Fr, or RMI Edwards 8Fr). The circuit was primed using lactated Ringer's solution and heparinized packed human red blood cells (hematocrit 30%). Trials were conducted at different flow rates (6Fr: 200-400 mL/min; 8Fr: 200-600 mL/min) and temperatures (35 and 28°C). Flow and pressure data were collected using a custom-based data acquisition system. Higher circuit pressure, circuit pressure drop, and hemodynamic energy loss across the circuit were recorded when using small-bore arterial cannula and small inner diameter arterial tubing in a neonatal CPB circuit. The maximum preoxygenator pressures reached 449.7 ± 1.0 mm Hg (Maquet 6Fr at 400 mL/min), and 395.7 ± 0.4 mm Hg (DLP 8Fr at 600 mL/min) when using 1/8 in ID arterial tubing at 28°C. Hypothermia further increased circuit pressure drop and hemodynamic energy loss. Compared with the others, the RMI 8Fr arterial cannula had significantly lower pressure drop and energy loss. Maquet 6Fr arterial cannula had a greater pressure drop than the DLP 6Fr. A small-bore arterial cannula and arterial tubing created high circuit pressure drop and hemodynamic energy loss. Appropriate arterial cannula and arterial tubing should be considered to match the expected flow rate. Larger cannula and tubing are recommended for neonatal CPB. Low-resistance neonatal arterial Cannulae need to be developed.

Shaun D Gregory - One of the best experts on this subject based on the ideXlab platform.

  • numerical prediction of thrombus risk in an anatomically dilated left ventricle the effect of inflow cannula designs
    Biomedical Engineering Online, 2016
    Co-Authors: Sam Liao, Benjamin Simpson, Michael Neidlin, Maria A Woodruff, Tim A S Kaufmann, Zhiyong Li, Shaun D Gregory
    Abstract:

    Implantation of a rotary blood pump (RBP) can cause non-physiological flow fields in the left ventricle (LV) which may trigger thrombosis. Different inflow cannula geometry can affect LV flow fields. The aim of this study was to determine the effect of inflow cannula geometry on intraventricular flow under full LV support in a patient specific model. Computed tomography angiography imaging of the LV was performed on a RBP candidate to develop a patient-specific model. Five inflow Cannulae were evaluated, which were modelled on those used clinically or under development. The inflow Cannulae are described as a crown like tip, thin walled tubular tip, large filleted tip, trumpet like tip and an inferiorly flared cannula. Placement of the inflow cannula was at the LV apex with the central axis intersecting the centre of the mitral valve. Full support was simulated by prescribing 5 l/min across the mitral valve. Thrombus risk was evaluated by identifying regions of stagnation. Rate of LV washout was assessed using a volume of fluid model. Relative haemolysis index and blood residence time was calculated using an Eulerian approach. The inferiorly flared inflow cannula had the lowest thrombus risk due to low stagnation volumes. All Cannulae had similar rates of LV washout and blood residence time. The crown like tip and thin walled tubular tip resulted in relatively higher blood damage indices within the LV. Changes in intraventricular flow due to variances in cannula geometry resulted in different stagnation volumes. Cannula geometry does not appreciably affect LV washout rates and blood residence time. The patient specific, full support computational fluid dynamic model provided a repeatable platform to investigate the effects of inflow cannula geometry on intraventricular flow.

  • Numerical prediction of thrombus risk in an anatomically dilated left ventricle: the effect of inflow cannula designs
    BioMedical Engineering OnLine, 2016
    Co-Authors: Sam Liao, Benjamin Simpson, Michael Neidlin, Maria A Woodruff, Tim A S Kaufmann, Shaun D Gregory
    Abstract:

    Background Implantation of a rotary blood pump (RBP) can cause non-physiological flow fields in the left ventricle (LV) which may trigger thrombosis. Different inflow cannula geometry can affect LV flow fields. The aim of this study was to determine the effect of inflow cannula geometry on intraventricular flow under full LV support in a patient specific model. Methods Computed tomography angiography imaging of the LV was performed on a RBP candidate to develop a patient-specific model. Five inflow Cannulae were evaluated, which were modelled on those used clinically or under development. The inflow Cannulae are described as a crown like tip, thin walled tubular tip, large filleted tip, trumpet like tip and an inferiorly flared cannula. Placement of the inflow cannula was at the LV apex with the central axis intersecting the centre of the mitral valve. Full support was simulated by prescribing 5 l/min across the mitral valve. Thrombus risk was evaluated by identifying regions of stagnation. Rate of LV washout was assessed using a volume of fluid model. Relative haemolysis index and blood residence time was calculated using an Eulerian approach. Results The inferiorly flared inflow cannula had the lowest thrombus risk due to low stagnation volumes. All Cannulae had similar rates of LV washout and blood residence time. The crown like tip and thin walled tubular tip resulted in relatively higher blood damage indices within the LV. Conclusion Changes in intraventricular flow due to variances in cannula geometry resulted in different stagnation volumes. Cannula geometry does not appreciably affect LV washout rates and blood residence time. The patient specific, full support computational fluid dynamic model provided a repeatable platform to investigate the effects of inflow cannula geometry on intraventricular flow

  • hydrodynamic evaluation of aortic cardiopulmonary bypass Cannulae using particle image velocimetry
    Perfusion, 2016
    Co-Authors: Charles Mcdonald, John F. Fraser, Eleonore C L Bolle, H F Lang, C Ribolzi, B Thomson, Geoffrey Tansley, Shaun D Gregory
    Abstract:

    The high velocity jet from aortic arterial Cannulae used during cardiopulmonary bypass potentially causes a “sandblasting” injury to the aorta, increasing the possibility of embolisation of atheromatous plaque. We investigated a range of commonly available dispersion and non-dispersion Cannulae, using particle image velocimetry. The maximum velocity of the exit jet was assessed 20 and 40 mm from the cannula tip at flow rates of 3 and 5 L/min. The dispersion Cannulae had lower maximum velocities compared to the non-dispersion Cannulae. Dispersion Cannulae had fan-shaped exit profiles and maximum velocities ranged from 0.63 to 1.52 m/s when measured at 20 mm and 5 L/min. Non-dispersion Cannulae had maximum velocities ranging from 1.52 to 3.06 m/s at 20 mm and 5 L/min, with corresponding narrow velocity profiles. This study highlights the importance of understanding the hydrodynamic performance of these Cannulae as it may help in selecting the most appropriate cannula to minimize the risk of thromboembolic events or aortic injury.

  • inflow cannula design for biventricular assist devices
    Institute of Health and Biomedical Innovation; Science & Engineering Faculty, 2013
    Co-Authors: Shaun D Gregory
    Abstract:

    Cardiovascular diseases are a leading cause of death throughout the developed world. With the demand for donor hearts far exceeding the supply, a bridge-to-transplant or permanent solution is required. This is currently achieved with ventricular assist devices (VADs), which can be used to assist the left ventricle (LVAD), right ventricle (RVAD), or both ventricles simultaneously (BiVAD). Earlier generation VADs were large, volume-displacement devices designed for temporary support until a donor heart was found. The latest generation of VADs use rotary blood pump technology which improves device lifetime and the quality of life for end stage heart failure patients. VADs are connected to the heart and greater vessels of the patient through specially designed tubes called Cannulae. The inflow Cannulae, which supply blood to the VAD, are usually attached to the left atrium or ventricle for LVAD support, and the right atrium or ventricle for RVAD support. Few studies have characterized the haemodynamic difference between the two cannulation sites, particularly with respect to rotary RVAD support. Inflow Cannulae are usually made of metal or a semi-rigid polymer to prevent collapse with negative pressures. However suction, and subsequent collapse, of the cannulated heart chamber can be a frequent occurrence, particularly with the relatively preload insensitive rotary blood pumps. Suction events may be associated with endocardial damage, pump flow stoppages and ventricular arrhythmias. While several VAD control strategies are under development, these usually rely on potentially inaccurate sensors or somewhat unreliable inferred data to estimate preload. Fixation of the inflow cannula is usually achieved through suturing the cannula, often via a felt sewing ring, to the cannulated chamber. This technique extends the time on cardiopulmonary bypass which is associated with several postoperative complications. The overall objective of this thesis was to improve the placement and design of rotary LVAD and RVAD inflow Cannulae to achieve enhanced haemodynamic performance, reduced incidence of suction events, reduced levels of postoperative bleeding and a faster implantation procedure. Specific objectives were: * in-vitro evaluation of LVAD and RVAD inflow cannula placement, * design and in-vitro evaluation of a passive mechanism to reduce the potential for heart chamber suction, * design and in-vitro evaluation of a novel suture-less cannula fixation device. In order to complete in-vitro evaluation of VAD inflow Cannulae, a mock circulation loop (MCL) was developed to accurately replicate the haemodynamics in the human systemic and pulmonary circulations. Validation of the MCL’s haemodynamic performance, including the form and magnitude of pressure, flow and volume traces was completed through comparisons of patient data and the literature. The MCL was capable of reproducing almost any healthy or pathological condition, and provided a useful tool to evaluate VAD cannulation and other cardiovascular devices. The MCL was used to evaluate inflow cannula placement for rotary VAD support. Left and right atrial and ventricular cannulation sites were evaluated under conditions of mild and severe heart failure. With a view to long term LVAD support in the severe left heart failure condition, left ventricular inflow cannulation was preferred due to improved LVAD efficiency and reduced potential for thrombus formation. In the mild left heart failure condition, left atrial cannulation was preferred to provide an improved platform for myocardial recovery. Similar trends were observed with RVAD support, however to a lesser degree due to a smaller difference in right atrial and ventricular pressures. A compliant inflow cannula to prevent suction events was then developed and evaluated in the MCL. As rotary LVAD or RVAD preload was reduced, suction events occurred in all instances with a rigid inflow cannula. Addition of the compliant segment eliminated suction events in all instances. This was due to passive restriction of the compliant segment as preload dropped, thus increasing the VAD circuit resistance and decreasing the VAD flow rate. Therefore, the compliant inflow cannula acted as a passive flow control / anti-suction system in LVAD and RVAD support. A novel suture-less inflow cannula fixation device was then developed to reduce implantation time and postoperative bleeding. The fixation device was evaluated for LVAD and RVAD support in cadaveric animal and human hearts attached to a MCL. LVAD inflow cannulation was achieved in under two minutes with the suture-less fixation device. No leakage through the suture-less fixation device – myocardial interface was noted. Continued development and in-vivo evaluation of this device may result in an improved inflow cannulation technique with the potential for off-bypass insertion. Continued development of this research, in particular the compliant inflow cannula and suture-less inflow cannulation device, will result in improved postoperative outcomes, life span and quality of life for end-stage heart failure patients.

  • flow analysis of ventricular assist device inflow and outflow cannula positioning using a naturally shaped ventricle and aortic branch
    Artificial Organs, 2010
    Co-Authors: Marco Laumen, Shaun D Gregory, Tim A S Kaufmann, Daniel Timms, Sebastian V Jansen, Kai Chun Wong, Thomas Schmitzrode, Peter Schlanstein, Ulrich Steinseifer
    Abstract:

    : Tip geometry and placement of rotary blood pump inflow and outflow Cannulae influence the dynamics of flow within the ventricle and aortic branch. Cannulation, therefore, directly influences the potential for thrombus formation and end-organ perfusion during ventricular assist device (VAD) support or cardiopulmonary bypass (CPB). The purpose of this study was to investigate the effect of various inflow/outflow cannula tip geometries and positions on ventricular and greater vessel flow patterns to evaluate ventricular washout and impact on cerebral perfusion. Transparent models of a dilated cardiomyopathic ventricle and an aortic branch were reconstructed from magnetic resonance imaging data to allow flow measurements using particle image velocimetry (PIV). The contractile function of the failing ventricle was reproduced pneumatically, and supported with a rotary pump. Flow patterns were visualized around VAD inflow Cannulae, with various tip geometries placed in three positions in the ventricle. The outflow cannula was placed in the subclavian artery and at several positions in the aorta. Flow patterns were measured using PIV and used to validate an aortic flow computational fluid dynamic study. The PIV technique indicated that locating the inflow tip in the left ventricular outflow tract improved complete ventricular washout while the tip geometry had a smaller influence. However, side holes in the inflow cannula improved washout in all cases. The PIV results confirmed that the positioning and orientation of the outflow cannula in the aortic branch had a high impact on the flow pattern in the vessels, with a negative blood flow in the right carotid artery observed in some cases. Cannula placement within the ventricle had a high influence on chamber washout. The positioning of the outflow cannula directly influences the flow through the greater vessels, and may be responsible for the occasional reduction in cerebral perfusion seen in clinical CPB.

John F. Fraser - One of the best experts on this subject based on the ideXlab platform.

  • tissue adhesives for bacterial inhibition in extracorporeal membrane oxygenation Cannulae
    Intensive Care Medicine Experimental, 2021
    Co-Authors: India Pearse, Amanda Corley, John F. Fraser
    Abstract:

    One of the most serious complications of extracorporeal membrane oxygenation (ECMO) therapy is ECMO Cannulae infection, which can occur at quadruple the rate of central venous catheter infections, and significantly impact morbidity and paediatric mortality. The objective of this in vitro observational study was to assess antimicrobial properties of two n-butyl-2-octyl cyanoacrylate tissue adhesive (TA) formulations for bacterial inhibition at peripheral ECMO Cannulae insertion sites. Antimicrobial properties were assessed using modified agar disk-diffusion (n = 3) and simulated agar cannulation insertion site (n = 20) models. Both assays used Staphylococcus epidermidis which was seeded at the edge of the TA or dressing. Microorganism inhibition was visually inspected and evidenced by the presence or absence of a TA bacterial inhibition zone at 24 and 72 h. Both TAs provided effective barriers to bacterial migration under cannula dressings, to cannula insertion sites and down cannula tunnels. Additionally, both TAs demonstrated distinct zones of inhibition produced when left to polymerise onto agar plates seeded with S. epidermidis. N-Butyl-2-octyl cyanoacrylate TA appears to inhibit bacterial growth and migration of S. epidermidis. Application of TA to Cannulae insertion sites may therefore be a potential bedside strategy for infection prevention in ECMO Cannulae, but requires further testing before being used clinically for this purpose.

  • assessing potential for aortoiliac vascular injury from venoarterial extracorporeal membrane oxygenation Cannulae an in vitro particle image velocimetry study
    Artificial Organs, 2021
    Co-Authors: Andrew B Haymet, Alice C Boone, Michael P Vallely, Maximilian V Malfertheiner, Jo P Pauls, Jacky Y Suen, John F. Fraser
    Abstract:

    Background: Limb ischemia is a major complication associated with peripheral veno‐arterial extracorporeal membrane oxygenation (VA ECMO). The high velocity jet from arterial Cannulae can cause “sandblasting” injuries to the arterial endothelium, with the potential risk of distal embolization and end organ damage. Aim: The aim of this study was to identify, for a range of clinically relevant VA ECMO Cannulae and flow rates, any regions of peak flow velocity on the aortic wall which may predispose to vascular injury, and any regions of low velocity flow which may predispose to thrombus formation. Methods: A silicone model of the aortic and iliac vessels was sourced and the right external iliac artery was cannulated. Cannulae ranged from 15 – 21 Fr in size. Simulated steady state ECMO flow rates were instituted using a magnetically levitated pump (CentriMag pump). Adaptive particle image velocimetry was performed for each cannula at 3, 3.5, 4 and 4.5 L/min. Results: For all Cannulae, in both horizontal and vertical side hole orientations, the peak velocity on the aortic wall ranged from 0.3 m/s ‐ 0.45 m/s, and the regions of lowest velocity flow were 0.05 m/s. The magnitude of peak velocity flow on the aortic wall was not different between a single pair versus multiple pairs of side holes. Maximum velocity flow on the aortic wall occurred earlier at a lower pump flow rate in the vertical orientation of distal side holes compared to a horizontal position. The presence of multiple paired side holes was associated with fewer low velocity flow regions, and some retrograde flow, in the distal abdominal aorta compared to Cannulae with a single pair of side holes. Conclusion: From this in vitro visualization study, the selection of a cannula design with multiple versus single pairs of side holes did not change the magnitude of peak velocity flow delivered to the vessel wall. Cannulae with multiple side holes were associated with fewer regions of low velocity flow in the distal abdominal aorta. Further in vivo studies, and ideally clinical data would be required to assess any correlation of peak velocity flows with incidence of vascular injury, and any low velocity flow regions with incidence of thrombosis.

  • extracorporeal membrane oxygenation line associated complications in vitro testing of cyanoacrylate tissue adhesive and securement devices to prevent infection and dislodgement
    Intensive Care Medicine Experimental, 2018
    Co-Authors: Taressa Bull, Amanda Corley, Danielle J Smyth, David J Mcmillan, Kimble R Dunster, John F. Fraser
    Abstract:

    Extracorporeal membrane oxygenation (ECMO) delivers cardiac and/or respiratory support to critically ill patients who have failed conventional medical therapies. If the large-bore cannulas used to deliver ECMO become infected or dislodged, the patient consequences can be catastrophic. ECMO cannula-related infection has been reported to be double the rate of other vascular devices (7.1 vs 3.4 episodes/1000 ECMO days respectively). The aim of this study was to assess the ability of cyanoacrylate tissue adhesive (TA) to inhibit bacterial growth at the ECMO cannulation site, and the effectiveness of TA and securement devices in securing ECMO cannulas and tubing. This in vitro study tested the (1) antimicrobial qualities of TA against standard transparent dressing with ECMO cannula; (2) chemical compatibility between cannula, TA and removal agent; (3) pull-out strength of transparent dressing and TA at the cannula insertion site; and (4) pull-out strength of adhesive bandage and commercial sutureless securement devices (SSDs) on circuit tubing. Fisher’s exact test was used to evaluate differences in bacterial growth observed between the transparent dressing and TA groups. Data from mechanical testing were analysed using one-way ANOVA, followed by Tukey’s multiple comparison test or t test as appropriate. Statistical significance was defined as p < 0.05. No bacterial growth occurred under TA-covered cannulas compared with transparent dressing-covered cannulas (p = 0.002). Compared to plates lacking TA or transparent dressing, growth was observed at the insertion point and under the dressing in the transparent dressing group; however, no growth was observed in the TA group (p = 0.019). TA did not weaken the cannulas; however, the TA removal agent did after 60 min of exposure, compared with control (p < 0.01). Compared with transparent dressing, TA increased the pull-out force required for cannula dislodgement from the insertion point (p < 0.0001). SSDs significantly increased the force required to remove the tubing from the fixation points compared with adhesive bandage (p < 0.01). Our findings suggest that the combined use of TA at the cannula insertion site with a commercial device for tubing securement could provide an effective bedside strategy to prevent or minimise infection and line dislodgement.

  • Extracorporeal membrane oxygenation line-associated complications: in vitro testing of cyanoacrylate tissue adhesive and securement devices to prevent infection and dislodgement
    Intensive Care Medicine Experimental, 2018
    Co-Authors: Taressa Bull, Amanda Corley, Danielle J Smyth, David J Mcmillan, Kimble R Dunster, John F. Fraser
    Abstract:

    Background Extracorporeal membrane oxygenation (ECMO) delivers cardiac and/or respiratory support to critically ill patients who have failed conventional medical therapies. If the large-bore cannulas used to deliver ECMO become infected or dislodged, the patient consequences can be catastrophic. ECMO cannula-related infection has been reported to be double the rate of other vascular devices (7.1 vs 3.4 episodes/1000 ECMO days respectively). The aim of this study was to assess the ability of cyanoacrylate tissue adhesive (TA) to inhibit bacterial growth at the ECMO cannulation site, and the effectiveness of TA and securement devices in securing ECMO cannulas and tubing. Methods This in vitro study tested the (1) antimicrobial qualities of TA against standard transparent dressing with ECMO cannula; (2) chemical compatibility between cannula, TA and removal agent; (3) pull-out strength of transparent dressing and TA at the cannula insertion site; and (4) pull-out strength of adhesive bandage and commercial sutureless securement devices (SSDs) on circuit tubing. Fisher’s exact test was used to evaluate differences in bacterial growth observed between the transparent dressing and TA groups. Data from mechanical testing were analysed using one-way ANOVA, followed by Tukey’s multiple comparison test or t test as appropriate. Statistical significance was defined as p  

  • hydrodynamic evaluation of aortic cardiopulmonary bypass Cannulae using particle image velocimetry
    Perfusion, 2016
    Co-Authors: Charles Mcdonald, John F. Fraser, Eleonore C L Bolle, H F Lang, C Ribolzi, B Thomson, Geoffrey Tansley, Shaun D Gregory
    Abstract:

    The high velocity jet from aortic arterial Cannulae used during cardiopulmonary bypass potentially causes a “sandblasting” injury to the aorta, increasing the possibility of embolisation of atheromatous plaque. We investigated a range of commonly available dispersion and non-dispersion Cannulae, using particle image velocimetry. The maximum velocity of the exit jet was assessed 20 and 40 mm from the cannula tip at flow rates of 3 and 5 L/min. The dispersion Cannulae had lower maximum velocities compared to the non-dispersion Cannulae. Dispersion Cannulae had fan-shaped exit profiles and maximum velocities ranged from 0.63 to 1.52 m/s when measured at 20 mm and 5 L/min. Non-dispersion Cannulae had maximum velocities ranging from 1.52 to 3.06 m/s at 20 mm and 5 L/min, with corresponding narrow velocity profiles. This study highlights the importance of understanding the hydrodynamic performance of these Cannulae as it may help in selecting the most appropriate cannula to minimize the risk of thromboembolic events or aortic injury.