Use of computational fluid dynamics in the design of the Avecor Affinity oxygenator

Goodin, Mark; Thor, Eric J; Haworth, William S.

doi:10.1177/026765919400900310

Cited by 27 publications

(17 citation statements)

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“…Near-total CO 2 removal allows significant reduction in airway pressures without hypercapnia or the complex circuit and monitoring required for conventional ECMO. We selected a low-resistance gas exchanger designed using computational flow dynamics 56 coupled with percutaneous arterial and venous cannulas selected for the flow ranges necessary for total CO 2 removal 57 in adult sheep. The extremely low resistance of the circuit and gas exchanger (Ͻ10 mmHg) allowed a blood flow of up to 12.8% of the cardiac output at a mean arterial blood pressure in the range of 120 mmHg.…”

Section: Discussionmentioning

confidence: 99%

Reduced Ventilator Pressure and Improved P/F Ratio During Percutaneous Arteriovenous Carbon Dioxide Removal for Severe Respiratory Failure

Alpard¹,

Zwischenberger²,

Tao³

et al. 1999

Annals of Surgery

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ObjectiveTo evaluate the effect of percutaneous arteriovenous carbon dioxide removal (AVCO 2 R) on ventilator pressures and P/F ratio in a clinically relevant large-animal model of severe respiratory failure. Summary Background DataAVCO 2 R was developed as a simple arteriovenous shunt with a commercially available low-resistance gas exchange device of sufficient surface area for near-total CO 2 removal. With an AV shunt 10% to 15% of cardiac output, AVCO 2 R allows a reduction in ventilator airway pressures without hypercapnia or the complex circuitry and monitoring required for conventional ECMO. MethodsAVCO 2 R was applied to a new, clinically relevant large-animal model of severe respiratory failure created by smoke inhalation and cutaneous flame burn injury. Adult sheep (n ϭ 9, 38 Ϯ 6 kg) received a 40% total body surface area, third-degree cutaneous flame burn and 36 breaths of cotton smoke insufflation. After injury, all animals were placed on volumecontrolled mechanical ventilation to achieve PaO 2 Ͼ 60 mmHg and PaCO 2 Ͻ 40 mmHg. Animals were placed on AVCO 2 R within 40 to 48 hours of injury when the PaO 2 /FiO 2 was Ͻ200. Animals underwent cannulation of the carotid artery and jugular vein with percutaneous 10F arterial and 14F venous cannulas. Shunt flow was continuously monitored using an ultrasonic flow probe and calculated as a percentage of cardiac output. ResultsAVCO 2 R flows of 800 to 900 ml/min (11% to 13% cardiac output) achieved 77 to 104 ml/min of CO 2 removal (95% to 97% total CO 2 production) while maintaining normocapnia. Significant reductions in ventilator settings were tidal volume, 421.3 Ϯ 39.8 to 270.0 Ϯ 6.3 ml; peak inspiratory pressure, 24.8 Ϯ 2.4 to 13.7 Ϯ 0.7 cm H 2 O; minute ventilation, 12.7 Ϯ 1.4 to 6.2 Ϯ 0.8 L/min; respiratory rate, 25.4 Ϯ 1.3 to 18.4 Ϯ 1.8 breaths/min; and FiO 2 , 0.88 Ϯ 0.1 to 0.39 Ϯ 0.1. The P/F ratio increased from 151.5 Ϯ 40.0 at baseline to 320.0 Ϯ 17.8 after 72 hours. ConclusionsPercutaneous AVCO 2 R allows near-total CO 2 removal and significant reductions in ventilator pressures with improvement in the P/F ratio.

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Section: Discussionmentioning

confidence: 99%

Reduced Ventilator Pressure and Improved P/F Ratio During Percutaneous Arteriovenous Carbon Dioxide Removal for Severe Respiratory Failure

Alpard¹,

Zwischenberger²,

Tao³

et al. 1999

Annals of Surgery

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“…at 2 l/min flow, most of the flow traveled through the bundle in approximately 2.5 s (frames [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. For the 2 l/min flow rate, no preferential flow was observed due to the position of the outlet port.…”

Section: Resultsmentioning

confidence: 99%

“…[4][5][6][7][11][12][13][14] it is important to verify that such results are both accurate and useful for design iterations. [4][5][6][7][11][12][13][14] it is important to verify that such results are both accurate and useful for design iterations.…”

Section: Analysis Of Angiographic Imagesmentioning

confidence: 99%

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Biplane Angiography for Experimental Validation of Computational Fluid Dynamic Models of Blood Flow in Artificial Lungs

Jones

Capasso²,

McDonough³

et al. 2013

ASAIO Journal

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This article presents an investigation into the validation of velocity fields obtained from computational fluid dynamic (CFD) models of flow through the membrane oxygenators using x-ray digital subtraction angiography (DSA). Computational fluid dynamic is a useful tool in characterizing artificial lung devices, but numerical results must be experimentally validated. We used DSA to visualize flow through a membrane oxygenator at 2 L/min using 37% glycerin at 22°C. A Siemens Artis Zee system acquired biplane x-ray images at 7.5 frames per second, after infusion of an iodinated contrast agent at a rate of 33 ml/s. A maximum cross-correlation (MCC) method was used to track the contrast perfusion through the fiber bundle. For the CFD simulations, the fiber bundle was treated as a single momentum sink according to the Ergun equation. Blood was modeled as a Newtonian fluid, with constant viscosity (3.3 cP) and density (1050 kg/m3). Although CFD results and experimental pressure measurements were in general agreement, the simulated 2 L/min perfusion did not reproduce the flow behavior seen in vitro. Simulated velocities in the fiber bundle were on average 42% lower than experimental values. These results indicate that it is insufficient to use only pressure measurements for validation of the flow field because pressure-validated CFD results can still significantly miscalculate the physical velocity field. We have shown that a clinical x-ray modality, together with a MCC tracking algorithm, can provide a nondestructive technique for acquiring experimental data useful for validation of the velocity field inside membrane oxygenators.

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“…A varying diameter in tubes/arteries that blood passes through can also affect viscosity since such variation leads to changes in shear rates (Gravlee et al 2007). However, it may be adequate for blood in various components of CPB circuits to be modeled as Newtonian under the approximation of steady-state nonpulsatile flow (Goodin et al 1994;Jegger et al 2007;Fiore et al 2009). We also point out that results in the literature show that it can take a shear rate change of around four orders of magnitude to change blood viscosity by a little over one order of magnitude (Yeleswarapu et al 1998).…”

Section: Treatment Of Blood As a Newtonian Fluidmentioning

confidence: 99%

Newtonian Viscous Effects in Ultrasonic Emboli Removal from Blood

Leckey

Hinders

2011

Ultrasound in Medicine & Biology

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Use of computational fluid dynamics in the design of the Avecor Affinity oxygenator

Cited by 27 publications

References 0 publications

Reduced Ventilator Pressure and Improved P/F Ratio During Percutaneous Arteriovenous Carbon Dioxide Removal for Severe Respiratory Failure

Reduced Ventilator Pressure and Improved P/F Ratio During Percutaneous Arteriovenous Carbon Dioxide Removal for Severe Respiratory Failure

Biplane Angiography for Experimental Validation of Computational Fluid Dynamic Models of Blood Flow in Artificial Lungs

Newtonian Viscous Effects in Ultrasonic Emboli Removal from Blood

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