An Intrapleural Lung Prosthesis: Rationale, Design, and Testing

Fazzalari, Franco; Bartlett, Robert H.; Bonnell, Mark R.; Montoya, J P

doi:10.1111/j.1525-1594.1994.tb03326.x

Cited by 15 publications

(5 citation statements)

References 14 publications

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“…Thus the vacuum pressures required in intravenous oxygenators for driving sufficient 0, sweep gas flow can be several hundred mm Hg. Similarly, intrathoracic artificial lungs also have design constraints which can lead to increased gas-flow resistance and larger vacuum pressure requirements for sufficient sweep gas flow (Fazzalari et al, 1994). Thus, gas compressibility is potentially of much greater importance in the gas-flow dynamics of intracorporeal oxygenators than their extracorporeal counterparts.…”

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confidence: 99%

Gas flow dynamics in hollow‐fiber membranes

1996

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Biomedical and chemical separations often use hollow-fiber membranes for exchanging diffusible species between segregated gas and liquid flow streams. A classic example is the hollow fibers used in extracorporeal and intracorporeal artificial lungs (cf., High et al., 1993). In artificial lung devices, oxygen and carbon dioxide diffuse oppositely across the fiber membranes between a blood phase flowing outside the fibers, and a gas phase flowing through the fiber lumen (sweep gas). The principal determinants of exchange are the overall mass-transfer coefficient of the device, the total membrane surface area, and the differences in gas species partial pressure driving the exchange. Although most of the mass-transfer resistance resides within the membrane and blood phases (Qi and Cussler, 1985a,b), the flow dynamics of the sweep gas play a key role by dictating the partial pressure of the exchanging species within the gas phase. That is, for a given species exchange rate (0, or CO,), the fractional gas species concentration along the fiber depends on the sweep gas-flow rate through the fiber, and in turn the species partial pressure along the fiber lumen, the key intrafiber determinant of exchange, depends directly on both the fractional species concentration and the total gas pressure along the fiber. Thus, understanding the gas-flow dynamics (pressure-flow behavior) within hollow-fiber bundles becomes essential to designing oxygenators and to modeling their gas-exchange performance.The dynamics of gas flow within hollow-fiber membranes may appear superficially as an application of simple incompressible Poiseuille flow theory. The internal caliber of these fibers is generally 300 ,um or smaller, and their length to diameter ratios are typically large. For the gas-flow rates usually involved, Reynolds numbers are therefore unity or smaller, and the flow can be considered fully developed and laminar. The incompressible Poiseuille flow paradigm predicts, for example, a linear relation between pressure drop Correspondence concerning this article should be addressed to W. J. Federspiel. and resulting gas-flow rate (Gerhart et al., 1992). Although the usual indices suggesting compressible flow are small (e.g., Mach number and kinetic energy variations), the gas flow in hollow-fiber membranes cannot necessarily be considered incompressible. The small size of the fibers, coupled with their great relative length, means that flow resistance and pressured drops can be appreciable, and that variations in fluid density are potentially important.Our interest in studying the gas flow dynamics within hollow-fiber membranes arose as part of development work (Hattler et al., 1992) on an intravenous membrane oxygenator (IMO). All artificial lung devices must flow sufficient 0, sweep gas to minimize CO, accumulation in the fibers, and to avoid reducing CO, exchange as a result (cf., High et al., 1993). Extracorporeal oxygenators typically use several thousand fibers in parallel ( -4,000 to S,OOO), each of a relatively short length ( -...

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confidence: 99%

Gas flow dynamics in hollow‐fiber membranes

1996

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“…Blood damage can be expressed as the Normalized Index of Hemolysis (NIH) 11,12 according to the equation (1 ) 100 100 ( /100 )…”

Section: Theorymentioning

confidence: 99%

“…ARDS can occur in individuals with or without previous lung disease and affects approximately 150,000 people per year in the United States. 1 Its treatment requires respiratory support using the conventional therapies of mechanical ventilation or extracorporeal membrane oxygenation in severe cases.…”

Section: Introductionmentioning

confidence: 99%

Gas transfer and hemolysis in an intravascular lung assist device using a PZT actuator

Hong

Kim

et al. 2009

Int. J. Precis. Eng. Manuf.

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NOMENCLATURE A = hollow fiber membrane (HFM) surface area D = diffusion coefficient in the liquid Ht = hematocrit K = overall gas exchange permeability K m = individual permeabilities of the HFM K l = individual permeabilities of the liquid phase P g = average oxygen partial pressures in the gas P l = average oxygen partial pressures in the liquid phases δ hl = permeability of a liquid boundary layer thickness α = gas solubility in the liquid ∆fHb = increase in free plasma hemoglobin concentration V = blood volume Q = blood volume flow rateThe purpose of this study was to investigate the effect of multiple mechanical forces in gas exchange and hemolysis in an intravascular lung assist device (IVLAD). Specific focus was given to the effect of membrane vibration. We designed the oscillatory type artificial lung assist device attached with a polyvinylidene fluoride sensor and a lead zirconate titanate (PZT) actuator (vibrator). Maximum oxygen transfer occurred at a frequency of 7 Hz for bovine blood and 35 Hz for distilled water. The normalized index of hemolysis oxygenator values for the circuit was 0.0014 g/mL for excitation of the PZT actuator with a sinusoidal 10-V wave and 0.0018 g/mL for a 50-V wave. The experiment results indicate effective performance in enhancing the gas transfer of the IVLAD. This novel hollow membrane filter IVLAD design demonstrates an acceptable level of gas exchange performance with an acceptable level of blood compatibility, and so it has potential as an implantable lung assist device for patients with acute respiratory distress syndrome.

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“…The disease affects approximately 150,000 people per year in the United States [1]. Its treatment requires respiratory support using the conventional therapies of mechanical ventilation, or extracorporeal membrane oxygenation (ECMO) in patients with severe ARDS.…”

Section: Introductionmentioning

confidence: 99%

Study on the Intravenous Lung Assist Device (ILAD) Using PZT Actuators and PVDF Sensors

Kim

Lee

et al. 2008

KEM

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The purpose of this study was to investigate the effect of vibration device in gas transfer rate for usage as intravenous lung assist device. Specific attention was focused on the effect of membrane vibration. Quantitative experimental measurements were performed to evaluate the performance of the device, and to identify membrane vibration dependence on hemolysis. Scaling analysis was then used to infer the dimensionless groups that correlate the performance of a vibrated hollow tube membrane oxygenator. The experimental design and procedure are then given for a device for assessing the effectiveness of membrane vibrations. This ILAD is used to provide some insight into how wall vibrations might enhance the performance of an intravascular lung assist device. The time and the frequency response of PVDF sensor were investigated through various frequencies in the ILAD. In these devices, the flow of blood and the source of oxygen were separated by a semipermeable membrane allows oxygen to diffuse into and out of the f1uid, respectively. The results of experiments have shown vibrating ILAD performs effectively.

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An Intrapleural Lung Prosthesis: Rationale, Design, and Testing

Cited by 15 publications

References 14 publications

Gas flow dynamics in hollow‐fiber membranes

Gas flow dynamics in hollow‐fiber membranes

Gas transfer and hemolysis in an intravascular lung assist device using a PZT actuator

Study on the Intravenous Lung Assist Device (ILAD) Using PZT Actuators and PVDF Sensors

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