A theoretical model for evaluation of the design of a hollow-fiber membrane oxygenator

Abstract

Geometric data are fundamental to the design of a contactor. The efficiency of a membrane contactor is mainly defined by its mass-transfer coefficient. However, design modifications also have significant effects on the performance of membrane contactors. In a hollow-fiber membrane oxygenator (HFMO), properties such as priming volume and effective membrane surface area (referred to as design specifications) can be determined. In this study, an extensive theoretical model for calculation of geometric data and configuration properties, and, consequently, optimization of the design of an HFMO, is presented. Calculations were performed for Oxyphan(®) hollow-fiber micro-porous membranes, which are frequently used in current HFMOs because of their high gas exchange performance. The results reveal how to regulate both the transverse and longitudinal pitches of fiber bundles to obtain a lower rand width and a greater number of windings. Such modifications assist optimization of module design and, consequently, substantially increase the efficiency of an HFMO. On the basis of these considerations, three values, called efficiency factors, are proposed for evaluation of the design specifications of an HFMO with regard with its performance characteristics (i.e. oxygen-transfer rate and blood pressure drop). Moreover, the performance characteristics of six different commercial HFMOs were measured experimentally, in vitro, under the same standard conditions. Comparison of calculated efficiency factors reveals Quadrox(®) is the oxygenator with the most efficient design with regard with its performance among the oxygenators tested.

A mathematical model of CO2, O2 and N2 exchange during venovenous extracorporeal membrane oxygenation

“…As the surface area increases, diffusion limitation becomes less important and CO 2 elimination becomes predominantly perfusion limited [ 21 ]. O 2 uptake increases linearly with blood flow in the Quadrox oxygenator, up to the rated maximum of 7 l/min [ 9 ], though this is not the case for all oxygenators. The assumption of predominantly perfusion limited gas exchange is unlikely to result in major inaccuracy during vv-ECMO, providing a suitable oxygenator is used.…”

“…Hollow fibre membrane oxygenators have become the standard of care for vv-ECMO [ 7 ]. Mathematical models of O 2 and CO 2 exchange in these devices have been developed [ 8 , 9 ], and provide useful information about how they behave. However, these models only examine oxygenator function, and do not consider its interaction with the cardio-respiratory system, so their clinical utility is limited.…”

A pH‐based experimental method for carbon dioxide exchange evaluation in cylindrical hollow fiber membrane oxygenators

“…A hollow fiber membrane oxygenator (HFMO), as a synonym for artificial lung, can be considered as a gas‐liquid or a liquid‐liquid HFMC, depending on flowing gas and/or liquid inside and outside of hollow fiber lumens . Partial venous CO 2 elimination is as substantial as blood oxygenation during the gas exchange function of the natural lung . Accordingly, an HFMO should have a sufficient CO 2 elimination rate similar to natural lung .…”

The frontier in Cardiac Surgery is intellectual

“…The technological breakthrough of the HLM was challenged by a number of technological and biological umprecedented problems related to the new interactions between machines and the human body. New materials and new technology resulted in sophisticated devices incorporating better pump heads, biocompatible surfaces for cardiopulmonary bypass tubing aiming at reducing inflammatory response [24] , multiple in-line sensors for better safety, more effective and less traumatic oxygenators with superior performance [25] , in-line filters of all kinds [26,27] , hemoadsorbers [28] and other complements that allowed safer conduct of cardiopulmonary bypass for repair of cardiac disease.…”