Designing Blood Oxygenators

Abstract

Extracorporeal blood oxygenators are used to provide cardiopulmonary support during open heart surgery. In the study reported here, mass transfer correlations were determined for commercially available blood oxygenators. Two configurations used commercially, flow outside and across bundles of hollow fibers and flow in thin channels between parallel flat sheet membranes, were investigated. Water and glycerol/water mixtures were used as a substitute for blood. Diffusion of oxygen into and out of these solutions was studied. For flow across bundles of hollow fibers, the mass transfer correlations derived here are in agreement with analogous correlations for crossflow heat exchangers. However, for flow in thin channels, the rate of mass transfer is often less than predicted from theory. This compromised mass transfer can be explained by considering slight variations in the thickness of the blood flow channels. The mass transfer correlations developed here could be used to design better blood oxygenators.

Haematocrit heterogeneity in blood flows past microfluidic models of oxygenating fibre bundles

“…Today most oxygenating bundles are manufactured from a continuous mat of hollow fibres typically arranged in bi-layers of alternating angles, which are either piled or wound around an inner rigid core. The main purpose of such an intricate distribution is to enhance blood mixing, preventing the development of large boundary layers that would limit the mass transfer 1,2 .…”

A Mathematical Model to Predict CO2 Removal in Hollow Fiber Membrane Oxygenators

“…The gas exchange efficiency of the device is dictated by the concentration gradient of O 2 and CO 2 between the blood and the sweep gas and by the size of the boundary layer that forms on the blood side of the fibers. 6,20,29 One approach to designing an efficient blood oxygenator is through trial and error by building and testing prototypes. The trial and error process can be expensive, labor-intensive, and may take many years before producing a more efficient oxygenator.…”

Extracorporeal membrane blood oxygenators: effect of membrane wetting on gas transfer and device performance

“…For these reasons, in the past few decades, membrane oxygenators have been introduced [4] at the aim to improve the gas transfer and the operation reliability. Nowadays, membrane BO are mostly employed, in many configurations and for different purposes, in extracorporeal circulation-assisted surgical operations; [5][6][7]3,[8][9][10][11][12] the most adopted configuration is the hollow fiber module.…”

“…Previous studies devoted to transport modeling in BO focused mainly on system fluid dynamics, [20,21,11,12] neglecting the effect of membrane wetting and chemical reactions occurring into the blood phase.…”