Design and in vitro evaluation of a parallel gas-exchange chambers oxygenator with reduced hemolysis and pressure drop.

BACKGROUND

Hemolytic complications remain a major limitation of membrane oxygenators in clinical support. Compared with human lungs, most commercial oxygenators generate substantial pressure drops and high shear stress, increasing the risks of hemolysis. Therefore, we aimed to develop a membrane oxygenator that reduces pressure drop and shear-induced blood damage while maintaining the oxygen transfer rate.

METHODS

We propose a parallel gas exchange chamber (PGEC) oxygenator in which the blood flow is divided into two identical gas exchange chambers connected in parallel. The computational fluid dynamics (CFD) model was used to design and analyze the oxygenators. The oxygen transfer rate and blood damage parameters of the PGEC and conventional oxygenator were evaluated by in vitro tests at a blood flow rate of 900 mL/min. Oxygen transfer rate, pressure drop, plasma free hemoglobin concentration, and thrombin-antithrombin complex (TAT) concentration were measured (n = 3).

RESULTS

Under the present identical in vitro test conditions, the oxygen transfer rate of the PGEC oxygenator (18.15 ± 0.69 mL/min) was not significantly different from that of the conventional oxygenator (17.73 ± 0.73 mL/min). The PGEC design reduced pressure drop by 42% and decreased the normalized index of hemolysis (NIH) by 63% (p = 0.028), while TAT concentrations did not differ significantly between the two circuits.

CONCLUSIONS

The parallel design of the gas exchange chambers decreases blood velocity in the hollow fiber membrane region, thereby lowering pressure drop and hemolysis while maintaining oxygen transfer rate under the tested conditions.