The effect of oxygenator membranes on blood: a comparison of two oxygenators in open-heart surgery

Preparation of Hyflon AD/Polypropylene Blend Membrane for Artificial Lung

A high-performance polypropylene hollow fiber membrane (PP-HFM) was prepared by using a binary environmentally friendly solvent of polypropylene as the raw material, adopting the thermally induced phase separation (TIPS) method, and adjusting the raw material ratio. The binary diluents were soybean oil (SO) and acetyl tributyl citrate (ATBC). The suitable SO/ATBC ratio of 7/3 was based on the size change of the L-L phase separation region in PP-SO/ATBC thermodynamic phase diagram. Through the characterization and comparison of the basic performance of PP-HFMs, it was found that with the increase of the diluent content in the raw materials, the micropores of outer surface of the PP-HFM became larger, and the cross section showed a sponge-like pore structure. The fluoropolymer, Hyflon ADx, was deposited on the outer surface of the hollow fiber membrane using a physical modification method of solution dipping. After modification, the surface pore size of the Hyflon AD40L modified membranes decreased; the contact angle increased to around 107°; the surface energy decreased to 17 mN·m^-1; and the surface roughness decreased to 17 nm. Hyflon AD40L/PP-HFMs also had more water resistance properties from the variation of wetting curve. For biocompatibility of the membrane, the adsorption capacity of the modified PP membrane for albumin decreased from approximately 1.2 mg·cm^-2 to 1.0 mg·cm^-2, and the adsorption of platelets decreased under fluorescence microscopy. The decrease in blood cells and protein adsorption in the blood prolonged the clotting time. In addition, the hemolysis rate of modified PP membrane was reduced to within the standard of 5%, and the cell survival rate of its precipitate was above 100%, which also indicated the excellent biocompatibility of fluoropolymer modified membrane. The improvement of hydrophobicity and blood compatibility makes Hyflon AD/PP-HFMs have the potential for application in membrane oxygenators.

Ex vivo evaluation of a new neonatal/infant oxygenator: comparison of the Terumo CAPIOX® Baby RX with Dideco Lilliput 1 and Polystan Safe Micro in the piglet model

Objective: A newly developed neonatal and infant oxygenator with a nonheparin biocompatible polymer coating, low priming volume (43 mL), high oxygen transfer, wide operating range (<1.5 L/min) and low pressure drop represents a promising solution for cardiac surgery in neonates and infants. We compared the new CAPIOX® Baby RX, Terumo (BRX) with two commonly used neonatal oxygenators: Dideco Lilliput 1 (DL1) and Polystan Safe Micro (PSM) in a piglet model.

Methods: Fifteen piglets (5.6±1.3 kg) were placed on standardized cardiopulmonary bypass (CPB) for 6 hours using one of the three oxygenators ( n = 5 in each group). After 120 min, the system was cooled to 25°C for 60 min and then returned to normothermia. Arterial and venous blood gas data and temperature were recorded continuously by a CDI500 System (Terumo). Pressure drop, FiO2 and gas flow were recorded. Blood samples were taken before CBP, after 10 min, before and after cooling, and at the end. Total blood counts, thrombin-antithrombin complex and plasma-free haemoglobin (PfHb) were measured.

Results: All oxygenators showed acceptable performance for the duration of CPB. The BRX had lower mean gas flow (0.33±0.05 L/min) and FiO2 (0.43± 0.02%) throughout CPB than the DL1 (1.14±0.25 L/min, p = 0.006 and 0.60±0.02%, p = 0.009, respectively) or the PSM (1.47±0.87 L/min and 0.54±0.08%, p = ns). Pressure drop in the BRX group ranged from 12 to 22 mmHg. This was significantly lower than in the DL1 group (39-65 mmHg, p = 0.005). In the PSM group, values ranged between 24 and 33 mmHg (p = ns). The increase in PfHb at six hours was significantly lower in the BRX (11.3±4.2 ng/dL) versus the DL1 (42.2±6.1 ng/dL, p = 0.004) and the PSM (56.7±15.5 ng/dL, p = 0.045).

Conclusions: The BRX is as safe as the DL1 and the PSM, with superior performance in pressure drop, efficient blood gas management and lower haemolysis. The BRX exhibited the lowest prime, hold-up volume and breakthrough time.