Oxygenation Effect Of Intravenous Membrane Oxygenator Using Hollo Fibers In A Braid-Shaped Configuration In Vitro

Backgound and Objection Intravenous membrane oxygenator (IVOX), anartificial lung usually located in vena caval system, can provideextra-pulmonary gas exchange for patients who suffered with ARDS. Theconfined caval space, however, limited gas exchange performance of IVOX.Thus, improving the structure of IVOX is focused for increasing theefficiency of gas exchange and reducing the influence to circulation. In thepresent study, the hollow member fiber of WOX was weaved in braids, andwe test the gas exchange efficiency and blood flow resistance of this IVOX invitro.Methods The test circuit consisted of a 20mm-diameter test conduit, ablood reservoir, a roll pump, a heat exchanger, and a membrane oxygenator.Anticoagulant porcine blood of 3000 ml was primed into the test circuit, andblood gas was adjusted to pH 7.35-7.45, PCO₂ 40±5mmHg, BE±3, and PO₂30±5mmHg at 37℃by calibrating gas before test. Then Pressure-drops wereinvestigated before and after IVOX (membrane area of 0.088m²) was insertedinto the circuit, and oxygen saturations were measured before and after 100%oxygen flowing at a rate of 1L/min was transferred into IVOX for oneminute. The differences of pressures between before and after theimplantation of IVOX were taken as pressure-drops. Total O₂ transfer is theproduct of the differences of oxygen saturations before and after theimplantation IVOX and blood volume and hemoglobin content as well as1.34.Results The pressure-drops of the circuit were 19.77±0.51 cmH₂O,18.53±0.99 cmH₂O, and 11.87±1.57 cmH₂O at the blood flow of 5L/min, 4L/min, and 3.5 L/min respectively. Wherever hemoglobin content was 120g/Lor 100g/L, total transferred oxygen was higher at the blood flow rate of5L/min (55.9±0.51ml/min of 120g/L, 46.73±0.29 ml/min of 100g/L) than at4L/min (38.5±0.17 ml/min of 120g/L, 34.3±3.43 ml/min of 100g/L, P＜0.05vs 5L/min) and 3.5L/min (28.4±0.15 ml/min of 120g/L, 23.7±0.2 ml/min of100g/L, P＜0.01 vs 5L/min). There were no differences of transferred O₂between hemoglobin content at 120g/L and 100g/L (P＞0.05).Conclusion After the insertion of IVOX into the circuit ,the resistance tothe circuit at 5L/min was higher than at 4 L/min, and 3.5 L/min. Blood flowresistance increased with blood flow from 3.5 L/min to 5L/min. TransferredO₂ with the IVOX was higher at the blood flow of 5L/min than at 4 L/min,and 3.5 L/min, and can meet 22% of the metabolic need about 70kg adultpatients. Transferred O₂ with the IVOX increased with blood flow from 3.5L/min to 5L/min, but did not increase with hemoglobin content from 100g/Lto 120g/L.