title: Evaluation of fiber bundle rotation for enhancing gas exchange in a respiratory assist catheter.
abstract: Supplemental oxygenation and carbon dioxide removal through an intravenous respiratory assist catheter can be used as a means of treating patients with acute respiratory failure. We are beginning development efforts toward a new respiratory assist catheter with an insertional size <25F, which can be inserted percutaneously. In this study, we evaluated fiber bundle rotation as an improved mechanism for active mixing and enhanced gas exchange in intravenous respiratory assist catheters. Using a simple test apparatus of a rotating densely packed bundle of hollow fiber membranes, water and blood gas exchange levels were evaluated at various rotation speeds in a mock vena cava. At 12,000 RPM, maximum CO2 gas exchange rates were 449 and 523 mL/min per m2, water and blood, respectively, but the rate of increase with increasing rotation rate diminished beyond 7500 RPM. These levels of gas exchange efficiency are two- to threefold greater than achieved in our previous respiratory catheters using balloon pulsation for active mixing. In preliminary hemolysis tests, which monitored plasma-free hemoglobin levels in vitro over a period of 6 hours, we established that the rotating fiber bundle per se did not cause significant blood hemolysis compared with an intra-aortic balloon pump. Accordingly, fiber bundle rotation appears to be a potential mechanism for increasing gas exchange and reducing insertional size in respiratory catheters.
authors.affiliation: Medical Devices Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania 15203, USA.
authors.forename: Heide J
authors.initials: HJ
authors.lastname: Eash
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Mihelc
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Frankowski
authors.forename: Brack G
authors.initials: BG
authors.lastname: Hattler
authors.forename: William J
authors.initials: WJ
authors.lastname: Federspiel
mesh_terms: D000818:Animals; D001798:Blood Proteins; D002245:Carbon Dioxide / Q000097:blood*; D002405:Catheterization, Central Venous / Q000295:instrumentation*; D002417:Cattle; D006400:Hematocrit; D006461:Hemolysis; D066298:In Vitro Techniques; D008422:Materials Testing; D008954:Models, Biological; D010100:Oxygen / Q000097:blood* / Q000493:pharmacokinetics; D011673:Pulsatile Flow; D012121:Respiration, Artificial / Q000295:instrumentation*; D012131:Respiratory Insufficiency / Q000628:therapy*; D012399:Rotation; D014684:Venae Cavae; D014867:Water / Q000378:metabolism
chemical_list: D001798:Blood Proteins; D014867:Water; D002245:Carbon Dioxide; D010100:Oxygen