title: An under-occluded roller pump is less hemolytic than a centrifugal pump.
abstract: The purpose of this study is to measure and compare the hemolysis produced by roller pumps with varied occlusion settings and a centrifugal pump. The null hypothesis is that there is no difference in the Index of Hemolysis (IH = gm Hb/100 L pumped) produced by a roller pump (RP) at four different occlusion settings and a centrifugal pump (CP) at the same blood flow rate (4.5 L/min) and afterload (250 mmHg, +/-10 mmHg) over three hours. Five identical closed-loop circuits were assembled and primed with saline. The pumps were then calibrated and occlusions were set. In three circuits, the occlusion for the RP was opened at 5 RPMs to support 150, 225, or 300 mmHg (+/-10 mmHg) against a clamped line. In one circuit, a RP was adjusted to a barely non-occlusive setting (1 cm drop/30 inch gradient). The fifth circuit employed a CP. Prior to testing, the saline in each circuit was replaced with one liter of fresh bovine blood (Hct = 22 +/- 2%). The IH for each treatment was compared in six trials yielding a statistical power > 0.80. Analysis of variance with multiple comparison (p < or = 0.05) demonstrated that compared to the barely non-occlusive setting, the IH in the centrifugal pump was not significantly greater. Under-occluded RP settings yielded IHs significantly less than the CP. It appears that opening the occlusion on a roller pump allows a lower IH compared to traditional RP occlusion setting or centrifugal pumping.
authors.affiliation: Clinical Services Department, College of Health Professions, Medical University of South Carolina, Charleston, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Rawn
authors.forename: H K
authors.initials: HK
authors.lastname: Harris
authors.forename: J B
authors.initials: JB
authors.lastname: Riley
authors.forename: D N
authors.initials: DN
authors.lastname: Yoda
authors.forename: M M
authors.initials: MM
authors.lastname: Blackwell
mesh_terms: D000818:Animals; D002315:Cardiopulmonary Bypass / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D002417:Cattle; D006461:Hemolysis; D066298:In Vitro Techniques