IMPACT OF OXYGENATOR DESIGN ON HEMOLYSIS, SHEAR-STRESS, AND WHITE BLOOD-CELL AND PLATELET COUNTS

Objective: To determine whether relative pressure drop, shear stress, hemolysis, and white blood cell and platelet counts are influenced by different oxygenator designs. To compare the oxygenator results with t he average shear stress over an arterial cannula. Design: Prospective; patients enrolled consecutively. Setting: University hospital. Partic ipants: Three groups of 12 adult patients, scheduled for routine cardi ac surgery. Interventions: Each group was submitted to a different oxy genator design: group 1 to a high-pressure hollow-fiber membrane oxyge nator (Sarns Turbo); group 2 to a medium-pressure hollow-fiber membran e oxygenator (Cobe Optima); and group 3 to a flat-sheet membrane oxyge nator (Cobe Duo). Measurements and Main Results: Although the investig ated oxygenators have important differences in pressure drop and shear stress, no statistical differences were found in hemolysis generation or blood handling among the different groups. Actually, the study sho ws much higher shear stress levels over an average arterial cannula th an over any of the evaluated oxygenators. Conclusions: the pressure dr op over an oxygenator does not correlate well with shear stress and he molysis because the dimensions of the system (radius and length) must be included in the calculation of shear stress from pressure drop. Cop yright (C) 1996 by W.B. Saunders Company