Determination of Reynolds Shear Stress Level for Hemolysis

• Published in: ASAIO journal (1992) Vol. 64; no. 1; p. 63
• Main Authors: Jhun, Choon-Sik, Stauffer, Megan A, Reibson, John D, Yeager, Eric E, Newswanger, Raymond K, Taylor, Joshua O, Manning, Keefe B, Weiss, William J, Rosenberg, Gerson
• Format: Journal Article
• Language: English
• Published: United States 01.01.2018
• Subjects: Animals; Blood Flow Velocity; Cattle; Erythrocytes - cytology; Hematocrit; Hematologic Tests - methods; Hemoglobins; Hemolysis - physiology; Humans; Laser-Doppler Flowmetry - methods; Stress, Mechanical
• DOI: 10.1097/MAT.0000000000000615

Reynolds shear stress (RSS) has served as a metric for the effect of turbulence on hemolysis. Forstrom (1969) and Sallam and Hwang (1984) determined the RSS threshold for hemolysis to be 50,000 and 4,000 dyne/cm, respectively, using a turbulent jet. Despite the order of magnitude discrepancy, the threshold by Sallam and Hwang has been frequently cited for hemolytic potential in blood pumps. We recreated a Sallam apparatus (SA) to resolve this discrepancy and provide additional data to be used in developing a more accurate hemolysis model. Hemolysis was measured over a large range of Reynolds numbers (Re) (Re = 1,000-80,000). Washed bovine red blood cells (RBCs) were injected into the free jet of phosphate buffered saline, and hemolysis was quantified using a percent hemolysis, Hp = h (100 - hematocrit [HCT])/Hb, where h (mg/dl) is free hemoglobin and Hb (mg/dl) is total hemoglobin. Reynolds shear stress was calculated using two-dimensional laser Doppler velocimetry. Reynolds shear stress of ≥30,000 dyne/cm corresponding to Re of ≥60,000 appeared to cause hemolysis (p < 0.05). This RSS is an order of magnitude greater than the RSS threshold that Sallam and Hwang suggested, and it is similar to Forstrom's RSS threshold. This study resolved a long-standing uncertainty regarding the critical values of RSS for hemolysis and may provide a foundation for a more accurate hemolysis model.