Measurement of Flow Through Hypodermic Needles With Modified Entrances for Reduced Hemolysis

Hemolysis during phlebotomy with hypodermic needles and other cannulae interferes with the assays of a number of metabolites, electrolytes and enzymes, notably potassium, glucose, creatinine, bilirubin and alkaline phosphatase, leading to inaccurate test results [Sharp & Mohammad 1998]. Hemolysis in cannulae can also cause pain and discomfort during dialysis sessions [Dhaene 1989]. Released from red cells, high concentration of plasma free hemoglobin (PFH) is toxic, resulting in renal dysfunction and other organ failure. Therefore, low hemolysis is an important and widely measured performance criterion for a wide range of devices, including artificial hearts [Westaby, et al. 1998], centrifugal blood pumps [Ahmed, et al. 1999], cardiopulmonary bypass pumps [Xiao, et al. 2000], prosthetic valves [Steegers, et al. 1999], blood oxygenators [Skogby, et al. 1998], central venous catheters [Boswald, et al. 1999], heparin anticoagulation bioreactors [Ameer, et al. 1999], visceral perfusion systems [Leijdekkers, et al. 1999], shock wave lithotripsy [Lokhandwalla, et al. 2001a & b], balloon angioplasty [Muhlestein, et al. 1992], and hemodialysers [Yang & Lin 2001]. Models for predicting flow-induced hemolysis promise to reduce the time and expense required to develop such devices [Chen & Sharp 2011]. Several models have been compared with respect to their fit with experimental hemolysis results in needles with modified entrance geometry to reduce fluid stresses on erythrocytes flowing through them [Chen & Sharp 2006]. This paper describes an experiment constructed to validate flows through the needles predicted by computational fluid dynamics (CFD).