6. In vitro testing devices for blood biocompatibility Available to Purchase

The current ASTM recommendation for the Standard Practice for Assessment of Hemolysis in Continuous Flow Blood Pumps was developed and approved in 1997 (ASTM F1841-97) and then reapproved in 2005. The scope of this standard covers the assessment of the hemolytic properties of continuous flow blood pumps used in extracorporeal or implantable circulatory assist devices and is based on an assessment of the device’s effects on hemolysis over a certain period of time. For this assessment, a recirculation test is typically performed for 6 hrs. The recirculation loop in Figure 6-1 demonstrates a recently designed test flow system. The major recommendations regarding the hemolysis test settings are that the loop should be washed with phosphate buffered saline that is recirculated for approximately 10–20 min to rinse and wet all of the blood-contacting surfaces prior to filling it with blood. The circuit is then primed with 450 ± 45 mL of fresh blood into the reservoir bag. Air collected in the reservoir should be eliminated and no air-blood interface should remain in the reservoir. A Hoffman clamp, applied to produce the required condition of pressure head, is positioned at the outlet side of the pump. Pressure monitoring is incorporated into the test loop both at the inlet and outlet of the device. For studies involving adult mechanical circulatory pumps, the pump revolution rate is adjusted to provide 5 ± 0.25 L/minute flow rate as determined by the in-line flow meter. Pediatric systems typically use a smaller loop setup and lower flow rates as appropriate to the size of the intended patient population. Since all test runs are of ∼6 hours duration, sterility is generally not considered necessary.