ISO 10993-4 describes the requirements for assessing the interactions of medical devices with circulating human blood and assigns a set of test categories and individual tests recommended for evaluation. The categories are based on intended use and duration of contact and include hemolysis and thrombosis. During 2017, ISO added a requirement for mechanically induced hemolysis as a subcategory and it is required for devices that redirect flow or create blood turbulence within the circulatory system. Examples include hemodialysis or hemofiltration equipment, circulatory support devices, cell separators, and mechanical heart valves. In addition, U.S. FDA generally requires a mechanically induced hemolysis assessment for blood administration sets, blood warmers, and infusion pumps.
Mechanical hemolysis protocols should be designed to simulate the intended use of the device and adequately measure red blood cell lysis caused by fluid dynamic factors such as blood flow rate, turbulence, and non-physiological shear force. Test methods that involve a single flow through of blood using gravity or an infusion pump are appropriate for blood administration sets. However, hemodialysis devices and equipment would require a protocol that involves circulating blood through a flow loop for an extended time period.
Consider the following when developing an appropriate protocol to assess mechanically induced hemolysis.
- Paired testing. Because there is not a recognized acceptance criterion, two separate and identical circulation loops should be included; one for a predicate device and one for the test article. The loops should use blood from the same pool.
- Total hemoglobin and plasma free hemoglobin concentrations should be assessed using a validated test method.
- The total volume of blood in the two test circuits should be identical and be minimized to increase the sensitivity of the test.
- Use a sample size of five test articles and five predicate devices.
- Blood flow rate should be tested at the maximum labeled rate. Run duration should typically be as long as is labeled for a clinical treatment.
Nelson Laboratories has been conducting mechanical hemolysis tests for more than a decade and has the experience to develop your custom protocol and execute the testing within a rapid time frame.
Please contact your Nelson Laboratories sales rep or one of us to discuss your hemocompatibility needs today.
