Haemocompatibility of Medical Devices

Medical devices that contact blood during use (e.g. biomaterials, implants) must be haemocompatible. Haemocompatibility can be tested with static or dynamic blood incubation systems depending on the application mode of the medical device. According to guidance DIN EN ISO 10993-4 tests are grouped into five proof categories (see below). The NMI TT GmbH offers tests in all test categories and with both incubation systems.

Chandler Loop Method
The Chandler Loop method simulates the circulation of blood by rotating tubes (green picture on the tight). Therefore the Chandler Loop incubation is the method of choice to test haemocompatibility for medical devices placed into the blood stream.

Medical device is placed into the tube. The tube is filled with freshly drawn human blood from healthy donor and closed to a ring. After circulated incubation samples are collected. The blood is frozen to be used in analysis of the test categories coagulation, platelets, haematology and complement. The medical device or parts of it are fixed and prepared to be used in test category thrombogenicity.

Test categories of DIN EN ISO 10993-4
• Coagulation
  Factors of the coagulation cascade and fibrinolytic system are measured.
• Platelets
  Platelet testing includes quantification of platelet number as well as analysis of their function.
• Haematology
  Study of blood including quantification of cellular and plasma components.
• Complement
  Complement activation during blood / material contact takes place as a defence reaction against a pathological invader.
• Thrombogenicity
  In contact with artificial surfaces platelets as well as leucocytes and fibrin can adhere to the material. The surface can be investigated by scanning electron microscopy.