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Hemocompatibility

Medical devices that contact circulating blood generally require a hemcompatibility assessment and, we offer multiple types of test depending on your product and data needs. These include Hemolysis (Material and Mechanically Induced), PTT, Complement Activation and In Vivo Thrombogenicity. These tests comply with the ISO 10993 biocompatibility guidelines.

Download the biocompatibility test matrix. [Based on ISO 10993-1 and FDA “Use of international standard ISO 10993-1”]

Applicable Standards

  • ISO 10993-4
  • ASTM F756

Hemolysis Test

The Hemolysis test is designed to determine the hemolytic properties of a medical device materials that have direct or indirect blood contact and fulfills hematological testing requirements for selection of tests for interactions with blood. Nelson Labs tests with fresh human blood rather than rabbit blood. Nelson Labs offers test systems which evaluate both biochemical factors (Material-Induced Hemolysis) and mechanical forces (Mechanically-Induced Hemolysis.

PTT Test

The Partial Thromboplastin Time (PTT) test is a general screening test for the detection of coagulation abnormalities in the intrinsic pathway. This test is performed on medical device materials that have direct contact with circulating blood.

Complement Activation

The Complement Activation test is used to determine the potential for activation of the complement system by a medical device. This humoral immune response may be caused by the introduction of a foreign material into the body and can lead to adverse effects such as inflammation and tissue damage. This test was designed to fulfill the immunology testing requirement for selection of tests for interactions with blood. Nelson Labs includes the evaluation of SC5b-9 production at time points in the assay to look at possible levels of activation over time.

In Vivo Thrombogenicity Test

The In Vivo Thrombogenicity test determines a comparative thrombo-resistant for medical devices that are intended for blood contact. This test enables manufacturers to see if the medical devices cause any potentially undesirable effects on humans, such as activation of platelets, formation of a thrombus, embolism, or injury to cells.

Testing Locations

Study Outline

Hemolysis (Material-Induced)

The ASTM F756 Hemolysis procedure was designed to determine the hemolytic properties of the test article. The procedure involves exposing the test material or material extract to a blood cell suspension and then determining the amount of hemoglobin released. The test is performed using citrated human blood.

ASTM F 756 and FDA recommends that both test methods (extract and direct contact) be performed unless the material application or contact time justifies the exclusion of one of these enpoints. If an extract test is being performed, please include the extraction parameters when you submit your samples.

 

Hemolysis (Mechanically-Induced)

This Hemolysis procedure is designed to provide an assessment of blood cell lysis caused by a medical device under dynamic test conditions and evaluates factors such as blood flow rate, turbulence and non-physiological shear. Nelson Labs can design a test system which mimics the simulated use of the medical device. Mechanically induced hemolysis tests can be designed to evaluate medical devices using circulating blood loops or in single pass through assays.

  • Flowing Loop: Uses a peristaltic pump to circulate blood from a reservoir and through the device creating a continuous loop. Examples of applications: Cardipulmonary bypass systems, homodialysis systems, blood access catheters, mechanical heart valves.
  • Single Pass-through: Studies designed to flow blood through the device without recirculation. Examples of applications: IV infusion sets and catheters, infusion pumps, needleless connectors, blood warmers, PICC (blood collections).

General Requirements

  • Paired testing. Two separate and identical circulation loops; one for the test article and one for the predicate.
  • Sample size of five test articles and five predicate devices.
  • Testing should be performed at the maximum labeled blood flow rate. Run duration is typically as long as a labeled for a clinical treatment.

Reporting Results/Interpretation

  • Data from individual experiments will be provided in both tabular and graphical format. The plasma hemoglobin will be reported as a concentration that increases over time using overlaying line plots for each of the different test circuits.
  • The plasma hemoglobin will be reported as a concentration that increases over time using overlaying line plots for each of the different test circuits.
  • The percent hemolysis will be reported over time using overlaying line plots for each of the different test circuits.

Partial Thromboplastin Time (PTT)

The unactivated Partial Thromboplastin Time (PTT) is designed to detect material mediated effects of the intrinsic coagulation pathway by exposing the test article in platelet poor citrated plasma. The PTT reagent is then added, followed by the addition of calcium chloride solution. The amount of time elapsed prior to the  clot formation is monitored and recorded. Evaluation of the clotting times is performed using statistical comparisons to the controls.

Complement Activation

The Complement Activation test is designed to determine the potential for activation of the complement system by a medical device. The test is performed by incubating the test article and predicate directly in human serum and then tested for the presence of the complement protein SC5b-9, using commercially Enzyme Immunoassay (EIA) kits. Analysis of variance (ANOVA) is used to compare the test article and predicate devices to determine if there are statistically significant differences in the mean populations.

  • Note: Nelson Labs recommends the use of a predicate device for PTT and Complement Activation testing. There are no established Pass/Fail criteria for these tests and establishing equivalency to a predicate device is recommended by most regulatory agencies.

In Vivo Thrombogenicity

In Vivo Thrombogenicity
The In Vivo Thrombogenicity test generates safety data for a blood-contacting device. While in use, blood-contacting medical device interactions may have potentially undesirable effects on humans. This test is designed to determine the comparative thromboresistance of a medical device intended for blood contact by implanting the test article in the venous system of a canine study model. Its performance is then compared to an appropriate negative control device.

If you have additional questions about Hemocompatibility Testing, or would like to consult with the experts at Nelson Labs, just send us a request or call us at +1 (801) 290-7500.