Effects of Surface Roughness on Mechanical Hemolysis

Area of Science:

• Biomedical Engineering
• Medical Device Design
• Hemodynamics

Background:

• In vitro hemolysis testing is vital for evaluating blood damage in medical devices.
• Previous studies highlighted the role of inlet geometry in reducing hemolysis.
• Computational fluid dynamics (CFD) analysis suggested shear rate and hemolysis are not always directly correlated.

Purpose of the Study:

• To investigate the impact of stenosis geometry and surface roughness on in vitro hemolysis.
• To further define the relationship between fluid dynamics and blood damage in stenotic connectors.
• To optimize medical device design for reduced hemolysis.

Main Methods:

• In vitro hemolysis testing of stenotic connectors with varying longitudinal lengths and surface roughness.
• Computational fluid dynamics (CFD) analysis to model blood flow and shear stress.
• Measurement of plasma-free hemoglobin levels after simulated circulation.

Main Results:

• Shortening the longitudinal length of the stenosis from 15 mm to 1 mm decreased plasma-free hemoglobin from 280 mg/dl to 70 mg/dl.
• A smooth surface (Ra = 0.45 μm) reduced the hemolysis rate by up to 80% compared to a rough surface (Ra = 1.35 μm).
• CFD analysis provided further insights into the mechanisms underlying hemolysis in these configurations.

Conclusions:

• Stenosis longitudinal length and surface roughness are critical factors influencing in vitro hemolysis.
• Smoother surfaces and shorter stenotic lengths significantly reduce blood damage.
• Optimizing these parameters in medical device design can enhance hemocompatibility and patient safety.