Do Catheter Side Holes Provide Better Blood Flows?

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Nephrology

Background:

• Hemodialysis requires efficient blood flow, often facilitated by vascular access catheters.
• Catheter design, including side hole configuration, influences hydraulic resistance and blood flow rates.

Purpose of the Study:

• To determine the hydraulic resistance of four different hemodialysis catheters under varying flow rates.
• To compare the performance of permanent and acute catheters, considering the impact of side holes.

Main Methods:

• In vitro testing of four catheters (Ash Split Cath, Tesio, Duo-Split, Duo-Flow) in a glycerin-water solution.
• Measurement of hydraulic resistance with side holes open and closed.
• Derivation of an equivalent diameter to characterize catheter performance.

Main Results:

• Pressure-flow relationship is quadratic, deviating from Poiseuillian theory.
• Permanent catheters exhibit larger equivalent internal diameters (1.8 mm) and higher flow rates (300 mL/min) compared to acute catheters (1.45 mm, 200 mL/min).
• Side hole obstruction significantly reduces flow in acute catheters but has minimal impact on permanent catheters.

Conclusions:

• Catheter design critically affects achievable blood flow rates during hemodialysis.
• Side holes are crucial for acute catheter performance but may be superfluous in permanent catheters.
• Obstruction of side holes or fibrin sleeve formation can severely limit blood flow, particularly in acute catheters.