Can the modified Allen's test always detect sufficient collateral flow in the hand? A computational study

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Medical Imaging and Modeling

Background:

• Assessing collateral circulation in the hand is crucial for preventing ischemia after radial artery procedures.
• The modified Allen's test (MAT) is commonly used but its accuracy can be compromised.
• Numerical modeling provides a powerful tool to investigate the hemodynamics of arterial networks.

Purpose of the Study:

• To numerically model blood flow in arm arteries to evaluate the modified Allen's test (MAT).
• To assess the suitability of MAT for detecting sufficient collateral hand circulation when radial artery supply is interrupted.
• To identify factors influencing the accuracy of MAT and digital pressure measurements.

Main Methods:

• One-dimensional numerical modeling of pressure and flow wave propagation in compliant arterial vessels.
• Simulation of arterial compression to replicate the modified Allen's test (MAT) conditions.
• Analysis of blood flow in the superficial palmar arch and digital systolic pressures during simulated radial artery compression.

Main Results:

• Small superficial palmar arch calibres and insufficient radial artery compression can lead to false-positive MAT results.
• Measurement of digital systolic pressure drop during radial artery compression is more sensitive for detecting ulnar collateral flow in small-calibre vessels.
• Digital pressure measurements can also be unreliable with insufficient radial artery compression.

Conclusions:

• The study highlights limitations of the modified Allen's test (MAT), particularly in cases of small superficial palmar arches.
• Digital systolic pressure measurement is a more sensitive indicator of collateral hand blood flow than MAT.
• Optimized compression techniques are necessary for both MAT and digital pressure measurements to ensure accurate assessment of collateral circulation.