Quantification of skin blood flow at patch test sites

Area of Science:

• Dermatology
• Allergology
• Biomedical Engineering

Background:

• Patch testing is crucial for diagnosing allergic contact dermatitis.
• Assessing irritancy from the patch test procedure itself is important for accurate results.
• Laser Doppler flowmetry offers a quantitative method to measure skin blood flow changes.

Purpose of the Study:

• To evaluate the irritancy potential of van der Bend and True test patches using laser Doppler flowmetry.
• To compare the irritancy of these new patches with previously studied patch types.
• To validate the standard 72-hour and 96-hour reading intervals for patch tests.

Main Methods:

• Healthy subjects underwent patch testing on the back and forearm.
• Van der Bend and True test patches, with and without nickel sulfate, were applied.
• Skin blood flow was measured using laser Doppler flowmetry before application and at intervals after removal.

Main Results:

• Increased skin blood flow was observed at 26 of 32 test sites immediately after patch removal.
• In most cases, skin blood flow returned to baseline levels by 72 hours post-removal.
• The tested patches exhibited less persistent irritancy compared to A1-test, Finn chambers, and Silver patches.

Conclusions:

• Van der Bend and True test patches demonstrate a transient irritancy effect.
• The findings support the established practice of relying on 72-hour and 96-hour readings for patch test interpretation.
• Laser Doppler flowmetry is a valuable tool for quantifying procedural irritancy in patch testing.