Reaction Time in Intradermal Anesthesia Sensitivity Testing
For intradermal tests used in perioperative allergy investigation, results should be read after 20-30 minutes. 1
Standardized Reading Times
The reaction time for intradermal anesthesia sensitivity testing follows established protocols:
- Intradermal tests: Results are read 20-30 minutes after injection of 0.02 to 0.05 mL of dilute drug solution 1
- Skin prick tests (performed first): Results are read after 15-20 minutes 1
Testing Protocol and Interpretation
Intradermal tests are performed only when skin prick tests are negative, as they are more sensitive but also less specific and carry higher risk of systemic reactions. 1
Key Technical Points:
- Test location: Forearm or back 1
- Volume injected: 0.02-0.05 mL of appropriately diluted drug solution 1
- Controls required: Histamine (positive control) and physiological saline (negative control) must be used simultaneously 1
- Reading window: The 20-30 minute timeframe captures immediate IgE-mediated hypersensitivity reactions 1, 2
Important Caveats
Antihistamine medications must be discontinued several days before testing, as they interfere with the wheal-and-flare response, though oral or inhaled steroids do not need to be stopped. 1
Testing must be performed by experienced personnel using standardized, non-irritant drug concentrations, particularly for neuromuscular blocking agents and opioids which can cause false-positive irritant reactions. 1
The diagnostic value of intradermal tests varies significantly by drug class—they are most reliable for latex, beta-lactam antibiotics, and neuromuscular blocking agents, but less useful for NSAIDs, dextrans, or radiological contrast media where non-IgE mechanisms predominate. 1