How to Prepare 15 Micrograms of Epinephrine for Epidural Test Dose
To prepare 15 µg of epinephrine for an epidural test dose, draw up 3 mL of commercially prepared 1.5% lidocaine with 1:200,000 epinephrine, which contains exactly 15 µg of epinephrine. 1, 2
Standard Preparation Method
The most straightforward approach uses commercially available lidocaine-epinephrine solutions:
Draw 3 mL of 1.5% lidocaine with 1:200,000 epinephrine - this pre-mixed solution contains 15 µg of epinephrine and is the standard epidural test dose used in clinical practice 1, 2, 3
The 1:200,000 concentration means 5 µg of epinephrine per mL, so 3 mL delivers exactly 15 µg 1, 2
Alternative Preparation from Stock Epinephrine
If you need to prepare the test dose from stock epinephrine (1:1,000 or 1 mg/mL):
Take 0.015 mL (15 µg) of 1:1,000 epinephrine and add it to 3 mL of 1.5% plain lidocaine 4
This creates the same final concentration as the commercial preparation (1:200,000 epinephrine in lidocaine) 4
Alternatively, you can add 1 mL of 1:1,000 epinephrine to 200 mL of lidocaine solution to create a 1:200,000 concentration, then draw up 3 mL 4
Clinical Context for Test Dose Use
Understanding when and how this dose is used helps ensure proper preparation:
The 15 µg epinephrine test dose is designed to detect intravascular catheter placement by producing hemodynamic changes 2, 3
Positive test criteria include: systolic blood pressure increase ≥15 mmHg (100% sensitivity and specificity), T-wave amplitude decrease ≥0.1 mV or ≥25% (100% sensitivity and specificity), or heart rate increase ≥10 bpm (though less reliable with only 67% sensitivity in some anesthetic conditions) 1, 3
The test dose produces peak hemodynamic changes at 40-80 seconds after IV injection 1, 2
Critical Pitfalls to Avoid
Do not confuse 1:1,000 with 1:10,000 or 1:200,000 concentrations - using the wrong dilution will result in 10-fold or 200-fold dosing errors 5
Verify the epinephrine concentration on the label before drawing up any dose - commercial preparations clearly state 1:200,000 on lidocaine-epinephrine mixtures 4
The 15 µg dose may be insufficient during deeper anesthesia (1 MAC isoflurane or higher), where minimum required doses range from 6-19 µg depending on anesthetic depth 2
Label your prepared syringe clearly with "Epidural Test Dose: 3 mL lidocaine 1.5% with 15 µg epinephrine" to prevent administration errors 5