Recommended Ratio of Lidocaine to Epinephrine for Suturing
The most commonly used and recommended concentrations of epinephrine combined with lidocaine for suturing are 1:100,000 or 1:200,000, with current evidence supporting 1:200,000 as optimal to minimize side effects while maintaining equivalent efficacy. 1
Standard Concentrations for Dermatologic Surgery
The American Academy of Dermatology guidelines establish that concentrations of 1:50,000,1:100,000, and 1:200,000 all provide equivalent vasoconstriction and prolong anesthetic duration by approximately 200%. 1
Use the lowest effective concentration (1:200,000 or 1:400,000) to provide optimal hemostasis while minimizing potential cardiovascular side effects such as palpitations and anxiety. 1, 2
More dilute concentrations (1:800,000 to 1:3,200,000) offer less effective vasoconstriction and only prolong anesthesia duration by approximately 100%. 1, 2
Practical Dosing Guidelines
Maximum safe dose of lidocaine is approximately 7 mg/kg when mixed with epinephrine (compared to only 3 mg/kg for plain lidocaine). 3
For a 70 kg patient using 2% lidocaine solution, this translates to approximately 29 mL maximum volume. 1
In pediatric patients under 6 months, reduce amide local anesthetic doses by 30%. 1
Timing and Technique Considerations
Allow 8-10 minutes after injection before making incisions to achieve maximal vasoconstriction benefit. 4
Facial injections reach peak effect at 8 minutes, while forearm injections peak at 10 minutes. 4
Buffering lidocaine with sodium bicarbonate 8.4% at a ratio of approximately 1 mL bicarbonate per 10 mL of 1% lidocaine with epinephrine reduces injection pain by neutralizing the acidic pH (typically 4.24 for 1% lidocaine with 1:100,000 epinephrine). 5
Safety Profile Across Patient Populations
Epinephrine is safe for use in digits (fingers and toes) contrary to historical teaching, with strong Level A evidence supporting its use without risk of necrosis. 6
Safe in patients with stable, controlled cardiovascular disease including hypertension, ischemic heart disease, and arrhythmias when used in small amounts. 1
In hemodynamically unstable patients, prefer 1:200,000 over 1:80,000 concentration as it causes significantly less elevation in systolic blood pressure and heart rate while maintaining equivalent anesthetic efficacy. 7
Common Pitfalls to Avoid
Do not use concentrations more dilute than 1:400,000 as they provide inferior vasoconstriction and shortened duration of action. 1, 2
Avoid excessive total volumes—calculate maximum allowable dose based on patient weight before beginning the procedure. 1
Be aware that epinephrine-containing solutions are approximately 1000 times more acidic than subcutaneous tissue, making buffering particularly valuable for patient comfort. 5