What is the appropriate lidocaine infiltration technique and dosage for incision and drainage of an abscess, including maximum dose limits and adjustments for allergies or comorbidities?

Lidocaine Administration for Incision and Drainage of Abscesses

Infiltrate lidocaine 1% with epinephrine 1:100,000 directly into the tissues surrounding the abscess using a maximum dose of 7 mg/kg (up to 500 mg) in adults, injecting slowly with frequent aspiration to avoid intravascular administration. 1

Recommended Technique and Dosing

Standard Infiltration Approach

• Use lidocaine 1% with epinephrine 1:100,000 as the first-line agent for local anesthesia during incision and drainage procedures 2, 1

• Maximum safe doses:

  • Adults: 7 mg/kg (up to 500 mg total) with epinephrine; 4.5 mg/kg (up to 300 mg) without epinephrine 1
  • Children: 3.0-4.5 mg/kg with epinephrine 1
  • Infants <6 months: reduce all doses by 30% 1

• For a 70 kg adult, this allows up to 490 mg (49 mL of 1% lidocaine solution) when combined with epinephrine 1

Injection Technique to Minimize Pain

• Buffer the lidocaine with sodium bicarbonate at a 1:9 or 1:10 ratio to reduce injection pain 1
• Warm the solution to body temperature before injection 1
• Use the smallest gauge needle feasible for the procedure 1
• Inject slowly with frequent aspiration to confirm extravascular placement and avoid intravascular injection 1, 3
• Infiltrate around the abscess rather than directly into the cavity, as the acidic environment of an abscess reduces local anesthetic efficacy 3

Alternative Technique for Sacrococcygeal Abscesses

• Aspirate the abscess first, then inject the same volume of local anesthetic directly into the abscess cavity through the same needle 4
• This technique eliminates multiple painful infiltrations and requires lower volumes of anesthetic 4

Critical Safety Considerations

Preventing Local Anesthetic Systemic Toxicity (LAST)

• Always aspirate before injection to avoid intravascular administration 1
• Monitor vital signs every 5 minutes when using high doses or injecting into highly vascular areas 1
• Have 20% lipid emulsion immediately available for treatment of suspected LAST 1, 5
• Watch for early toxicity signs: slurred speech, tinnitus, light-headedness, circumoral numbness, facial tingling, metallic taste 1
• Serious toxicity (CNS depression, seizures, cardiac arrest) occurs at plasma levels of 9-10 μg/mL 1, 5

Timing Restrictions with Other Local Anesthetics

• Do not use lidocaine within 4 hours of any other local anesthetic intervention (nerve blocks, fascial plane blocks, epidural boluses, or additional infiltration at other sites) to prevent cumulative toxicity 6, 1

Dose Adjustments for Special Populations

Calculate Using Ideal Body Weight in Obese Patients

• Use ideal body weight, not actual weight, for dose calculations in patients with BMI >30 kg/m² 6, 1
• Formula: Ideal body weight = (height in cm - 100) for men; (height in cm - 105) for women 6

Reduce Doses in High-Risk Patients

• Reduce doses by 30-50% in patients with hepatic dysfunction, cardiac failure, hypoalbuminemia, low body weight, reduced muscle mass, or those taking beta-blockers or amiodarone 1

Alternatives for Lidocaine Allergy

If true lidocaine allergy is documented:

1. First choice: Ester-type local anesthetic (procaine or tetracaine) - cross-reaction between amide and ester agents is rare 1
2. Second choice: 1% diphenhydramine injection - onset ≈5 minutes (versus ≈1 minute for lidocaine), suitable for small procedures 1
3. Third choice: Bacteriostatic saline (0.9% benzyl-alcohol-containing normal saline) - may be less painful than diphenhydramine when combined with epinephrine 1

Expected Onset and Duration

• Onset of action: approximately 1 minute for infiltrative anesthesia 2
• Duration with epinephrine: 90-200 minutes 2, 1
• Duration without epinephrine: 60-90 minutes 1

Common Pitfalls to Avoid

• Injecting too rapidly increases both patient pain and systemic absorption 1
• Forgetting to aspirate before injection raises the risk of intravascular delivery and LAST 1, 5
• Using actual body weight instead of ideal body weight in obese patients leads to overdosing 1
• Failing to account for cumulative doses from multiple injection sites or recent local anesthetic use 1
• Injecting directly into the abscess cavity (except for the specialized sacrococcygeal technique) reduces anesthetic efficacy due to the acidic environment 3

Evidence Quality Note

While topical lidocaine/tetracaine patches have been studied, injectable lidocaine remains the standard approach as it provides clinically equivalent analgesia with more reliable onset 7. Buffering lidocaine with sodium bicarbonate reduces injection pain in non-infected tissues but may not significantly reduce procedural pain during incision and drainage of abscesses 8.