Lidocaine-Epinephrine-Tetracaine (LET)

  • Use on non-mucosal skin surfaces (including lacerations)
  • Apply 1-3mL to the wound with firm pressure for 15-30 minutes


Drug Dose
Lidocaine 1%


4.5 300mg (30mL)
Lidocaine 1% (w/epi)


7 500mg (50mL)
Bupivacaine 0.5%


2 175mg (35mL)


Injecting local anesthetics with low pH can be painful (the pH of lidocaine with epinephrine is 4.0). Buffering with sodium bicarbonate creates a solution approaching physiologic pH and may reduce pain.

  1. Using a 10mL syringe, draw up 1mL of 8.4% sodium bicarbonate
  2. Add 10mL of lidocaine, for a total volume of 11 ml (yes, the syringe can handle the extra mL), to achieve a 10:1 ratio

Local Anesthetic Systemic Toxicity (LAST)


  • Life-threatening adverse reaction to local anesthetic toxicity
  • Occurs in ~0.2% of nerve blocks
  • Generally occurs within minutes of injection


  • Injection of local anesthetic into systemic circulation
    • Most common source of toxicity
    • Intravascular injection can cause toxicity below the maximum recommended dose
  • Exceeding the maximum dose of local anesthetic (see table above)
  • Absorption of anesthetic into systemic circulation by injection into extremely vascular area

Clinical Features

  • CNS
    • Auditory changes/Tinnitus
    • Metallic taste
    • Seizures or drowsiness
    • Coma
    • Respiratory arrest
  • Cardiovascular
    • Early signs
      • Tachycardia
      • Ventricular dysrhythmia
      • Hypertension
    • Late signs
      • Bradycardia
      • Conduction block
      • Cardiovascular collapse
      • Asystole


  1. Aggressive supportive care: Airway management, ACLS, seizure management
  2. NaHCO3 1 ampule IV q2 minutes for: VT/VF, severe acidosis
  3. Lipid emulsion 20% solution
    1. 1.5 mL/kg bolus over 1 minute
    2. Then, 0.25 mL/kg/min for 20 min or until hemodynamic stability achieved
    3. ↑ to 0.5 mL/kg/min if hemodynamic status declinesc
    4. Maximum total dose 12 mL/kg.


  1. WikEM