Maximum Safe Doses

Maximum Safe Doses - Dose Cap Decode

• Max Safe Dose (MSD): Highest dose (mg/kg) unlikely to cause systemic toxicity. Calculate using lean body weight.
• Plain Solutions (mg/kg):
  • Lidocaine: 4.5 (Max 300 mg)
  • Bupivacaine: 2 (Max 175 mg)
  • Ropivacaine: 3 (Max 200 mg)
  • Prilocaine: 6 (Max 400 mg)
• With Epinephrine (1:200,000) (mg/kg):
  • Lidocaine: 7 (Max 500 mg)
  • Bupivacaine: 2.5 (Max 225 mg)
  • Prilocaine: 8 (Max 600 mg)
    • ⚠️ Prilocaine: Risk of methemoglobinemia.
• 📌 Mnemonic (mg/kg): Lidocaine (Plain 4.5, Epi 7), Bupivacaine (Plain 2, Epi 2.5).

• ⭐ Bupivacaine is the most cardiotoxic LA. Levobupivacaine and Ropivacaine offer improved cardiac safety.

Maximum Safe Doses - NumbByNumbers

• Lidocaine (Xylocaine)
  • Plain: 4.5 mg/kg (Max: 300 mg)
  • With Adrenaline: 7 mg/kg (Max: 500 mg)
  • 📌 "Lido: 4.5 plain, 7 with adrenaline's gain."
• Bupivacaine (Marcaine)
  • Plain: 2 mg/kg (Max: 175 mg)
  • With Adrenaline: 2.5 mg/kg (Max: 225 mg)

  • ⭐ Bupivacaine: High cardiotoxicity. Treat severe toxicity with Intravenous Lipid Emulsion (ILE).

• Ropivacaine (Naropin)
  • Dose: 3 mg/kg (Max: 200-250 mg) (Plain or with Adrenaline)
  • Less cardiotoxic than Bupivacaine.
• Levobupivacaine (Chirocaine)
  • Dose: 2 mg/kg (Max: 150 mg)
  • S-enantiomer of bupivacaine; reduced cardiotoxicity.
• Prilocaine
  • Plain: 6 mg/kg (Max: 400 mg)
  • With Adrenaline: 8 mg/kg (Max: 600 mg)
  • Risk: Methemoglobinemia (esp. > 8 mg/kg or total > 600 mg).
• Chloroprocaine (Nesacaine)
  • Plain: 11 mg/kg (Max: 800 mg)
  • With Adrenaline: 14 mg/kg (Max: 1000 mg)
  • Ester; rapid hydrolysis; safest in obstetrics.
• Cocaine (Topical)
  • Dose: 1.5-3 mg/kg (Max: 150-200 mg)
  • Intrinsic vasoconstrictor.

Maximum Safe Doses - Toxic Shock Talk

Exceeding max safe doses leads to Local Anesthetic Systemic Toxicity (LAST).

• Max Doses (Plain / +Epinephrine):
  • Lidocaine: 4.5 mg/kg / 7 mg/kg
  • Bupivacaine: 2.5 mg/kg / 3 mg/kg
• LAST Symptoms (CNS → CVS): 📌 S.A.M.S. - Speech (slurred), Altered mental status, Muscle twitches, Seizures.
  • Early CNS: Tinnitus, metallic taste, circumoral numbness.
  • Late CNS: Seizures, coma.
  • CVS: Bradycardia, hypotension, arrhythmias, cardiac arrest. (Bupivacaine = high cardiotoxicity).
• Management (STOP LA!):
  • Airway, Breathing, Circulation (ABC). 100% O₂.
  • Seizures: Benzodiazepines.
  • Lipid Emulsion (20%): Bolus 1.5 mL/kg, then 0.25 mL/kg/min.

⭐ Intravenous lipid emulsion (20%) is the specific antidote for severe LAST, especially bupivacaine-induced cardiotoxicity.

High‑Yield Points - ⚡ Biggest Takeaways

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