Local Anesthetic Max Dose

CRNA Study Suite · LAST Prevention
All Calculators Fluid Calculator LA Max Dose
Patient & Drug
Planned Dose (Optional)
1% = 10 mg/mL
0.5% = 5 mg/mL
0.25% = 2.5 mg/mL
Maximum Allowable Dose
Max Dose
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mg
Max Volume
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mL
Planned Dose
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mg
⚠ OVERDOSE WARNING: Planned dose (-- mg) exceeds the maximum safe dose (-- mg). Reduce volume or concentration.
Absolute ceiling: --
Methemoglobinemia risk: Prilocaine & benzocaine can cause methemoglobinemia. Treat with methylene blue 1-2 mg/kg IV over 3-10 min (Nagelhout, 2023, pp. 134-135).
Calculation Breakdown
1. Maximum mg/kg Dose
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Max Dose = -- mg
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Max Volume Calculation
Volume (mL) = Max Dose (mg) ÷ Concentration (mg/mL)
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Max Volume = -- mL
Drug Properties
Property Value Source
⚠ LAST Treatment (Nagelhout Ch 10, pp. 130-133) 1. AIRWAY FIRST — 100% O₂, prevent hypoxia/acidosis
2. Seizure: Benzodiazepine (avoid propofol if CV instability)
3. Lipid Emulsion 20%: 1.5 mL/kg IV bolus, then 0.25 mL/kg/min infusion
4. Epinephrine: Small doses only (<1 µg/kg or 10-100 µg boluses)
5. AVOID: Vasopressin, calcium channel blockers, β-blockers, other LAs
6. Monitor ≥30 min after potentially toxic doses
Clinical note: Nagelhout emphasizes "Body weight dosing should only be used in pediatric patients" (p. 132). In adults, mg/kg max doses are a guideline — total dose, block site, patient comorbidities, and incremental injection technique are more predictive of LAST risk than weight alone.
References

Nagelhout, J. J. (2023). Local anesthetics. In S. Elisha, J. S. Heiner, & J. J. Nagelhout (Eds.), Nurse anesthesia (7th ed., pp. 118-137). Elsevier.

Note: Nagelhout Ch 10 explicitly documents max doses for lidocaine (p. 130) and bupivacaine (p. 130). Values for ropivacaine, mepivacaine, prilocaine, chloroprocaine, procaine, and tetracaine reflect widely accepted clinical ranges (confirm with institutional formulary/package insert).

How this works

How maximum doses work

Maximum local anesthetic doses are weight based ceilings meant to keep peak plasma levels below the threshold for local anesthetic systemic toxicity (LAST). Lidocaine is 4.5 mg/kg plain and 7 mg/kg with epinephrine (Nagelhout, 2023, p. 130). Bupivacaine is 2 mg/kg plain and 3 mg/kg with epinephrine, capped at 175 to 225 mg regardless of weight because it is the most cardiotoxic amide in clinical use (Nagelhout, 2023, p. 130). Mepivacaine runs 4 to 5 mg/kg plain and 7 mg/kg with epinephrine, while ropivacaine is dosed at 3 mg/kg with or without epinephrine (Qiao & Lin, 2024, pp. 1646-1647). Epinephrine raises the ceiling by slowing systemic absorption, not by changing inherent toxicity.

Local anesthetic systemic toxicity

LAST begins with perioral numbness, tinnitus, and agitation before progressing to seizures and cardiovascular collapse, and is treated with airway control, seizure suppression, and 20% lipid emulsion (Nagelhout, 2023, pp. 128-133).

References

Nagelhout, J. J. (2023). Local anesthetics. In Elisha, Heiner, & Nagelhout (Eds.), Nurse anesthesia (7th ed., pp. 118-137). Elsevier. Qiao, W. P., & Lin, Y. (2024). Local anesthetics. In Barash, Cullen, and Stoelting's clinical anesthesia (9th ed.). Wolters Kluwer.