## Maximum Recommended Doses of Local Anesthetics in Peripheral Nerve Blocks **Key Point:** Maximum recommended doses vary based on the local anesthetic agent, presence of epinephrine, and type of block. Bupivacaine dosing is critical to prevent systemic toxicity. ### Bupivacaine Dosing Guidelines | Scenario | Maximum Dose (mg) | Notes | | --- | --- | --- | | Bupivacaine without epinephrine | 225 | Single-shot peripheral nerve block | | Bupivacaine with epinephrine | 300 | Epinephrine reduces systemic absorption | | Lidocaine without epinephrine | 300 | Higher margin due to lower toxicity | | Lidocaine with epinephrine | 500 | Epinephrine allows higher dosing | **High-Yield:** The maximum recommended dose of bupivacaine **without epinephrine** is **225 mg** (3 mg/kg, max 225 mg). With epinephrine, it increases to **300 mg** (4 mg/kg, max 300 mg). This is a frequently tested fact in NEET PG anesthesia. **Warning:** Exceeding these doses increases risk of local anesthetic systemic toxicity (LAST), which presents as cardiovascular collapse and seizures. Bupivacaine is particularly cardiotoxic and has a narrow margin between therapeutic and toxic concentrations. **Clinical Pearl:** In an average 70 kg adult, 225 mg bupivacaine = 3.2 mg/kg (safe). Addition of epinephrine 1:200,000 reduces systemic absorption by 25–30%, allowing the dose to be increased to 300 mg (4.3 mg/kg). ### Calculation Example For a 70 kg adult receiving bupivacaine 0.5% (5 mg/mL): - Maximum volume without epinephrine = 225 mg ÷ 5 mg/mL = **45 mL** - Maximum volume with epinephrine = 300 mg ÷ 5 mg/mL = **60 mL** 
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