Derm Cases · Dermatology / Procedural safety
OSCE — safe local anaesthesia for office skin surgery
An 8-minute OSCE on choosing lidocaine ± epinephrine, calculating maximum dose from % concentration, pain-minimising infiltration, recognising LAST, and distinguishing tumescent from standard infiltrative practice.
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Target exams
NEET-PGINICETPLABMRCPFRCDerm
Prompt
An 8-minute OSCE on choosing lidocaine ± epinephrine, calculating maximum dose from % concentration, pain-minimising infiltration, recognising LAST, and distinguishing tumescent from standard infiltrative practice.
Brief (to candidate)
You will infiltrate local anaesthetic for a back ellipse on a 70 kg adult using 1% lidocaine with epinephrine. Explain dose limits, injection technique for comfort, and what you would do if the patient develops tinnitus and perioral numbness mid-procedure.
[1]Candidate instructions
- State amide class and role of epinephrine.
- Convert 1% → 10 mg/mL and apply a classical max dose framework.
- Describe pain-minimising injection (buffer/warm/slow/fine needle).
- Recognise LAST prodrome and list stop / ABC / oxygen / emergency help / lipid pathway.
- Note tumescent ≠ routine infiltrative dosing if asked about large volumes.
- Optional: digital epinephrine myth revisited with caveats.
Examiner checklist
| Domain | Key actions expected |
|---|---|
| Drug class | Lidocaine amide ± epinephrine for haemostasis/duration |
| Maths | 10 mg/mL; ~7 mg/kg with epi classical teaching example for 70 kg ≈ 490 mg[3] |
| Comfort | Buffer, warm, slow, small needle[1][2] |
| LAST | Stop injection; supportive care; lipid concept[3] |
| Scope | Tumescent specialised literature vs small-field infiltration[5] |
| Digits | Dilute epi not absolute ban in selected cases[4] |
Common errors
- Cannot convert % to mg/mL.
- Continues injecting through clear CNS prodrome.
- Quotes tumescent mega-doses for a simple punch without context.
References5ShowHide
- [1]Nadir U, et al. How to minimize pain with local anesthesia and improve patient experiences: a review. An Bras Dermatol, 2026.PMID 42107926
- [2]Desai SR, et al. In-office compounding of buffered lidocaine and epinephrine - A stability and safety review. JAAD, 2026.PMID 41665574
- [3]Wang A, et al. Toxicity of Infiltrative Lidocaine in Dermatologic Surgery: Are Current Limits Valid? Dermatol Pract Concept, 2021.PMID 34631267
- [4]Krunic AL, et al. Digital anesthesia with epinephrine: an old myth revisited. JAAD, 2004.PMID 15523354
- [5]Klein JA, Jeske DR. Estimated Maximal Safe Dosages of Tumescent Lidocaine. Anesth Analg, 2016.PMID 26895001