Board-style heuristic for relative local anesthetic systemic uptake by route/site, with LAST-risk context and caveats about technique and vascularity.
Review the core table first, then launch practice to convert recognition into faster recall.
This is a classic board-review heuristic, not an exact invariant ranking. Real plasma levels vary with the drug, dose, epinephrine use, tissue vascularity, ultrasound guidance, and whether inadvertent intravascular injection occurs.
| Rank | Route/site | Relative absorption rate |
|---|---|---|
| 1 | Intravascular exposure (reference point, not a block site) | Fastest |
| 2 | Intercostal | Very high |
| 3 | Caudal | High |
| 4 | Epidural | Moderately high |
| 5 | Brachial plexus | Moderate |
| 6 | Sciatic / femoral | Lower |
| 7 | Subcutaneous | Slowest |
Faster systemic uptake produces higher plasma concentrations sooner, which increases the risk of local anesthetic systemic toxicity (LAST). The heuristic is most useful as a relative risk anchor, not as a dosing rule.
This tool is for educational purposes only. Always verify clinical values against current authoritative sources before patient care.