This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Regional Anesthesia, Subject name: Anaesthesia
Fastest to slowest route of absorption of local anaesthetic is? 
Select and explain. 
A. Tracheal >Lumbar epidural > Intercostal block > Subcutaneous., B. Tracheal > Intercostal block > Lumbar epidural > Subcutaneous., C. Subcutaneous> Intercostal block > Lumbar epidural >Tracheal., D. Lumbar epidural > Intercostal block >Tracheal > Subcutaneous.
B: Tracheal > Intercostal block > Lumbar epidural > Subcutaneous.
Answer: B: Tracheal > Intercostal block > Lumbar epidural > Subcutaneous. 
Explanation: According, the rate of systemic absorption is greatest with intercostal nerve blocks followed by caudal, lumbar epidural, brachial plexus block femoral and sciatic nerve blocks. Sequence of systemic absorption IV > Tracheal > Intercostal block > Para cervical block > Caudal > Lumbar epidural > Brachial Plexus > Sciatic > Subcutaneous.