Anesthesia Techniques and Agents
What you must understand
Distinguish general anesthesia (IV and inhalational), regional anesthesia (neuraxial, plexus, peripheral blocks), and local anesthesia. Know the agents: propofol, etomidate, ketamine, thiopental, opioids, muscle relaxants (depolarizing and nondepolarizing), volatile agents, and local anesthetics (esters versus amides). Understand induction, maintenance, and emergence phases, and the concept of balanced anesthesia. Know the pharmacology of local anesthetics, including onset, duration, maximum safe dose, and the difference between additive and systemic toxicity. Understand neuraxial anesthesia levels, sympathetic blockade, and contraindications (coagulopathy, infection, hypovolemia). Recognize malignant hyperthermia triggers (volatile agents and succinylcholine) and the antidote (dantrolene).
Traps in questions
A classic trap is mixing up maximum local anesthetic doses or ignoring additive toxicity when combining agents. Another is giving succinylcholine to a patient with hyperkalemia risk (burns, crush injury, denervation). Watch for questions that confuse spinal and epidural effects, or that assume regional anesthesia has no systemic risk.
Rule of thumb
For local anesthetics, calculate the maximum dose before drawing up, and remember that epinephrine prolongs duration and reduces systemic absorption but does not raise the safe dose of every agent equally.