Pain is a relay with four handoffs — transduction, transmission, perception, modulation — and almost every drug you give interrupts one of them. Pick the kind of pain your patient has, switch interventions on, and watch where each one lands on the relay. Then leave the residual pain running and read the physiologic bill.
1 · What kind of pain is this?
2 · Where will you intervene?
3 · Leave the residual pain running
The shortcut. A student who learns the four steps never has to memorise a drug list. Ask “where does this molecule act?” Multimodal analgesia is simply the decision to hit four targets with small doses rather than one target with a large one.