# Postoperative Pain Management

> Postoperative pain for BDS General Surgery — nociception pathway, multimodal analgesia, WHO ladder, opioid side effects and pain assessment scales.

- Canonical URL: https://prepelephant.com/topics/bds/general-surgery/pain-postoperative-bds
- Exam / course: BDS · Subject: General Surgery
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Postoperative Pain Management", PrepElephant, https://prepelephant.com/topics/bds/general-surgery/pain-postoperative-bds

## Direct answer

Untreated postoperative pain is not merely unkind — it is physiological sabotage: shallow breathing breeds atelectasis, immobility breeds deep vein thrombosis and chest infection, and unrelieved acute pain primes the nervous system for persistent pain. The modern answer is multimodal analgesia: combining paracetamol, a non-steroidal anti-inflammatory drug, a local anaesthetic block and an opioid where needed, so that smaller doses of each hit different points of the pain pathway and side effects stay manageable. Nociception runs transduction (inflammatory mediators on peripheral endings), transmission (A-delta and C fibres to the dorsal horn and upward), perception (cortex) and modulation (descending inhibition) — and every drug class can be located on that map. Assessment is by number: a pain score of 3 or less out of 10 is the usual treatment target, and the visual analogue or numeric rating scale at rest and on movement is how it is tracked on every postoperative chart.

## What you must remember

- **The nociception map:** transduction at the injured ending (prostaglandins, bradykinin, histamine sensitize it), transmission by A-delta (sharp, fast) and C fibres (dull, slow) to the dorsal horn, perception in the cortex, modulation by descending pathways — name a drug's target and you can reason its use.
- **Multimodal principle:** paracetamol plus NSAID plus local anaesthetic plus opioid-sparing adjuncts — better analgesia at lower doses of each than any single agent pushed to its toxicity.
- **Drug doses and ceilings:** paracetamol 1 g every 6-8 hours to a maximum of 4 g per day (lower in liver disease and low body weight); NSAIDs for dental and post-surgical pain with the standard cautions — avoid in peptic ulcer, renal impairment, aspirin-sensitive asthma and bleeding risk; tramadol for moderate pain; morphine for severe.
- **WHO analgesic ladder:** step 1 non-opioid (paracetamol, NSAIDs), step 2 weak opioid for mild-to-moderate, step 3 strong opioid for moderate-to-severe — originally for cancer pain, applied in graduated postoperative analgesia.
- **Local anaesthesia in dentistry and surgery:** lignocaine 1-2 per cent with adrenaline 1:100,000 for intraoperative haemostasis and analgesia; long-acting bupivacaine for prolonged postoperative relief; never exceed the maximum safe dose (lignocaine about 4-7 mg/kg with adrenaline as commonly quoted).
- **Opioid effects and antidote:** respiratory depression, sedation, nausea, constipation, pruritus, urinary retention and dependence with prolonged use; naloxone reverses respiratory depression; laxatives and antiemetics accompany prescriptions.
- **Patient-controlled analgesia:** intravenous opioid self-administered with a lockout, better matched to individual need after major surgery.
- **Pre-emptive and preventive analgesia:** analgesia started before or at incision blunts central sensitisation — the rationale for giving analgesics before the local anaesthetic wears off, a rule directly applicable after third molar surgery.

## The third molar patient: multimodal plan worked through

A healthy 24-year-old faces bilateral impacted third molar removal under sedation. The plan is written before the incision: paracetamol 1 g and a NSAID given pre-emptively, so both are working when the surgical insult lands; local anaesthetic infiltration and inferior alveolar blocks with lignocaine and adrenaline for anaesthesia and haemostasis, with the long-acting agent chosen if evening pain is expected. Postoperatively, the NSAID continues on a fixed schedule (round-the-clock, not wait-for-pain) with paracetamol between, an opioid reserved as rescue for breakthrough pain, ice packs and elevated sleeping. The result is a patient who eats, talks and sleeps — and who rarely meets the opioid at all, which is the entire point. Contrast the same plan in a patient with ulcer disease or renal impairment: the NSAID drops out, paracetamol carries the base, and short-course weak opioid covers the peak. Every dental prescription written this way — scheduled, multimodal, purpose-limited — is a postoperative pain syllabus applied daily.

## Where students slip

The recurring exam error is treating analgesia as reactive rather than scheduled: writing "SOS" for every drug guarantees the patient cycles between pain and sedation, while round-the-clock dosing for the first 48 hours keeps pain below the sensitisation threshold. The second slip is NSAID blindness — prescribing ibuprofen or diclofenac to the patient who just described a duodenal ulcer, or aspirin to a bleeding tooth socket. And in the viva, learn one sentence of mechanism per drug: NSAIDs block prostaglandin synthesis at transduction, opioids bind receptors in the dorsal horn and above, local anaesthetics block sodium channels along the entire pathway, and ketamine tackles the NMDA receptor that drives wind-up.

## Frequently asked questions

### Why is multimodal analgesia superior to single-drug therapy?

Combining drugs acting at different points of the nociceptive pathway achieves better pain control with lower individual doses, reducing each drug's dose-dependent side effects.

### What is the maximum daily dose of paracetamol in adults?

4 grams per 24 hours in divided doses, reduced in liver disease, chronic alcohol use and low body weight, because overdose causes centrilobular hepatic necrosis.

### When should NSAIDs be avoided postoperatively?

In peptic ulcer disease, significant renal impairment, aspirin-sensitive asthma, active bleeding or thrombocytopenia, and where prostaglandin-dependent renal perfusion is compromised.

### What is pre-emptive analgesia?

Administering analgesia before or during the surgical insult to prevent central sensitisation, so pain is easier to control afterwards — giving drugs before the local anaesthetic wears off is the everyday application.

### How is postoperative pain assessed at the bedside?

By a numeric rating scale of 0-10 (or visual analogue scale and faces scale in children), recorded at rest and on movement, with a score of 3 or less as the usual target for function and recovery.