Postoperative Pain Management
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Direct answer
Unrelieved postoperative pain is not merely cruel — it drives atelectasis, tachycardia, ileus, immobility, deep vein thrombosis and chronic pain, so analgesia is therapy, not comfort. The organising principle is multimodal, opioid-sparing analgesia: paracetamol as the universal base (1 g up to four times daily, a 4 g ceiling), an NSAID where kidneys and bleeding permit, and a regional technique for major surgery — thoracic epidural, transversus abdominis plane and rectus sheath blocks, erector spinae blocks — with opioids reserved for breakthrough pain, delivered by patient-controlled analgesia as standard. Pain is scored at rest and on movement; a trajectory that rises after laparotomy warns of a complication, not a dosing problem.
What you must remember
- Score and treat to target: numerical rating scale 0-10; moderate pain is 4 and above and demands adjustment, and dynamic pain (cough, mobilisation) matters more than rest pain.
- The multimodal ladder: paracetamol 1 g six-hourly (reduce in low body weight and liver disease) + NSAID/COX-2 (beware renal impairment, gastropathy, and caution around gastrointestinal anastomoses) + regional technique + opioid for breakthrough — each drug lowers opioid need and side effects.
- PCA settings worth quoting: morphine 1 mg bolus, lockout 5-7 minutes, commonly a 4-hour maximum, and no background infusion in opioid-naive patients.
- Epidural analgesia: best evidence for thoracotomy and upper abdominal surgery — improves diaphragm function, cough and gut recovery; complications include hypotension, urinary retention, motor block (check hourly), epidural haematoma or abscess (rare but devastating — new back pain with motor deficit is an emergency MRI).
- Wall blocks: TAP and rectus sheath blocks cover the abdominal wall, not viscera; erector spinae plane blocks cover the thoracic wall and rib fractures.
- Opioid housekeeping: prescribe laxatives and antiemetics with every opioid order; tramadol causes serotonin syndrome with SSRIs; renal impairment prolongs morphine metabolite action (fentanyl preferred); naloxone reverses respiratory depression.
- Special situations: opioid-tolerant patients keep their baseline dose and gain multimodal cover plus ketamine (NMDA antagonism); neuropathic components get gabapentinoids cautiously — sedation and respiratory depression compound with opioids.
- Chronic post-surgical pain — pain beyond three months — follows a fraction of thoracotomy, hernia and breast surgery; the strongest preventable risk factors are severe acute pain and intercostal or ilioinguinal nerve injury, which is why technique and early analgesia are preventive medicine.
A postoperative evening worked through
Day 0 after open hemicolectomy: epidural running, paracetamol scheduled, NSAID held for a creatinine bump. At 8 p.m. the patient scores 6/10 on coughing; dense sensory block, but rising shoulder-tip pain and a rigid abdomen — the correct read is surgical review, not "more opioid": new severe pain after a quiet afternoon is a leak sentinel. The contrast, day 1 after laparoscopic cholecystectomy with TAP blocks: 3/10 at rest, 5/10 walking — oral paracetamol plus tramadol, early feeding, discharge per pathway. The third case, an opioid-tolerant patient on chronic oxycodone: continue baseline, add ketamine and paracetamol, and plan weaning with the acute pain team. Three beds, one principle: assess the pain, but assess the patient more.
Perspective: exam and Indian ward reality
The theory paper tests pharmacology and settings: PCA lockout and bolus, paracetamol ceiling, the epidural-abscess red flags, first-line regional technique for a named incision. The viva trap is the patient with falling blood pressure under epidural — candidates who push intravenous fluids blindly miss checking the block height and the surgical drain; the disciplined answer is assess block, vasopressor support, exclude bleeding, then reduce infusion. Indian ward reality: PCA pumps and acute pain services cluster in tertiary centres, while district analgesia still runs on intramuscular pethidine — substituting scheduled paracetamol, cheap field blocks and early oral multimodal therapy is the examiner-respected answer.
Frequently asked questions
What does multimodal analgesia mean in practice?
Combining paracetamol, an NSAID or COX-2 inhibitor, a regional block and only rescue opioid, so each drug lowers the dose and side effects of the others.
What are standard patient-controlled analgesia settings for morphine?
A 1 mg intravenous bolus with a 5-7 minute lockout and a set 4-hour maximum, without background infusion in opioid-naive patients to avoid respiratory depression.
Which findings suggest an epidural haematoma or abscess?
New severe back pain with motor weakness or radicular symptoms in a patient with an epidural catheter — stop the infusion and obtain an urgent MRI; delay causes permanent paraplegia.
Why are TAP blocks useful if they do not cover visceral pain?
They anaesthetise the abdominal wall (skin, muscle, parietal peritoneum), covering incision and port pain and dramatically cutting opioid need, while visceral pain is handled by systemic multimodal agents.
What is chronic post-surgical pain and how is it prevented?
Persistent pain beyond three months after surgery (common after thoracotomy, hernia and breast operations); prevention centres on controlling severe acute pain and avoiding intra-operative nerve injury.