Multimodal Analgesia Protocols
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Direct answer
Multimodal analgesia attacks postoperative pain through several mechanisms at once so that no single drug — least of all the opioid — has to carry the whole load: paracetamol 1 g every six hours (ceiling 4 g daily, 3 g in liver disease or chronic use) plus a non-steroidal or COX-2 inhibitor where kidneys permit, a regional or field block (transversus abdominis plane block, epidural, wound infiltration), and adjuvants such as low-dose ketamine (N-methyl-D-aspartate receptor antagonist, 0.1-0.3 mg/kg), intravenous lidocaine or dexmedetomidine for selected patients. Opioids remain available — patient-controlled analgesia with morphine 1 mg demand doses and a 5-10 minute lockout is the classic bridge — but every adjunct exists to reduce them. The protocol is embedded in Enhanced Recovery After Surgery pathways, where analgesia exists to get the patient eating, moving and home sooner.
What you must remember
- Paracetamol ceilings: 1 g per dose, 4 g per 24 hours in adults, reduced to about 3 g in low weight, liver disease, chronic alcohol use or regular dosing in the elderly.
- Non-steroidal strategy: preferential where inflammation drives pain; withheld in renal impairment, hypovolaemia, peptic ulcer disease and around coronary artery bypass surgery; COX-2 selective agents spare platelets and gut at cardiovascular cost.
- Regional techniques: single-shot or catheter blocks — transversus abdominis plane for abdominal wall incisions, epidural for thoracic and major abdominal surgery, wound infiltration everywhere — the strongest opioid-sparing element.
- Local anaesthetic systemic toxicity: perioral numbness, tinnitus, seizure then collapse — stop injecting, call for help, lipid emulsion 20% at 1.5 mL/kg bolus with an infusion; the resuscitation drill every candidate must recite.
- Ketamine adjuvant: subanaesthetic 0.1-0.3 mg/kg infusion for opioid-tolerant and neuropathic-heavy pain; psychotomimetic effects blunted with a benzodiazepine where needed.
- Opioid hygiene: patient-controlled analgesia morphine 1 mg per demand, 5-10 minute lockout, no basal rate in opioid-naive patients; stimulant laxative from the first dose; continuous pulse oximetry where risk warrants.
- Gabapentinoids: still written in many protocols despite dizziness and sedation; their contribution in modern trials is modest — worth conceding in a viva.
- ERAS integration: carbohydrate loading, minimally invasive surgery, early feeding, early mobilisation — analgesia is what makes the mobilisation possible.
A worked colectomy protocol
A 60-year-old is scheduled for laparoscopic right colectomy on an ERAS pathway. Her analgesia begins before the incision: paracetamol 1 g and dexamethasone in the anaesthetic room, a transverse abdominis plane block under ultrasound guidance, and wound infiltration at closure. Intraoperatively she may receive a lidocaine or magnesium infusion; postoperatively, scheduled paracetamol 1 g six-hourly and a short non-steroidal course once oral fluids and renal function permit. Opioids are rescue, not foundation — oral tramadol or morphine for breakthrough, with the expectation of a few doses, not a week of them. She is eating on day one and walking the corridor that afternoon, and pain is scored with movement, not at rest.
Every element answers a specific failure: the block covers the somatic wall pain that opioids handle poorly; paracetamol and the non-steroidal lower the opioid requirement measurably; the laxative prevents the opioid-induced ileus that used to masquerade as surgical complication. Should confusion with tinnitus follow a top-up injection, the drill is lipid emulsion — the protocol includes knowing its own antidotes.
Where examiners probe
The guaranteed marks are numbers: the paracetamol ceiling (and its reduction in liver disease), the morphine patient-controlled analgesia demand and lockout, the ketamine adjuvant dose band, and — as a formal question or a viva ambush — the local anaesthetic toxicity regimen, where "call for lipid emulsion 20%, 1.5 mL/kg" is the sentence being fished for. The second tier tests understanding rather than recall: why multimodal beats unimodal (different receptors, different adverse-effect ceilings, opioid-sparing), and why the COX-2 choice is a trade-off rather than an upgrade. The Indian-context angle is resource realism: continuous nerve catheters and patient-controlled pumps are concentrated in tertiary centres, while most Indian postoperative wards run skilful oral-and-intramuscular multimodal regimens — paracetamol, a non-steroidal, truncal blocks where ultrasound exists — and saying how multimodal analgesia is actually delivered at district level shows the examiner a doctor, not a brochure.
Frequently asked questions
What is the daily ceiling for intravenous paracetamol in adults?
4 g per 24 hours, reduced to about 3 g in liver disease, low body weight, chronic alcohol use or frailty.
How is local anaesthetic systemic toxicity treated?
Stop injection, airway and circulation support, seizure control, and intravenous lipid emulsion 20% at 1.5 mL/kg bolus followed by an infusion.
What role does ketamine play in postoperative analgesia?
Low-dose (0.1-0.3 mg/kg) NMDA antagonism for opioid-tolerant patients and neuropathic-heavy pain, reducing opioid requirements with psychotomimetic cautions.
Why avoid a basal rate on patient-controlled opioid analgesia in opioid-naive patients?
Continuous background infusion adds sedation and respiratory depression risk without proportional analgesia — demand-only dosing is safer.
Which single element of multimodal analgesia spares the most opioid?
Regional anaesthesia — truncal blocks, epidural or field infiltration — because it removes the somatic pain component opioids manage least well.