Anaesthesiology
Pain and Its Management
Pain management for MBBS and NEET-PG: pain physiology and fibres, gate control, pain scales, WHO analgesic ladder, opioids and neuropathic pain, and palliative care, mapped to NMC codes AS8.
MedNext Academy | 3 min read
Pain and Its Management
Pain management for MBBS and NEET-PG: pain physiology and fibres, gate control, pain scales, WHO analgesic ladder, opioids and neuropathic pain, and palliative care, mapped to NMC codes AS8.
This chapter covers the physiology of pain and its assessment and treatment, from the fibres and pathways that carry it to the pharmacology of analgesics. It sets out the WHO analgesic ladder, multimodal and neuropathic pain management, and the principles of pain relief in palliative and terminal care.
High-yield: Pain and Its Management
- First pain is sharp and fast and carried by myelinated A-delta fibres; second pain is dull and slow and carried by unmyelinated C fibres.
- The gate control theory holds that activity in large touch fibres can close a spinal gate and reduce the transmission of pain from small fibres.
- Nociceptive pain arises from tissue injury, while neuropathic pain arises from nerve damage and is described as burning, shooting or electric.
- Neuropathic pain responds poorly to simple analgesics and is treated with agents such as amitriptyline, gabapentin or pregabalin.
- Pain is assessed with a validated scale, such as the visual analogue scale or numeric rating scale in adults.
- In young children the FLACC scale (face, legs, activity, cry, consolability) or the Wong-Baker faces scale is used to score pain.
- The World Health Organization analgesic ladder rises from non-opioids to weak opioids and then to strong opioids as pain increases.
- Paracetamol and non-steroidal anti-inflammatory drugs are the first step, and non-steroidal drugs are avoided in renal impairment and peptic ulcer disease.
- Morphine is the reference strong opioid; its effects include analgesia, respiratory depression, constipation, miosis and nausea.
- Opioid-induced respiratory depression is reversed by naloxone, which has a short half-life and may need repeated doses or an infusion.
- Multimodal analgesia combines drugs with different mechanisms to improve pain relief and reduce opioid requirement and side effects.
- Total pain in palliative care has physical, psychological, social and spiritual components, and each must be addressed.
- The doctrine of double effect allows adequate symptom relief even if a foreseen but unintended side effect, such as sedation, may shorten life.
- Patient-controlled analgesia lets the patient self-administer small, safe boluses of opioid within programmed limits to match their pain.
WHO analgesic ladder
- **Step 1:** Non-opioids: paracetamol and NSAIDs for mild pain.
- **Step 2:** Weak opioids such as codeine or tramadol, with a non-opioid, for moderate pain.
- **Step 3:** Strong opioids such as morphine, with a non-opioid, for severe pain.
- **Adjuvants:** Amitriptyline, gabapentin or pregabalin for neuropathic pain at any step.
NMC competencies in this chapter
- **AS8.1:** Anatomical and physiological basis of pain
- **AS8.2:** Eliciting and assessing pain: level, quality and tolerance
- **AS8.3:** Pharmacology and use of drugs in pain management
- **AS8.4:** Principles of pain management in palliative care
- **AS8.5:** Principles of pain management in the terminally ill
Frequently Asked Questions
What is the difference between first and second pain?
First pain is sharp and rapid, carried by myelinated A-delta fibres. Second pain is dull, aching and slower, carried by unmyelinated C fibres, and follows the initial sharp sensation.
What is the WHO analgesic ladder?
A stepwise approach that moves from non-opioids to weak opioids and then to strong opioids as pain increases, with adjuvants such as gabapentin added for neuropathic pain at any step.
How is neuropathic pain treated?
It responds poorly to simple analgesics and is managed with adjuvant agents such as amitriptyline, gabapentin or pregabalin, which act on the abnormal nerve signalling rather than on inflammation.
What is the doctrine of double effect?
It is the principle that giving adequate treatment to relieve suffering is justified even if a foreseen but unintended effect, such as sedation, might shorten life, provided the intention is symptom relief.
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