Post-Operative Pain

An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage (L.A.S.P, Merskey 1979).

Important: Pain is a complex and unpleasant phenomenon, indicating some problem, and often causing further physiological, psychological, and social difficulties (Hawthorne and Redmond, 1999).

Pain is a combination of severe discomfort, fear, autonomic changes, reflex activity, and suffering.

Key Points:

• Pain is common in all age groups, including newborns.
• Pain does not discriminate based on gender or race.
• Only the sufferer can decide what hurts and how much.

The RAT System

• Recognize
  • Does the patient have pain?
  • Do other people know the patient has pain?
• Assess
  • Measure severity
  • Classify types of pain
  • Assess other factors
• Treat
  • Non-pharmacological
  • Pharmacological

Pain Assessment

Pain Rating Methods

Adults:

1. Verbal rating scale (VRS)
2. Numerical rating scale (NRS)
3. Visual analogue scale (VAS)

Paediatrics:

1. Clinical observation: for those under 4 years of age.
2. Wong-Baker faces scale uses varied facial expressions
3. Color scales
4. FLACC

1. Nociceptive, which is caused by tissue damage
   • Somatic – transmitted by myelinated A delta fibers
   • Visceral - arises from internal organs and hollow viscera organs. Transmitted by unmyelinated C fibers
2. Neuropathic, which arises from peripheral neuropathy, neuralgia, nerve entrapment, and direct nerve trauma

CLASSIFICATION

Nociceptive

• Somatic
  • Superficial (soft tissue, e.g., skin)
  • Myofascial structures
  • Bone
• Visceral
  • Solid organs
  • Hollow organs

Neuropathic

• Peripheral
  • Nerve compression
  • Neuropathy
  • Neuralgia
  • Nerve infiltration
• Central

When evaluating pain, it is useful to try to determine whether the pain is of one of these types or a mixture of the two. Cancer pain is a mixed mechanism pain, rarely presenting as a pure neuropathic, visceral, or somatic pain.

Pain can also be described by its

Duration:

• Acute
• Chronic

Situation:

• Incidental pain
• Breakthrough pain
• Procedural pain

Acute Pain

• Well-defined onset
• Clear means of relief
• Associated with increased sympathetic activity
• Anxiety
• Short-term or one-off analgesia
• Protective

Chronic Pain

• Gradual/ill-defined onset
• Progressive
• Depression
• Ongoing analgesic requirement
• No useful purpose, described as a major scourge of humanity

1. Non-Pharmacological Treatment
   • Physical
     • Rest
   • Psychological
     • Explanation
     • Assurance
     • Counseling
2. Pharmacological Treatment (Analgesics)
   • Multimodal Analgesia (Balanced Analgesia)
     • As pain mechanisms rely on different receptor systems, reliance on a single analgesic for perioperative pain management is no longer acceptable.
     • New pain management paradigms incorporate multimodal analgesia.
     • Multimodal analgesia combines a broad group of analgesic agents from different classes and different sites of action/techniques that target different pain receptors and pathways (peripheral and central nervous systems), to enhance pain control by producing additive or synergistic effects, and in the process helps to minimize any side effects that are associated with the use of a large dose of a single agent, particularly opioids.

Analgesic Treatment Principles

• By the Mouth

  Use the oral route whenever possible.

• By the Clock
  • Administering analgesics according to a regular schedule based on the duration of effectiveness rather than 'as needed'.
  • Giving only 'as required' medication will be ineffective and expose the patient to needless suffering.
  • It is essential to ensure all prescriptions are given with an awareness of the duration of action of each analgesic.
• By the Ladder

  Use the WHO analgesic ladder. If after giving the optimum dose and analgesic does not control pain, move up the ladder, do not move sideways in the same ladder.

• By the Patient

  The right dose is the one that relieves pain. Titrate the dose upwards until pain is relieved or side effects prevent moving up further.

Requirements for the Effective Use of WHO Analgesic Ladder

The effective use of the WHO analgesic ladder relies on certain basic fundamentals:

• Know the severity of the pain: mild, moderate, severe
• Understand the characteristic/quality of the pain: nociceptive (somatic & visceral) and neuropathic
• Know the classification of analgesics: opioids (weak opioids, strong opioids), non-opioids (acetaminophen and NSAIDs), and adjuvants.
• The rule is to combine an opioid and non-opioid for good effect and avoid combining drugs of the same class.

Parenteral Analgesia (i.m, i.v, s.c, transdermal, pca)

Opioids:

• Morphine
• Meperidine
• Hydromorphone
• Tramadol

Non-opioid Analgesics:

• Paracetamol
• NSAIDs (Non-Steroidal Anti-Inflammatory Drugs)

Regional Analgesia

• Local Anesthetic Wound Infiltration
• Peripheral Nerve Blocks
• Epidural Analgesia (Intermittent Boluses, PCA - Patient-Controlled Analgesia)

• Age: Elderly individuals may require smaller doses.
• Pre-operative analgesic use.
• Coexisting Medical Conditions
• Preoperative Patient Education
• Site of Operation