Pain (Principles/Meds/Comfort Care)

Basics

Description

  • Unpleasant sensory and emotional experience, arising from actual or perceived damage, influenced by biologic, psychological, and social factors
  • Acute pain:
    • Sudden onset, typically lasting less than 3 mo
    • Most often a normal physiologic response to tissue damage, surgery, trauma, or inflammation
    • Often resolves as the underlying cause heals
  • Chronic pain:
    • Persists beyond normal healing time, typically lasting longer than 3 mo
    • May arise from an initial injury or illness but continues independent of tissue damage
    • Can be neuropathic, nociceptive, or idiopathic, with central and peripheral sensitization contributing to its persistence
    • Often leads to functional impairment psychological distress, and reduced quality of life
    • Affects approximately 30–40% of the global population, with a higher burden in aging and comorbid populations
  • Pain is reported in up to 70–80% of emergency department visits and remains the leading presenting symptom among patients seeking emergency care
  • Prevalence of neuropathic pain is 21.4% in EDs
  • The US remains among the highest consumers of prescribed opioids globally, although recent guidelines have aimed to reduce overprescription

Etiology

  • Nociceptive pain:
    • Results from tissue injury or inflammation, activating nociceptors (pain receptors) in the skin, muscles, joints, or organs
    • Visceral pain:
      • Stimulation of visceral nociceptors
      • Diffuse, difficult to locate, and often referred to a distant, usually superficial, structure
      • Sickening, deep, squeezing, dull
    • Deep somatic pain:
      • Stimulation of nociceptors in ligaments, tendons, bones, blood vessels, fasciae, and muscles
      • Dull, aching, poorly localized pain
    • Superficial somatic pain:
      • Stimulation of nociceptors in the skin or other superficial tissue
      • Sharp, well defined, and clearly located
  • Neuropathic pain:
    • Results from damage or dysfunction in the nervous system, either in the peripheral nerves or central nervous system
    • Exacerbation of normally nonpainful stimuli (allodynia)
    • Paroxysmal episodes likened to electric shocks
    • Continuous sensations include burning or coldness, “pins and needles” sensations, numbness, and itching
  • Psychogenic pain:
    • Pain that is primarily influenced by psychological factors rather than a direct physical injury or nerve damage
    • Not “imaginary” but rather real pain that is influenced or exacerbated, increased, or prolonged by mental, emotional, or behavioral factors
  • Functional pain (disordered pain processing):
    • Pain without clear tissue damage or nerve injury, thought to arise from abnormal pain processing in the central nervous system
    • Examples include fibromyalgia, irritable bowel syndrome, and tension-type headaches
  • Different components of pain can be combined in a same patient

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