On Call: Pain Management

Definitions

Pain

  • Pain – An Unpleasant Sensory or Emotional Experience Associated that Associated with Actual or Potential Tissue Damage
  • Mechanisms:
    • Tissue Injury – Causes Release of Inflammatory Mediators
      • Incision
      • Dissection
      • Thermal/Burn Injury
    • Nerve Injury
      • Transection
      • Stretching
      • Compression

Painful Sensation

  • Allodynia – Pain Due to a Stimulus that Does Not Normally Provoke Pain
  • Hyperalgesia – Increased Pain Due to a Stimulus that Normally Provokes Pain
  • Hypoalgesia – Decreased Pain Due to a Stimulus that Normally Provokes Pain
  • Paresthesia – Burning or Prickling Sensation

General Sensation

  • Hyperpathia – Exaggerated Response to Stimuli (Touch, Vibration, Temperature & Pressure)
  • Hyperesthesia – Increased Sensitivity to Stimulation
    • Includes Both Allodynia & Hyperalgesia
  • Hypoesthesia – Decreased Sensitivity to Stimulation
  • Dysesthesia – An Unpleasant Abnormal Sensation
    • Includes Both Allodynia & Hyperalgesia

Management

Principles

  • Multimodal Approaches are Preferred
  • Patients Should Understand the Expected Level of Pain
    • Generally the Goal Perioperatively is Not “No” Pain but Rather Control of Pain to a Manageable Level
  • Ensure that Pain is Not Due to an Underlying Pathologic Process (Abscess, Leak, etc.)

Preventive Analgesia

  • Preventive Analgesia – Efforts Before, During & After Surgery to Prevent or Minimize the Painful Effects of Noxious Stimuli
  • Approaches:
    • Local Anesthesia – Given Before Making an Incision
      • Decreases Analgesia Requirements but No Difference in Postoperative Pain Scores
    • Systemic Agents – Oral/IV Agents Given Before Pain Starts
      • Generally Describes Nonnarcotic Medications Temporarily Prescribed on a Scheduled Basis

General Approach

  • Generally Start with Tylenol & NSAIDs
    • Consider Scheduling Doses
    • Consider COX-2 Selective NSAIDs to Avoid GI Effects
    • Avoid NSAIDs in Renal Insufficiency or After CABG
    • IV Tylenol May Also Be Considered – Has Been Limited Largely Due to Cost
  • Oral Opioids Generally the First Line for Moderate-Severe Pain
    • Common Dosing: 5 mg for Moderate & 10 mg for Severe Pain
    • If Tylenol is Not Being Given Scheduled, Consider Using a Tylenol-Narcotic Combination Agent (Percocet, Norco, etc.)
  • IV Opioids Often Reserved for Breakthrough Pains if Other Oral Agents are Not Sufficient at First
    • Avoid Morphine in Renal Failure

Further IV Narcotic Dosing

  • Patient-Controlled Analgesia (PCA)
    • Patient is Provided a Button that Delivers a Low-Dose Bolus of Analgesia On-Demand
    • Settings:
      • Demand Dose – Dose Delivered with Each Push
      • Lockout Interval – Minimum Length of Time Before Patient is Able to Deliver Another Dose
      • Basal Dose – Continuous Rate
        • Generally Not Recommended in Opioid-Naïve Patients
      • Maximum Cumulative Dose
    • Patient Must Be Able Understand & Follow Instructions on Use
  • Continuous Infusion
    • Increased Risk of Opioid Overdose with Respiratory Failure
    • Generally Discouraged for Most Perioperative Settings
    • Should Only Be Given in a Monitored Setting (ICU)

Adjuncts

  • Muscle Relaxants for Muscle Spasms
    • Generally Avoid in Elderly Due to Sedation & Delirium Effects
  • Gabapentinoids for Neuropathic Pain
  • Lidocaine Patch for Site Specific Somatic Pains, Particularly in Rib Fractures
  • Regional Anesthesia (Epidural or Neuraxial) Can Provide Benefit in Select Circumstances

Dosing