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
- Tissue Injury – Causes Release of Inflammatory Mediators
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
- Local Anesthesia – Given Before Making an Incision
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