2.3 Pain Medicine
PM_1.3 Describe alterations in pain physiology and perception in extremes of age, opioid tolerance and addiction
1. Extremes of Age
Neonates and Infants
Immature Nociceptive Pathways:
Pain pathways are underdeveloped but functional, with a lower pain threshold than adults.
Heightened Sensitivity:
Underdeveloped inhibitory pathways in the spinal cord result in amplified pain perception.
Delayed Behavioral Responses:
Behavioral pain responses may appear delayed, but physiological markers like tachycardia, hypertension, and changes in oxygen saturation are reliable indicators.
Clinical Implications:
Neonates require specialized pain management, such as sucrose or breastfeeding during minor procedures, and opioid-sparing strategies to minimize adverse effects.
Elderly
Reduced Peripheral Pain Sensitivity:
Decreased density of nociceptors and slower nerve conduction contribute to diminished peripheral pain perception.
Altered Central Processing:
Reduced endogenous opioid production and altered pain modulation increase susceptibility to chronic pain and central sensitization.
Common Pain Conditions:
High prevalence of osteoarthritis, neuropathy, and chronic musculoskeletal pain due to comorbidities.
Risk of Underreporting Pain:
Cognitive decline, fear of addiction, or reluctance to burden others may lead to underreporting of pain.
Clinical Implications:
Adjust analgesic dosing for altered pharmacokinetics (e.g., slower renal clearance), and consider non-pharmacological approaches such as physiotherapy or mindfulness.
2. Opioid Tolerance
Pathophysiology
Receptor Downregulation:
Chronic opioid use leads to reduced expression and sensitivity of opioid receptors, decreasing analgesic efficacy.
Neurotransmitter Dysregulation:
Upregulation of excitatory neurotransmitters (e.g., glutamate) contributes to opioid-induced hyperalgesia (OIH).
Cross-Tolerance:
Prolonged use of one opioid results in reduced efficacy of others, requiring higher doses for adequate pain relief.
Clinical Impact
Reduced Analgesic Response:
Standard opioid doses become insufficient, necessitating dose escalation or multimodal analgesia.
Enhanced Pain Sensitivity:
OIH leads to increased baseline pain and sensitivity to normally non-painful stimuli (allodynia).
Clinical Implications:
Consider opioid rotation, adjunctive medications (e.g., ketamine, gabapentinoids), or regional anesthesia to optimize analgesia and mitigate tolerance.
3. Opioid Addiction
Neuroadaptations
Reward Pathway Dysregulation:
Chronic opioid use disrupts dopaminergic reward pathways, leading to dependence on opioids for pain relief and euphoria.
Endogenous Pain Control Impairment:
Decreased endogenous opioid production exacerbates pain perception during withdrawal or insufficient opioid dosing.
Pain Perception
Heightened Sensitivity:
Addiction results in chronic nociceptive pathway activation, contributing to hyperalgesia and allodynia.
Psychological Amplification:
Pain is often amplified by emotional and psychological factors, including catastrophizing or anxiety.
Clinical Implications:
Emphasize integrated pain management, combining pharmacological treatment (opioid-sparing strategies) with psychological support, including cognitive-behavioral therapy.
Summary and Study Notes
Pain Perception Across Populations:
Pain thresholds and central processing vary significantly between neonates, the elderly, opioid-tolerant individuals, and those with addiction.
Neonates: Amplified pain sensitivity due to underdeveloped inhibitory pathways.
Elderly: Diminished peripheral pain sensitivity but increased susceptibility to central pain sensitization and chronic pain conditions.
Opioid Tolerance: Reduced receptor sensitivity and hyperalgesia necessitate multimodal analgesia and cautious opioid use.
Addiction: Neuroadaptations amplify pain and emotional distress; requires holistic, multidisciplinary pain management.
Key Focus: Tailor pain management to individual physiological and psychological profiles using multimodal strategies and non-opioid options to optimize outcomes.
PM_1.4 Describe the principles of acute pain assessment, including a pain history, the role and limitations of pain assessment scales, the relevance of functional assessment and assessment of adverse effects
1. Pain History
Onset and Duration: When did the pain start? Is it sudden or gradual? Continuous or intermittent?
Location: Ask the patient to pinpoint the pain. Is it localized, referred, or radiating?
Quality: Describe the pain (e.g., sharp, dull, burning, throbbing).
Intensity: Use appropriate scales (e.g., Numeric Rating Scale) to quantify severity.
Aggravating and Relieving Factors: What exacerbates or alleviates the pain (e.g., movement, rest, medications)?
Associated Symptoms: Presence of nausea, vomiting, sweating, or autonomic signs.
Impact on Daily Life: Assess how pain affects mobility, sleep, and ability to perform daily tasks.
Role and Limitations of Pain Assessment Scales
Commonly Used Scales:
Numeric Rating Scale (NRS): Rates pain 0–10, simple and widely used.
Visual Analogue Scale (VAS): Measures pain along a continuous line, requiring fine motor control.
Faces Pain Scale (FPS): Useful for children or non-verbal patients.
Role:
Provides objective, reproducible measures of pain severity.
Aids in monitoring response to treatment.
Limitations:
Pain is subjective—scores may not correlate with functional impairment or distress.
Less reliable in non-verbal or cognitively impaired patients.
Does not capture multidimensional aspects (e.g., emotional, psychological).
Functional Assessment
Evaluates how pain affects mobility, self-care, and daily activities.
Functional tests (e.g., timed walking, range of motion) provide objective impact measures.
Relevance:
Guides treatment goals.
Measures therapy effectiveness beyond numerical pain scores.
Assessment of Adverse Effects
Monitor for treatment-related side effects:
Opioids: Sedation, nausea, constipation, respiratory depression.
NSAIDs: Gastric irritation, renal impairment.
Neuropathic agents: Drowsiness, dizziness.
Balancing Pain Relief with Tolerability:
Optimize analgesia while minimizing harm.
Adjust medications based on patient response and side effect profile.
Conclusion
A comprehensive acute pain assessment integrates history, pain scales, functional assessment, and monitoring for adverse effects to ensure effective and patient-centered pain management.
PM_1.7 Outline the role of local anaesthesia infiltration in the management of acute pain
Role of Local Anaesthetic Infiltration in Acute Pain Management
Mechanism of Action
Local anaesthetics (LAs) block voltage-gated sodium channels, inhibiting nerve conduction and preventing pain transmission.
Advantages
Targeted pain relief at the site of injury or surgery.
Reduced opioid use, minimizing side effects such as nausea, vomiting, and respiratory depression.
Anti-inflammatory effects via modulation of the inflammatory response.
Clinical Applications
Surgical Settings: Postoperative analgesia in procedures like hernia repair, caesarean section.
Trauma: Pain control for minor lacerations, fractures, burns.
Outpatient Procedures: Dental work, dermatological surgeries, biopsies.
Techniques
Direct infiltration into surgical or wound sites.
Combination with adrenaline to prolong effect and limit systemic absorption.
Use of long-acting agents (e.g., bupivacaine) for extended relief.
Role in Multimodal Analgesia
Integral to enhanced recovery protocols (e.g., ERAS).
Synergistic with NSAIDs, acetaminophen, and nerve blocks.
Limitations
Short duration (unless using catheters or extended-release formulations like liposomal bupivacaine).
Potential complications: Local hematoma, infection, systemic toxicity with high doses.
Evidence
Meta-analyses demonstrate lower pain scores and reduced opioid consumption when LAs are part of perioperative pain management.
Studies show faster recovery and improved patient satisfaction in surgeries incorporating LA infiltration.
Conclusion
Local anaesthetic infiltration is a key component of acute pain management, providing effective, site-specific analgesia and enhancing recovery when integrated into a multimodal pain strategy.
PM_1.8 Outline the role of non-pharmacological measures in the management of acute pain
Non-Pharmacological Measures in Acute Pain Management
Non-pharmacological interventions play a crucial role in acute pain management by complementing pharmacological treatments, reducing the required dose of analgesics, and addressing the multidimensional nature of pain. These measures are particularly beneficial for enhancing recovery, minimizing side effects, and improving patient satisfaction.
Psychological Interventions
Cognitive Behavioral Therapy (CBT):
Helps patients reframe pain perceptions and develop coping strategies.
Relaxation Techniques:
Breathing exercises, progressive muscle relaxation, and guided imagery reduce stress and modulate pain perception.
Distraction Methods:
Using activities such as music therapy, video games, or reading to divert attention from pain.
Physical Interventions
Physiotherapy:
Promotes mobilization, improves joint function, and reduces muscle spasms.
Techniques include passive/active exercises and range-of-motion therapy.
Application of Heat or Cold:
Heat promotes blood flow and reduces stiffness, while cold minimizes swelling and numbs pain.
Massage Therapy:
Reduces muscle tension, improves circulation, and releases endorphins.
Regional Techniques
Transcutaneous Electrical Nerve Stimulation (TENS):
Electrical stimulation of nerves can inhibit pain signals and stimulate endorphin release.
Acupuncture and Acupressure:
Stimulates specific points to alleviate pain and improve well-being.
Environmental and Supportive Measures
Patient Education:
Providing information about the cause of pain and recovery expectations reduces anxiety and empowers patients.
Supportive Environment:
Creating a calm, reassuring, and empathetic atmosphere reduces stress-induced pain amplification.
Complementary and Integrative Therapies
Mindfulness and Meditation:
Enhances self-regulation of pain and reduces emotional distress.
Aromatherapy:
Certain essential oils (e.g., lavender) have been shown to alleviate pain and promote relaxation.
Benefits of Non-Pharmacological Measures
Reduced Analgesic Requirements:
Minimizes the risk of side effects and complications associated with medications, such as opioids.
Enhanced Recovery:
Facilitates early mobilization and functional rehabilitation.
Individualized Care:
Tailored interventions address the physical, emotional, and psychological aspects of pain.
Integration with Pharmacological Strategies
Non-pharmacological measures should be used in combination with pharmacological approaches for a multimodal pain management strategy, ensuring comprehensive and effective relief.
PM_1.9 Describe the assessment and management of patients with severe pain in the post anaesthesia care unit
Assessment and Management of Severe Pain in the Post Anaesthesia Care Unit (PACU)
Assessment
Pain History
Intensity: Use pain scales like the Numeric Rating Scale (NRS) (0–10).
Location: Is the pain localized, referred, or radiating?
Quality: Ask the patient to describe the pain (e.g., sharp, dull, burning, throbbing).
Timing: Is the pain continuous or intermittent?
Aggravating and Relieving Factors: Identify any factors that worsen or alleviate the pain (e.g., movement, position, medication).
Clinical Examination
Inspect Surgical Site: Check for signs of complications like hematoma, infection, or wound dehiscence.
Palpation: Assess for tenderness, swelling, or signs of complications.
Neurological Examination: Evaluate for potential nerve damage or failure of regional block.
Monitor Vital Signs
Signs of Severe Pain: Tachycardia, hypertension, tachypnea, or sweating may indicate uncontrolled pain.
Identify Contributing Factors
Inadequate intraoperative analgesia or failed regional block.
Surgical complications such as internal bleeding or compartment syndrome.
Pre-existing conditions (e.g., chronic pain, opioid tolerance).
Management
Pharmacological Approaches
Opioids: IV titration of morphine, fentanyl, or hydromorphone.
Consider Patient-Controlled Analgesia (PCA) for ongoing management.
Multimodal Analgesia:
Non-opioid options like paracetamol and NSAIDs (if no contraindications).
Adjuncts: Gabapentinoids (e.g., gabapentin, pregabalin) for neuropathic pain.
Regional Techniques:
Top-up of epidural or nerve blocks if in place, or consider adding a local anaesthetic infiltration.
Non-Pharmacological Interventions
Positioning: Adjust the patient's position to reduce discomfort.
Ice/Heat Application: Use for localized pain (e.g., muscle spasm, swelling).
Reassurance: Provide emotional support to reduce anxiety, which can exacerbate pain.
Monitor and Reassess
Pain Scales: Reassess pain regularly using objective measures like NRS or Visual Analog Scale (VAS).
Side Effects Monitoring: Watch for opioid-related side effects such as sedation, nausea, and respiratory depression.
Address Underlying Causes
Investigate and treat complications like hematomas or internal injury (e.g., imaging or surgical intervention).
Referral
If pain persists despite initial interventions, escalate care to the acute pain service or senior anaesthetist.
Documentation and Handover
Record: Document pain scores, interventions, and outcomes.
Handover: Ensure detailed communication with ward staff or the acute pain team for ongoing care and monitoring.
Conclusion
Effective assessment and timely intervention in the PACU are crucial for optimizing patient comfort, minimizing postoperative complications, and ensuring a smooth recovery.
PM_1.10 Discuss the indications, contraindications, side effects, risks and monitoring requirements for patients receiving patient-controlled analgesia (PCA); continuous opioid infusion; and intermittent administration of opioids for acute pain management
Learning Objectives for Acute Pain Management with Opioids
Patient-Controlled Analgesia (PCA)
Indications:
Postoperative pain management for moderate-to-severe pain.
Patients capable of understanding and operating the PCA device.
Situations where titration of analgesia is required to balance pain relief and side effects.
Contraindications:
Cognitive impairment or inability to operate the PCA device.
Severe respiratory depression or high risk of opioid sensitivity.
Uncontrolled pain conditions requiring specialized management (e.g., neuropathic pain).
Side Effects:
Nausea, vomiting, pruritus, sedation, respiratory depression.
Risk of overdose if pump programming errors occur.
Risks:
Dependency or tolerance with prolonged use.
Mechanical failure or misprogramming of the device.
Monitoring:
Regular pain assessment and documentation (e.g., numerical rating scale).
Observing respiratory rate, oxygen saturation, and level of sedation.
Monitoring pump function and cumulative opioid doses delivered.
Continuous Opioid Infusion
Indications:
Severe, constant pain unresponsive to intermittent boluses.
In patients with a stable opioid requirement (e.g., ICU patients on ventilators).
When PCA is not appropriate due to patient limitations.
Contraindications:
Unstable pain or rapidly changing opioid requirements.
High risk of respiratory depression or opioid sensitivity.
Side Effects:
Risk of opioid accumulation, sedation, and respiratory depression.
Potential for opioid-induced hyperalgesia with prolonged use.
Risks:
Difficulty titrating dose for fluctuating pain levels.
Risk of pump or catheter complications.
Monitoring:
Continuous monitoring of respiratory status and sedation levels.
Frequent reassessment of pain and infusion settings.
Monitoring for signs of opioid toxicity.
Intermittent Administration of Opioids
Indications:
Mild-to-moderate acute pain.
Pain with predictable onset and duration (e.g., procedural pain).
As a step-down from PCA or continuous infusion.
Contraindications:
Unpredictable or rapidly escalating pain.
Inability to achieve consistent pain relief due to dosing intervals.
Side Effects:
Breakthrough pain due to uneven plasma levels.
Nausea, vomiting, sedation, respiratory depression.
Risks:
Inadequate pain control due to missed doses.
Increased risk of side effects with higher bolus doses.
Monitoring:
Frequent pain assessments to adjust dosing.
Observation of vital signs and sedation after each dose.
Documentation of cumulative opioid doses over time.
By understanding the unique considerations for each modality, clinicians can optimize acute pain management while minimizing risks to patients.
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