Pain Management: Factors Related to Undertreatment

Factors Related to Undertreatment of Pain

• Patient-related and provider-related factors contribute to the undertreatment of pain.

Patient-Related Factors

• Fear of Addiction: Patients may avoid pain medications, especially opioids, due to concerns about addiction.
• Cultural and Social Beliefs: Some individuals view enduring pain as a sign of strength and avoid seeking treatment.
• Lack of Communication: Patients may not effectively communicate the severity of their pain.
• Fear of Side Effects: Concerns about nausea, drowsiness, or long-term effects of medications can lead to refusal of treatment.
• Cognitive Impairments: Older adults or individuals with cognitive conditions like dementia may struggle to express their pain, leading to undertreatment.

Provider-Related Factors

• Bias and Stereotypes: Healthcare providers may underestimate pain in certain groups, such as racial minorities, women, or older adults, leading to disparities in treatment.
• Lack of Proper Training: Some providers may not be adequately trained in pain management or the latest guidelines, leading to inappropriate treatment.
• Fear of Opioid Misuse: Due to concerns about the opioid crisis, providers may be overly cautious in prescribing pain medications, even when necessary.
• Time Constraints: In busy healthcare settings, providers may not have adequate time to conduct thorough pain assessments.
• Subjective Assessment: Reliance on a patient's verbal report alone may lead to underestimation, especially in nonverbal individuals, as pain is a subjective experience.
• Emphasis on Non-Opioid Alternatives Without Adequate Support: Non-opioid treatments may not always be accessible or effective for all patients.

Pain Threshold vs. Pain Tolerance

• Pain threshold: The minimum intensity at which a person begins to perceive pain.
• Measurement: The point at which a stimulus (e.g., heat, pressure) starts to be felt as painful.
• Variability: Generally similar across individuals, with minor variations.
• Influencing Factors: Physiological factors such as nerve sensitivity and receptor function.
• Example: A person starts feeling pain when a hand is placed in ice water at a specific temperature.
• Pain Tolerance: The maximum level of pain a person can endure before it becomes unbearable.
• Measurement: The highest intensity of pain an individual can tolerate before needing relief or stopping the stimulus.
• Variability: Highly variable, influenced by psychological, cultural, and personal factors.
• Influencing Factors: Emotional state, past experiences, cultural background, and mental resilience.
• Example: How long the person can keep their hand in the ice water before they need to remove it.

Key Differences Between Pain Threshold and Pain Tolerance

• Pain threshold is about when pain starts, while pain tolerance is about how much pain can be endured.
• Pain threshold is relatively stable across individuals, whereas pain tolerance varies greatly from person to person.
• Pain tolerance can be influenced by factors like stress, fatigue, or psychological state, whereas pain threshold is more biologically determined.

Methods Used in the Assessment of Pain

• Assessment of Pain Intensity and Character: The Patient Self-Report
• A patient's description of their pain is the cornerstone of pain assessment.
• The best way to ensure an accurate report is to ask the right questions and listen carefully to the answers.
• Onset and temporal pattern, location, quality, intensity, modulating factors, previous treatment, and impact should be included.
• Diagnostic Tests: The battery of diagnostic tests includes imaging studies (CT scan, MRI, neurophysiologic tests, and tests for tumor markers in blood).
• Ensure that abnormalities identified in the diagnostic tests explain the patient's pain.
• Psychosocial Assessment: Consider the impact of significant pain on the patient in the past, the patient's usual coping responses to pain and stress and their preferences regarding pain management methods.
• Also consider, the patient's concerns about using opioids and other controlled substances (anxiolytics, stimulants), changes in the patient's mood (anxiety, depression) brought on by cancer and pain, and the impact of cancer and its treatment on the family.
• Lastly, consider the level of care the family can provide and the potential need for outside help (e.g., palliative care or hospice).
• Pain Intensity Scales: Descriptive scale and numeric scales are used for adults and older children and the FACES scale is used for young children and patients with cognitive impairment.

Mu (μ) Receptor Activation

• The mu receptor is the most clinically significant opioid receptor.

Effects of Mu Receptor Activation

• Analgesia (Pain Relief): Mu receptor activation provides strong pain relief, particularly for severe pain.
• Euphoria: Activates the reward system, creating a sense of well-being or euphoria and contributing to the addictive potential of opioids.
• Respiratory Depression: Inhibition of respiratory centers in the brainstem, leading to slowed or suppressed breathing, which is the primary cause of opioid overdose fatalities.
• Sedation: Causes general drowsiness and mental clouding.
• Miosis (Pupil Constriction): Leads to small, pinpoint pupils due to parasympathetic activation.
• Decreased Gastrointestinal Motility (Constipation): Slows down intestinal movement, leading to opioid-induced constipation (OIC).
• Physical Dependence and Addiction: Chronic use can lead to tolerance, dependence, and withdrawal symptoms.
• Bradycardia and Hypotension: May cause slowed heart rate and low blood pressure.

Examples of Mu Receptor Agonists

• Examples: Morphine, Fentanyl, Oxycodone, Hydromorphone, and Heroin (converted to morphine in the body).

Kappa (κ) Receptor Activation

• The kappa receptor has a different profile compared to the mu receptor.
• It often produces moderate analgesia but with fewer addictive properties.

Effects of Kappa Receptor Activation

• Analgesia: Kappa activation provides moderate pain relief, more effective for visceral and spinal pain.
• Dysphoria and Psychotomimetic Effects: Unlike mu activation, kappa receptor stimulation can cause dysphoria (unpleasant mood), hallucinations, and paranoia.
• Sedation: Causes drowsiness, but less intense than mu receptor activation.
• Diuresis (Increased Urine Output): Due to inhibition of antidiuretic hormone (ADH), leading to increased urination.
• Miosis (Pupil Constriction): Less pronounced than mu receptor activation.
• Minimal Respiratory Depression: Kappa agonists do not significantly suppress breathing, making them safer in terms of overdose risk.
• Reduced Abuse Potential: Kappa agonists are less addictive than mu agonists.

Examples of Kappa Receptor Agonists

• Butorphanol, Pentazocine, and Nalbuphine.
• Salvinorin A is a naturally occurring hallucinogenic compound.

Mu Receptor Activation vs. Kappa Receptor Activation

• Mu receptor activation is more potent for pain relief but has higher risks (e.g., addiction, respiratory depression, constipation).
• Kappa receptor activation provides moderate analgesia with fewer addictive risks but may cause dysphoria and hallucinations.

Conclusion

• Opioid drugs and treatments should be carefully chosen based on pain severity, patient history, and side effect profiles.

Major Adverse Effects Related to Narcotic Opiate Analgesics

• CNS Effects: Sedation and drowsiness, euphoria, dysphoria and hallucinations, and cognitive impairment.
• Respiratory Effects: Respiratory depression (life-threatening), bronchospasm and airway obstruction.
• GI Effects: Constipation (major and persistent side effect), nausea and vomiting (common in the initial stages), delayed gastric emptying (gastro paresis), and biliary spasm.
• Cardio Effects: Hypotension and Bradycardia.
• GU Effects: Urinary retention and Decreased Libido and Sexual Dysfunction
• Endocrine Effects: Hormonal imbalances (opioid-induced endorphinopathy), menstrual irregularities in women and osteoporosis.
• Immuno-Suppressive Effects: Increased susceptibility to infection.
• Withdrawal effects: Flu-like symptoms, GI distress, Muscle pain and tremors, and severe Anxiety.

Therapeutic Uses of Opioid Analgesics

• Acute Pain: Management of post-surgical, trauma, and severe pain
• Chronic Pain: Used in cancer pain or palliative care when other analgesics fail.
• Anesthesia Adjunct: Used in general anesthesia for sedation and analgesia
• Cough Suppression: Reduces cough reflex (limited use due to addiction risk).
• Diarrhea Management: Decreases intestinal motility in severe diarrhea cases
• Opioid Dependence Treatment: Used to manage withdrawal symptoms and reduce cravings
• Pulmonary Edema: Reduces breathlessness in acute pulmonary edema (via vasodilation)

Opioid Classification with Prototypes

• Pure Opioid Agonists (Full Agonists): Bind to mu receptors and produce strong analgesia
• Used for severe pain, anesthesia, and chronic pain management
• Prototype Drug: Morphine
• Other Examples: Fentanyl, Oxycodone, Hydromorphone, Codeine, and Methadone.
• Mixed Agonist-Antagonists (Partial Agonists): Activate Kappa receptors (providing moderate pain relief) and block Mu receptors (reducing euphoria and addiction risk)
• Used for moderate pain and opioid addiction treatment
• Prototype Drug: Buprenorphine
• Other Examples: Nalbuphine, Pentazocine, and Butorphanol
• Opioid Antagonists: Completely block opioid receptors, reversing opioid effects
• Used for opioid overdose and respiratory depression reversal
• Prototype Drug: Naloxone (Narcan)
• Other Examples: Naltrexone and Methylnaltrexone (for opioid-induced constipation)

Side Effects, Adverse Effects and Precautions Associated with Opioid Narcotics

• Common, Expected Reactions: Sedation & Drowsiness, Constipation, Nausea & Vomiting, Dizziness & Lightheadedness, Itching, Miosis (Pupil Constriction), and Mild Euphoria
• Adverse Effects (Severe, Potentially Harmful Reactions): Respiratory Depression, Bradycardia & Hypotension, Opioid-Induced Hyperalgesia (OIH), Severe Dependence & Addiction, Overdose (Toxicity), Severe Constipation (Bowel Obstruction), QT Prolongation & Arrhythmias, Hormonal Imbalance, and Urinary Retention.
• Precautions & Safety Measures: Monitor for Respiratory Depression, Avoid Alcohol & CNS Depressants, Gradual Tapering for Long-Term Users, Use Laxatives for Opioid-Induced Constipation, Caution in Elderly & Renal Impairment Patients, Limit Use in Patients with Respiratory Diseases (COPD, Asthma), Monitor for Signs of Dependence & Misuse, and Naloxone Availability for High-Risk Patients
• Classic Triad of Opioid Overdose (Hallmark Signs): Respiratory Depression, Unresponsiveness (Coma), and Miosis (Pinpoint Pupils)

Contraindicated Narcotic Agonist-Antagonists

• Patients with Opioid Dependence or Opioid Use Disorder, Severe Asthma due to less respiratory depression
• Patients with Head Trauma or Increased Intracranial Pressure (ICP), Pupillary constriction can interfere with assessing level of consciousness.
• Patients with Severe Hepatic or Renal Impairment due to reduce drug metabolism.
• Patients with Myocardial Infarction (MI) or Coronary Artery Disease
• Pregnant women - risk of neonatal withdrawal symptoms if used in opioid-dependent pregnant women.
• Patients with Psychiatric Disorders (History of Hallucinations, Psychosis)

Naloxone

• Opioid Antagonist
• Competitively blocks opioid receptors
• Indications: opioid overdose and respiratory depression.
• Short half life causes need for re-dosing.

Adult vs Pediatric Dosing

• Adults:
  • IV: 0.4mg - 2mg
  • IM: 0.4mg - 2mg
  • IN (spray): 4mg in one nostril.
• Children:
  • 0.1 mg/kg every 2-3 minutes, up to a max of 2 mg per dose.
• Narcotic Analgesics: Pain-relieving drugs that act on the central nervous system (CNS).
• High risk for addiction.
• Non Narcotic Analgesics: Act peripherally and there is no addiction associated.

Maximum Daily Dose of Acetaminophen

• The recommended maximum daily dose for adults is 4,000 mg (4g)
• Pediatric Dosing: 0-15 mg/kg every 4 to 6 hours as needed; Max daily dose: 75 mg/kg per day, not exceeding 4,000 mg in 24 hours and no more than 5 doses in 24 hours.
• Antidote: N-acetylcysteine (NAC) is used to prevent liver damage if administered promptly.
• Caution: Alcohol increases risk for liver damage.
• Symptoms of Liver Toxicity: Nausea, vomiting, loss of appetite, abdominal pain, jaundice, dark urine, confusion, and liver failure.

Contraindications with Aspirin

• Aspirin is not recommended for children under 18 years in most cases due to the risk of Reye's syndrome, viral infections, bleeding disorders, active peptic ulcer disease, aspirin allergy or hypersensitivity, severe liver disease, and severe kidney disease.

Signs of Salicylism

• Begin when plasma salicylate levels >200 mcg/mL.
• Severe toxicity begins at >400 mcg/mL.
• Overts signs are tinnitus and dizziness.
• Treatment for Salicylism includes using activated charcoal, and IV fluids.

Precautions of ASA/NSAIDs

• Contraindicated in patients with peptic ulcer disease, bleeding disorders.
• Used with extreme caution by pregnant women and by children who have chickenpox or influenza.
• GI Risks: Take NSAIDS with food in order to reduce GI upset
• Kidney damage: NSDAIDS can blood flow to kidneys leading to acute kidney injury.

Reye's Syndrome

• Aspirin can cause Reye's syndrome in children with viral infections (flu, chicken pox)

NSAIDs vs. COX-2 Inhibitors

• NSAIDs - Inhibit both COX-1 and COX2 enzymes while COX2 Inhibitors selectively inhibit COX-2
• NSAIDs - High risk of stomach ulcers while COX2 Inhibitors have lowr risk of stomach ulcers.
• NSAIDs - Some increase hear attack risk whilw COX1 1 Inhibitors increase risk of heart attack to a higher degree.
• NSAIDs impair kidney function -Examples of COX-2 Inhibitors include: Celecoxib (Celebrex)
• Examples of NSAIDs include: Ibuprofen and Aspirin