Pain Management, Nociception, and Pharmacology Study Notes

Pain Signs and Symptoms

Tinnitus (ringing in ears), dizziness, headache, confusion, sweating, hyperventilation, nausea/vomiting, metabolic acidosis
Facial expressions: frowning, grimacing, rapid blinking, wince, clenched teeth, narrowed eyes
Body movements: clenching fists, rigid/tense posture, fidgeting, pacing, gait changes, rocking, rubbing affected area
Changes in activity patterns or routines: restlessness, refusing food, appetite changes, sleep/rest pattern changes, increased wandering
Autonomic/physiologic signs: increased pulse, increased RR, increased BP, diaphoresis
Example pulse: $104\,\text{beats/min}$ ; depth and frequency of respirations increased
Heat therapy cautions: should be limited to $30\,\text{minutes}$ to prevent tissue injury
Nociception basics: afferent pathways are activated by pain receptors called nociceptors
Nociceptors are stimulated and signals travel to the spinal cord and brain
Purpose of nociception: transduction, transmission, perception, modulation of pain signals
TENS (Transcutaneous Electrical Nerve Stimulation): unit stimulates skin and underlying tissues to decrease pain intensity and release endorphins
Student teaching point: when a patient says “it’s unfortunate to be in the hospital for this treatment,” it indicates a need for further teaching/education about TENS
Endorphins and enkephalins: natural opioid-like substances that block pain perception; stress and pain can trigger endorphin release to lessen pain
Endorphins, enkephalins, and dynorphins: body’s natural opioids
COX-2 inhibitors have advantages: fewer adverse GI effects
Pain assessment components: onset, duration, and severity of pain
Sounds of pain: sighing, moaning, groaning, calling out, noisy breathing, cursing during movement
Changes in social interactions: aggressive behavior, striking out, resisting care, withdrawal, decreased social interactions
Mental status changes with pain: crying, increased confusion, irritability, distress
Q1: Symptoms of salicylate toxicity? → Symptoms include tinnitus, dizziness, headache, confusion, sweating, hyperventilation, nausea/vomiting, and metabolic acidosis (from the transcript list)
Q2: Objective signs of pain? → Elevated pulse, RR, BP; diaphoresis; facial expressions; vocalizations; changes in activity/rest patterns
Q3: Max duration to apply heat therapy? → $30\,\text{minutes}$
Q4: Steps of nociception? → Transduction, Transmission, Perception, Modulation
Q5: What is the T.E.N.S unit and what is it? → Transcutaneous Electrical Nerve Stimulation; delivers mild electrical impulses through the skin to block pain signals and release endorphins
Q6: What natural opiates does your body make? → Endorphins, enkephalins, dynorphins
Q7: Everything to know about acetaminophen? → Acetaminophen (Tylenol) class: non-opioid analgesic, antipyretic; Indications: pain and fever, NOT for inflammation; Side effects: GI upset, heartburn (pyrosis), hepatotoxicity; Dosing: each tablet $500\,\text{mg}$ ; typical dose $1000\,\text{mg}$ (2 tablets); max daily $4000\,\text{mg/day}$ (there is caution about toxicity at higher total daily doses); Overdose antidote: Acetylcysteine; Contraindication: avoid alcohol; Extra strength often contains $500\,\text{mg}$ per tablet; recommended daily max often cited as $3000-4000\,\text{mg/day}$ ; hepatotoxicity risk with higher daily totals (e.g., $4000-9000\,\text{mg/day}$ )
Q8: NSAIDS that are COX-2 inhibitors? → Celecoxib (Celebrex); Etoricoxib
Q9: Sympathetic nervous system response to pain? → Activates fight-or-flight: ↑HR, ↑BP, ↑RR, pupil dilation, diaphoresis, pallor
Q10: Common causes of hyperalgesia? → Opioid-induced hyperalgesia, nerve injury, chronic pain conditions
Q11: Steps of pain assessment? → Assess pain; determine onset, location, quality, intensity; identify aggravating/alleviating factors; examine the site; identify coping methods; document assessment, interventions, and evaluate effectiveness (reassessment after interventions is important)
Q12: Steps to engage in pain medication? → Assess pain; check orders; administer medications; reassess pain relief; document
Q13: Therapeutic effects of docusate sodium? → Stool softener; prevents constipation by drawing water into stool
Q14: Physical manifestations of peripheral vascular disease (PVD)? → Cool skin, weak pulses, pale/blue skin, claudication (pain with walking), ulcers on toes/feet
Q15: What kind of pain during a colonoscopy? → Visceral pain: cramping, gas, abdominal discomfort; management includes medications plus non-pharmacologic methods like relaxation, heat/cold, positioning
Q16: Variety is the best approach to pain management
Q17: Administer pain medications before a procedure? → Approximately $30\,\text{minutes}$ prior to procedure
Q18: Addiction vs tolerance vs toxicity vs withdrawal? → Addiction: psychologic dependence with cravings and compulsive use despite harm; Tolerance: physiologic need for higher doses to achieve same relief; Toxicity: harmful levels of a drug causing damage; Withdrawal: symptoms when drug is stopped after dependence
Q19: Nitrous oxide for pain and side effects (beyond miscarriage context in the source)? → Side effects include dizziness, nausea/vomiting, drowsiness, headache; prolonged or frequent misuse can cause severe, possibly irreversible health issues including nerve damage, psychological issues, and brain damage
Q20: Muscle spasm medications? → Muscle relaxants: Methocarbamol (Robaxin), Cyclobenzaprine (Flexeril), Baclofen, Tizanidine; Diazepam (Valium) is well known but often avoided due to many side effects
Q21: Neuropathic pain (referred to)? → Nerve damage from a variety of anatomic/physiologic conditions; symptoms include burning, shooting pains, and abnormal sensations that occur even without a painful stimulus
Q22: Adverse effects of opiates? → Constipation, nausea/vomiting, sedation, respiratory depression, confusion, hypotension, dizziness/itching, urinary retention
Page 3: Addiction to opioids (heading for further discussion) → Overview topic to be explored further within addiction context

Nociception, Analgesia, and Pain Modulation (Core Concepts)

Pain pathway overview: nociceptors detect noxious stimuli; afferent signals travel to spinal cord and brain where pain is perceived and modulated
Transduction: conversion of a painful stimulus into electrical signals at the nociceptor
Transmission: conduction of the signal from nociceptor to dorsal horn and up the spinal cord
Perception: conscious awareness of pain
Modulation: alteration of pain signal by neurons and endogenous pathways (e.g., endorphins)
TENS unit mechanism: interrupts pain signal transmission at the skin level; can promote endorphin release
Endogenous opioids: endorphins, enkephalins, and dynorphins; contribute to natural analgesia and can be leveraged by certain modalities to reduce pain perception

Pharmacology and Pain Management Essentials

Acetaminophen (Tylenol)
- Class/indication: non-opioid analgesic, antipyretic; for pain and fever, not anti-inflammatory
- Common dosing: $500\,\text{mg}$ per tablet; typical dose $1000\,\text{mg}$ (2 tablets)
- Maximum daily dose: $4000\,\text{mg/day}$ (many guidelines caution toward lower totals in certain patients); some notes indicate 3000-4000 mg/day range
- Overdose/toxicity: hepatotoxicity at high daily totals; antidote: Acetylcysteine
- Side effects: GI upset, heartburn (pyrosis); avoid in alcohol use; overdose is a critical concern
NSAIDs and COX-2 inhibitors
- Examples: Celecoxib (Celebrex), Etoricoxib
- COX-2 inhibitors: fewer GI adverse effects than non-selective NSAIDs
Sympathetic response to pain
- Physiology: increased heart rate, blood pressure, respirations; pupil dilation; diaphoresis; pallor
Hyperalgesia
- Common causes: opioid-induced hyperalgesia, nerve injury, chronic pain conditions
Pain assessment fundamentals
- Onset, duration, severity; location; quality; aggravating/alleviating factors; psychosocial context
Pain management strategies
- Use a variety of modalities; tailor to patient needs; document and reassess effectiveness
- Administer medications before procedures when appropriate (e.g., ~ $30\,\text{minutes}$ pre-procedure)

Practical Interventions and Clinical Manifestations

Heat therapy and cold therapy
- Heat: max duration $= 30\,\text{minutes}$ ; used for warmth and muscle relaxation
- Cold: limit to $15\,\text{minutes}$ per session to prevent tissue injury or frostbite
Peripheral vascular disease (PVD) considerations
- Do not use cold therapy for PVD; heat therapy is usually preferred in certain contexts
Colorectal/colonoscopy-related pain
- Pain during colonoscopy is visceral; management includes medications plus non-pharmacologic methods (relaxation, positioning, etc.)
Docusate sodium (colace)
- Therapeutic effect: stool softener; draws water into stool to ease passage
Nitrous oxide (laughing gas)
- Pain management use; side effects: dizziness, nausea/vomiting, drowsiness, headache; potential for misuse leading to nerve, brain, and psychological complications
Muscle spasm/relaxants
- Agents: Methocarbamol (Robaxin), Cyclobenzaprine (Flexeril), Baclofen, Tizanidine; Diazepam (Valium) reserved due to broad side effects
Neuropathic pain (definition and features)
- Definition: nerve-damage–related pain; sensations such as burning or shooting pains even in absence of a painful stimulus

Opioids: Addiction, Tolerance, Toxicity, and Withdrawal

Addiction: psychological dependence with cravings and compulsive use beyond pain relief; continued use despite harm
Tolerance: physiologic adaptation requiring higher doses for same analgesic effect
Toxicity: harmful drug levels causing damage; dose-related risk
Withdrawal: symptoms when drug is abruptly stopped after dependence
Opiate adverse effects (general): constipation, nausea/vomiting, sedation, respiratory depression, confusion, hypotension, dizziness/itching, urinary retention
Opioid abuse risk in general: commonly discussed metrics (e.g., potential for abuse is often described as low in some contexts, but clinical caution is essential)

Addiction to opioids (page 3 topic)

Overview: understanding opioid addiction mechanisms, risk factors, management strategies, and safe prescribing practices
Note: This section serves as a prompt for deeper exploration in related lectures or modules on substance use and pain management