CH 9: Pain Management

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CH 9: Pain Management

Fundamental Concepts of Pain

Pain is a multidimensional experience that affects physical, emotional, and psychosocial functioning. Understanding its definition, effects, and types is essential for effective assessment and management.

Pain is defined by the International Association for the Study of Pain (IASP) as an unpleasant sensory and emotional experience associated with actual or potential tissue damage.
Pain is subjective and best assessed by patient self-report, which is the most reliable indicator.
Pain can affect individuals of all ages, genders, and backgrounds, and is a leading reason for seeking healthcare.

Effects of Pain

Pain can have widespread effects on multiple body systems, especially if unrelieved. These effects can be acute or chronic and may persist throughout life.

System Affected	Specific Responses to Pain
Endocrine	Increased stress hormones (cortisol, ACTH), altered metabolism, hyperglycemia, poor wound healing.
Metabolic	Catabolism, muscle protein breakdown, impaired glucose use, negative nitrogen balance.
Cardiovascular	Tachycardia, hypertension, increased cardiac workload, risk of ischemia, DVT, and arrhythmias.
Respiratory	Shallow breathing, decreased lung expansion, risk of atelectasis and pneumonia.
Genitourinary	Urinary retention, fluid overload, electrolyte imbalance.
Gastrointestinal	Decreased motility, nausea, constipation, ileus.
Cognitive	Impaired cognition, confusion, mental status changes.
Immune	Suppression of immune response.
Functional/Quality of Life	Reduced physical activity, sleep disturbance, depression, anxiety, impaired social relationships.

Table of harmful effects of unrelieved pain on body systems

Types and Categories of Pain

Pain is classified by duration and by inferred pathology, which guides assessment and treatment strategies.

Acute pain: Short-term, often from surgery, trauma, or procedures.
Chronic pain: Lasts beyond normal healing, may be cancer or noncancer in origin.
Nociceptive pain: Results from tissue damage and normal pain processing.
Neuropathic pain: Caused by lesion or disease of the somatosensory system.
Mixed pain: Involves both nociceptive and neuropathic mechanisms.

Pathologic Process	Nociceptive Pain	Neuropathic Pain	Mixed Pain
Examples	Somatic (bone, joint, muscle, skin) or visceral (organ) pain; e.g., surgical incision, arthritis.	Central or peripheral nerve injury; e.g., diabetic neuropathy, post-stroke pain.	Combination; e.g., low back pain with nerve involvement, cancer pain.
Pharmacologic Treatment	Nonopioids, opioids, adjuvants.	Adjuvant analgesics (antidepressants, anticonvulsants), sometimes opioids.	Multimodal therapy tailored to components.

Table classifying pain by inferred pathology

Nociceptive Pain: The Four Processes

Nociceptive pain involves a sequence of neural processes: transduction, transmission, perception, and modulation.

Transduction: Nociceptors are activated by noxious stimuli (mechanical, thermal, chemical, infectious). Excitatory compounds (serotonin, bradykinin, histamine, substance P, prostaglandins) are released. Prostaglandins initiate inflammation; NSAIDs inhibit COX enzymes to reduce pain.
Transmission: Action potentials travel along A-delta (fast, sharp pain) and C-fibers (slow, dull pain) to the spinal cord, where modulation occurs.
Perception: Pain becomes conscious through activation of higher brain centers (thalamus, cortex), involving awareness and emotional response.
Modulation: Neurochemicals (serotonin, norepinephrine, endogenous opioids) alter pain signals at every level from periphery to cortex.

Diagram of nociceptive pain pathways and processes

Neuropathic Pain

Neuropathic pain arises from injury or disease affecting the somatosensory nervous system, leading to abnormal pain processing.

May result from traumatic or nontraumatic nerve injuries.
Common symptoms include allodynia (pain from non-painful stimuli) and hyperalgesia (increased pain from painful stimuli).
Peripheral mechanisms: Damaged nerve endings, maladaptive neuroplasticity, increased sodium channel activity (peripheral sensitization).
Central mechanisms: Hyperexcitability of central neurons, central sensitization, NMDA receptor activation, windup, CNS reorganization.

Diagram of neuropathic pain mechanisms

Pain Assessment

Because pain is subjective, assessment relies primarily on patient self-report, supported by observation and clinical judgment.

Self-report is the gold standard for pain assessment (recommended by The Joint Commission).
Clinicians must avoid letting personal opinions interfere with patient care.
When self-report is not possible, use a hierarchy of pain measures: consider pathology, observe behaviors, evaluate physiologic indicators, and conduct analgesic trials.

Strategies for when patient's pain report is not accepted

Comprehensive Pain Assessment: Patient Interview

A thorough pain assessment should be conducted at admission, with each new pain report, or when the patient's condition changes.

Assess location, intensity (using validated scales), quality, onset, duration, aggravating/relieving factors, and impact on function and quality of life.
Consider cultural background, past pain experiences, comorbidities, and diagnostic data.

Pain assessment interview components

Assessment Tools for Pain

Validated tools are used to assess pain in different populations, including those unable to self-report.

Numeric Rating Scale (NRS), Verbal Descriptor Scale (VDS), Faces Pain Scale-Revised (FPS-R), and Critical-Care Pain Observation Tool (CPOT) are examples.
For adults unable to self-report, use Adult Nonverbal Pain Score (NVPS), CPOT, or Pain Assessment in Advanced Dementia Scale (PAINAD).

Assessment tools for pain in adults unable to self-report

Nonpharmacologic Pain Management Methods

Nonpharmacologic interventions can complement medication and are especially important in multimodal pain management.

Type	Examples	Nursing Considerations
Physical modalities	Heat/cold, massage, TENS, acupuncture	Assess for contraindications, monitor for adverse effects
Cognitive-behavioral	Relaxation, distraction, imagery, hypnosis	Evaluate cognitive ability to participate
Movement therapy	Yoga, Tai Chi	Assess physical ability to perform
Psycho/spiritual	Therapeutic touch, faith, healing rituals	Obtain permission before using interventions

Table of nonpharmacologic pain management methods

Reassessing Pain

Pain should be reassessed regularly to evaluate the effectiveness of interventions. The timing depends on the route of analgesic administration and patient status.

Reassess at least every 15–30 minutes after parenteral analgesics and every 1–2 hours after oral analgesics.
In post-anesthesia care, reassessment may be as frequent as every 10 minutes during IV opioid titration.

Special Populations: Veterans

Veterans have a high prevalence of pain-associated disorders, such as headaches and orthopedic conditions. Multimodal and multidisciplinary approaches are recommended, and nonpharmacologic treatments are commonly used in the Veterans Health Administration.

Clinical Judgment Exercises

Applying knowledge of pain management in clinical scenarios is essential for safe and effective patient care.

Clinical judgment exercises for pain management

Sample Exam Questions

What is the most reliable indicator of pain? Self-report by the patient.
Does increased sodium channel activity result in central sensitization? False. It results in peripheral sensitization.
What is the recommended minimum frequency for reassessing pain after oral analgesic administration? Every 1 to 2 hours.