1. Initial Clinical Assessment

A structured history and focused physical exam are the cornerstones of pain assessment, even when communication is limited.

A. History (PQRST Framework)

A systematic approach to characterizing pain is crucial. The PQRST framework helps differentiate pain types and identify underlying causes.

• Provocation/Palliation: What makes the pain worse or better? Identify triggers like movement or procedures, and note effective relief measures such as positioning or specific medications.
• Quality: How does the pain feel? Characterize it as sharp, dull, stabbing, burning, or electric to help infer nociceptive versus neuropathic mechanisms.
• Region/Radiation: Where is the pain and does it travel? Map the location and spread; radicular patterns are highly suggestive of neuropathic involvement.
• Severity: How intense is the pain? Use self-report scales (0–10) whenever possible. For non-communicative patients, anticipate and document behavioral signs of distress.
• Timing: Is the pain constant or intermittent? Note any association with procedures, and document exacerbating/relieving factors and responses to prior analgesics. Solicit collateral history from family or caregivers if the patient is unable to communicate.

B. Physical Examination

• Inspection: Look for objective signs such as erythema, swelling, surgical wounds, drains, or abdominal distension.
• Palpation: Localized tenderness accompanied by guarding indicates somatic pain. Rebound tenderness or rigidity suggests visceral causes and may signal a surgical emergency.
• Neurologic Signs: In awake patients, test dermatomal sensation for allodynia or hyperalgesia. Assess reflexes and motor strength to identify deficits pointing to neuropathic pain.
• Sedated Patients: Rely on validated behavioral scales during minimal sedation windows rather than isolated autonomic signs (tachycardia, hypertension), which are nonspecific.

2. Diagnostic Modalities

Laboratory and imaging studies help confirm the etiology of pain, identify contraindications to certain therapies, and refine management plans.

A. Laboratory Tests

B. Imaging and Specialized Procedures

Targeted imaging with ultrasound, CT, or MRI is used to detect underlying pathology such as abscesses, ischemia, compartment syndrome, or other structural lesions. When feasible and safe, point-of-care ultrasound can guide diagnostic and therapeutic procedures like nerve blocks.

3. Pain Classification Systems

Classifying pain by its duration and underlying mechanism is fundamental to selecting an appropriate therapeutic strategy and setting realistic expectations.

A. Classification by Duration

B. Classification by Etiology

• Nociceptive Somatic: Arises from injury to skin, muscle, or bone. Typically described as sharp and is well-localized.
• Nociceptive Visceral: Originates from internal organs. Often described as dull, aching, or cramping and is poorly localized. May be associated with autonomic features like nausea or sweating.
• Neuropathic: Caused by a lesion or disease of the somatosensory nervous system. Described as burning, electric, or shooting pain and is often associated with sensory changes. Requires adjuvant agents like gabapentinoids or SNRIs.
• Mixed: A combination of nociceptive and neuropathic features. Requires a multimodal approach combining traditional analgesics with neuropathic adjuvants.

4. Severity and Behavioral Scales

Validated scoring tools are essential for quantifying pain, guiding protocolized interventions, and ensuring consistent communication among the care team.

A. Self-Report Scales

When a patient can communicate, self-report is the gold standard. The Numeric Rating Scale (NRS) is preferred for its simplicity and responsiveness.

• Numeric Rating Scale (NRS): A 0–10 scale where 0 is “no pain” and 10 is the “worst imaginable pain.” Scores ≥4 are typically considered moderate-to-severe pain requiring intervention.
• Visual Analog Scale (VAS): A 10 cm line where the patient marks their pain level. It is more granular but less practical for frequent use in critically ill or cognitively impaired patients.

B. Behavioral Scales for Non-Communicative Patients

For sedated, intubated, or delirious patients, validated behavioral scales are the standard of care.

5. Risk Stratification and Urgency

Early identification of risk factors, functional goals, and contraindications allows for the development of tailored analgesic pathways.

A. Functional Goals and Opioid Tolerance

• Define patient-centered functional goals, such as the ability to participate in mobilization, cooperate with spontaneous breathing trials, or rest comfortably.
• Assess for baseline opioid exposure and tolerance. High-tolerance patients may require higher doses, opioid rotation, or the addition of adjuvant infusions (e.g., ketamine) to achieve adequate analgesia.

B. Contraindications to Analgesic Therapies

• Regional/Neuraxial Techniques: Contraindicated by coagulopathy (e.g., platelets <100×10⁹/L, INR >1.5) or infection at the proposed block site.
• Renal Impairment: Severe renal dysfunction (e.g., eGFR <30 mL/min) favors the use of fentanyl or hydromorphone over morphine due to the risk of active metabolite accumulation.
• Hepatic Dysfunction: Requires careful dose adjustments for most opioids and adjuvant medications, particularly methadone and certain antidepressants.

6. Documentation and Electronic Health Record Integration

Standardized templates and automated triggers within the electronic health record (EHR) are crucial for ensuring consistency, compliance, and continuous quality improvement in pain management.

A. Standardized Templates and Flow Sheets

• Incorporate parallel fields for pain scores (NRS/BPS/CPOT), sedation scores (RASS), and details of all analgesic therapies.
• Use dropdown menus with standardized descriptors (e.g., sharp, burning, dull) to harmonize terminology across providers.
• Embed audit logs to track assessment frequency and interprofessional compliance with pain management protocols.

B. Reassessment Triggers and Clinical Decision Support

• Configure the EHR to send an automated alert to the nursing and prescribing team for high pain scores (e.g., NRS ≥4, BPS >5, or CPOT >2).
• Build escalation and de-escalation logic into order sets. For example, define thresholds for increasing an infusion (e.g., by 10–20%) or for considering a reduction after a sustained period of adequate pain control.
• Balance alert sensitivity to provide timely reminders without causing alarm fatigue. Allow for clinician override with a required justification.