Acute pain management

Acute pain is typically sudden in onset and less than a month in duration. It can indicate actual or potential tissue damage and is associated with trauma, surgery, and illness. Acute pain requires prompt treatment. Analgesics should be tailored to the inciting cause, patient factors (e.g., opioid naive or opioid tolerant, contraindications for NSAIDs), and the care setting. The WHO analgesic ladder can help guide the selection of the most appropriate pain management strategy. When possible, nonpharmacological analgesia and nonopioid analgesics are preferred for acute pain management. Opioids should only be used if the benefits outweigh the risks and additional precautions are taken to minimize the associated harms, e.g., risk mitigation for opioid prescribing. Management of acute exacerbation of chronic pain can be challenging, as complete pain relief is usually not possible; the primary aim is return to baseline function. Pain management in the emergency department often involves local anesthesia, regional anesthesia, and/or analgesics for procedural sedation. Specialized pain scales and scoring systems are used to assess pain in patients who are unable to communicate verbally (e.g., critically ill patients, neonates, and infants).

See “Principles of pain management” for more information on pain evaluation, analgesics and dosages, nonpharmacologic analgesia, and pain management in children.

• Provide prompt analgesia for severe acute pain.
• Evaluation of pain
  • Obtain a thorough patient history.
  • Perform a comprehensive physical examination.
  • Assess pain severity with a pain intensity scale.
• Document recent analgesic use (e.g., type and dosage).
• Tailor the treatment strategy to the patient, ; the underlying condition, ; and the care setting.
  • Use the WHO analgesic ladder as a guiding principle.
  • Maximize nonpharmacological analgesia and nonopioid analgesia whenever possible. ^[2]
  • See “Choice of analgesic for acute pain” for cases in which opioids are required.

Administer acute pain management promptly; withholding it does not improve the accuracy of a physical examination. ^[1]

See also “Management of pain using WHO analgesic ladder.” For specific dosages, see “Oral analgesics,” “Parenteral analgesics,” and “Adjuvant analgesics.”

Risk mitigation ^[2]

• Only prescribe opioids if the benefits outweigh the risks.
• See “Risk mitigation for opioid prescribing.”

Prescribing principles ^[2]

• Use immediate-release opioids rather than extended-release or long-acting opioids.
• Start at the lowest effective dose.
• Prescribe PRN doses rather than scheduled doses.
• Limit prescription duration to the expected duration of severe pain.
• Reevaluate the risk-benefit ratio if dosage increases are required. ^[2]
• See “Oral analgesics” and “Parenteral analgesics” for dosages.
• For management of overdose, see “Opioid overdose.”

General principles ^[1]

Management of acute-on-chronic pain requires significant empathy and skill. Follow local departmental policies if available.

• Establish treatment goals.
  • The goal of treating the acute episode is to allow the patient to return to baseline function.
  • Complete alleviation of pain is typically not possible.
• Obtain detailed pain assessment and review existing care plans.
• Consult the clinical provider in charge of long-term pain management whenever possible.
• Identify and treat reversible causes of pain, e.g., a new:
  • Comorbid condition (e.g., renal colic in patients with chronic back pain)
  • Episode of a recurrent condition (e.g., vasoocclusive crisis in patients with sickle cell disease)
  • Condition that affects pain medication metabolization (e.g., malabsorption)
• Consider systemic barriers to accessing treatment.
• Consider admission for individual management of patients with progression of terminal illnesses if no reversible cause is identified.
• See “Chronic noncancer pain management” and “Pain management in palliative care” as needed.

Acute-on-chronic pain management in hospital-based settings ^[1][2]

• For patients already on an opioid regimen who have uncontrolled pain:
  • Preferentially add nonopioid analgesics (e.g., NSAIDs, acetaminophen, adjuvant analgesics).
  • If additional opioids are required:
    • Match duration to that of the expected superimposed severe pain.
    • Aim to return to baseline opioid dosage as soon as possible; consider a taper if additional round-the-clock opioids are required for more than a few days.
    • See also “Risk mitigation for opioid prescribing.”
• Individualized therapy is recommended for patients with sickle cell disease, cancer, and palliative care and/or end-of-life care needs. ^[2]

Involve the patient's regular health provider in treatment decisions whenever possible and be aware of the potential for drug diversion of prescriptions made by other health providers.

Severe pain

• Follow approach to acute pain for choice of analgesic. ^[1]
• For specific dosages, see “Oral analgesics,” “Parenteral analgesics,” and “Adjuvant analgesics.”
• Reassess pain severity every hour or more frequently if necessary.
• For emergency procedures, consider analgesics for procedural sedation.
• Consider a subanesthetic ketamine infusion as a stand-alone treatment or an adjunct to opioids. ^[3]
• See also “Acute-on-chronic pain management in hospital-based settings.”

Extremity injuries

• Administer ice, elevation, and immobilization as indicated.
• Offer initial parenteral analgesics for pain caused by an acute deformity (e.g., fracture, dislocation) that is unresponsive to immobilization.
• Consider local anesthesia or regional anesthesia for localized pain.

Minimize undertreatment ^[1]

• ED patients' pain can be undertreated for a variety of reasons, e.g., communication barriers, atypical presentations, and implicit biases.
• Patients at risk of undertreatment include children, individuals of different cultural and/or linguistic backgrounds, and individuals with neurocognitive disorders.

Ambulatory opioid prescriptions

• Limit duration to < 3–5 days.
• Arrange rapid follow-up with a regular health provider for dosage adjustments.
• See also “Opioids for acute pain.”

Pain in critically ill patients

Assessment of pain in the ICU

• Patients in ICU are typically unable to communicate and require a specialized pain scale ^[4]
• Behavioral pain scale
  • Used to identify pain in critically ill patients on mechanical ventilation
  • Three items are evaluated and awarded points: facial expression, movement of the upper limbs, and mechanical ventilation compliance.
  • ≥ 5 points indicates significant pain
• Critical care pain observation tool (CCPOT)
  • Used to identify pain in critically ill patients.
  • Four items are evaluated and awarded points: facial expressions, body movements, ventilator compliance in intubated patients or vocalization in nonintubated patients, and muscle tension
  • ≥ 3 points indicates significant pain
• For subjective grading of pain severity by the patient, see “Pain intensity scale”

Pain management ^[5]

• Preemptive analgesia for extubation and invasive procedures
• Multimodal analgesia depending on the severity and type of pain
  • Lowest effective dose IV opioids (first-line)
  • Adjuvant NSAIDs
  • Gabapentin or carbamazepine in case of neuropathic pain
• Consider using continuous infusions or regular doses of analgesics
• Regular assessment of the severity of pain and response to analgesia

Be aware of the adverse effects of opioids (e.g., delirium, CNS depression, tolerance) or NSAID therapy!

Acute pain in children

See “Pain management in children.”