General principles of acute pain management

Acute pain usually occurs due to an acute illness (eg appendicitis), or following surgery or trauma. It lasts less than 3 months, and there is an expectation of recovery and return to usual function.

Acute pain usually resolves with healing of the underlying illness or injury. However, nervous system sensitisation that occurs in the acute phase may continue after complete healing, and chronic pain may develop. Acute pain can also be complex from the outset (eg spinal cord injury) and may persist. See The transition from acute to chronic pain for further information.

Accurate assessment of acute pain informs the management approach. Identify the:

  • cause of pain—assessment, investigations and definitive management of the underlying cause can be performed in parallel with acute pain management
  • pain type(s)—acute pain usually has a nociceptive component that occurs in response to tissue injury and inflammation; acute neuropathic pain may also occur, usually in conjunction with nociceptive pain
  • pain intensity—consider the anticipated pain severity (ie the severity of pain usually associated with the presentation), patient-reported pain severity and impact on the patient’s function; see Features of mild, moderate and severe acute pain for the features of mild, moderate and severe acute pain.

If patient-reported pain severity is not consistent with other assessment findings (eg physical function, examination findings), it is important to explore the patient’s perception of their pain, and determine if sociopsychobiomedical factors (eg anxiety) are contributing to their pain experience.

When a patient with chronic pain presents with acute pain, assess whether the acute pain is caused by a new pathology (eg acute myocardial infarction, bowel obstruction, trauma) or if it is an exacerbation of chronic pain (ie a flare). Flares should be managed according to the general principles of chronic pain management.

Figure 1. Features of mild, moderate and severe acute pain.

[NB1]

Acute pain intensity is determined by functional activity scores, pain scores and anticipated pain severity.

Mild acute pain—minimal difficulty carrying out activities despite pain. A low pain score may be reported [NB2].

  • Example presentations include sinus headache, minor sprain, superficial wound.

Moderate acute pain—pain causes some difficulty carrying out activities.

  • Example presentations include uncomplicated appendicitis, laparoscopic or minimally invasive surgery, minor fracture.

Severe acute pain—pain causes considerable difficulty carrying out activities. A high pain score may be reported [NB2].

  • Example presentations include major burns, renal colic, total joint replacement, long bone fracture.
Note:

NB1: Pain severity occurs on a spectrum between no pain and worst pain imaginable. To help practitioners choose the treatment regimen that best matches the pain experienced by their patient, especially when opioids are indicated, these guidelines include specific definitions of mild, moderate and severe pain. However, there are no universal definitions of mild, moderate and severe pain, and other organisations (including the Therapeutic Goods Administration) and literature define these categories differently.

NB 2: Pain scores should never be used to determine pain intensity.

Acute pain is managed using nonpharmacological and pharmacological interventions. The management strategy depends on the cause of pain, pain type(s), pain intensity, and the available staff and resources for monitoring. Management strategies for acute pain based on pain intensity outlines management strategies for acute pain.

When starting an analgesic for acute pain, always have a tapering and stopping plan; analgesics should not be continued after the acute illness or injury has resolved.

Additional considerations are required for acute pain management in:

Some acute pain conditions have specific pain management strategies; see Pain management strategies for specific indications. For procedure-related pain, see Procedural sedation and analgesia.

Figure 2. Pain management strategies for specific indications