Acute Pain Assessment:
"Pain is whatever the experiencing person says it is, existing whenever he says it does" (McCaffery 1968)
General principles
- Assess regularly, with a consistent tool (e.g. visual analog scales, numerical rating scales etc.), and treat promptly in multimodal manner
- Multimodal:
- Combining different classes of medications to work together and at times synergistically (acetaminophen, NSAID, gabapentin, TCA, SSRI, opioids).
- Benefit: allows lower dose of each medication with improved effect and less side-effects.
- Generally, NSAIDs and acetaminophen establish base analgesia.
- Consider local anesthetic infiltration or a nerve block.
- Patient controlled IV opioid analgesia is valuable for severe pain and can be monitored by the acute pain service.
- Populations at higher risk of poor assessment and treatment include:
- Children
- Elderly
- Those who aren’t able to communicate
- Certain cultural backgrounds where pain is expected and "complaining" is stigmatized.
- Predictors of severe post-operative pain include:
- Pre-existing chronic pain or taking > 30 mg oral morphine equivalent per day.
- Planned major spine, thoracic or abdominal surgery OR surgery around nerves.
- The most reliable and valid method to quantitatively assess pain in adults is the Numeric Rating Scale (NRS) from 0 to 10 (0 being no pain – 10 being severe pain)
- In cases of language barrier, the Visual Analogue Scale may be used.
- The McGill Pain Questionnaire is most used to assess neuropathic pain.
Pain classification
Somatic pain:
- The most common (e.g. surgical incision or fracture).
- Described as sharp or aching, well localized.
- Treated with NSAIDS, acetaminophen, and/or opioid analgesics.
Visceral pain:
- Related to irritation or inflammation of the pleura, peritoneum (e.g. appendicitis), pericardium (e.g. angina), etc.
- Described as a poorly defined aching-type pain which comes in waves or spasms.
Neuropathic pain:
- Related to nerve irritation.
- Described as stabbing or burning.
- Difficult to treat. Options include anticonvulsants (e.g. gabapentin), opioids, tricyclic antidepressants (e.g. amitriptyline), and serotonin-norepinephrine reuptake inhibitors (e.g. venlafaxine).
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