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A review of the literature on multiple factors involved in postoperative pain course and duration.

OBJECTIVE
To review the literature on the progression from acute to chronic postoperative pain, to evaluate the evidence for the risk of progressing to persistent postoperative and chronic pain, and to identify characteristics of pharmacologic treatments to best tailor therapy to an individual patient's pain profile.


BACKGROUND
Pain is most commonly classified by duration (acute, chronic) and pathophysiology (nociceptive, neuropathic); however, these descriptors alone incompletely describe pain. Additionally, the transition between acute and chronic postoperative pain is not well understood.


METHODS
We conducted a qualitative review and evaluation of the literature on postoperative pain with respect to the above objectives.


RESULTS
Individualized pharmacologic treatments require a complete characterization of a patient's pain profile, in terms of frequency of pain over the course of a 24-hour day and over time thereafter, frequency and duration of pain flares, and presence of neuropathic pain. These considerations can help guide the choice of pharmacologic treatment to meet patient needs over a 24-hour day and over time after surgery. With respect to opioid analgesics, acute pain requires rapid onset of analgesia and the ability to titrate analgesia to the changing characteristics of pain over a short period. For these reasons, short-acting opioid analgesics have been preferred; however, there are opioid formulations with rapid onset and extended release for reduced dosing frequency. Although nociceptive pain can typically be controlled by titration of the dose of an opioid analgesic, neuropathic pain may respond better to the addition of an antineuropathic medication rather than to opioid dose escalation.


CONCLUSION
Advances in individualized pharmacologic treatment for postoperative pain have resulted in better pain control. Moreover, the recognition of sub-acute pain as a new entity is important because many surgical patients will need therapy beyond the first 8 days after surgery. In this group of patients the diagnosis of a neuropathic pain component will be important so that appropriate multimodal therapy may be implemented.