Preventive pharmacotherapy is the administration of an analgesic before the onset of pain. This can be achieved with a scheduled dosing regimen or with medications that can actually reduce the tissue trauma from insults such as surgery. Preemptive analgesia, on the other hand, means total elimination of pain during and after a surgical procedure; this is much harder to achieve. Too often, total elimination of pain is not desirable because, along with total pain elimination, the patient's motor and desirable sensory functions are also impaired. Therefore, balanced preemptive analgesia is much more difficult to achieve.
The evidence on the clinical outcome with preemptive analgesia remains inconclusive (147,148). The preventive use of a nonsteroidal anti-inflammatory agent presurgically is promising in reducing postoperative opioid use in arthroplasty; however, concrete data on longer term outcome of patient progression with physical therapy or the range of motion over time postarthroplasty remain sparse. For fractures, the preemptive use of NSAIDs has also been shown to reduce postoperative opioid use; again, whether this translates to improvement in overall outcomes, such as early ambulation and hospital discharge, has not been adequately studied (24,147-156).
The use of epidural analgesia intraoperatively and during the immediate postoperative period has been demonstrated to reduce postoperative ileus in gastrointestinal and gynecological surgeries (157-162). Whether this method is effective in reducing the hospital stay and reducing post-surgical ileus in other types of surgery has not been adequately studied.
In orthopedic and spine surgeries, a single epidural opioid injection intraoperatively can improve the patient's pain control during the first 24 hours; however, it has not been shown to be effective in reducing pain in the second postoperative day even when the patient is given patient-controlled analgesia (PCA) at the onset compared to patients who received PCA opioid analgesics only immediately postsurgically.
Patient satisfaction is much harder to measure. It does not appear to be associated with the intensity of pain experienced, but it is associated with the staff response received when help is needed. Patients tend to be more satisfied as long as the staff tries to relieve their pain (163-168).
When preventive NSAIDs are used for surgery, theoretically they should be administered before any tissue trauma is produced; however, other data seem to show that central prostaglandins might be more important in producing pain than peripheral prostaglandins. The central prostaglandins appear to respond to NSAIDs that can penetrate the CNS rapidly, which may alter our current thoughts about the need for preop-erative administration of NSAIDs. In the literature involving knee surgeries (169-173), the use of preemptive NSAIDs has been shown to have some value in terms of postoperative opioid consumption; however, it may not have any impact on the patients' longer term outcomes. The use of preemptive opioids for joint arthroplasties produced a mixed outcome.
Besides surgeries, preventive analgesia should also apply to patients with chronic pain with episodic acute exacerbations, such as in the case of osteoarthritis. A patient's pain often is activities related, which may limit the patient's function and quality of life. The use of analgesics prior to these painful activities may be more appropriate because it improves function and quality of life. In some cases, it is the difference between independence and relying on someone else. The selection of an analgesic agent for use in the geriatric population requires special care because the clinician must take into account concomitant disease states and pharma-codynamics.
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