Intravenous indomethacin for postoperative pain. A double-blind study of ankle surgery

Management of Pain in the Critically Ill

Analgesia for critically ill patients can be provided most effectively by the use of modern techniques. Under standing of the anatomical pathways for nociceptive sig nal transmission allows the use of techniques that mod ulate or block nociceptive information at several levels (periphery, spinal cord, and systemic). A comprehen sive discussion of analgesic techniques at each level is presented. Formulation of a treatment plan is discussed. Several examples are presented to show the decision- making process for the use of modern analgesic tech niques in critically ill patients.

Single dose oxycodone and oxycodone plus paracetamol (acetominophen) for acute postoperative pain

BACKGROUND

Oxycodone is a strong opioid agonist which is useful for the management of severe pain. It is becoming increasingly important to assess the relative efficacy and harm caused by different treatments. This can be determined when an analgesic is compared with control under similar clinical circumstances.

OBJECTIVES

To quantitatively assess the analgesic efficacy and adverse effects of single-dose oxycodone and oxycodone plus paracetamol in randomised trials in acute postoperative pain.

SEARCH STRATEGY

Published reports were identified from Medline, Biological Abstracts, Embase, the Cochrane Library and the Oxford Pain Relief Database. Additional studies were identified from the reference lists of retrieved reports.

SELECTION CRITERIA

The inclusion criteria were: full journal publication, clinical trial, random allocation of adult patients to treatment groups, double blind design, moderate to severe baseline pain, postoperative administration of study drugs, treatment arms which included oxycodone or oxycodone plus paracetamol and placebo (or active control for which comparable efficacy data exist), and oral, intramuscular or intravenous administration of study drugs.

DATA COLLECTION AND ANALYSIS

Summed pain intensity and pain relief data over 4-6 hours were extracted and converted into dichotomous information yielding the number of patients obtaining at least 50% pain relief. Estimates of relative benefit and number-needed-to-treat were calculated. Single-dose adverse effect data were collected.

MAIN RESULTS

Seventy-seven reports were identified. Seven reports met the inclusion criteria; all assessed oral oxycodone. For efficacy, a significant benefit of active drug over placebo was shown for all doses of oxycodone and oxycodone plus paracetamol, except oxycodone 5 mg. For adverse effects, the number of patients reporting adverse effects was extracted for each dose of active drug versus placebo. When these data were pooled for the individual doses significantly more adverse effects with active drug than with placebo were shown for all doses, except oxycodone 5 mg and its combination with paracetamol 325 mg. This was also shown for drowsiness/somnolence. Significantly more nausea, vomiting and dizziness/lightheadedness were reported with oxycodone 10 mg plus paracetamol (650 mg and 1000 mg) than with placebo.

REVIEWER'S CONCLUSIONS

Single-dose oral oxycodone, with or without paracetamol, appears to be of comparable efficacy to intramuscular morphine and non-steroidal anti-inflammatory drugs. Central nervous system adverse effects were common.

Ketorolac and indomethacin are equally efficacious for the relief of minor postoperative pain

Injectable ketorolac is an effective analgesic in ambulatory surgery patients. However, no studies have compared ketorolac with other NSAIDs in this setting. The analgesic efficacy of intramuscular ketorolac, rectal indomethacin and placebo was compared in healthy women undergoing gynaecological or breast surgery as outpatients. Ninety patients received 30 mg im ketorolac, 100 mg pr indomethacin or placebo in a prospective, randomized, double-blind manner. A standardized anaesthetic protocol was followed. Patients graded their pain on a 10 cm visual analogue scale in the recovery room, twice in the surgical day care unit and during the car ride home. The patients' postoperative fentanyl requirements, time to recovery milestones, and side effects were recorded. The placebo group received more fentanyl in the PACU but did not achieve the same pain relief as either of the NSAID-treated group (ketorolac 44 +/- 53 micrograms, indomethacin 39 +/- 55 micrograms, placebo 87 +/- 100 micrograms, P < 0.05). Patients who received an NSAID had less pain at 15 and 90 min (P < 0.05). The PACU stay was longer for the placebo group (ketorolac 50 +/- 13 min, indomethacin 49 +/- 12 min, placebo 62 +/- 35 min, P < 0.05). Time to ambulation was also longer in the placebo group (ketorolac 117 +/- 25 min, indomethacin 121 +/- 49 min, placebo 140 +/- 51 min, P < 0.05). However, no differences were observed between the two NSAIDS. Side effects were similar in all groups. We conclude that im ketorolac and pr indomethacin are equally effective analgesics in this group of patients.

A risk-benefit appraisal of injectable NSAIDs in the management of postoperative pain

The inadequacy of pain treatment has been demonstrated in many patient groups suffering from acute pain. The injectable nonsteroidal anti-inflammatory drugs (NSAIDs), including indomethacin, diclofenac, ketoprofen and ketorolac, provide relief from the pain associated with several different conditions. When administered alone or in combination with low doses of opioids, NSAIDs provide good pain relief after musculoskeletal trauma or operation. The main advantage of these agents is that they may form the first-line therapy for pain relief and thus decrease the need of opioids. This avoids respiratory depression which can be associated with opioids. In contrast to opioids, NSAIDs do not cause respiratory depression or have marked adverse effects on the central nervous system. However, they may be associated with adverse effects of the gastrointestinal tract, liver and kidneys, and may increase pre- and postoperative bleeding and cause allergic reactions. These effects are related to the ability of NSAIDs to inhibit prostaglandin synthesis. Use of NSAIDs has to be considered carefully in patients with asthma, allergy to aspirin and NSAIDs, atopy, peptic ulcer or bleeding disorders (such as abnormalities in blood coagulation or coagulation deficits). These considerations are especially important in elderly patients. Having taken these contraindications into account, many clinical studies have demonstrated that NSAIDs are at least as safe as opioids when administered in the short term. However, few studies have specifically monitored adverse effects or included patients over 65 to 70 years of age. In addition, patients with risk factors have often been excluded from the trials. Therefore, the risk-benefit ratio of NSAIDs requires further assessment.

Piroxicam spares buprenorphine after total joint replacement. Controlled study of pain treatment in 81 patients

In a blinded, placebo-controlled study, the nonsteroidal antiinflammatory drug piroxicam, in combination with the partial morphine agonist/antagonist buprenorphine, was compared with buprenorphine alone for analgesic effect and side-effects in a 10-day period following total replacement of the hip or knee. 117 patients entered and 81 completed the study. The patients receiving piroxicam consumed less buprenorphine. There were no differences concerning side-effects between the two treatment groups, apart from a tendency towards less nausea after the third postoperative day in the group receiving piroxicam.

The efficacy of intravenous indomethacin in prevention of postoperative pain

Since intravenous prophylactic anti-inflammatory agents have been suggested to reduce or even replace opiates in postoperative pain therapy, we studied the demand for morphine in 45 patients recovering from abdominal surgery who had received a baseline infusion of either indomethacin, morphine or saline placebo. When extubated after inhalational anaesthesia, each patient received an i.v. bolus of either 0.5 mg.kg-1 indomethacin, 0.07 mg.kg-1 morphine or saline placebo. Thereafter a 20-h infusion of the same test analgesic was started, either 0.1 mg.kg-1.h-1 indomethacin, 0.03 mg.kg-1.h-1 morphine or saline placebo. For additional analgesia, a patient-controlled analgesia device (PCA) delivering 5-mg boluses of morphine was used. For the first 5 postoperative hours, significantly more (P less than 0.05) PCA morphine was needed in the indomethacin group (35 mg) than in the morphine group (24 mg), while the placebo group demanded mean 30 mg. For equal analgesia (measured by VAS and VRS) between 5-20 h, similar amounts (mean 23 and 19 mg) of PCA morphine were required in the indomethacin and morphine groups, in contrast to the placebo group (mean 40 mg) (P less than 0.001). Morphine infusion increased the total consumption of morphine by 25% as compared to placebo. We conclude that, following abdominal surgery, the analgesic effect of indomethacin infusion became apparent after the first 5 postoperative hours, thereafter reducing the demand for PCA morphine by about 40%. Continuous morphine infusion diminishes the postoperative demand for PCA morphine, but also increases the total morphine consumption.

Indomethacin as a postoperative analgesic for total hip arthroplasty

This prospective, randomized, double-blind trial evaluated the efficacy of rectal indomethacin as an adjunct to morphine for controlling postoperative pain. Fifty healthy patients undergoing elective hip arthroplasty were investigated. Group 1 (n = 25) received placebo suppositories, Group 2(n = 25) received indomethacin suppositories, 100 mg q8hr for five doses, starting at the end of the procedure. Both groups received morphine via a PCA pump, which recorded the amount of morphine delivered each hour. After a standardized general anaesthetic, PCA was begun in the recovery room. Pain was measured with a standard 100 mm VAS at 2, 6, 20, 28, 42 hr after surgery and the morphine consumption recorded. Over the 42-hr study period, patients in Group 2 required less morphine than those in Group 1 (34.8 +/- 21.8 mg vs 89.6 +/- 43.7, P less than 0.01). Pain scores were lower in Group 2 at 20, 28, 42 hr postoperatively. The incidence of side-effects did not differ between groups and no patient had excessive postoperative bleeding. The combination of indomethacin and morphine provided superior pain relief to morphine alone even though the control group had liberal access to morphine. This synergistic effect would make indomethacin a useful adjunct to intramuscular or epidural narcotics.