The value of "multimodal" or "balanced analgesia" in postoperative pain treatment

Perioperative pain management

The clinical anesthesia, general surgery, and gynecology literature addressing the pathophysiology and management strategies for perioperative pain were reviewed. There are few prospective, randomized studies from which to draw meaningful conclusions. Nevertheless, a theoretical construct has been developed which may help the gynecologic surgeon optimizing pain management. The era of managed care and shorter hospital stays has focused physicians and, in particular, surgeons on elements of patient care that can be addressed and improved. Reducing or eliminating postoperative pain without excessive sedation promotes rapid mobilization and return to self-care. Strategies for pain management can be adopted that reduce postoperative ileus and other adverse reactions to analgesics.

Intravenous regional anesthesia using lidocaine and ketorolac

Nonsteroidal antiinflammatory drugs (NSAIDs) interfere with the synthesis of inflammatory mediators and can supplement postoperative pain relief. We postulated that using the parenterally available NSAID ketorolac (K) as a component of intravenous regional anesthesia (IVRA) would suppress intraoperative tourniquet pain and enhance postoperative analgesia. Sixty patients were assigned randomly and blindly to receive either intravenous (i.v.) saline and IVRA with 0.5% lidocaine, IV K and IVRA 0.5% lidocaine, or i.v. saline and IVRA 0.5% lidocaine with K. The patients who received IVRA K reported significantly less intraoperative tourniquet pain, with lower verbal analog pain scores at 15 and 30 min after tourniquet inflation. Similarly, IVRA-K patients experienced less postoperative pain with lower visual analog scale (VAS) pain scores at 30 and 60 min, and required no fentanyl for control of early postoperative pain in the postanesthesia care unit (PACU). They also required fewer analgesic tablets in the first 24 h (1.9 +/- 1.4 Tylenol No. 3 tablets compared to the other two groups, 4.6 +/- 1.3 and 3.0 +/- 1.1; P < 0.05). We conclude that K improves IVRA with 0.5% lidocaine both in terms of controlling intraoperative tourniquet pain and by diminishing postoperative pain.

Analgesia following day-case knee arthroscopy--the effect of piroxicam with or without bupivacaine infiltration

Sixty patients presenting for day-case arthroscopy of the knee under general anaesthesia were studied. Patients were randomly allocated to receive, in addition to intramuscular piroxicam 20 mg, either bupivacaine 0.25% 20 ml applied locally to the knee at the end of the procedure (n = 30) or no further intra-operative analgesia (n = 30). Visual analogue pain scores were significantly lower at 1, 2 and 4 h postoperatively in the bupivacaine group (p < 0.05). A higher proportion of patients in the piroxicam-only group required supplemental analgesia before discharge from hospital. The combination of piroxicam and bupivacaine provided superior analgesia to piroxicam alone.

Synergism between analgesics

The concept and value of 'multimodal' or 'balanced' analgesia in the treatment of postoperative pain is reviewed. Based upon the relatively few multimodal studies compared to unimodal studies, it is concluded that a combination of analgesics will improve pain relief including movement-associated pain. Since analgesic combination therapy is rational, further studies are needed to evaluate the optimal combination for each surgical procedure, as well as to assess the risk of side effects and need for surveillance in large-scale studies.

Visceral pain: mechanisms of peripheral and central sensitization

This paper describes the responses of peripheral and central visceral nociceptive systems to acute injury and discusses these observations in relation to the concept of 'pre-emptive analgesia'. Visceral nociceptors are known to respond to injury but are also known to become sensitized to non-noxious stimuli during the inflammatory process that follows intense noxious stimulation. The afferent barrages triggered in visceral nociceptors by the acute injury and the enhanced responses evoked in sensitized nociceptors during the repair process can, in turn, increase the excitability of central nociceptive systems. The maintenance of central hypersensitivity is, however, dependant on the continuing presence of afferent volleys from sensitized nociceptors because the central changes cannot be sustained in the absence of a peripheral drive. Therefore it is proposed that the concept of 'pre-emptive analgesia', as such, has no neurophysiological basis. Any analgesic procedure aimed at reducing postoperative pain must not only prevent the arrival in the CNS of the initial afferent barrage evoked in nociceptive endings but also reduce or eliminate the persistent discharges of sensitized nociceptors during the inflammatory repair process that are critically important for the maintenance of the central pain state.

Bupivacaine 0.125% improves continuous postoperative epidural fentanyl analgesia after abdominal or thoracic surgery

The addition of 0.125% and 0.25% bupivacaine to continuous postoperative epidural infusions of fentanyl, in a 10 micrograms.ml-1 concentration, were studied in 39 patients following abdominal or thoracic surgery in prospective, random, double-blind fashion. Patients received an initial bolus of 0.1 ml.kg-1 of the the study solution and an infusion of 6 ml.hr-1 which was titrated to maintain analgesia (VAS < 40). Assessments of pain (VAS), pulmonary function (pH, PaCO2), and bowel function (time to flatus or po fluids) were made until the second post-operative morning. There was a difference among the three groups in analgesia (means VAS scores) over time (P < 0.01), with the fentanyl-alone group producing less analgesia than the 0.125% bupivacaine group (P < 0.01). There was no difference in the average infusion rates, postoperative pulmonary function, or bowel function. The incidence of side effects including somnolence, nausea and vomiting, and pruritus was also similar. Fewer patients in the 0.125% bupivacaine group than in the 0.25% group developed a transient sensory loss to pinprick and ice (3 vs 10, P < 0.001). Four patients in both bupivacaine groups had leg weakness, those in the 0.125% were all a Bromage 1 score, while in the 0.25% group one had a Bromage 1, one a Bromage 2, and two Bromage 3 scores. The addition of 0.125% bupivacaine improves the analgesia of epidural infusions of fentanyl (10 microgms.ml(-1)) when used following abdominal or thoracic surgery and results in minimal sensorimotor disturbance.