Preoperative acupuncture: postoperative analgesia?

In the linked study by Coura and collaborators , it is reported that acupuncture the day before surgery can reduce postoperative pain (see article on page 16). 1 Although the study is small and there are gender differences between the groups, the fi ndings are novel, suggesting that acupuncture may be used the day before surgery rather than given in the immediate preoperative period. This suggestion is supported by results showing that acupuncture given to patients just before operative removal of impacted mandibular third molars resulted in increased pain as compared with a control group receiving no treatment. 2 A relevant question is whether the results obtained may be explained from a physiological perspective—that is, if acupuncture given the day before surgery may be used to prevent or reduce the postop-erative pain. Nociception is the term for pain that results from activation of noci-ceptors (high threshold peripheral sensory receptors) by noxious stimuli. Such pain may result from a scalpel blade cutting through skin. It signals the existence, location, intensity and duration of the stimulus and fades once the scalpel blade is removed. However, surgery commonly results in tissue injury, infl ammation and infl ammatory pain, a state charac-terised by heightened pain sensitivity. This is triggered by the release of sensitising infl ammatory mediators (eg, prostaglandins, ions, cyto kines and growth factors) that leads to peripheral sensitisation (a reduction in the threshold of nociceptors). 3 The peripheral sensitisation then results in an increase in the excitability of neu-rons in the central nervous system, central sensitisation. These phenomena , although evoked within a matter of minutes, can outlast the surgical tissue injury for several hours or days and drive acute postoperative pain until the surgical wound has healed. 4 Pre-emptive analgesia is a treatment that prevents establishment of the altered sensory processing that ampli-fi es postoperative pain. The treatment should cover the entire duration of high-intensity noxious stimulation that can lead to establishment of central and peripheral sensitisation caused by incisional and associated infl ammatory injuries. Of these two injuries, the associated infl ammatory reactions are probably of greater clinical signifi cance. 5 Two approaches have been used to reveal pre-emptive analgesia. One is to demonstrate a reduction in pain intensity and/or analgesic use beyond the period during which an effective concentration of a drug is maintained in the vicinity of its site of action. This approach is based on a study …