◊ BACKGROUND:
Surgery-associated tissue injury leads to nociception and inflammatory reaction, accompanied by increased production of proinflammatory cytokines. These cytokines can induce peripheral and central sensitization, leading to pain augmentation. Recently, a frequently used local anesthetic, lidocaine, was introduced as a part of a perioperative pain management technique. In addition to its analgesic effects, lidocaine has an antiinflammatory property, decreasing the upregulation of proinflammatory cytokines. We focused on the effects of preincisional and intraoperative IV lidocaine on pain intensity and immune reactivity in the postoperative period.
◊ METHODS:
Sixty-five female patients (ASA physical status I–II) scheduled for transabdominal hysterectomy were recruited to this randomized, placebo-controlled study. Thirty-two patients in the treatment group received IV lidocaine starting 20 min before surgery, whereas the control group (33 patients) received a matched saline infusion. Both groups received patient-controlled epidural analgesia during the postoperative period. Blood samples were collected before, 24, 48, and 72 h after surgery to measure ex vivo cytokine production of interleukin (IL)-1 receptor antagonist (IL-1ra) and IL-6, as well lymphocyte mitogenic response to phytohemagglutinin-M. A 10-cm visual analog scale was used to assess pain intensity at rest and after coughing.
◊ RESULTS:
Patients in the lidocaine + patient-controlled epidural analgesia group experienced less severe postoperative pain in the first 4 and 8 h after surgery (visual analog scale 4/3.7 at rest and 5.3/5 during coughing versus 4.5/4.2 and 6.1/5.3, respectively, in the placebo group). There was significantly less ex vivo production of IL-1ra and IL-6, whereas the lymphocyte proliferation response to phytohemagglutinin-M was better maintained than in the control group.
◊ CONCLUSIONS:
The present findings indicate that preoperative and intraoperative IV lidocaine improves immediate postoperative pain management and reduces surgery-induced immune alterations.
◊ Reviewed by J. Raeder, MD, PhD
Chairman of Clinical Ambulatory anaesthesia / Professor in Anaesthesiology,
Dept. of Anaesthesia, Oslo University Hospital, Oslo, Norway
This is a clinical paper looking at the use of intravenous (iv) lidocaine bolus and infusion during open hysterectomy. The objectives were to look at the postoperative analgesic effect of lidocaine in terms of perceived pain and use of epidural rescue analgesia as well as to analyse three key parameters of immune function and inflammation. The design was explanatory in the sense that no other confounding non-opioid analgesics were used, except for bupivacaine during the postoperative epidural opioid infusion and as on-demand rescue treatment.
The results confirm previous studies showing a minor but significant analgesic effect of iv lidocaine on postoperative pain (5-10% decrease in VAS) during the first 8 hours post-surgery. i.e. after the end of lidocaine infusion. The study also confirmed an anti-inflammatory effect of iv lidocaine. Thus, there is no doubt that iv lidocaine has some positive effects. The question is what might be the clinical implications of these results.
As both groups received continuous epidural bupivacaine and rescue boluses postoperatively, the effect of subsequent systemic absorption of bupivacaine also in the control group may have diminished some beneficial effect by lidocaine. However, from a clinical point of view, an explanatory research design generally overestimates the effectiveness of study drugs. No other anti-inflammatory or analgesic agents have been used in the control group. This is fair enough to show whether the study drug has an effect or not, but it does not allow conclusions for clinical practice. In the clinical situation, the epidural analgesia probably would have been activated at the start of surgery, thus delivering some local anaesthetic into the epidural and subsequently into the systemic circulation. In addition, the surgeon may also have used local anaesthesia wound infiltration with some systemic absorption. A knowledgeable clinician probably would have used a multimodal non-opioid analgesic regimen with some anti-inflammatory properties: paracetamol+NSAID or even a glucocorticoid. Would iv lidocaine still add any effect on top of such a non-opioid multimodal regimen? This question is important as it is a little cumbersome to establish a pump with an ongoing lidocaine infusion and also because iv lidocaine has a quite narrow therapeutic range.
There is one study showing that iv lidocaine adds to the analgesia achieved by paracetamol and NSAID [1], but also the design of this study was suboptimal because the other non-opioids were given postoperatively and not preoperatively as lidocaine. Thus, while iv lidocaine certainly has analgesic and anti-inflammatory effects we still do not know whether it adds benefit to patients receiving an otherwise optimal non-opioid and anti-inflammatory analgesic regimen.
◊ References
[1] Kaba A, Laurent SR, Detroz BJ, et al. Intravenous lidocaine infusion facilitates acute rehabilitation after laparoscopic colectomy. Anesthesiology 2007;106:11-8.
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