Efficacy of wound analgesia for controlling post-thoracotomy pain: A randomized double-blind study

OBJECTIVES: Continuous wound infusion of local anaesthetics has been successfully applied for postoperative pain control in several procedures but, surprisingly, it is underused in thoracic surgery. We aimed to investigate the effects of wound analgesia associated with systemic patient-controlled analgesia in patients undergoing lung cancer resection with muscle-sparing thoracotomy. METHODS: Sixty consecutive patients undergoing lung cancer resection via standard muscle-sparing thoracotomy were randomized into two groups (wound analgesia and placebo groups). Bupivacaine in the wound group and free-saline solution in the placebo group were injected using a multiholed catheter connected to an elastomeric pump inserted at the end of operation between the pericostal sutures and the serratus muscle and removed 48 h after. The inter-group differences were assessed by the following criteria: (i) level of cytokines [IL-6, IL-10 and tumour necrosis factor-alpha (TNF-alpha)]; (ii) pain on a visual analogue scale at rest and after coughing; (iii) recovery of respiratory functions (flow expiratory volume in 1 s % and forced vital capacity %) and (iv) narcotic medication consumption at different time points of the postoperative course. RESULTS: Five out of a total of 60 patients were excluded from the final analysis. Thus, the wound and placebo groups comprised 27 and 28 patients, respectively. The wound group compared with the placebo group had a significant decrease of IL-6 (P < 0.001), IL-10 (P < 0.001) and TNF-alpha (P < 0.001) blood concentration levels, pain scores at rest (P < 0.001) and after coughing (P = 0.01), and a reduction of additional morphine intake (P = 0.03) and Ketorolac (P = 0.01) during the entire postoperative course. The recovery of the flow expiratory volume in one second % (P = 0.01) and the forced vital capacity % (P = 0.02) was also better in the wound than in the placebo group. CONCLUSIONS: Our data prove that wound analgesia is an effective, easy and safe procedure. It significantly reduces systemic inflammatory markers, pain scores and opioid intake; and accelerates the recovery of respiratory function. Catheter placement does not require particular manoeuvres by the surgeon nor does the elastomeric pump need any adjustment or care by physicians or nurses.