Topical anesthesia with lidocaine aerosol in the control of postoperative pain

Postoperative pain was assessed in patients undergoing inguinal hernia repair. Ten patients received lidocaine aerosol in the surgical wound before skin closure, ten patients received placebo aerosol devoid of lidocaine, and ten patients were untreated. The lidocaine-treated group had significantly lower pain scores and meperidine requirements during the first postoperative day compared to the control groups. During the second day after surgery, these variables did not differ between groups. Wound anesthesia, assessed by palpation of the wound 24 h after surgery by a blinded investigator, was significantly more pronounced in the group treated with lidocaine aerosol than in the control groups. Similarly, in patients undergoing bilateral herniorraphy, wound pain following palpation was significantly reduced on the lidocaine-treated side compared to the untreated side. Patients in the group receiving lidocaine aerosol indicated less pain in connection with mobilization than untreated patients, but not compared to patients treated with placebo aerosol. Plasma substance P (SP) and beta-endorphin (BE) measured in lidocaine-treated patients and in untreated patients before and after drug administration showed no significant differences regarding SP, while BE was significantly increased 1 h after surgery in the untreated group. Plasma lidocaine concentrations were well below toxic levels. Results show that lidocaine aerosol used as topical anesthetic in the surgical wound is simple to use, and results in a long-lasting reduction of pain after a single administration. Moreover, postoperative mobilization is facilitated, and the requirement for postoperative analgesics is reduced. Wound healing was normal, and no adverse reactions to lidocaine were reported.