A randomized blinded trial of preemptive local anesthesia in laparoscopy.

Objective: Laparoscopy, while routinely performed in the outpatient setting, is associated with considerable postoperative discomfort. Continuing pain experienced after surgery is due to post-traumatic functional changes in both the peripheral nervous system (hyperalgesia) and the central nervous system (hyperexcitability). Local anesthetic infiltrated at time of incision closure has limited effect because hypersensitivity and hyperexcitability have already developed. Preemptive analgesia refers to the blockage of afferent nerve fibers, before painful stimulus, which prevents or reduces subsequent pain even beyond the effect of the block. We tested the hypothesis that local anesthetic administered before skin incision, an example of preemptive analgesia, reduces postoperative pain for women undergoing laparoscopy, as compared to postincisional local anesthetic or placebo. Materials and Methods: Seventy-five patients undergoing laparoscopy for pelvic pain, infertility, or sterilization were randomized to one of three treatment groups. Two 10 mL syringes, labeled “Pre” and “Post,” were prepared at time of laparoscopy and contents blinded to anesthesiology, surgeons, and the patient. For treatment group A (preincisional), the presyringe contained 10 mL of 0.5% bupivacaine (50 mg) and the postsyringe contained 10 mL of 0.9% saline. For treatment group B (postincisional) patients, the presyringe contained 10 mL of 0.9% saline and the postsyringe contained 10 mL of 0.5% bupivacaine. For treatment group C (control) patients, both syringes contained 10 mL of 0.9% saline. All patients underwent a standardized general anesthetic induction and maintenance. After the patient was properly positioned and draped, 5 mL of the presyringe was infiltrated into the umbilical incision site. The remaining 5 mL was infiltrated in a similar fashion at the suprapubic trocar placement site. After laparoscopy and immediately prior to closure of the incisions, the postsyringe was infiltrated into both incisions above and below the fascia in a diamond-shaped pattern. For postoperative pain, oral ibuprofen was given, as needed, with 30 mg intramuscular ketorolac tromethamine given if the patient was unable to tolerate oral pain medication. All patients were discharged with 800 mg ibuprofen tablets and asked to take as needed for pain relief. The modified McGill Present Pain Intensity scale was evaluated by nurse interview at 30 minutes, 2 hours, 4 hours, and 24 hours after incision closure. Statistical analysis was accomplished using χ2 tests for proportional data and ANOVA for pain scores and other parametric data. Results: Fifty-seven patients completed the study protocol. Age, weight, height, race, indication, and operating time did not vary significantly between the three groups. Patients in treatment group A (n = 20) could tolerate a significantly longer time delay to their first analgesic medication. (A: 486.7 ± 435.3 minutes; B: 229.4 ± 330.4; C: 143.1 ± 156.7, P < .001). Their 24-hour pain scores were also significantly lower than either treatment group B (n = 19) or C (n = 18) (A: 0.50 ± 0.9; B: 1.61 ± 1.3; C: 1.2 ± 1.2, P < .02). Although statistical significance was not reached, patients in treatment group A required less total doses of analgesic than either treatment group B or C (A: 2.4 ± 1.6 doses; B: 3.1 ± 1.5; C: 3.1 ± 1.2, P = .07). Conclusions: Preemptive local anesthesia in patients undergoing laparoscopy results in a longer time before analgesic is required and significantly lower pain 24 hours after surgery.