Intravenous Lidocaine Lowers Pediatric Postoperative Pain

Author: Michael Vlessides

Anesthesiology News

Intraoperative IV lidocaine is a viable analgesic alternative in children undergoing laparoscopic hernia repair, according to a Korean research team. Their study concluded that although the therapeutic approach did little to curb moderate to severe postoperative pain, it resulted in significantly fewer children presenting with severe postoperative pain in the first 48 hours after surgery.

“Although pediatric laparoscopic hernia repair is far less invasive than open hernia repair, there’s still pain with the laparoscopic approach,” said Ji-Min Lee, MD, an attending anesthesiologist at the Yonsei University College of Medicine, in Seoul, South Korea. “Nevertheless, this pain is very localized and therefore not very effectively controlled by regional blocks. Also, in children who are unable to speak for themselves, pain can be underestimated and poorly controlled.

“Since systemic lidocaine is known to be a reliable analgesic option in adult patients, it could be used in children also,” said Dr. Lee, who is the lead author of the study. “Therefore, we hypothesized that systemic lidocaine would help those children have better postoperative analgesia.”

To answer this question, the researchers enrolled 60 patients (aged 1-6 years) into the prospective, randomized, double-blind, placebo-controlled trial; all were undergoing laparoscopic inguinal hernia repair. The children were randomly assigned to receive either lidocaine—a 1-mg/kg bolus for one minute followed by an infusion of 1.5 mg/kg per hour until the end of surgery—or the same volume of saline. For anesthesia, the researchers used sevoflurane, rocuronium and fentanyl, the latter of which was dosed at 1 mcg/kg, with an additional 0.5 mcg/kg administered at the end of surgery.

To assess postoperative pain, the researchers used the Face, Legs, Activity, Crying, Consolability (FLACC) scale in the PACU, as well as at four, eight, 12 and 24 hours on the ward. After discharge, parents scored their children with the Parents’ Postoperative Pain Measure (PPPM) score at 48 hours after surgery. “The PPPM is a yes-or-no questionnaire that looks at whether children’s behavior changed after surgery,” Dr. Lee explained. “It asks questions related to things like a child’s crying and eating patterns.” The study’s primary outcome was moderate to severe pain in the immediate postoperative period.

As Dr. Lee reported at the 2018 annual meeting of the International Anesthesia Research Society (abstract PED123), 50% of children in the lidocaine group and 73% in the control group had immediate postoperative FLACC scores of at least 4, suggesting moderate to severe pain (P=0.063). However, when the investigators focused on children presenting with severe pain (FLACC scores ≥7), they found the ratios to be quite different. Indeed, only four children (13.3%) in the lidocaine group experienced severe pain, compared with 15 (50%) controls (P=0.002).

“The lidocaine group also showed consistently lower FLACC scores at four, eight, 12 and 24 hours in the ward,” Dr. Lee said. “And there was a statistically significant difference in the degree of improvement of pain scores in the two groups over time.”

At 48 hours, children receiving the lidocaine infusion had lower PPPM scores than the controls (mean difference, 2.07; 95% CI, 1.11-3.03). “The lidocaine group mostly presented with scores of 0 and 1,” she explained, “while the control group had a mean PPPM score of 3.2.”

Despite these promising results, the researchers were quick to point out that systemic lidocaine treatment is not without considerations. “Lidocaine has a narrow therapeutic window, and dose selection is very important,” Dr. Lee said. “And although we found that the lidocaine infusion reduced the number of patients with severe pain, there was not a statistically significant difference in the percentage of patients with moderate to severe pain. So that is something that can be studied in the future.”

Session moderator Jeffrey Berman, MD, a professor of anesthesiology at the University of North Carolina at Chapel Hill School of Medicine, questioned the choice of systemic lidocaine over other possible treatment modalities. “I’m curious why you would choose IV lidocaine over local anesthetic infiltration,” he asked.

“When we do open hernia repair surgery, we do local infiltration,” Dr. Lee explained. “But since this is laparoscopic repair, the pain is both somatic and visceral. And visceral pain is hard to localize; therefore, we decided that it would be controlled better by systemic lidocaine infusion.”

“In the PACU, children undergoing laparoscopic surgery present their pain a little bit differently compared with the open hernia surgery,” added study co-investigator Jeong-Rim Lee, MD, PhD, a clinical assistant professor of anesthesiology at the institution. “They are uncomfortable, but they can’t localize where their pain comes from. They feel the pain, but in a different way than with open surgery.”

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