Ketamine as an adjunct to fentanyl improves postoperative analgesia and hastens discharge in children following tonsillectomy - a prospective, double-blinded, randomized study.

Abstract

Objective:   To evaluate the effect of ketamine, as an adjunct to fentanyl, on postoperative analgesia and duration of Postoperative Care Unit (PACU) stay, in children undergoing tonsillectomy.

Background:   Ketamine, as an N-methyl-d-aspartate antagonist, has been recognized to have an opioid sparing effect. In addition, it does not depress respiration or affect airway tone. Hence, addition of ketamine could be potentially beneficial in children undergoing tonsillectomy, due to the high incidence of sleep apnea in these patients.

Methods:   In a double blinded, randomized trial, 60 ASA status I and II children between 2 and 7 years of age, scheduled to undergo elective tonsillectomy were recruited. They were randomly assigned to one of four groups to receive fentanyl 1 mcg·kg(-1) (F1 group), fentanyl 2 mcg·kg(-1) (F2 group), ketamine 0.5 mg·kg(-1) (K group), or fentanyl 1 mcg·kg(-1) plus ketamine 0.5 mg·kg(-1) (FK group) pre-incision. Postoperative pain was scored on arrival to the PACU and at 30, 60, and 90 min thereafter. Any incidence of nausea/vomiting and time to discharge from the PACU were also recorded.

Results:   Important predictors found for postoperative pain on arrival to the recovery room are the group (P = 0.02) and duration of surgery (P = 0.02). Least square means and standard errors of pain scores on PACU arrival were 4.87±0.69, 3.04±0.68, 2.10±0.68 and 2.03±0.69 for F1, F2, K and FK groups, respectively. On group-wise comparison adjusted for surgical time, significant difference was detected between F1 and K (P = 0.02), and F1 and FK (P = 0.0048) groups. Marginal significance was detected in duration of PACU stay among groups (P = 0.08); F2 and FK group had a shorter PACU stay than F1 (P = 0.05 and 0.04 respectively). No significant difference was detected in the need for supplemental analgesia.

Conclusion:   We conclude that the administration of ketamine 0.5 mg·kg(-1) with 1 mcg·kg(-1) fentanyl in children undergoing tonsillectomy may improve postoperative pain control without delaying home discharge.