Background
Postoperative pain relief is a desired goal after tonsillectomy. Respiratory depression from opioid, bleeding from nonsteroidal antiinflammatory drugs, and airway edema all these factors make pain control is judges. Peritonsillar infiltration of a local anesthetic has been used for reduction of post-tonsillectomy pain.
Objective
This study aims to compare the postoperative analgesic efficacy and side-effects of preincisional peritonsillar infiltration of either ketamine or ropivacaine in children undergoing tonsillectomy.
Methods
In this prospective randomized double blind study, 60 children 7–12 years scheduled to tonsillectomy were divided into three groups: the tonsils were infiltrated by 0.2 ml kg ropivacaine, 0.75% in ropivacaine group R (=21), group 0.5 mg kg ketamine in the ketamine group K ( = 20), and 0.2 ml kg normal saline in the control group S ( = 19). All drugs were prepared in normal saline (3 ml per tonsil) infiltrated 3 min after induction of anesthesia and before surgical incision. Surgery was performed by a single otolaryngology fellow using the same dissection and snare technique. Postoperative pain was compared during 8-h period using a visual analog scale (VAS). The fast-tracking score was used to determine the post-anesthesia care unit discharge criteria. Patients were evaluated for: time of first request and the total analgesic requirement, time of first oral intake, nausea, vomiting, bleeding, and hallucination.
Results
In the post-anesthesia care unit, groups K and R had comparable pain scores that were significantly lower than S group ( < 0.04). Pain scores in the postoperative ward at 2, 6, and 8 h were significantly higher in group S than in K and R groups ( < 0.05). The time of first analgesic demand was significantly longer in R group (5.52 ± 1.7) h than in K group (3.83 ± 0.16) h  = 0.003. It was the shortest in S group (2.57 ± 0.84) h  = 0.001. The time of first oral intake was significantly longer in S than in R and K groups (5 ± 1.72 versus 3.2 ± 1.97 and 3.65 ± 1.72 h) respectively = 0.006. Total analgesic consumption (mg) was significantly higher in S group than in R and K (12. ± 5.3 versus 8, 2 ± 2.3 and 8.6 ± 3.1)  = 0.004. There were no significant differences between groups regarding nausea, vomiting, or bleeding, and there was no other side-effect recorded.
Conclusion
Perincisional peritonsillar infiltration of both ropivacaine and ketamine was effective in reduction of post-tonsillectomy pain. Ropivacaine was superior to ketamine in reduction of time to first analgesic demand.