Comparison of Effect of Peritonsillar Infiltration of Ketamine and Tramadol on Pediatric Posttonsillectomy Pain: A Double-blinded Randomized Placebo-controlled Clinical Trial

Adenotonsillectomy is one of the most common ambulatory surgical procedures performed to children. Tonsillectomy or adenotonsillectomy have a high incidence of postoperative pain. There is still debate about the optimal analgesia for this common surgical procedure. Different methods have been described and used to reduce pain including. The main goal of the preventive analgesia is the pain relief with minimum side effects. The role of local anesthetic infiltration in the reduction of postadenotonsillectomy pain is still controversial. Blockage of N-methyl-D-aspartate (NMDA) activation and interception of nociceptive in put are important factors to achieve the reduction in subsequent pain. Ketamine hydrochloride is an NMDA receptor antagonist. The blockage of the NMDA channel and analgesic properties are both at subanesthetic doses for the ketamine. Ketamine also prevents central sensitization of nociceptors. Previous studies described the analgesic effect of intravenous application or peritonsillar infiltration of ketamine intraoperatively in children after tonsillectomy. Tramadol is another analgesic and a synthetic opioid of the aminocyclohexanol group which is a central opioid agonist with less respiratory depression compared to morphine. We knew that tramadol has both systemic and local anesthetic effect on peripheral nerves from human and animal studies.

The study was approved by the Ethics Committee of the University. The consents will be taken from all parents. Patients will be randomized from seald envelope into tramadol, ketamine or control (serum physiologic) to receive the preincisional peritonsillar infiltration before the surgery. There will de 36 patients in each group. The study drug is supplied of a liquid identical in color and volume. All surgeons, anesthesiologists, nurses, patients and parents will be blinded to study group until the end of the study All children will receive a premedication including midazolam hydrochloride (0.5 mg/kg; maximum dose, 20 mg) followed by a standard general inhalational anesthetic (50% O2-N2O and 8% sevoflurane). Children also received 0.1 mg/kg of fentanyl citrate and 0.2 mg/kg mivacurium intravenously. After the intubation maintenance anesthesia will be keep with nitrous oxide (50%) in oxygen and sevoflurane. All patients will receive the peritonsillar injection of the study drug before the excision of the anesthesia. Tramadol group will receive 2 mg/kg (2 ml), ketamine group 0.5 mg/kg (2cc), control group 2 ml of serum physiologic. All infiltrations will be through the peritonsillar fossa. For each tonsil 1 ml will be applied to upper pole, lower pole and between the upper and lower pole with 25-G needle. After the infiltration surgeons will wait 3 min for tonsillectomy. The same standard blunt dissection will be performed to all children by the same surgeon. During the operation heart rate oxygen saturation, average blood pressure, respiration rates will be recorded in every 5 min. Operation, anesthesia times will also be recorded. Postoperatively pain, nausea, vomiting, sedation scores, the existence of dysphagia, bleeding were recorded at 2, 6, 12, 24 h postoperatively. Children's pain scores will be measured by using Visual Analogue Scale (VAS).If the pain score is greater than 5, Ibuprofen will be given to children. Pains with the request for analgesic requirements, the time of analgesia requirement, patient satisfaction will be also recorded.

Data analysis will be performed by using SPSS for Windows. The relationship between categorical variables will be test by Chi-square test and Anova test will be performed to compare groups according to continuous variables. Also LSD test will be used to detect subgroup differences. p Values higher than 0.05 will be considered as significant. Mean and standard deviations and percentages will be given as descriptive statistics.