This study was a randomized, double-blind, and prospective trial. Between June 2015 and January 2019, 120 adult patients underwent septoplasty at Otorhinolaryngology Clinic of Bozok University Research Hospital were included to the study. The approval of the Ethics Committee was obtained (date: May 25, 2015, number: 25/12). This trial was registered retrospectively (The ACTRN: ACTRN12619001652167, registration date: 26/11/2019).
The informed consents were obtained from all patients and followed the guidelines of Helsinki. In the operation room, all patients were randomly classified into two groups by using a computer-generated randomization table with an allocation ratio of 1:1. The randomization table was obtained from the website http://www.randomization.com. The randomization was performed by an anesthesiologist who was not involved in the anesthetic management. Intraoperative and post-operative data was collected by an anesthesiologist and anesthetic nurses who did not participate in the study. For post-operative analgesia, the first group (n=60) used tramadol and the second group (n=60) were given fentanyl in the induction initially. In both groups, fentanyl (1 µg/ kg-i.v.), propofol (2-3 mg/ kg), and muscle relaxant (rocuronium bromide 0.6 mg/ kg) were administered to all patients for induction. After endotracheal intubation, the rest of the anesthesia procedure was maintained with 2-3% sevoflurane. Sixty percent NO2 in 40% O2 was delivered to the patients in both groups. Although at the end of the surgery to first group patients was given tramadol (1-2 mg/ kg) for post-operative analgesia, no agent was given to the control group for post-operative analgesia. The patients in control group received same amount of placebo instead of tramadol 100 mgvial (50 mg/ml, 2 mL). The medications given intravenously to each group before awakening were performed by the Anesthesia Care Team. Acetaminophen with codeine analgesic 325/30 mg (p.o.) was used as an additional analgesic agent in the post-operative period.
The inclusion criteria for the study consisted of patients between the age of 18-45 years, who were categorized as I and II according to the American Society of Anesthesiology physical status classification and scheduled for elective surgery for septoplasty operation under general anesthesia. The exclusion criteria consisted of the patients who had electrocardiogram (ECG) changes, receiving opioids for chronic pain, additional nasal pathologies and thus receiving additional surgical intervention, and history of allergies to local anesthetics, pregnancy, renal insufficiency, cognitive dysfunction and refusal of participation to the study.
All patients were operated by the same surgical team with similar techniques under general anesthesia by using the classic septoplasty operation technique including the correction of a deviated septum, classic submucosal resection, traditional septoplasty, and open techniques [11]. Since the genetic analysis of the samples was not available in our institute, venous blood samples were obtained from patients for research to determine the μ-Opioid receptors activities in the pre-operative period. The sera were transferred into unused cover tubes. The tubes were stored at -20ºC in the deep-freezer and analyzed for μ-Opioid receptors levels using an Olympus AU 600 auto-analyzer (Olympus Optical Co., Japan) using Randox kits.
All the patients’ vital signs were monitored during the operation. In all patients, the changes of mean arterial pressure, heart rate and Ramsay Sedation Scales (RASS) were measured at predetermined time points as arrival to the recovery room, and at the 1st, 3rd, 7th, 10th, and 24th hours in post-operative period.
To determine the level of post-operative pain, a continuous 10 cm visual analog scale (VAS), was used. On the scale, 0 indicated ‘no pain’, and 10 indicated ‘severe pain’. The patients were asked to mark their pain at different times on the scale, and the results were recorded. First measurements were made on arrival to the recovery room in postoperative period, and they were repeated at the 1st, 3rd, 7th, 10th, and 24th hours. When VAS pain scale was evaluated at postoperative 1st hour (in addition to the patient's level of consciousness), clinical signs and vital signs were also evaluated. At the times when the pain was severe (VAS ≥ 4), the patients were given upon arrival to the recovery room: Acetaminophen 1g (10 mg/mL, 100 mL) intravenously due to difficult peroral intake, at other time points: Acetaminophen with codeine analgesic 325/30 mg perorally as rescue analgesic, and both timing and amount of analgesics used were recorded. The relations between μ-Opioid receptors level and VAS pain scale and second analgesic need was investigated in patients. The primary outcome was the postoperative pain level difference in relation with pre-operative μORs level. The secondary outcomes were the needed rescue analgesic agent (Acetaminophen with codeine analgesic 325/30 mg. per-oral) timing and amount, the changes of mean arterial pressure, heart rate, the degree of sedation of the patients, incidence of postoperative nause and vomiting in post-operative period.
Statistical Analysis
Sample size calculation were performed with a power analysis based on data from a previous study [12]. In this study, which included a total of 96 patients, the relationship between Human mu opioid receptor gene A118G polymorphism and efficacy of a combination of tramadol and acetaminophen was investigated in painful neuropathy. In the study, the researchers revealed that Human mu opioid receptor gene A118G polymorphism decreased analgesic efficacy of opioid agents in pain control. Power estimation analysis suggested that 53 patients per group with a power of 80% (1-β error =0.80), considering a type I error of 0.05 (α error=0.05). To compensate for unexpected losses, recruitment was increased by 20%. The data were analyzed using the SPSS 21.0 software package. The number, mean and standard deviations of the demographic variables were tabulated, and student t test was used to compare the groups. ANOVA test (two ways classification with repeated measures) was used for statistical analysis of VAS values. A p-value of less than 0.05 was accepted as statistically significant.