Conditions: Nasal Polyps
Keywords: Drug: remifentanil Drug: tramadol Drug: metoprolol Functional endoscopic sinus surgery Controlled hypotension
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 88
Healthy volunteers: yes

Brief summary:
Functional endoscopic sinus surgery (FESS) is indicated in diseases such as chronic sinusitis refractory to medical treatment, nasal polyposis, mass lesions in the nasal cavity. The purpose of this study is to determine whether tramadol and metoprolol are as effective as remifentanil in providing controlled hypotension during FESS.

Detailed description:
This study aims to compare two techniques for controlled hypotension during FESS. In both cases, the patients will be evaluated during the preoperative anesthetic visit, and will be given care by an anesthesiologist during the perioperative period.

Patients who are scheduled for an elective FESS operation will be included in the study. During the preoperative anaesthetic visit, patients who do not meet any of the the exclusion criteria will be offered to participate in hte study. Patients accepting to contribute tot he study will be randomised into one of the two groups via closed envelope technique.

A pilot study with 20 patients resulted in similar means and slightly different standard deviations of mean blood pressure. This pilot study showed that 44 patients in each group are sufficient to obtain 80% power with an alpha error of 0.05 and beta error of 20%. To compensate for missing/inconsistent data, or allow for better matching of the demographic variables, 3-5 additional patients will be recruited.

The anesthesiologist in charge of the patient will not be blinded to the groups, and will be responsible for maintaining the hypotension (and patient safety) with either remifentanil in one group, or tramadol and metoprolol in the other group. Systolic, diastolic, and mean blood pressures, and heart rate will be recorded into a spreadsheet every three minutes during the anaesthetic and surgical period. The data will be recorded via an excel form, which will validate the entries upon entrance. The accuracy and completeness of registry data will be verified by a third investigator, who will compare the registry data to the medical monitor records at the end of each operative day.

The surgeon will be blinded to the groups, and will be responsible for scoring the surgical vision and bleeding with the intraoperative bleeding score. The study drugs will be administered via the same type of infusion pump to facilitate the blinding process.

Any adverse event will be reported in the patient chart and study records.

Statistical analysis will be carried out using R and Statistical Package for the Social Sciences (SPSS) programs. Demographic variables (age, gender, American Society of Anesthesiologists (ASA) score, comorbidities) will be analysed using descriptive statistics. Study variables such as duration of operation, variance of the hemodynamic parameters, amount of bleeding, bleeding score, occurrence of adverse events will be analysed with the appropriate statistical tests.

Arms:
arm 1: Following an intravenous bolus dose of 0.5 µg/kg remifentanil administered just before the induction of anaesthesia, patients will receive an intravenous infusion of remifentanil at a dose of 0.25-0.5 µg/kg/min throughout the surgery. The rate of infusion will be adjusted to maintain a mean blood pressure within %70-80 of the baseline value. At the end of the surgery, the rate of infusion will be decreased to 0.05 µg/kg/min, and continued until the patient is extubated. arm 2: Just before the induction of anaesthesia, an intravenous infusion of 1 mg/kg of tramadol in 100 ml isotonic fluid will be started. The infusion will be completed in 30 minutes using a perfusor. Additionally, following the administration of the neuromuscular blocking agent, 0.1 mg/kg of intravenous metoprolol will be administered within 5 minutes.

Interventions: intervention 1: Remifentanil intervention 2: Tramadol intervention 3: Metoprolol
Intervention descriptions: intervention 1: Remifentanil infusion will be started with a bolus dose of 0.5 µg/kg before the induction, and will be continued throughout the surgery at a dose of 0.25-0.5 µg/kg/min. At the end of the surgery, the rate of infusion will be decreased to 0.05 µg/kg/min, and continued until the patient is extubated. intervention 2: 1 mg/kg tramadol will be added to 100 ml of isotonic fluid, and will be administered intravenously in exactly 30 minutes via a perfusor. The infusion will be started just before the induction. intervention 3: 0.1 mg/kg of metoprolol will be administered intravenously within 5 minutes following the administration of neuromuscular blocking agent.

Protocol document: