الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Functional Endoscopic Sinus Surgery (FESS) is a therapeutic procedure involving the use of fibreoptic endoscope to visualize inside the face sinuses and nasal cavity. It is now the main technique for the surgical treatment of sinusitis and nasal polyposis and recurrent acute and chronic sinus diseases.
Sinuses are small cavities with hyghly vascularised mucous. They are closed to important structures (brain, eye, great vessels and nerves). Minimizing surgical blood loss during FESS lead to improvement of surgical field visibility, short duration of surgery and avoid injuring surrounding structures. Controlled hypotension (hypotensive anaesthesia) is used during anaesthesia for this purpose.
Many drugs have been used for hypotensive anaesthesia, and several randomized controlled trial studies reported alpha-2 adrenergic agonists (clonidine or dexmedetomidine) to be superior to other medications (propofol, remifentanil, anaesthetic inhalant gases, esmolol, propranolol, labetalol, sulfate magnesium, sodium nitroprussiate, nitoglycerine, hydralazine, calcium chanel blockers ).
Few randomized controlled trials have been conducted to compare clonidine and dexmedetomidine regarding their efficacy and safety when used as adjuvant to hypotensive anaesthesia especially in the setting of ambulatory surgery.
The aim of this work was to compare primarily blood loss and surgical field quality. Secondarily, hemodynamic parameters (heart rate and mean aterial blood pressure), postoperative sedation assessed by Ramsay Sedation Score, and surgeon satisfaction.
The present study was a randomized controlled trial, double blinded, comparing clonidine and dexmedetomidine use for controlled hypotension during FESS. It was conducted in the Main Teaching University Hospital of the University of Alexandria, department of Oto-Rhyno-Laryngolology (ORL), Rhinology unit, in 80 patients, 20-50 years old, ASA I or II, undergoing elective FESS. Patients were excluded if they had systemic hypertension, anemia with hemoglobin 10g/dL, cardiac disease and arrhythmias, diabetes mellitus, obesity, medical history of stroke, chronic kidney disease, liver disease, coagulopathies or under anticoagulants and patients with known allergy on clonidine or dexmedetomidine.
Sample size was calculated, and patients were allocated in two groups, 40 patients each. The allocation to group C (received clonidine) or D (received dexmedetomidine) was done by closed envelop method.
In group C, patients received intravenous clonidine. A loading dose of 3 g/ kg in 10mL 0.9% normal saline intravenous infusion for 10 minutes and followed by maintenance dose of 0.4 g/ kg which could be titrated up to 0.8 g/ kg to maintain mean arterial blood pressure (MAP) between 55-65 mmHg and heart above 50 beats per minute.
In group D, patients received intravenous dexmedetomidine. A loading dose of 1 g/ kg in 10mL 0.9% normal saline intravenous infusion for 10 minutes and followed by maintenance dose of 0.4 g/ kg which could be titrated up to 0.8 g/ kg in order to maintain mean arterial blood pressure (MAP) between 55-65 mmHg and heart above 50 beats per minutes.
Anaesthetic management was similar in both groups (induction, maintenance, emergence and post anaesthesia care).
Blood loss and surgical field quality (surgeon satisfaction) was ranked by the surgeon at the end of surgery using the Fromme-Boezaart score. Hemodynamic parameters (heart rate and mean arterial blood pressure) variations at different time interval (baseline, before loading dose, after loading dose, before laryngoscopy and intubation, after intubation, at surgical incision, at 5, 15, 30, 45, 60, 75, 90, 105, 120 minute and at the end of surgery ), duration of surgery, recovery profile (time of recovery from anaesthesia: defined as time from discontinuation of isoflurane and clonidine or dexmedetomidine infusion up to the time patient gain consiousness, time mean arterial blood pressure range in 20% of baseline, and postoperative sedation was assessed by Ramsay Sedation Score),intra-operative and postoperative complications were recorded.
The two groups were comparable in terms of age, sex, weight, BMI, and ASA classification. There were no statistically significant difference regarding blood loss and there were no difference regarding surgical field quality ( surgeon satisfaction). Both drugs provided significantly reduced and stable heart rate and mean arterial blood pressure comparing to baseline. Dexmedetomidine provided statistically significant lower heart rate and mean aterial blood pressure than clonidine. There was no statistically significant difference regarding duration of surgery. Time of recovery from anaesthesia and time mean arterial blood pressure range in 20% of baseline was longer in group D comparing to group C and the difference was statistically significant. Post-operative sedation was prolonged in group D comparing to group C. There was difference regarding occurrence of complications, 2 patients (5%) developed severe bradycardia, and 2 patients (5%) developed severe hypotension in group D while no complication was reported in group C.