AIM OF THE WORK The aim of this work was to compare the effect of hypotensive anaesthesia using Nitroglycerine versus phentolamine on Event related potentials, quantitative Electroencephalograghy and cognitive function, in patients undergoing septoplasty.

METHODS:

Study design and population: This is a pilot prospective randomized clinical trial that will be carried out on 60 patients candidate for septoplasty subjected to general hypotensive anaesthesia. The patients will be recruited from Ear, nose and throat surgery department, Beni-Suef University Hospital. All the participants will be required to offer a written informed consent

Sampling Technique:

Patients will be randomly assigned into one of two equal groups; the first group will receive nitroglycerine (30 participants) (nitroglycerine group) and the second group will receive phentolamine (30 participants) (phentolamine group). Randomization will be carried out using a closed opaque envelope technique with the anesthetist will pick up a sealed envelope which contains a paper with the name of the group to which the patient will be randomized is written. Whichever the group written on the paper, the patient will be scheduled to it.

All included patients will be subjected to the following:

1) Cognitive assessment:

Cognitive functions for the patients will be assessed (preoperative and 1 week postoperative) using the following psychometric tests:

1. Paired Associate Learning test (PALT) Aim: to assess auditory verbal memory. The test uses the concept of semantic cueing

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2. Benton Visual Retention test (BVRT) Aim: to assess visual perceptual, visual memory, visual motor and visuoconstructive abilities.

2) Neurophysiological assessment: Digital Electroencephalograghy (EEG), quantitative Electroencephalograghy (QEEG) and Event related potentials (ERPs) and will be done for all included patients (preoperative and 1 week postoperative).

Statistical analysis The sample size will be calculated using G*Power version 3.1.9.2 Software based on this pilot study. The probability of type I error (α) will be 5%, and the statistical power (1-β) should exceed 80%. The data will be coded and entered using: the statistical package for social science version 15 (SPSS v 15). Descriptive statistics will be reported as mean ± SD and number (%) for categorical variables. Student t- test will be used for comparison between means of two unpaired groups of quantitative variables. Paired sample t- test will be used for comparison between means of two paired groups of quantitative variables. Chi square test will be used for comparison between two groups of categorical data. Mixed ANOVA test will be used for comparing paired data in two unpaired groups. The probability/significance value (P value) ≥ 0.05 is not statistically significant and <0.05 is statistically significant.

Inclusion Criteria:

• Patients who are candidate for septoplasty
• Patients from both sexes, aged between 20-50 years

Exclusion Criteria:

• Patients who develop intraoperative shock or major bleeding
• Patients with ischemic heart diseases, heart block, congestive heart failure, valvular heart diseases, or uncontrolled hypertension
• Patients with a history of central neurological system disorder
• Patients with concomitant medical or metabolic illness known to affect cognition
• Pregnant females
• Allergy to any of the anaesthetic or hypotensive drugs used in the study