Evaluation of Neurotoxic Effect of Sevoflurane-Based AnaesthesiaGuided by Short-Term Olfactory Identification

Study Overview
=================
Brief Summary
-----------------
Nowadays there is increasing doubts about the safety of anesthesia . Anesthesiologists have to console the worried patients, who are anxious about the potential risks of anesthetic-induced brain damage, by suggesting that any detrimental effects would be mild.Anesthetics are responsible for postoperative taste and odor defects and cognitive dysfunction.

Detailed Description
-----------------
Aims: The aim of this study is to assess the effect of isoflurane, sevoflurane, propofol and regional anesthesia on the olfactory threshold, olfactory identification and endocrine regulation of associative memory in the postoperative period in old age group. Methods: 600 patients (> 60years ) fulfilling the criteria of the American society of anesthesiologists and II status were selected for this prospective single-blinded randomized controlled study. Patients were randomized into one of four groups to receive regional anesthesia (control group), general anesthesia with sevoflurane, general anesthesia with isoflurane and total intravenous anesthesia with propofol. Mini-Mental State Examination (MMSE), olfactory threshold, and olfactory identification were tested at 12 hours preoperatively (T0), at 3 hours postoperatively (T1) and at the time of discharge or postoperative 3 days (T2). In addition, serum melatonin levels were estimated at T0 and T1. N-butyl alcohol was used to test the olfactory threshold and the Pocket Smell Test TM series (PSTs) was used to test olfactory identification. Data were analyzed using the one-way analysis of variance, Kruskal-Wallis or Mann-Whitney tests.

Official Title
-----------------
Evaluation of Neurotoxic Effect of Sevoflurane-Based Anaesthesia Guided by Significant Short-Term Olfactory Identification Impairment in Old Age

Conditions
-----------------
Neurotoxic Effect of Sevoflurane-Based Anaesthesia

Intervention / Treatment
-----------------
* Drug: Sevoflurane


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: American Society of Anaesthesiologists I and II physical status aged from 60 to 75years scheduled for elective surgery with the anticipated duration of 100-120 min. surgical procedures included hernia repair, varicose vein surgery, incisional hernia repair, minor gynecological procedures, lower limb orthopedic procedures, minor urological procedures Exclusion Criteria: Patients with recent airway infection, allergic rhinitis, nasal polyps, history of alcoholism, smoking, mental retardation, psychiatric illness, neurosurgical or oto-rhino-laryngeal surgery patients with a history of olfactory deficits and cognitive impairment

Ages Eligible for Study
-----------------
Minimum Age: 60 Years
Maximum Age: 75 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| control group<br>regional anesthesia | |
| general anesthesia(S)<br>general anesthesia with sevoflurane | Drug: Sevoflurane<br>* Assess the effect of isoflurane, sevoflurane, propofol and regional anesthesia on the olfactory threshold, olfactory identification and endocrine regulation of associative memory in the postoperative period in old age group.<br>* Other names: Propofol;|
| general anesthesia(I)<br>general anesthesia with isoflurane | |
| total intravenous anesthesia<br>total intravenous anesthesia with propofol. | |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The changes in Mini-Mental State Examination (MMSE) | Cognitive function evaluated by MMSE scores. The Mini-Mental State Examination (MMSE) or Folstein test is a 30-point questionnaire that is used extensively in clinical and research settings to measure cognitive impairment. It is commonly used in medicine and allied health to screen for dementia. | basically at 12 hours preoperatively (T0), then 3 hours postoperatively (T1) and at the time of discharge or postoperative 3 days (T2) | 
| The changes in olfactory threshold | Was measured using serial dilutions (10 dilutions) of 4% n-butyl alcohol in deionized water. The test consists of 10 steps. In each step, the odorant and a blank were presented to the participant. The test progressed from weaker-to-stronger concentrations of odorant. Two bottles were presented to each participant, an odorant bottle and an identical bottle filled with distilled water. The participant sniffed each one for approximately 9 s and then chose which one smelled stronger. If the participant was incorrect at one concentration, the next higher concentration was presented. When the correct choice was made, the same concentration of odorant was presented to the participant until four consecutive correct responses were given. The threshold was defined as the butyl alcohol concentration correctly chosen over water in four consecutive trials, and the corresponding number of the concentration was taken as the threshold value. | basically at 12 hours preoperatively (T0), then 3 hours postoperatively (T1) and at the time of discharge or postoperative 3 days (T2) | 
| The changes in olfactory identification | Was assessed using the Pocket Smell TestTM series (PSTs). The test uses four booklets containing labels impregnated with odorous substances. The test is in multiple-choice format, with four written response alternatives for each odor. The odors are released when the labels are scratched. The examiner scraped each target patch and instructed participants to smell the patch and then select the name of the released odor from among four alternatives. Olfactory identification tested using the (PSTs) assessed both the recent memory and the remote memory of the patient as it contained odors which were a mixture of both the familiar and unfamiliar ones to the study population. Here, it is not utilized to identify patients with anosmia or hyposmia. Instead, the (PSTs) is used as a linear, unbiased unidimensional Rasch measure of human smell recognition abilities. | basically at 12 hours preoperatively (T0), then 3 hours postoperatively (T1) and at the time of discharge or postoperative3 days (T2) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The changes in olfactory melatonin levels | Melatonin levels were measured in plasma by the enzyme-linked immunosorbent assay (ELISA) (IBL, Hamburg, Germany). | serum melatonin levels were estimated basically at 12 hours preoperatively (T0), then 3 hours postoperatively (T1) and at the time of discharge or postoperative3 days (T2) | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
General anesthesia., neurotoxicity,, olfaction,, olfactory identification., sevoflurane.