Effects of Intravenous Anesthesia and Balanced Anesthesia on Flash Visual Evoked Potentials

Study Overview
=================
Brief Summary
-----------------
Intraoperative flash visual evoked potentials (FVEPs) could monitor visual function during neurosurgery. There are fewer reports comparing the effects of sevoflurane-propofol balanced anesthesia and propofol-based total intravenous anesthesia under comparable bispectral index (BIS) levels on the amplitude and latency of flash visual evoked potentials (FVEPs) for sellar or parasellar tumors resection neurosurgeries.

Detailed Description
-----------------
The overall incidence rate of sellar tumors is 10-20% of brain tumors. Most of the initial symptoms of this tumor are visual or visual impairment. One of the primary complications of these operations is visual impairment, which directly relates to the quality of patients' life. Flash visual evoked potentials (FVEPs) is an important means of intraoperative visual function evaluation under general anesthesia. Intraoperative visual function damage can be avoided or reduced by observing the changing of FVEPs waves to guide the choice of surgical path. However, since the diversity of anesthetic drugs and methods, there is still a great uncertainty impact on FVEPs, which will interfere with the interpretation and judgment of surgeons and neuroelectrophysiological physicians respect to the changes of FVEPs amplitude and latency, and further affect the operation decision-making. Therefore, it is urgent to establish a perfect anesthesia method for intraoperative monitoring of FVEPs. Although total intravenous anesthesia has been widely accepted for FVEPs monitoring, there are still some limitations, such as the possibility of intraoperative body movement and cough due to the restriction of muscle relaxant use under electrophysiological monitoring, as well as the depression on FVEPs of high maintained dosage under total intravenous anesthesia. The purpose of this study was to investigate the feasibility of FVEPs monitoring during endoscopic sellar tumor resection under combined intravenous anesthesia compared with total intravenous anesthesia.

Official Title
-----------------
Comparison of the Effects of Total Intravenous Anesthesia and Balanced General Anesthesia on Flash Visual Evoked Potential Monitoring During Sellar Tumors Resection

Conditions
-----------------
Brain Tumor Adult

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


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Age 18-65 years; ASA I-III; Elective sellar or parasellar tumors resection; Informed written consent Exclusion Criteria: Preoperative visual acuity<0.3; BMI>30kg/cm2; Uncontrolled hypertension, diabetes or cardiac diseases; Preoperative cognitive disorders; Sedatives, alcohol or analgesic addiction history; Allergy to drugs of this study or contact allergy to Silicone products

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 65 Years

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

Accepts Healthy Volunteers
-----------------
No

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

Design Details

Primary Purpose: Diagnostic
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: sevoflurane-propofol balanced anesthesia<br> | Drug: Sevoflurane<br>* Balanced general anesthesia with sevoflurane will be administered for anesthesia maintenance in patients randomized to the balanced general anesthesia arm of the study. In order to record the VEPs, standard spiral electrodes or subcutaneous electrodes will be inserted subcutaneously around the visual area and the Nicolet Viking IV System will be used to monitor VEP during surgery.<br>|
| Active Comparator: propofol-based total intravenous anesthesia<br> | Drug: Propofol<br>* Propofol will be administered for anesthesia maintenance in patients randomized to the propofol-based TIVA arm of the study. In order to record the VEPs, standard spiral electrodes or subcutaneous electrodes will be inserted subcutaneously around the visual area and the Nicolet Viking IV System will be used to monitor VEP during surgery.<br>|

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

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| N2 amplitudes of FVEPs | N145-P100 of FVEPs wave | 90min after anesthesia induction | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| P100 latencies of FVEPs | P100 latencies of FVEPs wave | 30, 60 and 90min after anesthesia induction | 
| The visual acuity | The visual acuity before and after operation. | The day before surgery, and one day after operation. | 
| The visual field | The field of patients before and after operation. | The day before surgery, and one day after operation. | 
| N2 amplitudes of FVEPs | N145-P100 of FVEPs wave | 30 and 60 after anesthesia induction |