Bispectral Index-Guided Versus Fixed Dose Administration of Desflurane During Balanced Anesthesia With Remifentanil

Study Overview
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Brief Summary
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Balanced anesthesia combining volatile anesthetics and opioids is commonly used in modern anesthesia. The purpose of this study is to compare two methods of administering desflurane, an volatile anesthetic during balanced anesthesia. The investigators hypothesized that administering desflurane at 1 MAC (minimum alveolar concentration) during balanced anesthesia will be more beneficial in terms of stability of the patient's vital signs and hypnotic depth than administering desflurane according to the patient's BIS (bispectral index) value.

Official Title
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Bispectral Index-Guided Versus Fixed Dose Administration of Desflurane During Balanced Anesthesia With Remifentanil

Conditions
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Stabilizing Hypnotic Depth and Vital Sign During Balanced Anesthesia

Intervention / Treatment
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* Drug: Administering desflurane according to the patient's BIS value
* Drug: Administering desflurane at 1 MAC


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients scheduled for operation under balanced anesthesia using desflurane and remifentanil Exclusion Criteria: Refusal of consent General anesthesia with agents other than desflurane and remifentanil Patients with allergy to neuromuscular blocker, volatile anesthetics, opioids History of malignant hyperthermia Patients taking CNS stimulants Chronic alcohol abuser Patients with severe depressed left ventricular function, EF < 30% Patients with convulsive disorders ASA class IV, V, VI Patients with systolic arterial blood pressure lower than 90mmHg before surgery Patients needing inotropic infusion during surgery Anesthesia time less than 30 minutes

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Administering desflurane according to the patient's BIS value<br>The anesthesiologist administers the volatile anesthetic desflurane to set the patient's BIS value at 50 during balanced anesthesia, and titrate the remifentanil dose to set the patient's systolic arterial blood pressure between 100-140mmHg. | Drug: Administering desflurane according to the patient's BIS value<br>* Administering desflurane according to the patient's BIS value<br>|
| Experimental: Administering desflurane at 1 MAC<br>The anesthesiologist administers the volatile anesthetic desflurane at 1 MAC during balanced anesthesia, and titrate the remifentanil dose to set the patient's systolic arterial blood pressure between 100-140mmHg. | Drug: Administering desflurane at 1 MAC<br>* Administering desflurane at 1 MAC<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The difference of 'wobble' value of the patients' BIS value between the two groups | 'Wobble' is a variable that can measure the performance measurement of a pharmacokinetic model, or the reaction of the patient to a drug. We can calculate the performance error from the target of the therapy and the actual measured value, and derive the wobble by a specific formulas, which are described below. PE=(BISmeasured-BIStargeted)x100/BIStargeted MDPEi = median{PEij, j=1,…,Ni} MDAPEi = median{|PEij|, j=1,…,Ni} Wobblei = median{|PEij-MDPEi|, j=1,…,Ni} Divergence = slope{|PEij|, j=1,…,Ni} | Every second from 10 minutes after skin incision to 10 minutes before surgery end. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The difference of 'wobble' value of the patients' systolic arterial blood pressure value between the two groups | Described above | Every 2.5 minutes from 10 minutes after skin incision to 10 minutes before surgery end |