Evaluation of the Analgesia Nociception Index With Varying Remifentanil Concentrations Under Sevoflurane

Study Overview
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Brief Summary
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Analgesia Nociception Index（ANI）which is derived from heart rate variability can be used to detect noxious stimulation during propofol while changing remifentanil concentrations. The aim of this study is to verify the effectiveness of ANI predictability for actual surgical noxious stimuli while satisfying the individual analgesic status by pre-tetanus-induced ANI determination during sevoflurane while changing remifentanil concentrations.

Detailed Description
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General anesthesia with sevoflurane and remifentanil is widely used in minor surgeries. Monitoring noxious stimulation during general anesthesia is still worth further studies and reaching clinical consensus. Analgesia Nociception Index can be used to detect noxious stimulation during propofol while changing remifentanil concentrations. Previous studies suggest that an ANI≥50 can be useful in detecting sufficient analgesia for patients who cannot self-report pain. The aim of this study is to verify the effectiveness of ANI predictability for actual surgical noxious stimuli while satisfying the individual analgesic status by pre-tetanus-induced ANI determination during sevoflurane while changing remifentanil concentrations.

Official Title
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Evaluation of the Analgesia Nociception Index With Varying Remifentanil Concentrations Under Sevoflurane

Conditions
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General Anesthesia

Intervention / Treatment
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* Device: Tetanic stimulation
* Procedure: Skin incision


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age between 18- 65 years ASA physical status I or II Elective surgery in general anesthesia planned Written informed consent Exclusion Criteria: Use of CNS-active medication or abuse of alcohol Presents of any neuromuscular or neurologic disease History of cardiac arrhythmia Pregnancy or using a pacemaker

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 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: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Sevoflurane with different site effect concentrations of remifentanil<br>The tetanic stimulus is conducted between laryngeal mask intubation and surgical stimulation, while no other noxious stimuli are presented. The effect site concentration of remifentanil is increased step-by-step via a Target Controlled infusion device to a concentration of 2, 4, 6 ng/ml. At least 5min of the steady-state period is maintained before tetanic stimulus. | Device: Tetanic stimulation<br>* For each participant, record the first concentration that ANI≥50 after the tetanic stimuli, as the sufficient concentration.<br>Procedure: Skin incision<br>* Infuse the sufficient concentration for at least 5min of the steady-state period, then surgical stimulus is applied. The surgical stimulus is defined as the first skin incision to establish pneumoperitoneum.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To verify the effectiveness of ANI predictability for actual surgical noxious stimuli while satisfying the individual analgesic status by pre-tetanus-induced ANI determination. | Tetanic stimulations are applied at different effect site concentrations of remifentanil under sevoflurane anesthesia. ANI is range from 0-100. Bigger number means better analgesic level. ANI≥50 is considered to be under adequate analgesia. Tetanic stimulation is a standard tester of nociceptive stimulus. The number of ANI will fall down if the patient is feeling pain. | Change from Baseline ANI that 2 minutes after applied tetanic stilumation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The ANI predictability for tetanic noxious stimuli | ANI is range from 0-100. Bigger number means better analgesic level. ANI≥50 is considered to be under adequate analgesia. The number of ANI will fall down if the patient is feeling pain. | Change from Baseline Systolic Blood Pressure that 2 minutes after applied tetanic stilumation | 
| The heart rate predictability for tetanic noxious stimuli | Heart Rate will go up if patient is feeling pain. | Change from Baseline Heart Rate that 2 minutes after applied tetanic stilumation | 
| The Bispectral Index predictability for tetanic noxious stimuli | Bispectral Index will go up if patient is feeling pain. | Change from Baseline Bispectral Index that 2 minutes after applied tetanic stilumation |