Pain Assessment During General Anesthesia

Study Overview
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Brief Summary
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During general anesthesia, two treatments are used : hypnotic and opioid treatment. Opioid treatment is used for pain assessment. The change in haemodynamic variables and clinical sign are evaluated during anesthesia for pain assessment but these changes are not specific every time. The main of this study is to investigate the relationship between calculated compartment concentration of remifentanil (opioid) and the parameters from HRV (Heart Rate Variability) and APV (Arterial Pressure Variability) before a standard noxious stimulation during general anesthesia at calibrated hypnosis level. Our hypothesis is that nociceptive stimulation would have reproductible effects on HRV, and that these effects would be blunted or abolished by by adequate analgesia. The current study is thus designed to analyse HRV and APV in patients with stable hypnosis, before and during nociceptive surgical stimulation, at different levels of analgesia.

Official Title
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Pain Assessment During General Anesthesia : DOLANS (DOULeur ANeSthesie) Study

Conditions
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Pain

Intervention / Treatment
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* Drug: opioid (remifentanyl)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult patients under 55 years-old ASA status 1 or 2 scheduled to undergo general anesthesia for different types of surgery (neurosurgical or medullar surgery, ear, nose or throat surgery or orthopedic surgery) Exclusion Criteria: history of cardiac or autonomic disease diabetes obesity (BMI>30 kg/m2) medication altering autonomic nervous system tone history of eyes surgery

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 55 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: Health Services Research
Allocation: Randomized
Intervention Model: Single Group Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: opioïd<br>Different levels of remifentanyl of each group during nociceptive stimulation | Drug: opioid (remifentanyl)<br>* Infusion of remifentanyl (opioid) will be started at different levels for each group of the randomized study : 0 ng/ml (group 0), 1 ng/ml (group 1), 3 ng/ml (group 3) or 4 ng/ml (group 4)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in HRV measurements during noxious stimulation | Analyse of HRV is a widely used, non-invasive technique to assess autonomic nervous system (ANS) activity. The typical spectral pattern of HRV includes two main spectral peaks : a low-freqency (LF) region, affected by both sympathetic and parasympathic activity, and a high-frequency (HF) peak centered at the respiratory frequency, which is associated with parasympathetic activity. | baseline and 5 minutes | 
| change from baseline in APV measurements during noxious stimulation | Analyse of APV is a widely used, non-invasive technique to assess autonomic nervous system (ANS) activity. The typical spectral pattern of APV includes two main spectral peaks : a low-freqency (LF) region, affected by both sympathetic and parasympathic activity, and a high-frequency (HF) peak centered at the arterial pressure, which is associated with parasympathetic activity. | baseline and 5 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in pupil change during noxious stimulation | pupil size will be monitored and recored using an infrared pupilometry system consisting of a camera, infrared lignt source, video monitor and video processing software, capturing pupil diameter as a real-time analogue signal (rate of 25 Hz). The pupil size variability will be used to estimate pain | baseline and 5 minutes | 
| change from baseline in heart rate during noxious stimulation | heart rate will be recorded before induction of anesthesia, just before nociceptive stimulation, then every 30 seconds up to the end of the five minutes after nociceptive stimulation. The heart rate measurement will be used to estimate pain. | baseline and 5 minutes | 
| Change from baseline in BIS (Bispectral Index) during noxious stimulation | bispectral index will be recorded before induction of anesthesia, just before nociceptive stimulation, then every 30 seconds up to the end of the five minutes after nociceptive stimulation. BIS will be used to estimate pain | baseline and 5 minutes | 
| change from baseline in systolic blood pressure during noxious baseline | Systolic blood pressure will be recorded before induction of anesthesia, just before nociceptive stimulation, then every 30 seconds up to the end of the five minutes after nociceptive stimulation. Systolic blood pressure measurement will be used to estimate pain | baseline and 5 minutes | 
| Change from baseline in diastolic blood pressure during noxious stimulation | diastolic blood pressure will be recorded before induction of anesthesia, just before nociceptive stimulation, then every 30 seconds up to the end of the five minutes after nociceptive stimulation. diastolic blood pressure will be used to estimate pain | basline and 5 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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pain assessment, anesthesia, analgesia, opioid, HRV, APV, autonomic nervous system (ANS), pupil size