Pain Assessment During General Anesthesia

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.