NoL and BIS Monitoring on Patients Recovery and Safety After Surgery

So far, only vital signs (mostly, blood pressure and heart rate) helped the anesthesiologist to administer hypnotic agents or analgesics. Many devices have offered pain monitoring for anesthetized patients, the most recent being the PMD200 device and its NoL index. The BIS index is widely used for depth of anesthesia monitoring. The hypothesis of this study is that the intraoperative combination of both the NoL and the BIS indices to guide the delivery of opioids and hypotonics respectively, will improve the quality of recovery as well as the safety after anesthesia in ERAS patients undergoing colonic surgery.

Hypothesis is that the intraoperative use of the combination of 1) the NoL index (given by the PMD200TM monitor, Medasense LTD inc, Ramat, Israel) to monitor pain levels and to guide opioids' administration during surgery, and 2) the BIS index (Medtronic, St-Laurent, QC, Canada) to monitor the depth of hypnosis during anesthesia and to guide the administration of anesthetic halogenous gases, will improve the quality of recovery as well as the safety after anesthesia in ERAS (Early Rehabilitation After Surgery) patients undergoing colonic surgery under general anesthesia + epidural analgesia.

This study will compare a group of patients monitored by the classical monitoring (with anesthesia/analgesia guided by these classical parameters: heart rate, blood pressure; Control "C" group; no BIS, no NoL) to a group of patients monitored by the same classical monitoring implemented with the NoL/BIS indices (with analgesia/anesthesia guided by these 2 indices; Monitoring "M" group).

The primary objective of the study will be the total consumption of desflurane that is expected to be significantly reduced in the M group. Secondary objectives will be evaluating safety and side effects of anesthesia and opioids and we expect a reduction of the following parameters: time for awakening from anesthesia, time for extubation, time for transfer to PACU, intraoperative opioid consumption, opioid consumption in PACU and for 48h, time for readiness for discharge from PACU, incidence of adverse effects such as: nausea-vomiting / sedation / respiratory depression / itching / dizziness / cognitive dysfunction in PACU and for 48h, satisfaction of the patients at 24 and 48hs, pain scores at rest and at mobilization in PACU, at 24h and 48h. Quality of postoperative recovery after surgery and treatment satisfaction are also expected to be higher in the M group than in the C group.

Eligibility Criteria:
Inclusion Criteria:

* ASA status I, II or III
* Patients aged 18 years
* Colo-rectal surgery
* Duration and type of surgery requiring an epidural analgesia via an epidural catheter placed prior the general anesthesia induction and an arterial line placed after induction of general anesthesia (classical management of ERAS program patients in our center)

Exclusion Criteria:

* chronic arhythmic condition
* chronic pain
* Adverse events prompting termination of protocol:
* Unexpected difficult airway requesting excessive, possibly painful airway manipulations.
* Unexpected surgical complications requiring strong haemodynamic support (transfusions, volume challenges, vasopressors, inotropic drugs)