The relationship between the target effect site concentration of remifentanil and the pupil diameter and reactivity in response to a standard noxious stimulus in cardiac surgery during extra corporeal circulation will be evaluated.

Anaesthesia will be induced with propofol to obtain loss of consciousness LOC in 30 patients who will undergo cardiac surgery requiring extracorporeal circulation and standardized support will be given to them till the extracorporeal circulation period. Thereafter, remifentanil will be titrated by increments of 0,5, from 1 up to 5 ng ml-1 during the extra corporeal circulation period. In the awake state, at LOC and at each plateau level of remifentanil CeT, mean arterial pressure, and BIS will be recorded. Pupil size and dilatation after a 60 mA, 100 Hz tetanic stimulation will be measured at LOC and at each plateau level of remifentanil.

Inclusion Criteria:

• general anesthesia for cardiac surgery programmed requiring the realization of a sternotomy and the use of extra corporeal circulation
• age> 18 years

Exclusion Criteria:

• contraindication to the use of the products defined in the protocol of anesthesia (alprazolam, remifentanil, propofol, atracurium)
• sedation in progress with use of morphinomimetics
• urgent surgery
• preoperative existence of circulatory assistance
• preoperative existence of an intra-aortic balloon pump,
• bilateral ocular pathology (severe cataract, amblyopia, glaucoma, keratitis, conjunctivitis) and / or history of bilateral ocular surgery affecting the iris
• history of epilepsy, cerebral palsy
• peripheral neuromuscular diseases
• pathology with dysautonomia impairing the pupillary dilation reflex: insulin-dependent type 1 or type 2 diabetes with diabetic retinopathy, multiple sclerosis, systemic amyloidosis, uncontrolled hypertension, advanced Parkinson's disease
• ongoing treatment interfering with the autonomic and central nervous system likely to alter the pupillary dilation reflex: antiemetic (droperidol, metoclopramide), alpha-2 agonist (clonidine, dexmedetomidine), high doses of nitrous oxide
• treatment with severe anticholinergic effect: such as amitriptyline, amoxapine, atropine, benztropine, chlorpheniramine, chlorpromazine, clemastine, clomipramine, clozapine, darifenacin, desipramine, dicyclomine, diphenhydramine, doxepin, flavoxate, hydroxyzine, hyoscyamine, imipramine, meclizine, nortriptyline, orphenadrine, oxybutynin, paroxetine, perphenazine, procyclidine, promazine, promethazine, propentheline, pyrilamine, scopolamine, thioridazine, tolterodine, trifluoperazine, trihexyphenidyl, trimipramine
• pregnant or lactating women
• Patient having objected to the processing of his data

Patients consulting for a general anesthesia for cardiac surgery programmed requiring the realization of a sternotomy and the use of extra corporeal circulation