Sleeping medication and analgesia are standard administered during anesthesia. Sleeping medication, Propofol (Diprivan, AstraZeneca), and analgesia, Remifentanil (GlaxoSmithKline), are most frequently used In the University Hospital Ghent.

The clinical effect of administration of pharmaca can be measured in the changes of heartbeat, blood pressure, respiration and the changes of brain activity by registering EEG. These measurements are performed standard, to secure the safety of the patient.

The heartbeat and the EEG will be measured by non invasive adhesive electrodes on the skin of the patient.

The blood pressure will be measured by non invasive blood pressure cuff around the arm and the respiration parameters will be measured by non invasive spirometry, which are all standard available on a anesthesia device.

Most of the pharmaca are administered by a fixed dosage schedule based on the patient's weight.

A more individualized administration of this pharmaca could lead to a better anesthesia quality.

Since considerable time, we know that a computer-controlled administration of these products by automatic coupling between the measured effects and the "spuit"pump to administer the product, could lead to a better administration, optimalisation of the administered dose, because the patients individual effect of the administration can be taken in consideration. This device is called the "closed-loop system". The department of Anesthesia has already proofed the utility of the device for automatic administration of Propofol and opiates in small specific patient groups.

Inclusion Criteria:

• Patients undergoing a surgery with general anesthesia
• Between 18 and 65 years of age
• Patient signed an informed consent

Exclusion Criteria:

• Patients that did not signed an informed consent

Patients undergoing a surgery with general anesthesia