Opioid Free Anesthesia (OFA) - which has been applied mainly in bariatric surgery - has begun to receive more and more attention and to obtain fanatical supporters versus conventional anesthesia. The advantages of this type of anesthesia are mainly achieved by the action and effect of the various drugs that compose it.

Functional Endoscopic Sinus Surgery is performed in cases where sinusitis or its complications are difficult to treat with medication. With special cameras and endoscopes, the narrow anatomical regions of the sinus can be depicted and precisely surgically approached. Usually surgery is conducted under general anesthesia. According to the literature, total intravenous anesthesia should be used for sinus surgery to achieve blood pressure control as well as controlled hypotension to prevent intraoperative bleeding. Most of the studies agree that the best type of anesthesia for this type of surgery is total intravenous anesthesia. When it comes to Opioid Free Anesthesia in FESS, there are not many studies, except of some studies that don't use solely Opioid Free Anesthesia but some of the drugs that consist it.

Patients scheduled for elective Functional Endoscopic Sinus Surgery will be randomised in two groups. One receiving OFA and one receiving TIVA.

Inclusion Criteria:

• Patients 18 - 75 years old
• Elective FESS

Exclusion Criteria:

1. Patients < 18 or >75 years of age
2. Patients who can't read of speak the Greek language
3. Patients with psychiatric disorders
4. Patients with atrioventricular block in ECG
5. Patients with musculoskeletal disorders
6. Patients with coronary artery disease
7. Patients uncapable of giving informed consent