Good surgical conditions are crucial for an optimal surgery result and safe procedure. Minimal blood loss in the surgical field is one of the most important conditions to maintain a good visualization, especially in surgeries with a small surgical field such as a FESS (functional endoscopic sinus surgery). The perioperative blood loss is determined by the main arterial and venous pressure, the local pressure and the capillary vascular filling pressure.

It has been proposed that propofol is a venodilator, which increases the blood flow, but decreases the capillary pressure. On the contrary, sevoflurane might act mainly on the arterioles, which causes an increase in the capillary pressure. In a previous study it has been demonstrated that despite blood pressure maintenance, propofol causes less bleeding during spinal surgery than sevoflurane.

The main aim of this study was to compare both anaesthetics on the perioperative bleeding and haemodynamics during FESS. Secondary, the postoperative nausea, vomiting, pain scores, surgery duration and length of stay at the post-anesthesia care unit will be evaluated.

2 X 30 patients which are planned for FESS surgery are randomized in a sevoflurane group or propofol group.

All patients will be induced with propofol (target-controlled infusion (TCI) 4 µg/mL) and remifentanil (TCI 4 ng/mL) and receive a multimodal intravenous analgesia.

Patients in the propofol group will receive further intravenous propofol until a bispectral index (BIS) value of 50 is reached.

The intravenous drip of propofol will be stopped after induction in the sevoflurane group and patients will receive sevoflurane as inhalation anaesthetic (1 MAC) until a BIS-value of 50. The surgeon will be blinded for patient allocation.

The surgical conditions will be graded postoperatively by the surgeon who performed the operation using the validated Boezaart grading scale. The endoscopic images will be evaluated in addition by 3 blinded surgeons using this same scale.

Besides the surgical conditions, haemodynamic parameters, nausea and vomiting scores (PONV), Visual Analogue Score (VAS), surgery duration, length of stay at the post-anesthesia care unit and postoperative analgesia and anti-emetics are registered.

Inclusion Criteria:

• patient planned for FESS surgery

Exclusion Criteria:

• patients which receive anticoagulants
• patients which have coagulation disorders
• patients with high bleeding risk
• patients with arterial hypertension
• other decided by surgeon

The surgeon and participant are blinded for randomization. The anesthesiologist is unblinded.