Endometriosis and Pain Treatment by Intraoperative Administration of Low-dose Ketamine

Inclusion Criteria:

* Patients undergoing surgery for endometriosis operation requiring general anaesthesia at the Inselspital, Bern University Hospital, University of Bern, Department of gynaecology and obstetrics.
* Age ≥ 18 years
* American Society of Anesthesiologist (ASA) physical status 1-3
* Patients with known or suspected endometriosis
* Written informed consent.

Exclusion Criteria:

* Age \< 18 years
* ASA physical status ≥4
* Higher-grade atrioventricular block without pacemaker
* Severe hypovolemia or bradycardia
* Uncontrolled hyper- or hypotension
* Liver disease
* Known malignant hyperthermia
* Cardiovascular instability or severe heart failure (New York Heart Association classification (NYHA) \> III)
* Myocardial infarction during the last 30 days prior to surgery
* Increased intracranial or increased intraocular pressure
* Limited peripheral autonomic activity, hypersensitivity to ketamine or propofol or its components
* Pregnancy
* Rejection or lack of consent of the patient or relatives