The MIRUS system (TIM, Andernach, Germany) as well as the AnaConDa uses a reflector to conserve volatile anaesthetics (VA). Both systems can be paired with ICU ventilators, but MIRUS features an automated control of end-tidal VA concentrations (etVA). We compare depth of 0.5 MAC inhalational long-term sedation with Isoflurane (ISO), Sevoflurane (SEVO) or Desflurane (DES).

The study was approved by the appropriate Institutional Review Board. Thirty ASA II-IV patients, undergoing elective or emergency surgery under general anaesthesia were included and randomized into three equal groups: ISO, SEVO or DES. We used MIRUS, a gas delivery system with a VA reflector, just like AnaConDa, that can be paired with common ICU ventilators. Additionally, MIRUS features the unique ability to maintain the end-tidal concentration (etVA) in target by automatically adjusting the delivery rate. Every 8 hours, the RASS was assessed by the nurse. The log of the EEG-Narcotrend Index (NI) was also included in the study.

Inclusion Criteria:

• Signing of the informed consent document (patient or relatives).
• Patient age 18 years or older.
• ASA I-III

Exclusion Criteria:

• ASA IV patients
• Epidural or spinal analgesia
• Allergy or known hypersensitivity to any of the study drugs
• Patients with known or suspected genetic susceptibility to malignant hyperthermia
• Previous participation in this trial
• Participation in another clinical trial within 4 weeks prior to selection.
• Pregnant women