Depth of Hypnosis and Postoperative Nausea and Vomiting During Xenon Anaesthesia
Condition: Anaesthetics Gases, Xenon; Anaesthetics Volatile, Sevoflurane; Depth of Anaesthesia; Postoperative Nausea; Postoperative Vomiting
MeSH terms: Nausea; Vomiting; Postoperative Nausea and Vomiting
Study type: Interventional
Phase: Phase 4

Summary: 
      The purpose of this study is ad 1) to measure the depth of hypnosis as assessed by BIS and
      cAAI during an average general anesthesia with xenon or sevoflurane and to establish a
      reliable monitoring system for measuring and documenting the actual depth of hypnosis for the
      volatile anesthetics investigated. Ad 2) the question is to be answered whether 4 mg
      dexamethasone i.v. is an effective prophylactic treatment against postoperative nausea and
      vomiting in case of xenon or sevoflurane anesthesia. Ad 3) it serves to gain evidence about
      the (non-)effectiveness and kinetics of ondansetron as antiemetic remedy after xenon or
      sevoflurane anesthesia.
    

Detailed description: 
      1. Patients included into the trial will randomly be allocated to either 0.8-1.1 minimum
           alveolar concentration (MAC) xenon in 30 % oxygen or 0.8-1.1 MAC sevoflurane (age
           adapted)/30 % oxygen. The MAC is defined and will therefore be applied according to the
           investigated subject's age. Premedication will be performed with midazolam 7.5 mg orally
           45 min before induction (standard dose and application form for adults as clinical
           practice of our department). Anesthesia will be induced in both groups with propofol 2
           mg/kg i.v. and remifentanil 0.5 mcg/kg/min by infusion over 60 s. For tracheal
           intubation non-depolarizing neuromuscular blocking agents can be used (rocuronium 0.6
           mg/kg). Both groups will receive remifentanil at a base rate of 0.2 mcg/kg/min. Xenon or
           sevoflurane can be titrated in the range from 0.8-1.1 MAC according to clinical needs
           based on the patient's hemodynamic, autonomic and somatic signs. Twenty minutes before
           the estimated cessation of all surgical procedures 0.05 mg kg-1 piritramide for post
           anesthetic pain management will be administered intravenously, as well as a short
           infusion of metamizole 15 mg kg-1.

           Depth of anesthesia (hypnosis) will be monitored with spontaneous EEG (BIS VISTA, Aspect
           Medical Systems, Newton, MA) and the mid latency auditory evoked potentials including a
           monitoring variable indicating the patients hypnotic state calculated from the MLAEP and
           the electroencephalogram, the composite A-Line ARX Index (cAAI) with the AEP Monitor/2
           (Danmeter A/S, Odense, Denmark). Dosing will be conducted according to the current
           clinical standard without the monitoring, thus the anesthesia provider will be blinded
           towards both measurements.

        2. After induction of anesthesia patients will be randomized to a second factor, i.e. 4 mg
           dexamethasone or placebo for the prevention of PONV. To avoid potential imbalances, this
           will be achieved using a factorial design. The application of dexamethasone or placebo
           will be blinded to the investigator assessing postoperative nausea and vomiting.

        3. Patients who experience significant nausea will be randomized to receive either 4 mg
           ondansetron or placebo and the course of nausea will be assessed for > 32 min. Again,
           the application of ondansetron or placebo will be blinded to the investigator assessing
           postoperative nausea and vomiting. If the symptoms of postoperative nausea and vomiting
           persist for more than 32 min after treatment additional rescue treatment will be
           offered. Of note, all patients are able to receive further rescue treatment at any time
           point of the study on demand.
    

Intervention name(s): Xenon; Sevoflurane; Dexamethasone; NaCl; Ondansetron; NaCl
Intervention type(s): Drug; Drug; Drug; Drug; Drug; Drug
Intervention description(s): Inhalational gas; maximum dose allowed: 70 % Xenon; the duration of the treatment will be defined through anesthesia-time.; Inhalation gas; age adapted MAC-values; the duration of the treatment will be defined through anesthesia-time; Intravenous use, 4 mg, single shot; Intravenous use; single shot; Intravenous use; 4 mg; single shot; Intravenous use; single shot
Other intervention name(s): LENOXe; Sevorane; Fortecortin Inject; Zofran
Intervention MeSH terms: Dexamethasone; Dexamethasone acetate; Ondansetron; Sevoflurane
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Treatment
Keywords: Xenon; Sevoflurane; Postoperative Nausea and vomiting; Depth of anaesthesia