Autonomous Nervous System Regulated Anaesthesia: A Randomized Controlled Trial Comparing Dexmedetomidine and Placebo in Heart Rate Variability Monitored Children

Study protocol

Screening of eligible patients before procedure day All children assigned for evaluation for abdominal or urology procedures are primarily seen by surgeons in an ambulatory visit. This takes place in the months or weeks before surgery. If surgery for abdominal or urology issues is decided, the paediatric surgeons hand out a patient s folder about the present study. The patient information folder is seen in supplement 1. Line Gry Larsen (LGL) will attend the surgeon's ambulatory visits in the start-up phase, assisting the paediatric surgeons in what information to give by handing out patient information folders. It is not the intent that the paediatric surgeons should give the full information. If the parents/legal representative(s) consent to further contact, they sign a brief consent form for primary contact, including the preferred phone number and time frame, see supplement 2 The parents are then contacted by phone by one of the researchers within the assigned time frame, and the study is now introduced in full, in line with the information given in the patient information folder. There will be time for questions and careful consideration about participation. The researchers who provide the information to the families are all experienced within the field of anaesthesia, research, and Good Clinical Practice (GCP)-guidelines. If the parents show immediate interest in participating, the importance of bringing a signed power of attorney if one of the parents/legal representatives is not attending on the procedure day is emphasized.

Progress on procedure day

Information, consent, and randomization On the procedure day, one of the researchers again consults with the child and its parents/legal representatives in a private meeting room. They are offered the possibility to bring a bystander or be provided one. A summary of information about the study previously given by phone is done, including the right to withdraw consent. Questions are again encouraged. If the parents/legal representatives after receiving oral and written information agree on participation, consent forms are now signed and randomization is done to either placebo or intervention group, blinded for the participant, researcher, and other staff. The procedure is then performed that same day. Contact information is stored in the REDCap database for follow-up data, and to provide the family conclusions of the study after finalization.

Anaesthesia One or both parents or legal representatives follow the child to the operating theatre. Induction of anaesthesia is set as time = 0 and the first RASS score is registered. The child is then anaesthetized via inhalation of sevoflurane 8% on a mask while she or he is sitting with one of the parents. As soon as the child is asleep, the parents are shown to a waiting area. I.v access is obtained, and fentanyl 2-4 mcg i.v is given, and adjusted to fit the planned procedure. Airway management is typically done with a laryngeal mask aiming to keep the child spontaneous breathing throughout the procedure. Standard monitoring is applied: ECG, blood pressure cuff measuring, and fingertip oxygen saturation. Furthermore, all children are ANI monitored. A continuous infusion of remifentanil 0,5 mcg/kg/hour is started immediately and withheld for the entire procedure. Sevoflurane concentrations, airway pressure, and end-tidal carbon dioxide tensions, are noted. When all monitoring equipment is applied, a bolus infusion of the study drug (dexmedetomidine 0,5 mcg/kg or placebo) is given within the first 10 minutes. With ANI values < 50, a bolus of fentanyl of 1 mcg/kg or remifentanil 0,1 mcg/kg is given. Which drug is given, is assessed, and decided by the anaesthetist. The effect of this intervention is evaluated every five minutes and repeated if ANI is still < 50. Sevoflurane concentration is adjusted, guided by a clinical evaluation in a usual manner, guided by Minimum Alveolar Concentration (MAC) values 0,7-1,4. In the case of bradycardia or other arrhythmias, bolus dexmedetomidine (DEX) is immediately discontinued, and remifentanil (REMI) is withheld until baseline heart frequency is achieved. If longer-lasting bradycardia exists, iv. Atropine/kg bodyweight is given. To connect specific events to ANI values, the following are registered via the monitor: "infusions", "airway in", "incision", "bolus remifentanil", "bolus fentanyl", "neuraxial", "local anaesthesia", "bolus sevoflurane", "suture"," intense surgical stimuli"," bradycardia", "other [note in anaesthesia chart]", and "airway out".