Comparison of Intensive and Conservative NOL®-Guided Analgesia Strategies During Opioid-free Anesthesia (OFANOL)

November 3, 2026 updated by: Prof Urs Zingg

Comparison of Intensive and Conservative NOL®-Guided Analgesia Strategies During Opioid-free Anesthesia for Bariatric Surgery: A Prospective Randomized Controlled Trial

Participants will be randomized to one of two predefined NOL®-guided analgesia strategies during bariatric surgery performed under OFA. In both groups the NOL® index will be continuously monitored intraoperatively and dexmedetomidine will be administered according to the assigned study algorithm based on the NOL® index using lean body weight (LBW) for dosing.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

The study aims to evaluate whether different intraoperative target ranges of the NOL® index during bariatric surgery performed under OFA are associated with differences in postoperative analgesic consumption and postoperative pain control without significant differences in intraoperative hemodynamics. Based on the physiological mechanisms outlined above, we hypothesize that during OFA with alpha-2 agonists such as dexmedetomidine, intensified NOL® target ranges (potentially 0-10) may be appropriate compared to the established range of 10-25 for opioid based TIVA. If this hypothesis is confirmed, clinical implications would include the need to establish OFA-specific NOL® target ranges to avoid under-treatment of nociception when applying TIVA-derived thresholds to OFA patients. Conversely, using inappropriately high NOL® targets derived from opioid-based anesthesia might lead to inadequate pain control and to excessive administration of analgesics postoperatively.

Study Type

Interventional

Enrollment (Estimated)

400

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Signed informed consent
  • Age ≥ 18 years
  • bariatric surgery (sleeve/bypass/Re-Do)

Exclusion Criteria:

  • Patients with contraindications for dexmedetomidine or lidocaine
  • Lack of ability to follow the study procedure, e.g. due to severe language barriers, mental disorders, dementia - Patients requiring preoperative or postoperative treatment in the intensive care unit (ICU) (excluding Obstructive sleep apnea syndrome (OSAS))
  • Patients with conditions precluding the use of the NOL® sensor, such as neuromuscular deficits affecting hand function
  • BMI <25 kg/m2

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Intensive NOL®-guided strategy

Induction: An initial dexmedetomidine bolus of 0.3ug/kg LBW will be administered, followed by a continuous infusion of 0.3 ug/kg LBW/h.
Procedure: Study Intervention

Induction: An initial dexmedetomidine bolus of 0.3ug/kg LBW will be administered, followed by a continuous infusion of 0.3 ug/kg LBW/h.
Experimental: Conservative NOL®-guided strategy

Induction: An initial dexmedetomidine bolus of 0.3ug/kg LBW will be administered, followed by a continuous infusion of 0.1 ug/kg LBW/h.
Procedure: Control Intervention

Induction: An initial dexmedetomidine bolus of 0.3ug/kg LBW will be administered, followed by a continuous infusion of 0.1 ug/kg LBW/h.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Postoperative pain intensity Measured by the numeric rating scale (NRS) in the Post-anesthesia care unit (PACU)
Time Frame: At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

To evaluate whether an intensive NOL®-guided analgesia strategy reduces postoperative pain intensity in the post-anesthesia care unit (PACU) compared to a conservative NOL®-guided analgesia strategy in patients undergoing bariatric surgery under OFA.
At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days
Postoperative pain intensity Measured by the Behavioral Pain Scale (BPS) in the Post-anesthesia care unit (PACU)
Time Frame: At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

To evaluate whether an intensive NOL®-guided analgesia strategy reduces postoperative pain intensity in the post-anesthesia care unit (PACU) compared to a conservative NOL®-guided analgesia strategy in patients undergoing bariatric surgery under OFA.
At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Difference between postoperative pain intensity measurement using the Behavioral Pain Scale (BPS) (outcome 1) and numeric rating scale (NRS) (outcome 2) in the Post-anesthesia care unit (PACU)
Time Frame: At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

Difference between the outcome 1 and outcome 2
At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days
Total opioid consumption in the Post-anesthesia care unit (PACU)
Time Frame: At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

Morphin (mg), Oxynorm (mg), Oxycodon/Naloxon (mg)
At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days
- Total non-opioid analgesic consumption in the Post-anesthesia care unit (PACU)
Time Frame: At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

Paracetamol (mg), Metamizol (mg), Ketamin (mg)
At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days
- Total non-opioid analgesic consumption in the Post-anesthesia care unit (PACU)
Time Frame: At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

Lidocain-P (mg/kgLBW/h)
At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days
- Total non-opioid analgesic consumption in the Post-anesthesia care unit (PACU)
Time Frame: At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

Ketamin-Perfusor (mg/h)
At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days
- Incidence of Postoperative nausea and vomiting (PONV)
Time Frame: At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

The proportion of patients who experience at least one episode of postoperative nausea, retching, or vomiting, or who require the administration of any antiemetic rescue medication (such as Ondansetron, Metoclopramide, Domperidone, or Itinerol).
At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days
- Richmond Agitation-Sedation Scale (RASS) scores during Post-anesthesia care unit (PACU) stay
Time Frame: At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days
At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days
- Quality of Recovery-15 (QoR-15) score on postoperative day 1
Time Frame: At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days
At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Safety endpoints
Time Frame: At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

- measures of intraoperative hemodynamic stability, including the incidence of hypotension, bradycardia, hypertension, tachycardia, and vasoactive medication use - occurrence of AEs and SAEs during the study period
At the Date of Surgery + 1 day after at Post-anesthesia care unit (PACU): two assessments within 2 consequent days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Prof Urs Zingg

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

November 1, 2026

Primary Completion (Estimated)

October 1, 2027

Study Completion (Estimated)

October 1, 2027

Study Registration Dates

First Submitted

October 5, 2026

First Submitted That Met QC Criteria

November 3, 2026

First Posted (Actual)

November 4, 2026

Study Record Updates

Last Update Posted (Actual)

November 4, 2026

Last Update Submitted That Met QC Criteria

November 3, 2026

Last Verified

November 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • 2026-01332

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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