The purpose of this clinical trial is to investigate whether the videolaryngoscope i-scoop makes airway management under spontaneous breathing and analgosedation more clinically practicable than the established standard device, the C-Mac D-Blade videolaryngoscope, in adults undergoing surgery under general anesthesia.
The main questions it aims to answer are:
• Is good clinical practicability - defined as a successful, easy, and complication-free intubation under spontaneous breathing - more frequently achieved with the i-scoop than with the C-Mac D-Blade?
Researchers will compare the standardized airway management procedure under spontaneous breathing using either the i-scoop or the C-Mac D-Blade.
Participants will:
* continue breathing on their own during the procedure * be randomly assigned (1:1) to one of the two videolaryngoscopes * receive standardized analgosedation and topical lidocaine anesthesia of the upper airway before the breathing tube is placed * be asked about discomfort and recall of the procedure after surgery (in the recovery room, on postoperative day 1, and at 7 days post-intubation) by a blinded interviewer
Age ≥ 18 years
Scheduled surgical procedure or intervention under general anesthesia
Capacity to give informed consent (free and independent decision-making capacity)
Willingness to provide written informed consent after comprehensive verbal and written information about study aims, procedures, and risks
Lack of, or withdrawal of, written informed consent
Lack of capacity to consent or legal guardianship for health-related decisions
Insufficient German language skills for qualified verbal and written informed consent (exclusion to protect patients, since legally valid and substantively meaningful consent is not possible without secured language comprehension)
Pregnancy or breastfeeding
Parallel
Airway management under spontaneous breathing with the i-scoop videolaryngoscope
Procedure/SurgerySingle intervention during anesthesia induction: 1. Preoxygenation via FFP2 mask, 18 L/min O₂ until intubation. 2. Analgosedation: remifentanil 0.3 µg/kg + propofol 0.6 mg/kg bolus, then continuous infusion; max. one additional remifentanil bolus (0.3 µg/kg); midazolam 1 mg if needed. 3. Topical anesthesia: 150-200 mg lidocaine 1% oropharyngeally, then 20 mg lidocaine 1% endotracheally via i-scoop channel. 4. Intubation 60-90 s later under continuous visual control via dual-optic sub-epiglottic i-scoop positioning. 5. Tube confirmation by capnography (PUMA criteria). Training: ≥30 intubations and ≥30 lidocaine applications per operator on airway trainer before study start. Monitoring: SpO₂, ECG, NIBP, capnography, EEG. Escalation and rescue strategies available at all times.
Airway management under spontaneous breathing with the C-Mac D-Blade videolaryngoscope
Procedure/SurgerySingle intervention during anesthesia induction, identical to Intervention 1 except for the videolaryngoscope used: 1. Preoxygenation via FFP2 mask, 18 L/min O₂ until intubation. 2. Analgosedation: remifentanil 0.3 µg/kg + propofol 0.6 mg/kg bolus, then continuous infusion; max. one additional remifentanil bolus (0.3 µg/kg); midazolam 1 mg if needed. 3. Topical anesthesia: 150-200 mg lidocaine 1% oropharyngeally, then 20 mg lidocaine 1% endotracheally via separate applicator (C-Mac D-Blade has no integrated channel). 4. Intubation 60-90 s later using C-Mac D-Blade standard technique with pre-shaped tube or stylet. (5) Tube confirmation by capnography (PUMA criteria). Training, monitoring, escalation, and rescue strategies identical to Intervention 1.
Number of Participants Achieving Good Clinical Practicability of Airway Management Under Spontaneous Breathing and Analgosedation
A composite dichotomous endpoint (yes/no) per participant. Good clinical practicability is achieved if all 12 predefined criteria are simultaneously met. Safety: (1) clear glottic view (Cormack-Lehane grade 1) before tube placement; (2) visual confirmation of correct endotracheal placement per PUMA consensus criteria (with the tube clearly seen between the vocal cords and/or above the arytenoids). Ease of performance: (3) VIDIAC score ≤0; (4) first-attempt success; (5) no more than three corrective maneuvers; (6) intubation time ≤60 seconds. Complication and complaint freedom: (7) no recall of laryngoscopy (including the first laryngoscopy for endotracheal lidocaine application) or intubation; (8) no SpO₂ \<90%; (9) no persistent apnea; (10) no clinically relevant hemodynamic instability; (11) no aspiration; (12) no relevant or persistent complaints/injuries (VAS \>3/10 at any postoperative time point, or persistent at 7 days).
Successful Intubation on the First Attempt
Successful placement of the endotracheal tube during the first laryngoscopy and first tube placement attempt, confirmed by exhaled carbon dioxide. Participants are classified dichotomously as first-attempt success or no first-attempt success.
Intubation Time
Time from insertion of the videolaryngoscope until the first exhaled carbon dioxide signal after successful tube placement, measured in seconds. Lower values indicate easier and faster intubation.
Number of Optimization Maneuvers Required for Intubation
Number of additional maneuvers required to achieve successful tube placement, including repositioning of the device, external laryngeal manipulation, or correction of tube direction. Lower values indicate easier intubation.
Visual Quality of Laryngoscopy (Cormack-Lehane Grade and POGO Score)
Cormack-Lehane classification of the glottic view and Percentage of Glottic Opening (POGO) score before tube placement. Assessed on the videolaryngoscope monitor by the operator and by a blinded second observer using pseudonymized video recordings.
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