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

1. Background - The Care Gap in Spontaneous-Breathing Airway Management

Despite clear national and international guideline recommendations, airway management under preserved spontaneous breathing is performed in only 0.2% of all routine cases of tracheal intubation, and in only 2.7% of cases where a difficult airway is anticipated (Cumberworth et al., Anaesthesia 2022). This is a striking implementation gap, given that severe complications occur up to 45-fold more often in patients with anticipated difficult airways than in those with anticipated normal airways - exactly the population that would benefit most from preserved spontaneous breathing during intubation.

The reason for this implementation gap is not a lack of awareness among anesthesiologists, nor a lack of suitable equipment. It is the limited clinical practicability of the currently established procedures: they are technically demanding, time-consuming, require extensive operator experience, and are often associated with patient discomfort.

Three interdependent factors determine the practicability of airway management under spontaneous breathing and analgosedation:

1. Videolaryngoscopy: a less invasive laryngoscopy permits lighter sedation and preserves spontaneous breathing.
2. Topical airway anesthesia: reliable suppression of airway reflexes reduces the need for deep sedation.
3. Analgosedation: lower-dose, well-titrated sedation preserves spontaneous breathing and protective reflexes longer.

Each factor influences the others. A truly practicable procedure requires that all three are optimized in parallel - not as isolated technical components but as a coherent overall procedure. This trial addresses the question of whether such an optimized overall procedure, combined with a less invasive videolaryngoscope, can close the implementation gap.

2. Historical Context

More Than 130 Years of Blade-Based Laryngoscopy The principle of direct laryngoscopy was first described by Alfred Kirstein in 1895, who introduced the "autoscope" - an L-shaped device with an electric light source and a curved blade that elevated the epiglottis to reveal the glottis. In 1943, Robert R. Macintosh introduced the laryngoscope that has remained the clinical standard ever since: a similarly curved blade that elevates the tongue base and lifts the epiglottis indirectly to align the oral, pharyngeal, and tracheal axes into a single straight visual line.

For more than 130 years, this fundamental principle has remained essentially unchanged. Every modern videolaryngoscope - including hyperangulated devices such as the C-Mac D-Blade, the Storz C-Mac, the GlideScope, the McGrath, the Airtraq, and the Pentax Airway Scope - still uses a blade to elevate the tongue and to lift the epiglottis. The blade is the mechanical interface between the operator and the airway anatomy.

This blade-based design has consequences. To position the camera in front of the laryngeal inlet, the blade must displace the tongue base, the soft tissues of the neck, and the mandible. This displacement requires the natural double-curved course of the upper airway (with two near-90° angles around the tongue base and entering the trachea) to be deformed into an approximately straight line of sight. In patients under general anesthesia with full muscle relaxation, this deformation is generally feasible. In patients under preserved spontaneous breathing and analgosedation - without muscle relaxation - the deformation is much less feasible, more invasive, and more likely to provoke airway reflexes such as cough, laryngospasm, or tube placement failure.

The OWN-BREATH 2 trial therefore investigates whether departing from the blade-based design - toward a bladeless, anatomy-guided videolaryngoscope - improves the clinical practicability of airway management under spontaneous breathing.

3. The i-scoop - A Bladeless, Anatomy-Guided Concept

The intubation scoop (i-scoop) was developed at Hannover Medical School and has been a CE-certified medical device since 2021 (CE conformity declaration most recently updated on 2025-11-19). It is manufactured by Vimed Medical Device, China; its development was jointly funded by Vimed and by Supporting Health Care, Netherlands.

Unlike all other videolaryngoscopes, the i-scoop has no blade. Instead, it consists of a thin, curved guiding bar that follows the natural anatomy of the upper airway - comparable to laryngeal mask insertion along the hard palate. A short, separately operated lever lifts the epiglottis. This decoupled design allows the optical system to be advanced into a sub-epiglottic position immediately in front of the laryngeal inlet, without the airway needing to be deformed into a straight visual line.

Two laterally placed optics provide simultaneous views of the laryngeal inlet from two perspectives. An integrated tube guide channel ends at the same sub-epiglottic position as the optics. As a consequence, the line of sight and the working axis of the endotracheal tube coincide directly in front of the laryngeal inlet. Tube placement into the trachea can therefore be guided, observed, and visually confirmed during the entire passage - from two perspectives - without losing visual contact with the glottis. This is a fundamental difference from blade-based videolaryngoscopes, in which the tube progressively obstructs the camera view during placement and the operator must rely on memory or stylet pre-shaping.

The intended consequences of this design are: less invasive insertion (no displacement of tongue base, soft tissues of the neck, or mandible), reduced provocation of airway reflexes, lower required sedation depth, and improved visual control of tube placement throughout passage. Whether these design features translate into better clinical practicability under spontaneous breathing and analgosedation is the question this trial addresses.

4. Pre-Existing Evidence

The rationale and design of the OWN BREATH 2 trial are informed by three lines of prior evidence and preliminary clinical experience:

1. Manikin Study (Raymondos et al., Anaesthesia 2014; 69:990-1001): A controlled study compared the i-scoop with eleven other videolaryngoscopes (Macintosh, GlideScope GVL/AVL/DI Trainer, McGrath Series 5/MAC, C-Mac with Macintosh blade and C-Mac D-Blade, A.P. Advance, A.P. Advance DAB, Airway Scope, Airtraq) in a simulated normal and a simulated difficult airway, performed by 25 board-certified anesthesiologists with extensive videolaryngoscopy experience. In the simulated difficult airway (modified retrognathia plus immobilized cervical spine), all 25 anesthesiologists achieved successful intubation with the i-scoop with a clear glottic view; success rates with the other devices ranged from 0% (Macintosh and most videolaryngoscopes) to 40% (Airtraq) and 20% (Airway Scope) (p < 0.001 vs. all twelve comparator devices combined). In the simulated normal airway, intubation with the i-scoop was even faster than with the standard Macintosh laryngoscope (p < 0.02). This study established the proof-of-concept of the bladeless, anatomy-guided design.
2. First Clinical Experience in Anesthetized Patients (Raymondos, EAMS Baveno September 2023): The CE-certified i-scoop was used in 125 anesthetized adult patients; data from 103 patients with written consent for scientific analysis were evaluated. All 103 patients were successfully intubated on the first attempt under Cormack-Lehane grade 1 view. The Percentage of Glottic Opening (POGO) score was 100% in 96 patients and 80-95% in 7 patients. In 90 patients intubated by one experienced operator, optimal glottic view was achieved at a median of 5 seconds (range 2-22) after tooth passage, and intubation was completed at a median of 4 seconds (range 1-57). In 13 patients intubated by four first-time users, these times were approximately twice as long (medians 13 s and 8 s, respectively). The VIDIAC (Videolaryngoscopic Intubation and Difficult Airway Classification) score was -1 (range -1 to 0) and the Intubation Difficulty Scale was 0 (range 0 to 5).
3. First Clinical Experience under Spontaneous Breathing - OWN BREATH 1 (Raymondos, WAMM Florence, November 2025): A retrospective analysis of the first 41 consecutive elective urological patients intubated under preserved spontaneous breathing and analgosedation using the i-scoop, after introduction of the standardized overall procedure on 2025-05-13 (data evaluated under separate ethics approval, reference 12063-BO-K-2025). Results: 35 of 41 patients (85%) met all 12 predefined criteria of "good clinical practicability". A clear glottic view (Cormack-Lehane grade 1, VIDIAC score -1) was achieved in all 41 patients; the median POGO score was 100% (range 75-100). First-attempt success was 90% (37/41); 98% were intubated within two attempts and 100% within three. One experienced operator (n = 34) intubated at a median time of 18 seconds (range 6-80); three first-time users (n = 7) required approximately three-fold longer (median 55 s, range 24-59). All 9 patients with an El-Ganzouri Index ≥ 4 (anticipated difficult airway) met all 12 criteria of good clinical practicability; in the 6 patients who did not meet all criteria, an anticipated difficult airway was never present. No serious complications occurred; no patient recalled the laryngoscopy or the intubation. Failure to achieve all 12 criteria was attributable in all 6 cases to insufficient topical anesthesia or sedation, not to insufficient visualization or device performance.

These three sources motivate the hypothesis of the present prospective, randomized comparison.

5. OWN-BREATH 2 - Study Design and Hypothesis

OWN-BREATH 2 is a prospective, randomized, monocentric, parallel-group trial conducted at the Department of Anaesthesiology and Intensive Care Medicine, Hannover Medical School, Germany. The Ethics Committee of Hannover Medical School approved the trial without reservations on 2026-01-15 (reference number 12062-BO-S-2025; approved study protocol AG-AuA-QM-Version V14.7 of 2025-12-14).

A total of 200 adult patients (≥ 18 years) scheduled for surgery under general anesthesia at the study center will be enrolled - independently of whether their airway is judged anatomically normal or difficult. Patients are allocated 1:1 to either the experimental arm (airway management with the i-scoop) or the active comparator arm (airway management with the established hyperangulated C-Mac D-Blade videolaryngoscope manufactured by Karl Storz SE & Co. KG, Tuttlingen, Germany). Allocation is centrally generated using a computerized randomization plan with permuted blocks of variable length and is concealed via sequentially numbered, opaque, sealed envelopes opened immediately before intervention.

The standardized overall procedure is identical in both arms except for the videolaryngoscope used. Patients are blinded to their group allocation. The operator cannot be blinded due to the visible nature of the device. Postoperative outcome assessors performing the structured patient interviews (recovery room, postoperative day 1, and 7 days post-intubation) are blinded to the assigned device.

Hypothesis: Because the line of sight and the working axis of the endotracheal tube coincide directly in front of the laryngeal inlet with the i-scoop, tube placement into the trachea can be guided under continuous visual control and visually confirmed throughout passage. This fundamental mechanical and optical advantage, in comparison with blade-based videolaryngoscopes, leads to the hypothesis that the standardized airway management procedure under spontaneous breathing and analgosedation more frequently meets the predefined composite endpoint of "good clinical practicability" with the i-scoop than with the C-Mac D-Blade.

Clinical implication: Improved clinical practicability would create the prerequisite for broader integration of spontaneous-breathing airway management into routine clinical practice - and thereby better serve the patient population with anticipated difficult airways, in whom the complication risk is currently 45-fold higher.

6. Standardized Procedure and Measurement Methodology

Analgosedation in both arms uses the following standardized scheme (reference weight, gender-independent: body height in cm minus 100): initial bolus of remifentanil 0.3 µg/kg and propofol 0.6 mg/kg; subsequent continuous infusion via syringe pump of remifentanil 0.05 µg/kg/min and propofol 2 mg/kg/h; on-demand boluses of propofol 0.3 mg/kg without quantity limit. For safety reasons - to prevent escalating sedation depth with loss of spontaneous breathing - remifentanil on-demand boluses are restricted to a maximum of one additional bolus of 0.3 µg/kg per procedure. Anxiolysis if required: midazolam 1 mg.

Topical airway anesthesia: 150-200 mg lidocaine 1% oropharyngeally in repeated single doses at intervals of 15-30 seconds, followed by videolaryngoscope-guided endotracheal application of 20 mg lidocaine 1% (in the i-scoop arm via the integrated channel; in the C-Mac D-Blade arm via a separate applicator). Intubation is performed 60-90 seconds after the endotracheal lidocaine application.

Oxygenation: continuous oxygen delivery at 18 L/min via FFP2 face mask is maintained from preoxygenation until successful intubation, with a target end-tidal oxygen fraction of ≥ 0.60.

Continuous monitoring during the procedure includes pulse oximetry, electrocardiography, non-invasive blood pressure measurement, impedance respirography, capnography, and processed electroencephalography for sedation depth.

Confirmation of correct endotracheal tube placement is performed by continuous capnography according to the consensus criteria of the Project for Universal Management of Airways (PUMA): seven consecutive carbon dioxide waveforms with a maximum value of at least 7.5 mmHg.

Standardized operator training prior to study start: each participating board-certified anesthesiologist completes at least 30 successful intubations and at least 30 successful endotracheal local anesthesia applications per device on the airway trainer (with scenarios of varying difficulty, including restricted mouth opening and reduced glottic mobility), followed by clinically supervised use until safe handling is achieved. More than ten board-certified anesthesiologists participate in the trial; the operator identifier is included as a covariate in multivariate statistical analyses.

Predefined escalation steps are available if visualization is insufficient or if tube placement is not feasible with the assigned device, including crossover to the alternative study device. Established airway adjuncts (e.g., laryngeal mask, fiberoptic bronchoscope) and standard rescue strategies remain available throughout. Patient safety has priority over adherence to the assigned study intervention.

Primary endpoint: good clinical practicability - a composite dichotomous endpoint requiring simultaneous fulfillment of 12 predefined criteria across three domains (safety: clear glottic view and PUMA-confirmed endotracheal placement; ease of performance: VIDIAC ≤ 0, first-attempt success, ≤ 3 corrective maneuvers, intubation time ≤ 60 s; complication and complaint freedom: no recall of laryngoscopy or intubation, no SpO₂ < 90%, no persistent apnea, no clinically relevant hemodynamic instability, no aspiration, no relevant or persistent complaints/injuries). Detailed criteria are described in the Outcome Measures module of this registration.

Sample size: 100 patients per arm, calculated for detection of a difference of 23.3 percentage points in the proportion meeting good clinical practicability (assumed: 90% with i-scoop, based on the OWN BREATH 1 pilot extrapolated to optimized routine conditions; 66.7% with C-Mac D-Blade, based on the published literature) using a two-sided exact Fisher test at α = 0.01 with 90% power. Confirmatory analysis: Pearson chi-square test (without continuity correction), two-sided, α = 0.01; effect measure: absolute difference of proportions with two-sided 99% confidence interval.

7. Patent Disclosures and Conflicts of Interest

Patents and patent-related income: Patents on the i-scoop are granted in the name of Hannover Medical School (European Union and United States of America). Additional patents are pending, some filed jointly with the industrial partners Vimed Medical Device, China, and Supporting Health Care, Netherlands, as co-patent holders. The principal investigator (Konstantinos Raymondos) holds a separate i-scoop patent solely in his own name. Patent-related payments to Hannover Medical School and/or to the principal investigator may arise during the trial period from ongoing or future licensing or exclusivity agreements; such payments are unrelated to the conduct of OWN-BREATH 2 itself but are disclosed here proactively because they may occur during the trial. At the time of registration, no such payments have been made or are concretely scheduled; updates will be made through the trial register and in subsequent publications.

Industrial cooperation without study sponsoring: Vimed Medical Device and Supporting Health Care jointly funded the technical development of the i-scoop in the years preceding study start, and both provide the i-scoop videolaryngoscopes and consumables for OWN-BREATH 2 free of charge. Neither company provides honoraria, expense reimbursement, or other monetary compensation for the conduct of this trial to Hannover Medical School, the study team, or the participants. The device is not yet commercially available.

Independence of trial conduct: All decisions on study design, data acquisition, analysis, and publication are made exclusively by the study team at Hannover Medical School. The Sponsor of the trial is Hannover Medical School.

Inclusion Criteria:

• 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

Exclusion Criteria:

• 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
• Current opioid therapy or chronic opioid therapy discontinued less than 1 month before the procedure
• Known drug or alcohol dependence
• Known hypersensitivity or allergy to lidocaine or its excipients (glycerol, propyl-4-hydroxybenzoate, methyl-4-hydroxybenzoate)
• Severe psychiatric disorder impairing capacity to consent or to cooperate
• Indication for nasal intubation
• Non-pain-related limitation of mouth opening to less than 16 mm
• Severe comorbidities with particular risk in the context of the study intervention (e.g., unstable cardiac or pulmonary disease, uncontrolled epilepsy)
• Participation in another clinical study within the previous 30 days that could influence the present study question

Participants are blinded to group allocation. The investigator performing the airway procedure cannot be blinded due to the visible nature of the device. The outcomes assessor for postoperative complaint interviews (T2, T3, T4) is blinded to the assigned device.