Comparison of the novel VieScope with conventional and video laryngoscope in a difficult airway scenario – a randomized, controlled simulation trial

The Ethics Committee of the University of Cologne approved the study on 02.02.2021 (ID 20-1475_2; Head: Prof. Dr. Raymond Voltz). The study was conducted in accordance with CONSORT guidelines.

The study was registered at the German Clinical Trials Register www.​drks.​de (Identifier: DRKS00024968) on March 31st 2021.

This study was conducted in April 2021 in the facilities of the University Hospital of Cologne as a randomized controlled manikin trial.

Thirty-five volunteers, all physicians from the Department for Anesthesiology and Intensive Care Medicine at the University Hospital of Cologne, were included after giving written and informed consent.

Inclusion criteria were individuals working as physician in Anesthesia or Critical Care, and age between 18 and 65 years. There were no other exclusion criteria.

After informed consent, the following demographic and medical background data of the test participants were recorded in pseudonymized form:

The participants were then asked to perform endotracheal intubation on a certified airway training manikin (AirSim Advance X, TruCorp Ltd., Lurgan, Northern Ireland) using either VieScope (Androit Surgical LCCC, Oklahoma City, USA), video-laryngoscopy (GlideScope, Verathon Medical, Bothell, USA) or conventional laryngoscopy (MAC - Macintosh-Blade Size 3, Heine, Herrsching, Germany) in randomized order.

In all scenarios, the tongue of the manikin was inflated to a pressure of 35 mbar (as recommended by the manufacturer) and a cervical collar (Stifneck, regular, Laerdal, Stavanger, Norway) was applied to simulate a difficult airway situation.

The order of the devices was randomized using sealed opaque envelopes. A blocked randomization strategy was generated using an online tool (Sealed Envelope Ltd. 2020: www.​sealedenvelope.​com/​simple-randomiser/​v1/​lists [Accessed 6 Oct 2020]).

Time measurements started with the beginning of airway measures (taking up the laryngoscope) and ended with the first ventilation (using a resuscitation bag).

A determination of the best Cormack & Lehane score was asked verbally and protocolled after every simulation for each airway management device.

The following data was recorded for all three devices in pseudonymized form:

Each simulation was terminated after successful intubation or after 5 min, at which irreversible hypoxia of the patient must be assumed.

For this study, the novel VieScope (VieScope “Training Demo”, Adult Size, Androit Surgical LCCC, Oklahoma City, USA) was used. It consists of a transparent circular straight tube (comparable to a Miller laryngoscope blade), which is illuminated by light emitting diodes (LEDs), and a battery handle. The VieScope is a standalone device, battery powered, and disposable after a single use (Fig. 1). As the scope itself has a straight, Miller-shaped blade, it facilitates a direct and straight view of the glottis, but does not allow direct intubation due to a small inner diameter. Instead, it requires the insertion of a bougie once sight to the vocal cords is achieved. Afterwards, an endotracheal tube can be passed into the trachea over the bougie, which then can be removed (Fig. 2). As bougie, the VOIR Tactical Bougie (Androit Surgical LCCC, Oklahoma City, USA) was used in the attempts with VieScope, whereas the rigid GlideRite stylet (Verathon Inc., Bothell, WA, USA) was used for intubation with GlideScope (Verathon Inc., Bothell, WA, USA).

For conventional Laryngoscopy (MAC) a Macintosh-Blade (Heine, Herrsching, Germany) Size 3 was used, a stylet (Portex Stylet medium, Smiths Medical, Ashford Kent, GB) was inserted into the endotracheal tube beforehand.

Statistical computations were carried out using IBM SPSS Statistics (Version 25; IBM Inc., Armonk, NY, USA).

Since the physicians did not have any experience with the novel VieScope, and there was no published data on success rates, we estimated a difference in first attempt intubation success of 25% compared to the Glide Scope (which was familiar to participants), which has a success rate of 95%. Based on this we calculated that the required sample size in order to achieve 80% power at a significance level of 5% would be 35 participants to detect a difference.

For the comparison of the primary endpoint “Tube position” with GlideScope, MAC and VieScope a Chi-Square-Test was performed.

Thirty-five participants, all staff anesthesiologists, were recruited for this study. Of these 35, 18 were female and 17 were male. The mean age was 35 years (range 27 to 47 years), with an experience in the job of < 1 year in n = 2 (6%), 1 to 3 years in n = 7 (20%), 3 to 6 years in n = 8 (23%) and > 6 years in n = 18 (51%). The average annual tracheal intubation per participant were less than 50/year in n = 3 (9%), 50 to 100 intubations in n = 11 (31%), 100 to 200 intubations in n = 7 (20%), and more than 200 intubations in n = 14 (40%).

Of all 35 participants, all n = 35 (100%) had experience with MAC (in the airway manikin and in the clinical setting), n = 34 (97%) had prior experience in the use of the GlideScope (in the airway manikin and in the clinical setting), while only n = 10 (29%) had prior experience in the use of the VieScope (only in the airway manikin, as this new device was not routinely used in clinical praxis at the time of the study).

In randomized order, each participant performed three endotracheal Intubation attempts in total, one with the GlideScope, one with VieScope, and one with a MAC laryngoscope. Thus, 105 data sets were acquired (Fig. 3).

The secondary endpoint “time until successful endotracheal intubation” in the difficult airway setting showed a mean ± SD time of 27.5 ± 20.3 s for the use of the GlideScope versus 20.8 ± 8.1 s for the use the MAC versus 36.3 ± 10.1 s for the use of VieScope.

An all pairwise multiple comparison procedures showed that both the GlideScope and the MAC had a shorter time until intubation, compared to the VieScope (p < 0.001 both). Time until endotracheal intubation for MAC was shorter compared to the GlideScope (p = 0.045).

Time until first ventilation showed a mean time of 39.3 ± 21.6 s for the use of GlideScope and 31.9 ± 9.5 s for MAC and 46.5 ± 12.4 s in VieScope group.

MAC had a shorter time until ventilation, compared to the VieScope (p < 0.001). GlideScope compared to Viescope showed a shorter time until ventilation (p < 0.001). Time until ventilation compared between Glide Scope versus MAC also showed a shorter duration (p = 0.046).

Time until bougie placement for VieScope showed a mean time of 20.7 ± 7.0 s compared to time until intubation with GlideScope 27.5 ± 20.3 s and MAC 20.8 ± 8.1 s.

We tested VieScope in an artificial adult simulation scenario. Of course, a manikin can hardly completely generate physiological situation of a patient and simulation studies are not able to fully assess human factor elements (stress, cognitive overload etc.) of the clinicians. However, we rely on simulations trials, as testing a new device always requires a degree of standardized laboratory testbed, before it can be evaluated in daily patient care. Additionally, emergency situations, such as “difficult airway”, are normally not predictably and study enrollment is normally only retrospectively feasible.