In the present study, a shorter TTV was achieved using video laryngoscopes with a hyperangulated blade in a group of 640 intubation attempts in an infant DA. In particular, TTV was shorter in both airway situations when applying the novel KV. The FPA, visualization of the glottis and subjective assessment in this comparative study were superior to those of conventional direct laryngoscopy. To date, only one study compared the novel KV with the traditional MiB in elective surgeries performed in children < 2 y of age [
19]. This study is one of the first studies comparing the KV with another hyperangulated blade and direct laryngoscopy in a simulated infant airway.
The demographics of the participants were comparable to those in other studies investigating the MaB, DB or MiB [
6,
10,
12,
20‐
22] in pediatric airways. In contrast to other studies comparing experienced and inexperienced practitioners [
6,
9‐
11,
19,
21,
22], this study demonstrated that TTV was similar between the groups. However, in this study, there were no institutional differences in FPA or TTV among the blades or airway scenarios. This likely reflects a familiarity with the direct and video laryngoscopy techniques. Furthermore, every participant only had 5 attempts with the novel KV or DB prior to the study.
A number of new devices have been introduced to facilitate tracheal intubation in pediatric patients with normal and difficult airways, with reports describing varying success rates and experience in pediatric airway management [
10,
11,
22]. In these experiments, manikins were used in various simulation scenarios, including tracheal intubation. In addition to their use in training, they have also been used in various clinical research projects to demonstrate the efficacy of one device over another. SimBaby™ has been used to teach clinical and decision-making skills while mimicking patient care scenarios [
9,
10,
23]. Tracheal intubation using a video laryngoscope might be easier to learn than conventional direct laryngoscopy [
8,
9]. The success rates vary considerably, and the proportion of patients in whom the glottic opening can be visualized but the ET cannot be inserted into the trachea is high [
20,
21,
24]. Several study results have noted that intubation time is longer when using a video laryngoscope with a hyperangulated blade [
6,
9,
21]. Surprisingly, TTV was significantly shorter for the novel KV blade in the NA (1.5 s) and DA (13 s) scenarios than for the other devices, which influence the occurrence of systemic complications (e.g., hypoxemia). TTV was longer for the MaB and MiB than for hyperangulated blades relative to the results of studies looking at two conventional blades; however, the values were within the range of published data [
6,
9,
23]. In two studies that evaluated children aged < 2 years of age, TTV was shorter for the MiB [
19,
22] than for the KV. Straight blades are often recommended for use in neonates and infants to lift the relatively large and floppy epiglottis [
22]. These blades avoid a situation in which the hyoid bone cannot be displaced forward and the epiglottis continues to obstruct a view of the larynx. In summary, a good laryngeal view with the intubating device did not equate with ease of intubation. Otherwise, a curved MaB provides more room in the oropharynx to maneuver the ET. The time to visualization of the glottis and successful ventilation were also comparable to the results reported in another study [
19]. However, the measurements differed between these studies in which the practitioner took hold of the handle of the device until the cuff of the ET was inflated [
9,
20,
24] or until confirmation of the first inflection of the end-tidal capnogram on the anesthesia respirator [
6,
19]. In three studies, time measurement stopped when successful lung expansion occurred [
9,
20,
21]. All intubations were successfully performed using the KV on FPAs. Comparing TTV or FPA using the DB is difficult because the literature is quite sparse with regard to the use of the DB in pediatric patients or in a suitable manikin. The prolonged intubation time and lower success rate in DB and conventional direct laryngoscopes might be explained as follows: first, the anterior view angle of 55 degrees achieved using the KV differs from the half-moon shaped DB (embedded optical lens with aperture angle of 80°); furthermore, the length differs between the two hyperangulated blades (KV, 7 cm vs. DB, 10 cm). Additionally, it is generally thought that the position of the head has an influence on the laryngeal view [
6]. We used a standardized position for the SimBaby in which a shoulder roll elevated the shoulders and a small donut was used to support the head. The goal was to align the oral, pharyngeal, and tracheal axes to facilitate tracheal intubation.
As a secondary outcome, visualization of the glottis was significantly easier with VL in both scenarios. These data are consistent with previously published data in simulated pediatric patients in whom the laryngeal view was found to be better with VL [
6,
9,
10,
19]. In contrast to other studies comparing hyperangulated blades with DL, we found a higher FPA and overall success rate when using the KV or DB [
11,
15,
21]. In fact, a higher FPA was shown with the KV in DA compared to the first study that evaluated the KV in a normal pediatric airway [
19]. These data are comparable to that in study with manikins where the results vary with the operator’s prior experience and familiarity with the equipment, institutional preferences, and how well the manikin simulates a real patient [
11,
20]. Finally, when considering the number of ELMs, which were slightly higher with direct laryngoscopy, and the participants’ subjective difficulty scores, which were also higher for these devices, our data agree with those reported on the management of adult patients [
18]. This fact may be derived from the absence of prior experience of the subjects with the DB and KV or with the specific characteristics of the conventional blades and the infant manikin’s airway anatomy.