Prospective Trial to Compare Direct and Indirect Laryngoscopy Using C-MAC PM® with Macintosh Blade and D-Blade® in a Simulated Difficult Airway

Abstract

Objective. Evaluation of C-MAC PM® in combination with a standard Macintosh blade size 3 in direct and indirect laryngoscopy and D-Blade® in indirect laryngoscopy in a simulated difficult airway. Primary outcome was defined as the best view of the glottic structures. Secondary endpoints were subjective evaluation and assessment of the intubation process. Methods. Prospective monocentric, observational study on 48 adult patients without predictors for difficult laryngoscopy/tracheal intubation undergoing orthopedic surgery. Every participant preoperatively received a cervical collar to simulate a difficult airway. Direct and indirect laryngoscopy w/o the BURP maneuver with a standard Macintosh blade and indirect laryngoscopy w/o the BURP maneuver using D-Blade® were performed to evaluate if blade geometry and the BURP maneuver improve the glottic view as measured by the Cormack-Lehane score. Results. Using a C-MAC PM® laryngoscope, D-Blade® yielded improved glottic views compared with the Macintosh blade used with either the direct or indirect technique. Changing from direct laryngoscopy using a Macintosh blade to indirect videolaryngoscopy using C-MAC PM® with D-Blade® improved the Cormack-Lehane score from IIb, III, or IV to I or II in 31 cases. Conclusion. The combination of C-MAC PM® and D-Blade® significantly enhances the view of the glottis compared to direct laryngoscopy with a Macintosh blade in patients with a simulated difficult airway. Trial Registration Number. This trial is registered under number NCT03403946.

Comparison of C-MAC D-blade videolaryngoscope and McCoy laryngoscope efficacy for nasotracheal intubation in simulated cervical spinal injury: a prospective randomized comparative study

“…These results agree with prior trials that suggested that the C-MAC D-Blade videolaryngoscope offers better glottic visualization in terms of a higher rate of CL grade I ratings compared with the McCoy laryngoscope during oropharyngeal intubation in patients who had limited neck mobility with a cervical collar [24]. These benefits on intubating condition may be explained by the pronounced curvature of the C-MAC D-Blade videolaryngoscope, which does not require alignment of oral, pharyngeal, and tracheal axes and its utility in cases of anterior placed larynx by providing an extended view of the vertical plane of the glottic areas [25,26]. The result of the present study would be applied to patients with head and neck trauma, cervical spine disorders and difficult intubation anticipated.…”

The videoscopic view may not be significantly superior to the directly sighted peroral view during Macintosh-style videolaryngoscopy: a randomized equivalence cadaver trial

“…Also using the Yentis 12 scale, a significant improvement in view from directly sighted to videoscopic views was reported in the cervical collar group. Raimann et al 6 also studied a small population of elective surgical patients with a cervical collar fitted, sequentially performing directly sighted laryngoscopy with the C-MAC reusable Macintosh blade, then indirectly sighted VL with the same blade. With and without ''backwards-upwards'' rightwards pressure (BURP), the videoscopic view was better than the directly sighted view in a moderate but statistically significant number of patients (defined as a change from Cormack-Lehane Grade 3 or 4 to Grade 2a, 2b or 1): six of 32 without applied BURP; seven of 25 with applied BURP; and 14 of 18 with BURP applied only during Mac-VL.…”

“…Third, our study methodology differed from some of the earlier trials by attempting to compare direct and videoscopic views at the same moment in time, with ratings done by different clinicians (the laryngoscopist and two independent videoscopic scorers), each blinded to the results recorded by the others. Fourth, only the Kaplan et al 3 Byhahn et al 5 and Raimann et al 6 studies compared the direct and videoscopic views obtained with the same Mac-VL; the Piepho and Aziz 1,2 studies documented videoscopic views obtained using the Macintosh-style C-MACÒ VL and those obtained in other patients undergoing Macintosh DL. Although unlikely, it is possible that the view obtained during regular DL may not equate exactly to direct peroral sighting using a Mac-VL, rendering a comparison of the present study with those studies invalid.…”

“…They reported that the videoscopic view was at least one Cormack-Lehane (C-L) 4 grade better in 41.5% of subjects. Subsequent studies by Byhahn et al 5 and Raimann et al 6 have also reported a substantial improvement in the videoscopic view compared with direct peroral sighting with Mac-VL, although the effect was most pronounced in patients with difficulty artificially induced by application of a stiff cervical collar. In contrast, our clinical impression is that incremental improvement is minimal with the indirect videoscopic view compared with the direct peroral view with Mac-VL in most patients.…”

Prospective Evaluation of the Safety and Efficacy of THRIVE for Children Undergoing Airway Evaluation

“… 7 Although this scoring system is designed for patients undergoing direct laryngoscopy, previous studies have also applied the CLS to describe the laryngeal view during indirect laryngoscopy. 8 , 9 We thus felt that this would also be an appropriate system to compare changes occurring during THRIVE use. Figure 2 highlights example images of CLS ranging from grades 1 to 3.…”