Channelled Astra-Vue versus non-channelled C-MAC D-blade Videolaryngoscope for Tracheal Intubation in Adults: a randomised controlled trial

Technical Summary: Channelled Astra-Vue versus Non-Channelled C-MAC D-Blade Videolaryngoscope

Problem Statement
Airway management remains a critical component of anesthesia and emergency medicine, where failed tracheal intubation is a significant contributor to perioperative morbidity and mortality. While videolaryngoscopy has largely replaced direct laryngoscopy due to improved glottic visualization and reduced need for axis alignment, the optimal blade design remains debated. Specifically, the efficacy of channelled blades (which incorporate an integrated guide to direct the endotracheal tube, theoretically eliminating the need for a stylet) versus non-channelled blades (which require a styletted tube) yields conflicting results in existing literature. Furthermore, there is a lack of published data regarding the performance of the novel Astra-Vue Ultrablade, a hyperangulated channelled device, particularly when compared to established non-channelled hyperangulated blades like the C-MAC D-blade.

Methodology
The authors conducted a single-centre, parallel-group, open-label, randomised controlled trial (RCT) at Universiti Malaya Medical Centre, Malaysia.

• Participants: 60 adult patients (ASA I–III, aged 18–80) scheduled for elective or semi-emergency surgery requiring tracheal intubation. Patients with predicted difficult airways, cervical spine pathology, or specific tube requirements (e.g., intra-operative neuromonitoring) were excluded.
• Intervention: Participants were randomised 1:1 to one of two groups:
  1. Astra-Vue Group: Intubation using the channelled hyperangulated Astra-Vue Ultrablade without a stylet.
  2. C-MAC Group: Intubation using the non-channelled hyperangulated C-MAC D-blade with a styletted tracheal tube.
• Operators: All procedures were performed by two experienced anaesthetists (>100 videolaryngoscopic intubations each).
• Outcomes:
  • Primary: Total time to intubation (from blade passage past inter-incisors to tube placement beyond vocal cords).
  • Secondary: Time to glottic visualisation, time from visualisation to tube placement, first-attempt and overall success rates, Percentage of Glottic Opening (POGO) score, need for external laryngeal manipulation, Modified Intubation Difficulty Scale (MIDS), haemodynamic response, and complications.
• Analysis: Statistical analysis utilized Mann–Whitney U tests for continuous variables and Pearson χ² or Fisher's exact tests for categorical variables. Multiple linear regression was employed to assess predictors of intubation time and the interaction between device type and mouth opening.

Key Results

• Total Intubation Time: There was no statistically significant difference in the total time to intubation between the two groups (Astra-Vue median: 21.1 s vs. C-MAC median: 19.8 s; p = 0.469).
• Intubation Phases: The devices demonstrated opposing performance characteristics in specific phases:
  • Glottic Visualisation: The C-MAC D-blade achieved glottic visualisation significantly faster (8.2 s) compared to the Astra-Vue (13.7 s; p < 0.001).
  • Tube Delivery: Once the glottis was visualised, the Astra-Vue facilitated significantly faster tube placement (7.2 s) compared to the C-MAC (11.2 s; p = 0.012).
• Success Rates: Both devices demonstrated high efficacy. First-attempt success rates were 93.5% (Astra-Vue) and 90.0% (C-MAC; p = 0.671). Overall success rates were 96.7% and 100% respectively (p = 1.000).
• Glottic View and Difficulty: POGO scores were excellent (≥75%) in all patients, with no significant difference between groups. The distribution of intubation difficulty (MIDS) and the need for external laryngeal manipulation were comparable.
• Haemodynamics and Complications: Haemodynamic responses (changes in MAP and heart rate) were similar. Complications were minor and infrequent, consisting primarily of lip lacerations and one case of arytenoid oedema in the Astra-Vue group. No stylet-related injuries occurred in the C-MAC group, though the study noted the theoretical risk of such injuries with stylet use.
• Predictors: Regression analysis indicated that mouth opening was a significant independent predictor of total intubation time. Notably, the time to glottic visualisation was more sensitive to mouth opening in the Astra-Vue group (β = -1.249 s/mm) than in the C-MAC group (β = -0.343 s/mm).

Significance and Claims
The paper concludes that for adult patients without predicted difficult airways, the channelled Astra-Vue and non-channelled C-MAC D-blade offer comparable total intubation times and similarly high success rates. The study highlights a "trade-off" mechanism: the C-MAC allows for faster visualization of the glottis, while the Astra-Vue's channelled design accelerates the delivery of the endotracheal tube once the view is established.

The authors assert that the choice between these devices in routine clinical practice should be guided by operator familiarity and patient-specific anatomy, particularly mouth opening. They note that the Astra-Vue's integrated channel design may be more dependent on adequate oral access for insertion, whereas the C-MAC's slim, detached-screen design may be advantageous in patients with restricted mouth opening. The study also identifies specific failure modes for the channelled design (arytenoid obstruction and floppy epiglottis) that operators should anticipate.

The authors maintain a modest tone regarding their claims, acknowledging that the study was underpowered for low-frequency binary outcomes (such as failed intubation) and that the findings should not be extrapolated to patients with anticipated difficult airways. They emphasize that while the Astra-Vue eliminates stylet-related risks, the overall clinical equivalence in non-difficult airways suggests that neither device is universally superior.