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Three Part Question

In [patients with anticipated difficult airway requiring endotracheal intubation], does the [use of hyperangulated videolaryngoscopy blades] result in [non inferior performance to McIntosh blades] ?

Clinical Scenario

A 50-year old obese man with a history of severe shellfish allergy is rushed into the resuscitation room for sudden onset of shortness of breath. On examination he had marked face and tongue swelling, stridor and his oxygen saturation remained ~75% despite given 15L/min oxygen via a face mask. You are the only trainee available at the moment and anaesthesia on call takes another 5-10 minutes to arrive. With the anticipation of difficult airway, you wonder if the use of a hyperangulated laryngoscopy blade would increase your first-attempt success rate of videolaryngoscopic intubation.

Search Strategy

PubMed database was searched for studies published between 2016 and 2025.

Search keyword (((hyperangulated) AND (intubation)) AND (MacIntosh))

Studies involving the use of mannequin, cadavers, practice models, subjects being paediatric patients, were excluded.

Search Outcome

This search strategy identified 59 relevant studies from PubMed. Majority was excluded from the title and reviewing the abstracts. Further papers were removed which included duplicates, papers which had no full text available. After full text review, papers which did not fully address the question were excluded. A total of 4 papers were left.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Jan Hansel, Andrew M Rogers, Sharon R Lewis, Tim M Cook, Andrew F Smith 2022 United Kingdom	26,149 adult patients from 219 RCTs, three quasi‐RCTs undergoing tracheal intubation by laryngoscopy performed with either a VL or a Macintosh direct laryngoscope (DL) in any clinical setting. Most studies recruited adults undergoing elective surgery requiring tracheal intubation. 21 studies recruited participants with a known or predicted difficult airway, and an additional 25 studies simulated a difficult airway. One hundred and two studies with 11,857 participants included a hyperangulated VL as one of the comparisons.	Systematic literature review of 219 RCTs and 3 quasi-RCTs	Rate of failed intubation, rate of oesophageal intubation, hypoxaemia, successfulirst attempt, dental trauma, Cormack-Lehane grade, time for tracheal intubation.	Hyperangulated VLs probably reduce rates of failed intubation (RR 0.51, 95% CI 0.34 to 0.76; 63 studies, 7146 participants) and oesophageal intubation (RR 0.39, 95% CI 0.18 to 0.81; 14 studies, 1968 participants). In subgroup analysis, hyperangulated VLs was noted to be more likely to reduce failed intubation when used on known or predicted difficult airways (RR 0.29, 95% CI 0.17 to 0.48; P = 0.03 for subgroup differences; 15 studies, 1520 participants). It may also increase rates of success on the first intubation attempt (RR 1.03, 95% CI 1.00 to 1.05; 66 studies, 8086 participants; low‐certainty evidence) and the glottic view is probably also improved (RR 0.15, 95% CI 0.10 to 0.24; 54 studies, 6058 participants; data for Cormack‐Lehane grade 3/4 views; moderate‐certainty evidence). In conclusion, hyperangulated VLs is noted to reduce rates of oesophageal intubation, failed intubation and Cormack‐Lehane grade 3 and 4 views with moderate certainties.	No relative weaknesses found – It is a comprehensive study expanding on a previous review with inclusion of different blade constructs.
C. C. de Carvalho, D. M. da Silva, V. M. Lemos, T. G. B. dos Santos, I. C. Agra, G. M. Pinto, I. B. 2021 Brazil	179 RCTs with the inclusion criteria of human patients from any population (e.g. elderly patients, neck immobilisation, pregnant women, obese patients, general population, etc.) aged ≥16 y. 16,478 patients undergoing endotracheal intubation in 141 studies were included in the network meta-analysis for failed intubation, evaluating for 16 different devices.	Systematic review and meta-analysis of RCTs	Primary outcome is the risk of failed intubation with the devices. Secondary outcomes were: failed first intubation attempt; failed intubation within two attempts; difficulty of intubation; percentage of glottic opening seen; difficult laryngoscopy.	Videolaryngoscopes (VLs) were at lower risk of failed intubation than the Macintosh direct laryngoscope, with a risk ratio (95%CI) of 0.41 (0.29–0.58); p < 0.000. Videolaryngoscopes also significantly reduced the risk of difficult laryngoscopy compared with the Macintosh direct laryngoscope, with a risk ratio (95% CI) of 0.24 (0.19–0.31); p < 0.0001ate of successful first attempt intubation with the Macintosh direct laryngoscope is around 89.6%, whereas for videolaryngoscopes, it is around 94%. Four videolaryngoscopes (C-MAC, McGrath MAC, Airtraq and Glidescope) were statistically significantly less likely to lead to failed first intubation attempt compared with the Macintosh direct laryngoscope. They also had a statistically significant higher percentage of glottic opening scores compared with the Macintosh direct laryngoscope.	This study is a network meta analyses of VLs performance against MacIntosh blades, of which most of the studies included were not solely selected for the comparison between hyperangulated blades and MacIntosh blades, although its network graph does suggest an array of hyperangulated blade options such as C-MAC D, Airtraq, McGrath MAC were adequately represented.
2024 Germany	2540 adult patients scheduled for elective head and neck surgery for eligibility who has undergone orotracheal intubation, of which 182 patients with expected difficult airways.	Single-centre, single-blind randomized controlled trial	Percentage of glottic opening (POGO) (2) Glottic view (with subcomponents of each anatomical structure) (3) Difficulty of videolaryngoscopic intubation (4) Time of intubation (5) Airway-related adverse events	Hyperangulated blades performed better than MacIntosh C-MAC blades in the following areas with significance (p<0.001) (1) higher percentage of glottic opening (POGO) (2) better glottic view (3) higher rate of first attempt success and without complications (4) shorter intubation time. It is not significantly different in terms of airway complications and time to first successful intubation. It was also notable that in patients allocated to the Macintosh videolaryngoscopy group, the first-line technique failed in 12 patients (13%); in all cases hyperangulated videolaryngoscopy was used successfully as rescue technique.	This is a single centre RCT, with the evaluation of only one model of hyperangulated blade (C-MAC D). One must also note that one of the primary outcomes, the glottic view, is rated on a visual analogue scale by multiple assessors.
Zhang J, Tan LZ, Toh H, Foo CW, Wijeratne S, Hu H, Seet E. 2022 Singapore	210 patients of ASA physical status I to III, aged 21 to 80 years old, undergoing general anesthesia requiring tracheal intubation.	Two-centre, single-blind randomized controlled trial	Primary outcome: first-attempt tracheal intubation success. Secondary outcomes: (1) overall successful intubation within 2 attempts or 120 s (2) time to intubation (3) glottic view obtained and (4) intubation-related complications.	First-attempt success rates insignificantly different between McGrath X blades (MGX) and MacIntosh C-MAC blade (CM): 71.4% in the MGX group vs. 79.0% in the CM group (p = 0.26) The Cormack & Lehane laryngeal grade was superior in the MGX group compared to CM group (Grade I: MGX 44%, CM 23%; Grade II: MGX 53%, CM 45%; Grade III: MGX 3%, CM 32%; p < 0.001) However, the median time to intubation using the MGX was longer than the CM [MGX 55.5 s (42.1-78.3), CM 43.8 s (38-55.3); p < 0.001] In summary, McGrath X-blade demonstrated a more superior glottic views but conferred no advantage over the C-MAC. McGrath-X blade, however, conferred no advantage over C-MAC blades in terms of first-attempt success rate. It also requires with a longer median time to intubation compared to the C-MAC blade.	It is a two-centre study and like Köhl et al, evaluated one model of laryngoscope blade (McGrath-X blade). This study also excluded patients with predicted difficult airway, pre-existing dental risks, hence it is lacking in terms of understanding the performance of hyperangulated blades in scenario of anticipated difficult airway.

Comment(s)

Hyperangulated videolaryngoscopes (HVLs) are hypothesized to improve glottic view and first-attempt success. In the current body of research, HVLS are gaining increased attention in scoping reviews in the recent decade, as a non-inferior blade construct for overcoming difficult intubation, among the array of direct and videolaryngoscopes available commercially. The 4 articles included (2 meta-analysis/ systematic review and 1 RCT) are selected for their inclusion of head-on comparison of hyperangulated VL with the classic MacIntosh-type blades. HVLs demonstrated better first-attempt success rate, better glottic view. There is no significant advantage in terms of intubation outcome such as hypoxemia, airway-related complications so far. Future aspects to explore would welcome studies selecting cases of anticipated difficult airway, to better understand the hyperangulated HVLs in an AED setting, where prior airway assessment for identifying these individuals is usually not available.

Clinical Bottom Line

HVLs are non-inferior to conventional MacIntosh style blades in adult endotracheal intubation. It is also superior in improving glottic view and securing first-attempt intubations. Its performance in difficult airway individuals and performance differences between different models and blade constructs of HVLs is underrepresented by current studies.

References

1. Jan Hansel, Andrew M Rogers, Sharon R Lewis, Tim M Cook, Andrew F Smith Videolaryngoscopy versus direct laryngoscopy for adults undergoing tracheal intubation Cochrane Database of Systematic Reviews 2022 Issue 4. Art. No.: CD011136.
2. C. C. de Carvalho, D. M. da Silva, V. M. Lemos, T. G. B. dos Santos, I. C. Agra, G. M. Pinto, I. B. Videolaryngoscopy vs. direct Macintosh laryngoscopy in tracheal intubation in adults: a ranking systematic review and network meta-analysis Anaesthesia 77(3), 326-338.
3. Köhl V, Wünsch VA, Müller MC, Sasu PB, Dohrmann T, Peters T, Tolkmitt J, Dankert A, Krause L, Zöllner C, Petzoldt M Hyperangulated vs. Macintosh videolaryngoscopy in adults with anticipated difficult airway management: a randomised controlled trial. Anaesthesia 79(9), 957-966.
4. Zhang J, Tan LZ, Toh H, Foo CW, Wijeratne S, Hu H, Seet E. Comparing the first-attempt tracheal intubation success of the hyperangulated McGrath X-blade vs the Macintosh-type CMAC videolaryngoscope in patients with cervical immobilization: a two-centre random J Clin Monit Comput 36, 1139–1145 (2022).