Association between video laryngoscope blade geometry and first-pass success during prehospital intubation: a...

Endotracheal intubation (ETI) is a cornerstone of advanced prehospital airway management but remains associated with considerable procedural risk, particularly when multiple intubation attempts are required. First-pass success (FPS) is an established quality indicator because repeated attempts increase the risk of hypoxaemia, aspiration, oesophageal intubation, haemodynamic instability and cardiac arrest [1-4]. Although video laryngoscopy (VL) is recommended by international airway guidelines [5-8], evidence regarding the optimal blade geometry for prehospital airway management remains limited. We investigated the association between video laryngoscope blade geometry and FPS in a physician-staffed helicopter emergency medical service (HEMS).

We conducted a prospective bicentric observational study at two German physician-staffed HEMS bases between January 2017 and December 2019. Consecutive prehospital ETIs performed using the C-MAC^® PM video laryngoscope were prospectively documented. Blade selection was at the discretion of the treating physician. The primary outcome was FPS. Secondary outcomes included glottic visualisation, intubation duration, number of attempts, airway-related adverse events and video laryngoscopy-associated technical problems.

A total of 283 video laryngoscopic intubations were analysed. Overall first-pass success (FPS) was 71.0% (201/283). Blade-specific FPS rates were 72.0% for Macintosh size 3, 72.6% for Macintosh size 4 and 61.9% for the hyper angulated D-Blade, without significant differences between blade geometries (p = 0.601). Adequate glottic visualisation (Cormack-Lehane grade I-II) was achieved in 96.8% of patients. Mean intubation duration was 42.5 ± 34.2 s. Airway-related adverse events occurred in 5.7% of patients and video laryngoscopy-associated technical problems in 12.6%. In an exploratory multivariable analysis, blade geometry was not independently associated with FPS, whereas difficult laryngoscopy conditions, poor glottic visualisation and technical problems were associated with failed first-pass intubation.

Video laryngoscopy provided excellent glottic visualisation irrespective of blade geometry. Neither univariable nor exploratory multivariable analyses demonstrated an independent association between blade geometry and first-pass success. Instead, difficult airway conditions, poor glottic visualisation and video laryngoscopy-associated technical problems appeared to exert a greater influence on procedural success. Given the observational design and limited number of hyper angulated blade intubations, these findings should be regarded as hypothesis-generating and require confirmation in larger prospective multicentre studies incorporating standardised difficult-airway assessment.