Accuracy, intra- and inter-rater reliability of three scoring systems for the glottic view at videolaryngoscopy

Abstract

SummaryAn accurate and reproducible recording of laryngoscopic view at tracheal intubation is an important aspect of anaesthetic practice. Unlike direct laryngoscopy, in which the view achieved by the line of sight directly relates to the ease of intubating the trachea, videolaryngoscopy can create a situation in which the view is good, but intubation difficult or impossible. Communicating this to a subsequent anaesthetist is important. We compared three scoring systems: Cormack and Lehane; POGO (percentage of glottic opening); and the Fremantle score, as used by 74 critical care doctors rating 30 anonymised videos of videolaryngoscopic intubations. Accuracy (degree of agreement of score with an expert panel assessment) was higher for POGO (75.5%) and the Fremantle score (73.9%) than for Cormack and Lehane (65.4%; p < 0.001). Intra-rater reliability (mean free marginal Kappa for ordinal scores and mean Cronbach's Alpha for continuous score) was higher for Fremantle score (0.796) and Cormack and Lehane (0.773) than POGO (0.693). Inter-rater reliability for Fremantle score (0.618) and POGO (0.614) were similar and higher than the interrater reliability of Cormack and Lehane 0.464 (p < 0.001). The higher accuracy and inter-rater reliability of POGO and the Fremantle score suggest they are preferable to Cormack and Lehane for use when documenting videolaryngoscopy. The additional information about ease of intubation conveyed by the Fremantle score may support its routine use in recording videolaryngoscopic intubation.

Nasotracheal intubation over a bougie vs. non‐bougie intubation: a prospective randomised, controlled trial in older children and adults using videolaryngoscopy

“…The two groups did not differ in terms of age, sex, BMI, mouth opening, neck extension, degree of retrognathia, Mallampati grade, the presence of nasal or oral anatomical abnormalities or best glottic view (Cormack and Lehane). Although glottic views are likely better described by other scoring systems [19], Cormack and Lehane grading was used due to provider familiarity. Learners who performed the intubations were primarily anaesthesia residents, of whom the majority were in their first year of clinical anaesthesia training.…”

Investigator-initiated, multicentre, open-label, two-arm, randomised controlled trial comparing intubating conditions in 25° head-up position and supine: the InSize25 study protocol

“…Indeed, Cormack-Lehane grade II can correspond to a view of almost the entire glottis or to only a tiny part of it, and so cannot serve predict easy or difficult intubation 24. Laryngoscopy attempts, use of external laryngeal manipulation and use of ancillary equipment are also reported in order to concretely describe the ease of intubation assessed, for example, by the Fremantle score in O’Loughlin et al 15. The laryngoscopy attempts was not chosen as the primary outcome because we doubted that it would make a significant difference with this outcome as most of intubation requires only one laryngoscopy.…”

“…Here, then, the choice of the better view captured to establish the POGO score is left to the anaesthetist incharge of the direct laryngoscopy who is unblinded to the allocation group. Regarding the use of videolaryngoscopy, the laryngeal exposure score can differ between direct laryngoscopy and videolaryngoscopy: in direct laryngoscopy, the view achieved by the line of sight correlates directly to the ease of intubating the trachea, as videolaryngoscopy can create a situation in which the view is good but intubation is difficult or impossible 15. This type of system was not included in the InSize25 trial design in order to ensure better feasibility among multiple centres.…”

“…Although indirect laryngoscopy by an external anaesthetist (blind to the patient’s position) using a videolaryngoscope connected to a smartphone to determine the intubation score could have been proposed as an option to ensure anaesthetist blinding, this type of system setup was not included in the trial design in order to ensure better feasibility among multiple centres. Furthermore, the laryngeal exposure score can differ between direct laryngoscopy and videolaryngoscopy, and the videolaryngoscopy can create a situation in which the view is good but intubation is difficult or impossible 15. Here we wanted to be close to real-world clinical conditions, and the videolaryngoscope is mainly applied as a rescue device (probably too expensive for routine use).…”

S‐shaped tracheal tubes for videolaryngoscopy

“…Even though the use of videolaryngoscopy is associated with an improved view of the glottis, the process of placing a tracheal tube can take longer and be more difficult . In the context of paediatric intubation with an unchannelled videolaryngscope, we have found that adding lateral curvature of the distal tube to proximal anterior curvature using a stylet creates an S shape, enabling more precise manipulation of the tracheal tube in all three dimensions and easier placement (Fig.…”