A Model to Predict Difficult Airway Alerts After Videolaryngoscopy in Adults with Anticipated Difficult Airways – the VIDIAC Score

K. Kohse, H. K. Siebert, P. B. Sasu et al.

Anaesthesia 2022; 77, 1089-1096 https://doi.org/10.1111/anae.15841

Aim of Study

  • Develop a model to classify the difficulty of videolaryngoscopic tracheal intubation

Design and Location

  • Hamburg; Observational study


  • Patient selection: Adults over 18 years old, undergoing ENT or OMFS between 1st April 2019 – 3rd April 2020 who were expected difficult airway management and underwent tracheal intubation aided by videolaryngoscopy (C-MAC)
  • 374 Anaesthetics in 320 participants (400 Anaesthetics eligible)
  • Anaesthetist and two observers independently assessed intubation-related characteristics during/directly following intubation

Primary outcome

  • Whether Anaesthetist expected future videolaryngoscopic tracheal intubations to be difficult and issued ‘difficult airway alert’ after videolaryngoscopy

Secondary outcomes

  • Compare the discrimination of VIDIAC and Cormack-Lehane classifications for difficult airway alerts
  • Assess the discrimination of the model for transition to hyperangulated blade


  • Fleiss’ to calculate agreement between anaesthetist + 2 observers ratings of each factor before model developed
  • Developed multivariable prediction model
  • 100,000 random forest analysis decision trees to select variables for the model
  • Calculated Gini impurity to quantify importance of intubation related variables to correctly classify patients with an alert
  • Lasso regression for variable selection, model development & internal validation


  • Anaesthetists issued airway alerts after 183/374 (49%) tracheal intubations
  • Produced a model with variables independently associated with issuing an alert:vidiac-score
  • VIDIAC score discriminated participants more or less likely to have secondary laryngoscopy with hyperangulated blades
  • Cormack-Lehane classification indicated less discrimination than the VIDIAC score

Limitations from the Study

  • Reproducibility of results – single-center, specific patient group & surgeries
  • Small sample size – 320 patients
  • Anaesthetic experience ranged from 1month – 14 years
  • Observers assessments truly ‘independent’
  • Score validated for use with C-MAC only

Discussion from journal club

  • Cormack-Lehane classification not validated for use with videolaryngoscopy
  • Need to document findings on videolaryngoscopy and ease of intubation – including type of videolaryngoscope and blade used
  • Mixed opinions on whether a specific scoring system is necessary
  • Most felt VIDIAC scoring system not especially ‘simple’

Summary by Dr K Edgerton. Journal Club Meeting 3 Nov 2022.

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