Anaes · Airway management
Video laryngoscopy — channelled vs non-channelled devices, GlideScope, McGrath, C-MAC, and the evidence versus direct laryngoscopy
Also known as Video laryngoscopy · Videolaryngoscopy · GlideScope · McGrath laryngoscope · C-MAC · Airtraq · Pentax AWS · Hyperangulated blade · Channelled video laryngoscope
Video laryngoscopy is the technique of laryngoscopy in which a camera mounted at the tip of the blade transmits an indirect view of the glottis to a monitor, dissolving the geometric constraint — the alignment of the oral, pharyngeal and laryngeal axes — that direct laryngoscopy imposes. The framework rests on six ideas: the principle of the indirect view from a tip-mounted camera on a hyperangulated blade; the two families of device — the channelled (Airtraq, Pentax AWS) that guide the tube through a built-in channel, and the non-channelled or hyperangulated (GlideScope, McGrath, C-MAC) that provide the view but leave tube delivery to the operator; the distinguishing features of each named device; the advantages over direct laryngoscopy — a better Cormack-Lehane view, no need to align the axes, less cervical-spine movement, a shared view for teaching and supervision, and recording; the disadvantages — fogging and secretions, the defining 'can see but cannot tube' failure of the non-channelled device, screen and power dependence, cost, and a learning curve; and the evidence, which reliably shows an improved glottic view but a conditional effect on outcome — large in the predicted difficult airway, modest in the routine case, and dependent on operator training and on the optimisation of the pharmacological conditions. Anchored to contemporary evidence on the optimisation of video laryngoscopy intubating conditions, the role of video laryngoscopy in infants, the soiled airway, and the airway management of neuromuscular disease.
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- The defining pitfall of the non-channelled device is 'can see but cannot tube' — a full, centred glottic view on the screen does not guarantee that the tube can be delivered to it. The tube must be steered around the hyperangulated corner with a pre-shaped hockey-stick stylet, introduced from the right corner of the mouth; a tip that catches anteriorly or in the vallecula is fixed by withdrawing, reshaping the stylet and re-advancing, not by repeating a failing delivery.
- Fogging, blood or secretions can blind the tip camera entirely. The camera sits at the mucosa, so where a direct laryngoscope looking from a distance may still see, the video laryngoscope can be rendered useless. Carry an anti-fog wipe or saline flush, and always have a direct laryngoscope immediately available for the bleeding or vomiting airway.
- The hyperangulated video laryngoscope is screen-dependent and cannot be used without power. A flat battery, a disconnected cable or a failed monitor converts it into a poor direct laryngoscope — the acute blade angle is not designed for a direct view, except in the dual-role devices (the C-MAC and the McGrath MAC). Check the battery and the image before induction, every time.
- The technique is a midline approach watching the screen, not the right-sided tongue sweep of direct laryngoscopy. A right-sided sweep distorts the hyperangulated blade's view, and the operator who delivers the tube while looking into the mouth has abandoned the one advantage the device provides.
- A substantial proportion of difficult intubations remain unanticipated — the preoperative airway assessment predicts difficulty imperfectly, and the airway that looked easy on the ward can still fail in theatre. The video laryngoscope must be immediately available for every induction, and the operator must be competent in its use before the crisis in which it is needed.
Meet the patient
A 55-year-old with a short neck, a beard, and a Mallampati III view is booked for elective cholecystectomy. On ward airway looked easy, but in theatre the direct laryngoscope gives a grade III view — the epiglottis, nothing more.[5]
You reach for the video laryngoscope. The camera at the blade tip sees around corner direct blade cannot, and the cords appear full on the screen. The question now is whether you can deliver the tube to them — and that is a separate skill.[1]
References8ShowHide
- [1]Uzun DD, et al. Direct- versus video laryngoscopy during suction assisted laryngoscopy and airway decontamination (SALAD): A randomized controlled simulation study Sci Rep, 2026.PMID 42362759
- [2]No author listed. Video Laryngoscopy vs. Direct Laryngoscopy for Infants Anesth Analg, 2026.PMID 42307927
- [3]Flynn SG, et al. Complementary views: addressing blind spots in the direct versus video laryngoscopy debate BMJ Paediatr Open, 2026.PMID 42336796
- [4]Ipsen EO, et al. Remifentanil Versus Rocuronium for Optimising Video Laryngoscopy Assisted Tracheal Intubation-The ROCVIDEO Trial Protocol Acta Anaesthesiol Scand, 2026.PMID 42304626
- [5]Kitsiripant C, et al. Mismatch Between Preoperative Airway Assessment and Unanticipated Difficult Tracheal Intubation: A Retrospective Case-Control Study Healthcare (Basel), 2026.PMID 42354478
- [6]Black KM, et al. Anesthesia Care, Complications, and Airway Management for Patients With Spinal Muscular Atrophy: A Retrospective Chart Review From a Quaternary Children's Hospital Anesth Analg, 2026.PMID 42363899
- [7]Lewis SR, et al. Videolaryngoscopy versus direct laryngoscopy for adult patients requiring tracheal intubation. Cochrane Database Syst Rev, 2016.PMID 27844477
- [8]Frerk C, et al. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth, 2015.PMID 26556848