In the field of airway management, no topic is more divisive than the merits of videolaryngoscopy. Proponents defend the technology and opponents assail it with equally valid arguments, and the differences in opinion are not purely ideological. These devices have their advantages and disadvantages. Videolaryngoscopes may be making things easier, but they are expensive, and there is concern regarding the loss of airway skills. Similarly, the McCoy blade has the ability to convert a difficult view into a slightly less difficult view, but at the cost of making an otherwise easy laryngoscopy more difficult.
Until Question 19 from the first paper of 2019, it has only ever come up once as an "identify this item" task in Question 26.3 from the first paper of 2009. The McCoy Blade has also made an appearance in Question 26.2 from the first paper of 2009. Thus far, the college has not made any mention of the classical Macintosh blade, presumably because it is too boring. For published literature on this subject, there are several good references. LITFL have a good overview of videolaryngoscopy. The 2014 article by Chemsian et al actually has an "advantages and disadvantages" section, which directly answers Question 19. Norris and Heidegger (2016) discuss the limitations of videolaryngoscopy in their BJA editorial.
Advantages of videolaryngoscopy
Arguments regarding education and communication
- You can show people what's happening. Airway anatomy can be visualised by junior team members, which prepares them for what they might expect to see when they are performing laryngoscopy themselves. Low et al (2008) used videolaryngoscopy to teach direct laryngoscopy with some degree of success. In reverse, direct laryngoscopy skills transfer well to videolaryngoscopy.
- The team can see what you're doing. The rapid response team sighs with relief as they all see the tube pass through the cords. Communication regarding difficulty is also made easier (i.e. the team leader can clearly see that you're having trouble).
- Direct laryngoscopy is dying anyway. The argument that videolaryngoscopy degrades the skills of direct laryngoscopy is similar to the argument that the printing press degraded the skills of calligraphy. Sure, you yourself might have trained in airway skills at the dawn of time, using the jawbone of an antelope as a laryngoscope, but as videolaryngoscopes become more available and their use becomes more widespread, it would be irresponsible for the training of junior medical staff to focus on obsolete devices and techniques.
Arguments regarding pragmatism
- It makes intubation easier. The ultimate quality of an intubation attempt is generally judged by whether or not the endotracheal tube ends up becoming endotracheal. Videolaryngoscopy improves the likelihood of a "successful" intubation in difficult intubation scenarios (Pieters et al, 2017) and unsorted critically ill patients (De Jong et al, 2014) as well as in general ward situations (Baek et al, 2018).
- It requires less skill. You are therefore less reliant on senior staff in the department. If you are a patient, your airway failure might be managed immediately and effectively by inexperienced junior staff, instead of having to wait for experienced seniors to arrive while your brain is stewing in hypoxia.
- It provides an official record. The laryngoscopy can be recorded for later review. When the boss ambles in at 9:30 the following morning, they can review the laryngeal oedema from the reintubation of the previous night. ENT specialists can see evidence of glottic damage without needing to perform laryngoscopy themselves, sparing the patient some trauma.
- It's not that expensive. Consider the public health cost of lifelong care for a patient disabled by a hypoxic brain injury in the wake of a preventable failed intubation. To speak nothing of the moral imperative to prevent such scenarios, the cost from purchase and maintenance of a videolaryngoscope would be covered several times over if that laryngoscope saves even one person from such an outcome during its entire operating lifespan.
Arguments regarding mechanical advantage
- It allows for a suboptimal position. In order to achieve a good view, it is not necessary to align the airway axes (oral-pharyngeal-laryngeal). This allows intubation to occur in scenarios where head and neck mobility is limited
- It allows informed assistance. Others are better able to manipulate the airway to improve your view. A blind BURP manoeuvre may actually degrade your view, but if the BURPer can see what they are doing, you are now working as a team.
- It should require less force; which should translate into less trauma and better tolerance. The upshot is the possibility of awake direct laryngoscopy, decreased mucosal trauma, less bleeding in patients with coagulopathy, less haemodynamic reflex responses to intubation and decreased induction agent requirements.
Disadvantages of videolaryngoscopy
Arguments regarding education and communication
- That's not what it looks like. Though airway anatomy is on display, the zoomed-in closeup view afforded by the videolaryngoscope is not the same as that afforded by the direct laryngoscope, and so it cannot be said to prepare junior staff for direct laryngoscopy. At this point there no studies to support videolaryngoscopy training for direct laryngoscopy outside of simulations (such as Low et al, 2008)
- The team are all watching what you are doing. The focus on the tiny webcam screen of the C-Mac takes focus off all the other tasks being performed by the intubation/resuscitation team, particularly the senior team leader who is anxiously aware of the potential need for them to step in to the role of airway technician (or cricothyroidotomist). The distraction may result in vital omissions (eg. nobody notices that the silenced monitor now displays VF). In short, it is not clear how staring at that screen is any better for communication than simply hearing the airway technician say "I'm in" or "I'm having trouble, can you have a look".
- Direct laryngoscopy will never die. The technique is "tried and tested" as only something with a hundred years of history can be. To argue that the new technique is clearly superior on the basis of only a decade of experience seems somewhat premature. Moreover, direct laryngoscopy remains the standard for routine intubation in anaesthesia, and over the course of one's anaesthetic career the vast majority of intubations will be performed with a direct laryngoscope which suggests that it is a skill worth maintaining.
Arguments from pragmatism
- The camera might get clogged with filth. The camera of the scope is a crucial failure point: the view may be obscured by secretions and blood on the camera, which will not resolve with suction. Or, the cameras may mist due to exhaled air. Or, high ambient light may make the video screen more difficult to see.
- The setup is expensive, and the components are often not disposable. The cost to a small department might be weighed against other priorities. What would you rather have, a fleet of videolaryngoscopes or an extra senior registrar? What will have a more direct positive effect on patient care?
- The maintenance if expensive and time-consuming. To sterilise equipment after use takes time, and there may be scenarios where the videolaryngoscope is out of commission for prolonged periods while waiting for the cleaning cycle to complete.
- It provides an official record. The laryngoscopy video, being on record, may now be used as a part of the argument against the airway technician if some sort of horrible problem ultimately develops which leads to medicolegal or disciplinary action. Those teeth in the video - they were clearly intact before the laryngoscopy, your honour.
- It is dangerous to describe it as the standard of care. There was a BJA editorial (Zaouter et al, 2014) which asked "why are videolarygnoscopes not used for all tracheal intubations?", suggested that "it is only a cost issue" and progressed to the blasphemy of "is it not time to integrate airway videos in the electronic charting?" The implication is that people who continue to routinely use direct laryngoscopy are not providing care at the gold standard, and if you are not posting your laryngoscopy videos to YouTube you are in dereliction of your duties. The flame war which followed in the comments section of this editorial suggests that the community of anaesthetists is currently not uniformly in favour of changing their standard of care to videolaryngoscopy.
- There are numerous devices to learn. Experience with the product of one manufacturer does not immediately guarantee the intuitive use of another device (by comparison, direct laryngoscopes are all essentially the same shape and once you're familiar with one you are familiar with them all).
Arguments regarding the supposed mechanical advantage
- Just because you can see it doesn't mean you can intubate it. Even though the glottis may be visualised without aligning the oral-pharyngeal-laryngeal axes, the ability of the operator to get the endotrachal tube into the vocal cords still requires some degree of alignment. Thus, there is no guarantee of success, even with a well-visualised glottis. You may be afforded an excellent view of your multiple failures.
- It should require less force but there is no evidence that it does. In fact, because the operator is hypnotised by the screen, the passage of airway equipment into the mouth and oropharynx is not directly observed. Dental and pharyngeal damage may result. Aziz et al (2008) reported a 1% rate of traumatic laryngoscopy, including vocal cord trauma, one tracheal injury, one trauma to the hypopharynx, one tonsillar perforation, and two dental injuries (21 cases from a series spanning 2 years).
The McCoy Blade
The McCoy Articularing Tip Laryngoscope, or the levering laryngoscope as McCoy himself called it (he did not name it after himself).
Instead of relying on brute force to elevate the epiglottis, the airway enthusiast can squeeze the lever and elevate it gently. It is particularly useful in situations where the larynx is very anterior.
The disadvantage is, sometimes the epiglottis can get caught in the hinge.
Cook and Tuckey published a nice article in Anaesthesia in 1996, comparing the McCoy with the conventional Mac. It turned out that the McCoy blade in the "neutral" position actually made laryngoscopy more difficult. In the "best" position, the views achieved by both blades were similar in the vast majority of patients. The McCoy showed itself as the clear superior in truly difficult patients, where conventional laryngoscopy failed completely (i.e. it converted Grade IV views into Grade IIIs and IIs).