Do not stop teaching anaesthesia trainees direct laryngoscopy

Abstract

Videolaryngoscopy is superior to direct laryngoscopy in difficult intubation and is quicker to master. Some anaesthesiologists have advocated for videolaryngoscopy as the primary tool for endotracheal intubation. We argue that while prioritising videolaryngoscopy allows earlier success and skill retention for novices and doctors who only occasionally intubate, anaesthesiology residents must achieve proficiency in both techniques since not only do they have ample opportunity, but there are situations in which direct laryngoscopy can be either a rescue or even the primary technique.

A 2022 systematic review has shown that videolaryngoscopy of all designs likely reduces the rate of failed intubation, results in a higher rate of first-attempt successful intubation with improved glottic view, and provides a safer risk profile compared with direct laryngoscopy for all adults undergoing endotracheal intubation. ¹ Videolaryngoscopy has also been shown to improve the first-attempt intubation success rate in children with anticipated difficult airways, neonates and infants.^2–5 Hansel and colleagues’ systematic review provides insights regarding the relative performance of videolaryngoscopy compared with direct laryngoscopy. ¹ As compared with direct laryngoscopy, videolaryngoscopy with standard geometry blades (i.e. VL-Macintosh) and channelled blades likely reduce the rates of hypoxaemic events with intubation. Furthermore, videolaryngoscopy with hyperangulated blades likely reduces the rate of oesophageal intubation and failed tracheal intubation in anticipated difficult airways compared with direct laryngoscopy. In infants, the use of standard geometry blades (i.e. Miller blade) with a video screen visible to the instructor significantly improves the intubation success of inexperienced operators as compared with direct laryngoscopy. ³

Citing the many superior aspects of videolaryngoscopy over direct laryngoscopy, some highly respected anaesthesiologists have advocated for videolaryngoscopy to be the primary tool for endotracheal intubation.^6,7 Apparently, many Danish ⁸ (and other ⁹ ) anaesthetic departments have gone further with prioritising videolaryngoscopy such that some younger anaesthesiologists have never learned (or have not had enough practice) to use direct laryngoscopy. For example, a recent survey of Irish anaesthesia trainees carried out in January 2023 showed that 40% of them avoid direct laryngoscopy for all intubations, and only 56% are confident in using direct laryngoscopy for critically ill patients. ¹⁰

Anaesthesiologists typically intubate a dozen or more patients every week. There are plenty of opportunities to become proficient in both videolaryngoscopy and direct laryngoscopy. The two techniques, therefore, need not to be mutually exclusive. We believe that using videolaryngoscopy to the total exclusion of direct laryngoscopy is unwise for anaesthesiologists in general, and for anaesthesiology trainees in particular, and might contribute to skill degradation with direct laryngoscopy.

Uncommonly, videolaryngoscopy can be difficult, or even fail, for many of the same reasons that make direct laryngoscopy difficult: the presence of airway pathology from previous surgery and/or radiation, a local mass, reduced cervical spine motion, ¹¹ small mouth opening, obesity, large tongue, soiled hypopharynx, etc. As airway experts, anaesthesiologists must be proficient with all airway techniques. If our trainees exclusively use videolaryngoscopy, they might never get to develop their direct laryngoscopy skills adequately and are left with no rescue plan in the case of videolaryngoscopy or flexible intubating scope unavailability or failure.

Griesdale et al. performed a meta-analysis of 12 randomised controlled trials (RCTs) and quasi-RCTs. ¹² In experienced hands using videolaryngoscopy, there were 108 (13.5%) intubation failures out of 799 attempts, a rather high percentage by current standards. In the same report, a meta-analysis of two RCTs reporting on intubation results by non-experts revealed that there were seven (5.8%) failures out of 120 attempts using the Glidescope®. What happens when videolaryngoscopy fails? In 60 failed first and subsequent attempts by videolaryngoscopy, Aziz et al. found that anaesthesiologists turned to (and succeeded with) direct laryngoscopy in 28 of the cases. ¹³ There is evidence that intubation time by experts might be slightly shorter with direct laryngoscopy,^11,12 which might have safety implications in ‘full-stomach’ patients undergoing rapid sequence intubation.

Arguably, there might be clinical circumstances where the confident application of direct laryngoscopy might be essential. Videolaryngoscopy equipment might not be as readily available for paediatric and neonatal patients as compared with adults, underscoring the importance of developing competence in performing direct laryngoscopy in these populations. Additionally, studies have suggested that if a foreign substance (e.g. food, toy block or vaping piece) is present in the hypopharynx requiring forceps to remove, direct laryngoscopy is superior to videolaryngoscopy. ¹⁴ In one-lung ventilation in small children, it is not clear whether videolaryngoscopy will make inserting a soft bronchial blocker into the trachea (a necessary step prior to inserting the endotracheal tube) easier or more difficult. In the correct clinical scenario, anaesthesia trainees who develop competence with direct laryngoscopy might find themselves able to secure an airway more rapidly, reducing the likelihood of airway-related complications.^11,12

Even in high-income countries, videolaryngoscopes are not present on every ward. In one recent Irish survey, only 21% of the intubations on the hospital ward had timely access to a videolaryngoscope. ¹⁰ Imagine an actively vomiting hypoxic patient with no anatomic features suggesting difficult intubation – which laryngoscope would we reach for, assuming that a videolaryngoscope is immediately available (which it sometimes is not)?

Some advocates of videolaryngoscopy replacing direct laryngoscopy liken it to internal jugular vein cannulation under ultrasound (US) guidance. ¹⁵ These beliefs are flawed because US-guided central line placement almost never fails, and if it does, it will not be due to anything that a landmark approach can rectify. A better analogy would be laparoscopic surgery. While a laparoscopic approach has well-established advantages over, say, an open appendicectomy, proficiency in both techniques is mandatory upon completion of a surgical residency program as surgeons occasionally need to use the latter as a last (and sometimes, the primary) approach. Hypothetically, if an RCT had been done comparing laparoscopic and open appendicectomy or most other forms of abdominal surgery, the superiority of the laparoscopic approach would be almost overwhelming by most metrics, yet no surgeon would ever advocate for the abolition of the open approach in residency training and in clinical practice. The same principle should apply to anaesthesiology trainees and anaesthesiologists in general when it comes to interpreting direct laryngoscopy versus videolaryngoscopy studies.

The educational emphasis for our anaesthesiology trainees should be on understanding the indications, advantages and limitations of direct versus indirect laryngoscopy. This includes an in-depth study of blade design (standard versus hyperangulated geometry) as well as the configurations of videolaryngoscopes (steering versus channelled). Furthermore, we should focus our efforts on using a hybrid approach, in which the use of videolaryngoscopy in airway teaching can enhance the development of skills important for direct laryngoscopy.

A practical approach to balancing videolaryngoscopy and direct laryngoscopy training in anaesthesia may include the use of VL-Macintosh to guide the development of skills important to direct laryngoscopy. The video screen can be covered or turned away from the learner, where the teacher can help to provide guidance using the video screen while the learner performs direct laryngoscopy with the VL-Macintosh blade (e.g. engagement of the hyoepiglottic ligament). Feedback can also be given regarding how learners troubleshoot common problems such as an anterior glottic view and the application of ‘backwards, upwards, and rightward pressure’, and tracheal tube impingement, skills essential to the practice of direct laryngoscopy.

Oppositely, confidence with the mechanics of laryngoscopy and repeated tracheal intubation using a stylet or bougie can be reinforced with the use of a shared video screen on the VL-Macintosh as an initial approach in bridging to training in direct laryngoscopy. Trainees can then be instructed to apply the same principles when performing direct laryngoscopy using the same blade. Although the use of standard geometry blades does not afford the same degree of glottic view as hyperangulated blades, it is often sufficient to identify relevant anatomy and offer the ability to quickly adapt between videolaryngoscopy and direct laryngoscopy approaches to tracheal intubation.

Development of competence with direct and indirect laryngoscopy with VL-Macintosh will help to protect anaesthesia trainees from rare problems with intubation somewhat unique to videolaryngoscopy: moisture and/or fluids obscuring the lens, inability to advance the endotracheal tube into the trachea because of the steep incident angle, and delays in positioning the videolaryngoscope centrally in the mouth, camera failure, etc. These problems might be compounded by airway trauma and physiologic derangements resulting from previous unsuccessful attempts at tracheal intubation by non-anaesthesia airway operators.

All airway operators must have a primary as well as a backup plan for airway management determined in advance. This is particularly true with anaesthesiologists who must react to events within seconds. Not having used videolaryngoscopy as a primary or rescue technique is a medicolegal liability in airway mishaps. We would argue that to a lesser extent, not having direct laryngoscopy as a backup plan for those rare videolaryngoscopy failures also puts the anaesthesiologist and the patient in a vulnerable situation.

Our position on this subject is different when it comes to non-anaesthetists. While it might be ideal for non-anaesthesia acute care physicians to also be proficient in videolaryngoscopy and direct laryngoscopy, in reality, they might need to prioritise videolaryngoscopy, even if it is to the total exclusion of direct laryngoscopy. For example, US emergency physicians working in urban trauma centres intubate an average of 28.9 times a year (just over once every two weeks). ¹⁶ Twenty-five percent of rural physicians in one American study intubated less than five times per year. ¹⁷ In 21% of US medical intensive care units, pulmonary and critical care Fellows were never or rarely responsible for intubation. ¹⁸ Some internal medicine residents finish their training with no more than several intubation attempts. They need a technique that gives better and earlier success and might need to focus on one to retain the skill. Dr Ron Walls, a prominent emergency physician with a special interest in airway management, once wrote, ‘I will unequivocally state that it is wrong for people to practise direct laryngoscopy in 2012.’ ¹⁹

At our institution, non-anaesthesia airway operators come to the operating theatre to learn endotracheal intubation. Studies have shown that the videolaryngoscopy learning curve is faster, and early intubation success rate is much higher, especially in less experienced hands.^20,21 For them, prioritising videolaryngoscopy from the start is sensible as it has a much faster learning curve. Having a shared video screen can also facilitate teaching. Airway trainees are more confident when, by the end of their short anaesthesia rotation, they have successfully intubated at least once or twice with videolaryngoscopy before facing the real world, as opposed to finishing their brief rotation not able to intubate at least once with direct laryngoscopy, a rather unsatisfying experience not just for them but for us too. For medical students, their positive experience might even influence their career direction to our favour.

In summary, we do not disagree with the suggestion that anaesthesiologists should opt for videolaryngoscopy as the primary tool, but only after we have already become extremely efficient in both. In short, we are of the opinion that we should teach anaesthesia residents videolaryngoscopy and direct laryngoscopy and prioritise videolaryngoscopy for non-anaesthesia residents.