JC – Video Laryngoscopy vs Direct Laryngoscopy for Tracheal Intubation of Critically Ill Adults

Estimated reading time: 8 minutes

This is not a new debate: the wonderful and much-missed Dr John Hinds gave a fantastic pitch seven years ago at a SMACC conference on the continued use of direct laryngoscopy (DL) for pre-hospital intubations.

In 2015 a meta-analysis was published^​1​. The authors concluded that video laryngoscopy (VL) did not increase intubation success. We know that intubating a critically unwell patient is a high-stakes procedure. With the golden rule of getting everything optimised to maximise the chances of orotracheal intubation on the first attempt, the use of a video laryngoscope has often been seen as a ‘part of the package’ for increasing intubation success. This paper published in the NEJM researches this further^​2​.

As always, we recommend you read the full paper yourself (or at the very least the abstract below) to draw your own conclusions. Our thoughts on this really interesting trial are below.

The Abstract -Video versus Direct Laryngoscopy for Tracheal Intubation of Critically Ill Adults^​2​

BACKGROUND: Whether video laryngoscopy as compared with direct laryngoscopy increases the likelihood of successful tracheal intubation on the first attempt among critically ill adults is uncertain.
METHODS: In a multicenter, randomized trial conducted at 17 emergency departments and intensive care units (ICUs), we randomly assigned critically ill adults undergoing tracheal intubation to the video-laryngoscope group or the direct-laryngoscope group. The primary outcome was successful intubation on the first attempt. The secondary outcome was the occurrence of severe complications during intubation; severe complications were defined as severe hypoxemia, severe hypotension, new or increased vasopressor use, cardiac arrest, or death.
RESULTS: The trial was stopped for efficacy at the time of the single preplanned interim analysis. Among 1417 patients who were included in the final analysis (91.5% of whom underwent intubation that was performed by an emergency medicine resi- dent or a critical care fellow), successful intubation on the first attempt occurred in 600 of the 705 patients (85.1%) in the video-laryngoscope group and in 504 of the 712 patients (70.8%) in the direct-laryngoscope group (absolute risk difference, 14.3 percentage points; 95% confidence interval [CI], 9.9 to 18.7; P<0.001). A total of 151 patients (21.4%) in the video-laryngoscope group and 149 patients (20.9%) in the direct-laryngoscope group had a severe complication during intubation (abso- lute risk difference, 0.5 percentage points; 95% CI, −3.9 to 4.9). Safety outcomes, including esophageal intubation, injury to the teeth, and aspiration, were similar in the two groups.
CONCLUSIONS: Among critically ill adults undergoing tracheal intubation in an emergency depart- ment or ICU, the use of a video laryngoscope resulted in a higher incidence of successful intubation on the first attempt than the use of a direct laryngoscope. (Funded by the U.S. Department of Defense; DEVICE ClinicalTrials.gov number, NCT05239195.)

Prekker ME, Driver BE, Trent SA, et al. Video versus Direct Laryngoscopy for Tracheal Intubation of Critically Ill Adults. N Engl J Med. Published online August 3, 2023:418-429. doi:10.1056/nejmoa2301601

What did they do?

This was a randomised control trial in the US across seven Emergency Departments and ten Intensive Care Units. They enrolled patients undergoing orotracheal intubation in these settings. The usual groups, such as pregnant patients and prisoners, were excluded.

Patients were also excluded if the intubating clinician decided that the use of video laryngoscopy or DL was needed for the best patient care. In total, 86 patients were excluded for this reason. The supplementary appendix detailed the reasons for this. 76 patients were excluded due to the operator stating VL was indicated with reasons given being “extreme upper airway anatomic difficulty (37), body fluid in the upper airway (12), hyper-angulated blade required (4) and other (23)”. For the patients excluded due to DL being the method of choice, the reasons cited again were “upper airway anatomic difficulty (3), body fluid(2) and other(1) “. As you can see, the reasons for either method of laryngoscopy being clinically indicated are very similar in both excluded groups.

I think this is a really important cohort of patients. I would have loved to have seen them included in this trial. It would help me understand what is going to help me the most for this procedure in the most difficult group of patients. So, what this trail really looks at is the use of direct laryngoscopy vs. video laryngoscopy for the intubation of a patient in the ED/ICU, for whom there is no predicted difficulty in endotracheal intubation.

Block randomisation was used. The blocks were “permuted” – meaning each block was a different size. Within each block, there was still an even number of direct laryngoscopy and video laryngoscopy allocations. Randomisation dictated video laryngoscopy or direct laryngoscopy for the first attempt, after this everything was the operator’s choice. Importantly the use of a stylet or bougie was seen as standard practice at all sites for the first attempt at intubation.

80 of the patients excluded were due to the operator preferring video laryngoscopy before randomisation. An additional 8 patients were excluded after randomisation in the direct laryngoscopy group. Instead, receiving video laryngoscopy on their first attempt. The main reason being cited is a change in patients’ condition. Does this reveal a bias in the operators? Did they inherently believe that video laryngoscopy is a better intubating technique? Does this make it more likely that DL is set up to fail as the operator thinks it won’t be successful? Does this belief mean the first attempt won’t be as good with direct laryngoscopy because subconsciously, “we know it is going to fail anyway”?

The primary outcome was successful intubation on the first attempt. A single secondary outcome was severe complications from induction to 2 minutes post-intubation.

What were the results?

1417 patients were included in the primary analysis. There were no significant differences in age, sex, or median BMI among patients in the two groups. In total, 988 (70%) intubations occurred in the emergency department. In each group, 45% of the patients were intubated due to altered mental status, with acute respiratory failure accounting for 30% of patients in both groups.

The primary outcome was ‘first pass success’ in the two groups and produced a statistically significant difference. However, it is probably worth just reiterating their definition:

“The primary outcome was successful intubation on the first attempt, defined as the placement of an endotracheal tube in the trachea with a single insertion of a laryngoscope blade into the mouth and either a single insertion of an endotracheal tube into the mouth or a single insertion of a bougie into the mouth followed by a single insertion of an endotracheal tube into the mouth.“

Successful first-attempt intubation in the video laryngoscopy group was 85.1% (600 of the 705 patients) vs 70.8% (504 of the 712 patients) in the DL group. Giving a p-value of < 0.001 and a 95% confidence interval of 9.9-18.7.

The operator reported the reason for the first-pass intubation failure. The most commonly cited reason in the video laryngoscopy group was an inability to insert the endotracheal tube or bougie (49 patients). Anecdotally, it is often said that video laryngoscopy will get you a better view of the cords. Still, it doesn’t make it easier to pass the tube, so, interestingly, these numbers were lower than in the DL group (51 patients). . The results reported in this trial could be due to using a bougie or stylet as standard practice.

The most common reason for failure to intubate in the direct laryngoscopy group was an inability to view the vocal cords. A 70% first-pass success rate in the DL group is very low and lower than cited in similar studies. This is probably due to a large proportion of the operators having minimal previous experience in intubating.

In the secondary outcomes, there was no statistically significant difference between the two groups. The 95% CI crossed 0 for all the predefined outcomes. 21.4% (151 of 705 patients) of the video laryngoscopy group had severe complications vs 20.9% (149 of 712 patients) of the direct laryngoscopy group, with a 95% CI of -3.9-4.9.

Do any operator characteristics make a difference to first-pass success?

Emergency physicians intubated most patients (70% in each group), with a resident physician being the most common operator (roughly 70% in each group). Data for operator experience were also collected. In total, 85% of intubations (1,202) were performed by operators with a log book of 100 or fewer prior intubations.

The method of previous intubations was also analysed. Figures in the supplementary appendix reveal that the majority of operators before this trial performed greater than 50% of their intubations using VL. With 510 (36%) operators have had over 75% of all their previous intubation experience with a video laryngoscope. Is it fair to compare intubation techniques using operators who are very inexperienced with one of the devices? This introduces inherent bias into this trial; all medical procedures take time and practice to master, and intubation with direct laryngoscopy or video laryngoscopy is no different. It is essentially asking an operator to proficiently perform as skill with a new technique they are not very practiced in and comparing it to a technique they are proficient in and comparing outcomes.

For those physicians who had intubated over 100 patients before the trial, first-pass success was 100% regardless of whether they used video laryngoscopy or direct laryngoscopy. For those with a log book of fewer than 25 intubations, first-pass success was 80% in the video laryngoscopy group compared to 54% in the direct laryngoscopy group. What this is saying is that if you have not yet mastered the skill of intubation, you are more likely to succeed with a VL. We could also take from this that DL is a tricker skill at which to become proficient. Therefore, when learning the skill of laryngoscopy, should direct laryngoscopy be used in preference in order to build competency in a supervised environment?

Another aspect that is not considered in the paper but is very relevant to the rest of the world is the cost of providing video laryngoscopy in all circumstances. They remain an expensive item and are simply unavailable in many parts of the world.

There are also many great reasons for using a video laryngoscopy for teaching and team dynamics. A recent podcast by Scott Weingart on the EMCRIT site explains this really well (well worth a listen). In practice, the ability to guide learners on their airway skills using a video laryngoscope is far superior to direct laryngoscopy, and we may see a reduction in the number of learning episodes required to achieve competence by using VL more routinely. This is certainly something Simon Carley^​3,4​ advocates (and is also stressed by Scott Weingart, who explains it really well). If you’re in a teaching unit, there are good arguments for having VL available beyond simply achieving great first-pass success rates.

Bottom Line

In this study, video laryngoscopy increased first-pass success for operators, with the biggest difference seen in those with less experience. Remember that this was a selected cohort of airways with (perhaps) less anticipated difficulty.