Video Laryngoscopy vs Direct Laryngoscopy. Fooled eyes.


 

Video Laryngoscopy vs Direct Laryngoscopy on Successful First-Pass Orotracheal Intubation Among ICU Patients A Randomized Clinical Trial , by Jean Baptiste Lascarrou et al [1].

 

Intubation! Source of love and hate since the 50s. You feel like the coolest guy in town every difficult airway you managed brilliantly like a Jedi master. All right! Send me another one! Cool! Chest bump! But, if there is one think that can make you feel like crap, is screwing up during an intubation. OK, screwing up might be a poor choice of words, let’s use poor procedural management instead. There are two types of intensivists: those who already failed to perform an intubation, and those who are lying. It’s simple math. Sooner or later, we will feel the taste of poorly digested rocuronium in our mouths. That being said, every tool or strategy that can increase our odds of success during an intubation is welcome.

The use of video laryngoscopy (VL) for orotracheal intubation seems to increase the rate of intubation success in operation rooms, when compared with our good old friend Macintosh laryngoscope (ML). But, a prospective study evaluating the role of VL in the ICU setting was still missing. Well, thanks to our baguette eating friends we now have one. The MACMAN trial (McGrath Mac Videolaryngoscope Versus Macintosh Laryngoscope for Orotracheal Intubation in the Critical Care Unit) [1] was just published in JAMA. It was a multicenter (7 ICUs in France), randomized, open-label trial, which included all ICU patients that needed orotracheal intubation (wide inclusion criteria = good). They did a pretty good job with the randomization strategy. A block randomization scheme was used, stratified by center and “expert or nonexpert status of the individual performing intubation”. Unfortunately the expert defying criteria did not include any experience with VL (here I mean “real experience”). Every time you play with a new toy there is a learning curve. It’s true for that new PS4 you just bought as it’s true for an astronaut learning how to pilot a space shuttle. But we will come back to this.

All physicians were trained in the use of the VL and the intubation protocol was the same for both groups. Preoxygenation [checked]; induction with hypnotic + neuromuscular blocking agent and no opioids (I’m loving this) [checked]; the intubation device was randomly chosen (VL vs ML) [checked]; tube position [checked]. If the first-pass attempt failed, the physician could choose between repeat laryngoscopy or an alternative intubation technique. The primary outcome was the proportion of first-pass success. With an expected 65% success rate for the ML group, with an alpha of 5%, power of 90% and assuming that VL would increase the success rate to 80%, 185 patients/arm were needed. Both intention-to-treat and per-protocol analysis were done.

What they found

The patients’ baseline characteristics are shown below. Both groups were well balanced, except for a slightly unbalances in BMI>26, Mallampati score and thyromental distance.

The first intubation attempts were made by a nonexpert in 83,8% of patients, which I think reflects the reality of most of the hospitals. There were no difference in first pass success between the VL (67,7%) and the ML (70,3%) groups (absolute difference, −2.5% [95% CI, −11.9% to 6.9%]; p = 0.60. These results were sustained even after adjusting for operator expertise and MACOCHA score. If we stop here, you’re probably going to say: “whatever! let’s stay with the good old Mac!”. In the end, this might really be true, however, let’s scrutinize the secondary endpoints.

The first thing that really caught my attention on the table above was the high percentage of Cormack 1 grade in the VL group (75,6%) compared to ML group (52,5). I know we’re discussing secondary endpoints, and here they did not adjusted for multiple comparisons, but even my one-eyed dog can see that the VL group performed better here. Now, take a look at the table below:

We have two valuable informations here: The main reason for intubation failure in the ML group was inability to see the glottis, and in the VL group was failure of tracheal catheterization. This is interesting. Your ability to see the glottis is related to your expertise with the procedure and the equipment you are using, either way, since the groups were balanced regarding the physicians expertise, the difference found between the two groups here might be because it is easier to visualize the glottis with the VL. Now, if you look at failure of tracheal catheterization, 70,7% (VL) vs 23,5% (ML), the only reasonable explanation for this difference is the “new toy learning curve”. Eye-hand coordination, especially when looking through a monitor, is not learned with a few training sessions. And the only good explanation for this difference is the lack of experience with the VL device. How if all physicians were read proficient with the VL? Probably the result would have been different.

Two more things: French doctors love etomidate (used in about 90% of all patients), and who the hell still does Sellick manouver? More than 15% in both groups! C’mon?! In the end, maybe if all physicians were proficient in VL, meaning, had a more extensive practice, instead of few ours at the lab tubing a doll, we could see different results regarding the primary endpoint. However, if we think about mortality, I don’t think any study with this design will show any difference. Maybe in a population with predicted difficult airway? I don’t know. The bottom line is that your eyes can fool you, specially if you are a young Padawan learning  how to play with a new toy.

 

 

1.     Lascarrou JB, Boisrame-Helms J, Bailly A, et al. Video Laryngoscopy vs Direct Laryngoscopy on Successful First-Pass Orotracheal Intubation Among ICU Patients: A Randomized Clinical Trial. JAMA. 2017.

 

Photo Credit

Jan


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Video Laryngoscopy vs Direct Laryngoscopy. Fooled eyes.

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