UPDATE: The manuscript of the MACMAN study was simultaneously published in JAMA and presented at SCCM (Lascarrou JB, et al. JAMA. Published Online Jan 24, 2017). While the peer reviewed primary results are unchanged, demonstrating that videolaryngoscopy improves the glottic view but does not improve the ability to pass the endotracheal tube compared to direct laryngoscopy, one of the secondary results deserves some mention. It wasn’t presented in the brief late-breaker presentation at ESICM, so I hadn’t discussed it previously. Lascarrou and colleagues also found a higher rate of severe life-threatening complications with videolaryngoscopy, namely severe hypoxemia, hypotension, and cardiac arrest. While I am not entirely sure what to make of this finding, I do think it should cause us some pause. If this is true (and it may just be a type 1 error that secondary analyses are prone to), then not only should we not use VL as the primary intubating device for all our intubations in the ICU, but we should think carefully about which ones we do use it for (and be selective in whom we use it in). And, while these most recent studies have been informative on the risks and benefits of both VL and DL, there remain unanswered questions. These studies do not include patients who the clinician believes they have to use VL for intubation, nor do they look exclusively at high risk populations such as morbid obesity or high Mallampati or MACHOCA scores. I suspect additional studies will be forthcoming in the future and that this field will continue to evolve. However, in the meantime, both of these most recent well-designed and conducted randomized controlled trials, make it apparent that we should not be using VL as the default intubation device in all our critically ill patients.
October 4, 2016; 08:55
In the last couple of decades, some of the biggest advances in medicine have involved technology. The videolaryngoscopy represents one of these technological advances for assisting with endotracheal intubation. FDA approval of devices simply requires demonstration that the device does what it claims to do, but does not require demonstration of improved outcomes or any clinical benefit. While there are a number of different videolaryngoscopes, they are all designed with a camera on the end of a laryngoscope connected to some form of a screen that displays the image the camera projects. Numerous studies have demonstrated that videolaryngoscopes improve the view of the glottis and vocal cords (Cormack Lehane Glottic View Grade) over direct laryngoscopy during endotracheal intubation. Some of these studies suggest that time to intubation may also be shorter using videolaryngoscope. These data (probably combined with some allure of new technology) resulted in many opining that the videolaryngoscopy should be the standard of care for intubation in critically ill patients, and should be used in all intubations in the ICU, especially by inexperienced operators. However, the studies providing the data supporting these recommendations were conducted in the operating room on patients undergoing intubation for surgical procedures. And most of them studied experienced anesthesiologists as the operators.
Recent studies have suggested that extrapolation of these older data into critically ill patients is premature. Our group conducted a study comparing VL with DL in critically ill patients undergoing intubation by relatively inexperienced operators (pulmonary and critical care fellows) (Janz DR, et al. Crit Care Med. 2016; Epub ahead of print, June 28). While difficulty of the glottic view was recorded, the primary outcome was actually first pass success – or whether or not the patient was successfully intubated on the first insertion of the laryngoscope. Any patient who was not thought to absolutely need either VL or DL, and whom the fellow had time to grab a randomization envelope from the ICU work room, was enrolled in the study, resulting in 150 patients randomized, all from the MICU. While any videolaryngoscope was eligible for use in the study, the McGrath was the one actually used by the fellows. The study confirmed the previous findings that VL improved the glottic view. However, despite this improved view, VL failed to demonstrate significantly improved first pass success compared to DL (68.9% vs 65.9%; P=0.68), and this held true even when the analysis was adjusted for operator experience in using VL (OR for first pass success with VL 2.02; 95% CI 0.82 – 5.02). Other clinical endpoints, including lowest oxygen saturation, time to successful intubation, ICU length of stay, and in-hospital mortality were not significantly different between VL and DL. During the review process of the manuscript, many believers in VL questioned the validity of these results, believing that VL had to be better, and that these results were either an anomaly, or specific to the McGrath laryngoscope.
However, additional data have now been published that support these results and demonstrate that they are not limited to the McGrath VL. Two recently published randomized trials comparing the C-Mac VL with DL in intubations conducted in the Emergency Department found similar results to ours (Driver BE, et al. Acad Emer Med. 2016;23(4):433-439; Sulser S, et al. Eur J Anaesthesiol. 2016 Aug 16. [Epub ahead of print]). The Sulser study also confirmed a better glottic view using the C-Mac VL over DL. However, in both studies, the C-Mac VL had similar rates of first pass success as DL, with no difference in clinical outcomes including time to intubation, aspiration pneumonia, or hospital length of stay. Interestingly, the operator may not matter as much as previously thought. Driver et al studied emergency medicine physicians and trainees as the operators while the Sulser study included mostly experienced anesthesiologists as the operators.
Now, the results of the largest randomized study of VL vs DL to date have been released. The results of the MACMAN study were presented yesterday at the European Society of Intensive Care Medicine (ESICM) International Conference (ESICM – ICU Clinical Trials). MACMAN is a randomized controlled, multicenter (7 centers in France) trial comparing the McGrath VL with Macintosh DL in orotracheal intubation of 370 critically ill adults (MACMAN Protocol). Any operator was eligible to participate, although most were “inexperienced ICU physicians” (defined as fewer than 5 years of ICU experience). Like the recently published studies, MACMAN demonstrated a better Cormack Lehane grade glottic view with the McGrath VL. However, there was again no difference in first pass success (71% for VL vs 68.5% for DL; P=0.54) with rates very similar to our results. During the study, the reason for failed first pass success was recorded – in the McGrath group, 70% of the failures were due to inability to pass the endotracheal tube (ETT) compared to the DL group where 70% of the failures were due to inability to visualize the trachea. Although clinical outcomes were similar in both groups, the VL group did have more severe life threatening complications (9.5% vs 2.2%), but similar overall hospital mortality.
Given all these studies, it seems pretty clear to me that VL does improve the glottic view – but at the expense of increased difficulty in passing the endotracheal tube. In thinking about it, I don’t think this is all that surprising. Using DL, you are passing the ETT directly in the line that you are visualizing. Using VL, you are trying to pass the ETT indirectly into the trachea using the video screen, and the direct line of passage is often not clear (or even very direct). So, what is my recommendation for which device to use? This is a like asking, “Is it better to have seen and failed or never to have seen at all?” I think it depends. I don’t think there is one single correct answer. Each likely has advantages and one should use those potential advantages to better facilitate endotracheal intubation. If you are supervising another physician and want confirmation that the ETT went through the cords, maybe VL is a better choice because it will allow you to see that. However, I would recommend that you become proficient in using both because the more tools you have in your armamentarium, the safer your patients are going to be during your intubations.
Let me know your thoughts.