Dr. Huang is a senior resident in the Olive View-UCLA Emergency Medicine Residency Program. Dr. Lovato is an associate professor at the David Geffen School of Medicine at UCLA, the ED director of clinical practice at Olive View-UCLA Medical Center, and the co-chair for the Emergency Medicine Best Practices Committee for the Los Angeles County Department of Health Services.
Emergency physicians develop extraordinary skill in securing the airway. In fact, some could argue that intubations in the ED are the most difficult. Unlike the elective surgical setting, they usually occur on an emergent basis with little time for preparation. Patients are generally sick and unstable, increasing the incidence of failed airways and the potential complications. Studies have shown that multiple attempts at endotracheal intubation can result in hypoxemia, aspiration, neurologic damage, cardiovascular complications, and death. (J Clin Anesth 2004;16:508.)
Direct laryngoscopy remains the primary method for performing intubations in the ED, though multiple video laryngoscopes have been developed in the past decade and are becoming more common in ED intubations.
Most studies to date comparing video with direct laryngoscopy success rates have been done in anesthesiology, making application to the ED setting difficult. A study on routine intubations for elective surgery found improved Cormack-Lehane scores from video laryngoscopy but no impact on reducing failed airway. (J Clin Anesth 2006;18:357.)
Another study specifically looked at the intubation success rate of video versus direct laryngoscopy in the expected difficult airway as defined by a Mallampati score of III or IV. They found that video laryngoscopy provides a better view of the cords, higher success rates, faster intubations, and less need for optimizing maneuvers. Similarly, patients were recruited from the outpatient surgical setting, and those undergoing rapid sequence intubation were excluded. (Br J Anaesth 2009;102:546]. Again, it is difficult to apply these results to the ED.
A relatively new video laryngoscope made by C-MAC is modeled after the curved Macintosh blade, and is designed for use with direct laryngoscopy or its attached video screen. Studies using the C-MAC video laryngoscope have shown increased success rate over direct laryngoscopy for difficult intubations in the operating room and ICU. (BMC Anesthesiol 2011;11:6; Crit Care 2012;16:R103.)
A Comparison of the C-MAC Video Laryngoscope to the Macintosh Direct Laryngoscope for Intubation in the Emergency Department
Sakles JC, Mosier J, et alAnn Emerg Med2012 May 4. (Epub ahead of print)
This study — the first comparing the C-MAC video laryngoscope with direct laryngoscopy in the ED — was a retrospective analysis of 750 intubations completed over 28 months in an academic ED. The operator completed a standardized data form after each intubation evaluating multiple aspects of the intubation, including patient demographics, indication for intubation, devices used, reason for device selection, difficult airway characteristics, number of attempts, and the outcome of each attempt.
The primary outcome was successful intubation with the initial device. Secondary outcomes were first-attempt success, Cormack-Lehane view, and esophageal intubation. The C-MAC resulted in successful intubation in 248 of 255 cases (97.3%; 95% CI 94.4% to 98.9%). Direct laryngoscopy resulted in successful intubation in 418 of 495 cases (84.4%; 95% CI 81% to 87.5%). Compared with direct laryngoscopy, the C-MAC was positively predictive of ultimate and first-attempt success and associated with a greater proportion of CL grade I/II views.
Unfortunately, the study has some key limitations. Most importantly, the intervention was not randomized, making it much more likely that patient characteristics, physician practice, some other variable, or a combination of these factors biased the chosen intervention and ultimately the study's conclusions. Video laryngoscopy was specifically chosen for 37 percent of the patients in the C-MAC arm because the operator expected the airway to be difficult while direct laryngoscopy was specifically chosen for the same reason in only 1.2 percent of the direct laryngoscopy cases. The study also occurred at a single academic center where, according to the authors, almost half of all intubations use video, potentially affecting the ability to apply these results to centers with limited video laryngoscopy experience or those who use it only as a rescue strategy.
Every emergency physician should take pride in his ability to secure a difficult airway. Direct laryngoscopy is a basic skill that every emergency physician should master. Promising studies of the video laryngoscope, however, have prompted its increased use in the ED not only as a rescue strategy but also a primary approach to intubation and educational tool for residents. This study concluded that the C-MAC was associated with a higher proportion of successful intubation with the initial strategy. Hopefully, this study has pioneered a foundation for randomized trials comparing the two devices in the ED. Nonetheless, the future of video laryngoscopy in the ED appears to be promising, and it seems prudent to encourage veteran emergency physicians to embrace this technology as much as the next generation already has.
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