It is time again to review the most interesting airway literature from this past year, one that gave us some impressive research that every emergency physician should read.
Preoxygenation and Prevention of Desaturation During Emergency Airway Management
Weingart SD, Levitan RM
Ann Emerg Med
2011 Nov 1 [Epub]
This review article, still in press as of January, gets my vote for the emergency medicine airway paper of the year. It has the potential to dramatically change behavior and patient outcomes if everyone reads it, and puts the suggestions to use.
Airway difficulty is related to time, and time is related to saturation. (See Braude D, McLaughlin SM. “Difficult airways are ‘LEMONS’ — Updating the LEMON mnemonic to account for time and oxygen reserve.” Ann Emerg Med 2006;47:581.) Improving oxygenation before and during intubation is critical.
The key points are the use of higher than normal oxygen flows for preoxygenation, risk stratification after initial preoxygenation, the selective use of positive pressure for preoxygenation for high-risk patients, positioning the patient in a sitting, head-elevated, ramped or reverse Trendelenburg position for preoxygenation, and use of high-flow nasal cannula oxygen delivery for apneic oxygenation during the intubation itself.
Every emergency physician needs to read this paper.
Major Complications of Airway Management in the UK: Results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 2: Intensive Care and Emergency Departments
Cook TM, et al
Br J Anaesth
This is one of the results paper from a big UK project, which also generated an impressive white paper. While this is primarily an anesthesia publication, it does address care in the ED and by EMS, and many of the themes are universal. Some of the take-home messages include the importance of having a plan and planning for failure, how multiple intubation attempts are a set-up for disaster, how percutaneous cricothyroidotomies were much less successful than surgical airways, why obesity must be recognized as a risk factor for a difficult airway, why capnography is required for every ED intubation, and the importance of using checklists for emergency airway procedures.
Out-of-Hospital Airway Management in the United States
Wang HE, et al
Comparison of Supraglottic Airway versus Endotracheal Intubation for Pre-Hospital Treatment of Out-of-Hospital Cardiac Arrest
Kajino K, et al
Wang and colleagues used a large database to characterize prehospital airway management in the United States. The overall success rate was 77 percent for endotracheal intubation, 81 percent for rapid sequence intubation, and 87 percent for alternate airways. Kajino and colleagues reviewed four years of prehospital airway data in Osaka, Japan, including 5,377 nontraumatic cardiac arrest cases with airway management. Some 1,679 were managed with intubation and 3,698 with supraglottic airways.
They noted that favorable neurological outcome was similar in the two groups, though intubation took longer. As a sneak peak, I can tell you that a year from now I will likely be reviewing several papers that look at potential complications of extraglottic airways so the waters will get muddier.
For now, we emergency physicians need to do a better job of training and supporting our prehospital providers and advocating for the safest and most appropriate airway techniques. The blanket removal of endotracheal intubation from paramedic practices is probably not the answer, especially in rural areas, but encouraging more use of extraglottic airways while simultaneously trying to provide intubation training is at least part of the answer.
The worst thing we can do as emergency physicians, however, is to instantly remove a well-functioning EMS-placed extraglottic airway when a patient arrives or fail to incorporate an extraglottic airway into our own difficult airway algorithms. A medic need only see you persist at intubation while the patient becomes hypoxemic and traumatized one time to decide that intubation must be the right course of action in all circumstances.
Out-of-Hospital Tracheal Intubation with a Single-Use versus Reusable Metal Laryngoscope Blades: A Randomized Controlled Trial
Jabre P, et al
Ann Emerg Med
I have reviewed papers comparing reusable metal blades with disposable plastic ones in previous columns, and found the latter inadequate. A number of metal disposable blades now on the market seem to perform as well as most standard reusable blades. Of course, the elephant in the room is how much longer we will be using direct laryngoscopy at all.
Comparison of Blind Tracheal Intubation through the Intubating Laryngeal Mask Airway (LMA Fastrach) and the Air-Q
Karim YM, Swanson DE
The LMA Fastrach was the original intubating LMA, but there is competition now, primarily from the Cookgas air-Q. In this OR study comparing blind intubation within two attempts, the LMA Fastrach was substantially more successful at 99 percent versus 77 percent. Despite these numbers, the air-Q is easier to use for simple oxygenation and ventilation, and the new model, the air-Q blocker, facilitates placement of an esophageal blocker/drain or gastric tube.
If you use an intubating LMA as part of your failed airway algorithm with the intention of facilitating blind intubation, the Fastrach is clearly preferable. If you and your EMS crews are placing the airway primarily to maintain oxygenation and ventilation with the possible option of intubation, then the air-Q is probably better. Most importantly, it still shocks me how few emergency physicians use a device like the Fastrach that can facilitate blind intubation in 99 percent of cases without much interference by obesity, cervical precautions, or secretions when they cannot accomplish such results with a laryngoscope!
Safety and Clinical Findings of BiPAP Utilization in children 20 kg or Less for Asthma Exacerbations
Williams AM, et al
Intensive Care Med
I like this paper because it continues to challenge some of the initial misperceptions of noninvasive ventilation: that it is difficult to use on sick patients, that it is only for adults, and that it is only for CHF. This paper demonstrates use of BiPAP for young asthma patients in the pediatric ED at Monroe Carell Jr. Children's Hospital at Vanderbilt. If you have not yet decided that CPAP and BiPAP are the greatest inventions since sliced bread, then you just haven't used them enough.
Click and Connect! Access the links in EMN by reading this issue on http://www.EM-News.com or in EMN's app for the iPad, available in the Apple app store.
Dr. Braude is an associate professor of emergency medicine and anesthesiology and the director of the EMS Fellowship, the Physician Field Response Program, and Airway911 at the University of New Mexico School of Medicine, and the author of Rapid Sequence Intubation and Rapid Sequence Airway, 2nd Edition: An Airway Guide, available at http://airway911.com. He is also the associate medical director of the Difficult Airway Course-EMS.