It's time again to review the most interesting contributions to the emergency airway literature from the past year. While 2007 did not bring any seminal papers, there were still plenty of interesting papers with lots for us to learn.
Manual In-Line Stabilization for Acute Airway Management of Suspected Cervical Spine Injury: Historical Review and Current Questions
Manoach S, Paladino L
Ann Emerg Med
This is more than a review article. This paper offers an insightful and critical look at something we all take for granted: maintaining in-line immobilization during intubation of any patient with possible spinal injury. I love challenging dogma, and this paper does just that.
It turns out there is extremely limited evidence that immobilization offers any clinical advantage. We all know it makes airway management more difficult, which may be far worse for the patient if it results in hypoxia. While such a review cannot offer any definitive conclusions, it has changed my approach. If I am getting into trouble on a trauma airway, I may allow some gentle head elevation. With optimal first-round techniques such as jaw thrust, reduction of cricoid pressure (see below), and external laryngeal manipulation as well as the advent of enhanced visualization devices, this situation should arise infrequently.
Cricoid Pressure in the Emergency Department Rapid Sequence Tracheal Intubation: A Risk-Benefit Analysis
Ellis DY, Harris T, Zideman D
Ann Emerg Med
This, too, is more than a review article. The authors have conducted a thorough survey of the literature, and present their dogma-challenging results in a very readable and clinically relevant way. Their conclusions are similar to ones I drew in my October 2006 column: Cricoid pressure is not without serious potential drawbacks, and should be released if there is difficulty intubating or ventilating the patient.
The Effect of Cricoid Pressure on Intubation Facilitated by the Gum Elastic Bougie
McNelis U, et al
Here is yet another caution about cricoid pressure to add to all those in the Ellis review: It may impair bougie use. This group compared 120 patients receiving either real or sham cricoid pressure during bougie-facilitated intubation. Impingement occurred in 38 percent with sham pressure and 60 percent with real cricoid pressure. The most important point: The typically recommended 90o counter-clockwise rotation of the tube (and/or releasing cricoid pressure) usually solved the problem. I think everyone should have a bougie, and everyone who has one must know this “trick.”
Pilot Study to Evaluate the Accuracy of Ultrasonography in Confirming Endotracheal Tube Placement
Werner SL, et al
Ann Emerg Med
I admit I am an ultrasound junkie who sometimes looks for reasons to use it even when other means would suffice; this may well fall into that category. In this study, emergency physicians used a high-frequency linear transducer (vascular probe) applied at the suprasternal notch while an anesthesiologist placed an ETT into the trachea and esophagus of 33 patients in the OR. Sensitivity and specificity were 100%. While it would be malpractice to run past the end-tidal CO2 detector, esophageal detector device, or bougie to get the ultrasound machine when you are unsure if you had tubed the goose, it may make some sense if done in real time by another provider such as an attending supervising a trainee. Of course, watching the intubation on a GlideScope would be even better! Ultrasound junkies also may want to check out “Role of Ultrasound in the Airway Management of Critically Ill Patients,” a review by Alan Sustic, MD, PhD. (Criti Care Med 2007;35[5Suppl]:S173.)
A Comparison of Plastic Single-Use with Metallic Reusable Laryngoscope Blades for Out-of-Hospital Tracheal Intubation
Jabre P, et al
Ann Emerg Med
This is a nice follow-up to the article by Amour reviewed in this column in April 2007. The results are essentially the same: Metal blades are superior to plastic blades. While plastic blades may be adequate for placement in crash carts that are infrequently used (especially because alternative airways should probably be used in most codes not managed by EPs, anesthesiologists, paramedics, or intensivists), I recommend metal blades in any setting where intubations are performed routinely.
Intravenous Lidocaine After Tracheal Intubation Mitigates Bronchoconstriction in Patients with Asthma
Adamzik M, et al
This was a well-designed study of 30 patients with asthma undergoing ETI for elective surgery. Airway resistance was measured immediately after intubation and at five, 10, and 15 minutes. Patients received either lidocaine 2 mg/kg IV or placebo at five minutes after intubation. Airway resistance was significantly and substantially reduced in the lidocaine group.
While lidocaine for cerebral protection is discussed frequently, lidocaine for asthmatics is much less often discussed by emergency physicians. We all know how poorly asthmatics do when intubated; I for one hate to intubate these patients. While the study was small and used lidocaine after rather than before intubation, I think I will start using it in the event I need to intubate a patient for an asthma exacerbation. I also will consider using it in any asthmatic who gets intubated for any reason, especially if airway pressures go up.
Reversal of Rocuronium-Induced (1.2 mg/kg) Profound Neuromuscular Block by Sugammadex: A Multicenter, Dose-Finding and Safety Study
de Boer HD, et al
I get a lot of questions about Sugammadex, the first drug specifically designed to bind steroid-based neuromuscular blockers such as rocuronium and to reverse paralysis. Sugammadex is currently in Phase III trials, but may be approved by the FDA this year. This is the first study to look at the ability to reverse full-strength rocuronium — the situation that would be encountered in the ED — and the drug performed well without any serious adverse effects. The bigger question appears to be not whether Sugammadex works but what role it should have in the ED.
In general, if reversal of paralysis is needed, I would question why appropriate back-up airways were not utilized. If reversal of paralysis were an option, I would question whether the patient really required emergent intubation in the first place. If its availability leads clinicians to perform RSI instead of sedation-facilitated intubation, then I am all for it.
Rapid Sequence Airway (RSA) – A Novel Approach to Prehospital Airway Management
Braude D, Richards M
Prehosp Emerg Care
A case report is very unlikely to be cited as one of the most interesting articles of the year unless it is written by the person doing the citing! This report describes the first use of Rapid Sequence Airway, a novel technique combining the best of RSI and new alternative airway technology. Essentially RSA involves all the preparation and medications of RSI with planned use of an airway such as LMA, Combitube, or King (i.e., without any prior attempt at laryngoscopy). RSA is intended to minimize transport delays and/or facilitate airway management in tight quarters. As alternative devices get better (King-LT, LMA-Supreme) and the pressure on EMS to improve RSI outcomes increases, RSA may offer one possible solution.
Practicing Paramedics Cannot Generate or Estimate Safe Endotracheal Tube Cuff Pressure Using Standard Techniques
Parwani V, et al
Prehosp Emerg Care
The most overlooked aspect of post-intubation care is probably proper cuff pressure. This study evaluated the ability of experienced paramedics to inflate an ETT cuff to a safe pressure (<25 cm H20) and assess inflated cuffs for excessive pressure. The results are frightening: The average pressure generated was more than 108 cm H20! Their ability to palpate a pilot balloon to assess overinflation was equally poor with only 11 percent able to accurately assess cuff pressures of 120 cm H20 as overinflated. My hunch: EPs are just as bad. With more evidence accumulating to suggest that high pressures may cause serious damage in the time it takes to transfer a patient and be seen by an ICU respiratory therapist or intensivist, it may be worth investing in a cuff manometer.