From bimanual laryngoscopy (which clearly should be routine in emergency medicine) to using the right-shaped stylet (angles more than 35 degrees can result in obstruction), the literature was rife with important airway papers last year. One study, for instance, looked at predictors of difficult mask ventilation, while another focused on digital intubation, an underused technique we should consider learning and teaching. This synopsis is the best of those articles, ones every emergency physician should read and incorporate into his practice.
Laryngeal View During Laryngoscopy: A Randomized Trial Comparing Cricoid Pressure, Backward-Upward-Rightward Pressure, and Bimanual Laryngoscopy
Levitan RM, et al, Ann Emerg Med, 2006;47:548
Richard Levitan, MD, the creator of the Airway Cam, is responsible for “rediscovering,” validating, and disseminating external laryngeal manipulation, also known as bimanual laryngoscopy, in emergency medicine. In this well performed study, the authors studied bimanual laryngoscopy, cricoid pressure, backwards-upwards-rightwards pressure (BURP), and no neck manipulation. Bimanual laryngoscopy was the clear winner while BURP and cricoid pressure were the clear losers. (See my article, “Right Amount of Cricoid Pressure Critical to Ventilation,” EMN 2006;28:24.)
It is clear to me that bimanual laryngoscopy should be routine, that we should no longer be teaching BURP, and that cricoid pressure must be reduced or released when the larynx cannot be visualized. I have now lost count of the number of intubations “saved” in our facility and flight program with this approach. This is the article of the year and a must-read by all airway practitioners.
Stylet Bend Angles and Tracheal Tube Passage Using a Straight-to-Cuff Shape
Levitan RM, et al, Acad Emerg Med, 2006;13(12):1255
It is amazing how often I hear a resident proclaim a great view of the cords only to fail at passing the tube through them. Levitan et al have shed light on something as simple yet critically important as stylet shape. He previously convinced me to do away with the “soft-curve” altogether in favor of the straight-to-cuff shape. In this paper, they compared four different angles of straight-to-cuff, and concluded that any angle exceeding 35 degrees can result in mechanical obstruction of tube passage. They recommend stopping the stylet at or before the cuff and removing the stylet if there is problem passing the tube with it in place. This is advice we should all heed.
Incidence and Predictors of Difficult and Impossible Mask Ventilation
Anesthesiology, Kheterpal S, et al, 2006;105(5):885
A difficult airway is one where intubation OR mask ventilation is predicted or proven to be difficult. While predictors of difficult intubation are frequently studied (see my article, “Predicting the Difficult Airway,” EMN 2007;29:29), few studies have looked at predictors of difficult mask ventilation. In this anesthesia-based study, the authors found the following predictors of difficult mask ventilation: obesity (BMI >30), beard, over age 57, snoring, severely limited jaw protrusion, and Mallampati 3 or 4. These predictors should be evaluated and considered whenever possible, especially in “semi-elective” intubations and deep procedural sedation.
Analgesic Use in Intubated Trauma Patients during Acute Resuscitation
Chao A, et al, J Trauma, 2006;60(3):579
Unfortunately, these authors have verified what I witness all the time: inadequate analgesia for intubated patients. The authors reviewed the charts of 120 trauma patients intubated in their ED. Only 51 percent of the patients received analgesia in the ED, and for those lucky enough to be medicated, the mean time was almost an hour after arrival. Nearly every trauma patient needs analgesia anyway, and intubation should be considered a painful procedure itself. Fentanyl is remarkably well tolerated in all but the most hypotensive of these patients, and I use ketamine for the remainder.
Is Digital Intubation an Option for Emergency Physicians in Definitive Airway Management?
Young SE, et al, Am J Emerg Med, 2006;24:729
How many times have you wondered about digital intubation? Does it really work? Is it even worth teaching and practicing? Young and colleagues at Darnell Army Community Hospital put it to the test on a cadaver model. There first-pass success rate among residents and faculty with limited or no prior experience with the technique was still 65 percent, increasing to 90 percent after three brief attempts. Digital intubation appears worth keeping in the toolbox.
The LMA CTrach: A New Laryngeal Mask Airway for Endotracheal Intubation Under Vision: An Evaluation in 100 Patients
Liu EHC, et al, Brit J Anaesth, 2006;96(3):396
While I usually take a low-tech and low-cost approach to airway management, I do believe the laryngoscope as we know it is archaic. This market has been discovered, and the technological advances are stunning. Using 100 patients in the OR for elective surgery, this study evaluated one of these new devices, the CTrach, an ILMA with attached video monitor to observe directly what was formerly blind intubation. The device allowed all patients to be ventilated, 96 percent successfully intubated, though not always with wonderful direct visualization. While I am not yet ready to recommend this or any other gadget for widespread use, stay tuned. I predict that in the next five to 10 years, we will no longer routinely be using traditional laryngoscopes.
The Effect of Lidocaine and Sufentanil in Preventing Intraocular Pressure Increase Due to Succinylcholine and Endotracheal Intubation
Moeini HA, et al, Eur J Anesthesiol, 2006;23(9):739
Pretreatment with Magnesium is Associated with Less Succinylcholine-Induced Fasiculations and Subsequent Tracheal Intubation-Induced Hemodynamic Changes than Precurarization with Vecuronium During Rapid Sequence Induction
Sakuraba S, et al, Acta Anesthesiol Belg, 2006;57(3):253
The “debate” still rages about what if any pretreatment is indicated before succinylcholine. Moeini and colleagues evaluated change in intraocular pressures (IOP) during laryngoscopy with and without pretreatment with lidocaine or sufentanil. Pretreated patients experienced a small reduction in IOP (a surrogate marker for intracranial pressure?) compared with untreated patients who experienced a small increase in IOP. It is unclear if these changes are clinically significant.
Sakuraba and colleagues compared magnesium sulfate — the wonder drug — with vecuronium as a pretreatment agent. Magnesium appeared more effective at reducing fasciculations and hemodynamic changes but required a five-minute infusion. I still don't believe that pretreatment prior to succinylcholine is standard of care for emergency intubations. If I recommend anything, assuming the patient is likely to have critically high ICP and you have three minutes to wait, use fentanyl. Of course, I have gotten around the issue altogether by switching to rocuronium for all of my intubations.
Intracuff Pressures of Endotracheal Tubes in the Management of Airway Emergencies: The Need for Pressure Monitoring
Galinski M, et al, Ann Emerg Med, 2006;47:545
I was taught that the new high-volume, low-pressure cuffs are very gentle on tissues, and that it takes a long time for complications to result; therefore, if it's a problem, it's an ICU problem. Evidence is mounting that this cavalier approach is no longer acceptable because damage can begin very quickly. Galinski et al measured cuff pressure in 107 patients intubated in the field or for interfacility transfer. Among these, 79 percent had elevated pressures, with the mean more than twice the upper limit of acceptable. It looks to me that it is time for us all to invest in cuff manometers.
Noninvasive Ventilation Improves Preoxygenation Before Intubation of Hypoxic Patients
Bailard C, et al, Am J Resp Crit Care Med, 2006;174:171
There is no question that preoxygenation is critical to safe intubation nor is there any question that noninvasive positive pressure ventilation (NIPPV) can prevent intubation in selected patients. If I am confident that intubation cannot be avoided, however, I have never wasted time with NIPPV. Baillard et al have demonstrated that NIPPV is still worth considering in such patients as a preoxygenation tool.
Comparison of Plastic Single-Use and Metal Reusable Laryngoscope Blades for Orotracheal Intubation during Rapid Sequence Induction of Anesthesia
Amour J, et al, Anesthesiology, 2006;104–60
Have you been approached to switch to disposable laryngoscope blades? We were asked to evaluate them last year as a cost-saving measure. This study by Amour and colleagues put an end to that trial. In an anesthesia setting, the authors found disposable blades, at least the Lite blade by Rusch, to be clearly inferior to traditional metal blades. For now, if asked, just say no!