External laryngeal manipulation refers to the crucial maneuver in any airway armament, used to obtain a better glottic view. While manipulation of the larynx is not a novel concept, see cricoid pressure and BURP, ELM encompasses any maneuver to improve your glottic view. Best part is, ELM is super easy to do and has good evidence to support it.
Has this been studied?
One of the first studies from 1996 demonstrated that in 181 consenting non-pregnant adults, ELM improved the the glottic view by at least one full grade. Furthermore, the worse the view was, the more likely ELM would improve that view.
Follow up in an OR study from 1997, the BURP maneuver demonstrated substantial improvements in view as demonstrated to the left. The BURP maneuver was very specific in the direction of ELM, we could infer that if the operator wasn’t on a prescribed geometric pattern, perhaps the results would be even better.
Finally and probably what took ELM out of the realm of anesthesia and into the EM world, was Levitan’s study in 2002. This study, which popularized the term “bimanual manipulation,” enrolled patients subjected to intern laryngoscopy and demonstrated that the percentage of glottic opening (POGO) score was improved in just about every attempt. If your POGO score was zero, it improved 61%, if it was 1-20% it improved 63% and if it was 21-50% it improved 43%; pretty substantial gains.
In 2013, we saw a term coined, the “modified bimanual larygnoscopy” which publicly announced the use of two operators, however my guess is that this was already being performed broadly. Since then, we’ve seen a number of studies confirm these findings since Levitan’s publication in 2002, such that the verdict is in; ELM is safe and highly effective.
Why does it work?
The crux of ELM’s utility is in bringing an anterior larynx more posterior and in direct line of sight. Secondly, the operator is able to engage the hyoepiglottic ligament from the reference point of the larynx. This is often discussed as the job of the macintosh blade: engage the hyoepiglottic ligament and roll the epiglottis anterior. But what we see over and over is the larynx being used to engage the macintosh blade and create an anterior tilt while moving the entire structure posterior.
How It’s Done:
The best way to perform ELM is with an assistant and video laryngoscopy. Your assistant handles the larynx, externally, and you, the largyngoscopist, focuses solely on getting the tube in the tube hole. This allows your assistant to watch in real time the movement of glottis and adjust accordingly.
If video is not available, have your assistant place his or her hand on the larynx and using your right hand, you maneuver their hand and the larynx into view. This helps translate the right location and the right amount of pressure from your hand through theirs. Direct laryngoscopy has the disadvantage that you are the only operator with the view of the glottis.
With either of these techniques, you manipulate the larynx, typically in the posterior direction and thus improving your POGO score. Check out the video below:
Great example of the larynx moving posterior with ELM. We see the POGO score go from about 50% to nearly 100%.
How to Mess it Up:
The number one way to do ELM wrong is by handling the larynx too far superiorly. This can actually evert the largynx and compress the vocal cords. You may have a great view with this maneuver but have a very difficult time passing the tube. Check out an example in this video below:
ELM done wrong- just when we thought it was fool proof. In this over-exposed example, the larynx operator is too cephalad and actually everts the glottis, definitely making tube delivery more difficult.
More video of ELM in action:
Thats a lot of froth. Watch the operator engage the hyoepiglottic ligament and the larynx operator manipulate the larynx and glottis around that focal point.
Substantial improvement of the view in this example. Now to get rid of that snot..
Hope you found this concept review helpful!
Terren Trott @tsquaredmd
- Benumof. Quantitative improvement in laryngoscopic view by optimal external laryngeal manipulation. Journal of Clin Anes. 1996.
- Takahata. The Efficacy of the “BURP” Maneuver During a Difficult Laryngoscopy. Anesthesia and Analgeseia. 1997.
- Levitan. Bimanual laryngoscopy: A videographic study of external laryngeal manipulation by novice intubators. Annals of Emer Med. 2002
- Hwang. Optimal external laryngeal manipulation: modified bimanual laryngoscopy. Am JEM. 2013