Tracheal intubation by direct laryngoscopy is a bread and butter procedure for emergency medicine physicians. Our goal, get plastic in the trachea. Success during this procedure is largely predicted by our setup in terms of patient positioning and pre-oxygenation, as well as patient factors that make visualization of the vocal cords more difficult.
In an anticipated difficult airway, we often prepare by having alternative airway adjuncts available in case our initial attempt fails. However something simple such as manipulation of the larynx externally can possibly make a difficult airway an easy one and avoid multiple attempts or prolonged apnea time.
Don't forget that you have two hands, one holding the laryngoscope, the other freely available to manipulate the larynx at will. This isn't cricoid pressure, this isn't BURP (backwards upwards pressure). This is manipulating the larynx in any way you can during laryngoscopy to maximize your view of the cords. This ladies and gentleman, is bimanual laryngoscopy...and it works.
How it works
While performing direct laryngoscopy, reach around the patient with the right hand, manipulating the larynx while directly observing your laryngeal view.
Once you have found the ideal view, have an assistant maintain pressure at the same location and in the same direction on the larynx to facilitate placement of the endotracheal with your right hand.
The mechanism of the improvement of laryngeal view is two fold:
(1) By manipulating the larynx externally, you are assisting with moving your laryngoscope blade into the proper position to allow optimal elevation of the epiglottis. This benefit only applies to curved blades that lie in the vallecula.
(2) With external laryngeal manipulation, you are moving the larynx more posteriorly and into the airway operator's line of sight. This benefit applies to both curved and straight blades.
The Modified Technique
While bimanual laryngoscopy is a highly effective technique to improve your laryngeal view, there is one small issue. Often after you work hard to find your ideal view, you hand it over to the assistant, only to find that they don't apply the exact pressure, in the exact location as you previously had done. If you have been the assistant before, you would understand that this is no easy task. Here is how to modify your technique:
This time have the assistant place their hand on the patient's thyroid cartilage. Use your hand to guide the assistant's hand to achieve the best laryngeal view possible and ask them to hold this position. Theoretically in this way, there is no phase where the optimal view is lost as the hand manipulating the larynx is not being exchanged.
Is There Any Evidence One is Superior?
Optimal external laryngeal manipulation: modified bimanual laryngoscopy. The American Journal of Emergency Medicine 2013.
A small single center RCT was done looking at comparison of the original method of bimanual laryngoscopy (conventional) versus the modified version (modified).
A total of 130 patients were initially enrolled in this study. The primary endpoints were improvement in percentage of glottic opening (POGO) after application of external laryngeal manipulation (ELM), # of ELM attempts, and time taken to best laryngeal view. 52 patients were initially excluded from randomization for having >50% POGO on initial view which did not require any ELM.
What they found was that the POGO score after ELM significantly increased in the modified group compared to the conventional group. More so, the POGO score improved after ELM for all modified patients on first attempt, however only in 87.2% on first attempt in the conventional group. In 5.1% of the conventional group, ELM actually worsened the view and in 23%, the ELM was considered a failure and "the next step in airway management proceeded at the laryngoscopist's discretion."
This was a very small study with end points that don't necessarily mean much in terms of patient outcomes. Also the 23% that were noted to be '"failures" in the conventional group is a bit scary if we assume that something bad happened, but this could have meant repositioning the patient, switching to video laryngoscopy or other airway adjuncts. There is also potential for bias here as the laryngoscopists and the observer who collected data were not blinded to the intervention.
In light of the study flaws, at minimum, this study does show that both conventional and modified techniques overall improve laryngeal views compared to no ELM.
I would conclude that it is both fair and reasonable to add bimanual laryngoscopy (conventional or modified) to your armamentarium of airway techniques.
And if you unfortunately happen to be the unlucky 5.1% that gets a worsened laryngeal view, well then I guess you can just stop pressing on the larynx.
Previous Airway Posts
- Bimanual laryngoscopy @ Airway Cam.
- Bimanual laryngoscopy video @ Airway Cam
- Hwang et al. Optimal external laryngeal manipulation: modified bimanual laryngoscopy. Am J Emerg Med. 2013 Jan;31(1):32-6. doi: 10.1016/j.ajem.2012.05.016. Epub 2012 Aug 4.