Tuesday, July 17, 2012

Direct Laryngoscopy May Be Dead - Just Not to Me

The Gist:  Video laryngoscopy (VL) augments patient safety and is a great tool for endotracheal intubation (ETI) but trainees should likely be comfortable with both DL and VL.  There's a solid argument for Emergency Physicians to maintain DL skills while using the capabilities proffered by VL in situations to improve training and patient safety.  (As a medical student, I recognize I have minimal experience and probably should not have an opinion on this issue but, like most things, I do).  For expert airway tips and tricks, visit Life in the Fast Lane's Own the Airway.

A couple of months back, I heard something frightening in the midst of shoulder presses at the gym - that direct laryngoscopy is dying.  On the superb Prehospital and Retrieval Medicine (PHARM) podcast, interviewee Dr. DuCanto discussed the importance of fiberoptic laryngoscopy during difficult airways.  Days later, I shuddered again, when I found that Dr. Ron Walls proclaimed DL "dead" via Twitter.  This discussion struck entirely too close to home.  

In preparation for intubation, many attendings, upon seeing my eager, young face, steer the Glidescope in my direction.  I discovered a little bit of confidence is a dangerous thing when the airway is involved; thus, I love having this tool powered up and ready.  It's perfect for airways during chest compressions/resuscitation and many difficult airways.  Like the faithful bougie, I like to have a fiberoptic device at the bedside during an ETI.  However, it seems that many physicians think one should learn to intubate solely with video laryngoscopy but in my limited experience, I have run into occasional problems where I converted from VL to DL with immediate success.  Of note, however, I wasn't taught any specific set of skills for VL.

Video laryngoscopy is superb in many ways.
  • It allows more than one person to visualize the airway well.  
    • This is especially valuable in training situations, allowing the trainer to give real time feedback to the trainee.  Additionally, this adds some theoretical patient protection (Although, in the age of apneic oxygenation, it probably routinely adds more trainee protection, "No, sir, that would be the gooose, try again.")  
    • Safer for some difficult airways. Again, VL allows more than one individual the opportunity to visualize the airway which, in my experience (dangerous words!),  can be helpful for team problem solving.   
  • Airway outsourcing (see EMCrit Wee:  I've always wanted a henchman/woman).  I think that most good Emergency Physicians have at least a third, if not fourth, hand tucked away somewhere.  Either that or they've mastered the art of preparation and adaptation for various procedures.  The following tasks can be outsourced, allowing the operator to keep their hands free/clutching the tube/bougie.   
    • I have a clear disdain for cricoid pressure as it has destroyed more views of the cords than it's created for me; however, laryngeal manipulation using the VL is an excellent idea, if needed.
    • Suction. Again, an assistant can direct the Yankauer to the necessary regions without getting in the way (too much, theoretically).  
    • Prepass bougie/ETT.
  • A combination VL/DL exists in the C-Mac device, which allows an intubator to use a VL view or DL view.  While I have no first hand experience with this device, studies such as this one in Anesthesia & Analgesia, look promising.  This study in BMC Anesthesiology demonstrates that the VL view resulted in faster visualization but actually required a greater number of attempts at ETI for success (perhaps due to operator familiarity/lack of training). 
So, why am I somewhat reticent?
  • Different skill set than DL, at least to do VL correctly.  Drs. Weingart and DuCanto on EMCrit Episode 73 highlight some necessary differences to properly perform VL. 
    • The individual performing ETI should focus their gaze as such:  Mouth -> Screen -> Mouth -> Screen
    • Hold the ETT further back and rotate 15 degrees, using a rotatory motion of the thumb and forefinger
  • Sometimes the VL screen gets obscured by blood, secretions, or fog.  Most airways in EM are less pristine than the ones I initially trained on in the OR.  In these cases, DL may allow for quicker ETI.  
  • Passing the tube is somteimes more difficult with the Glidescope as there seems to be less space in the mouth.  Sometimes good technique can overcome this, but some studies demonstrate the ETI time isn't consistently lower in the VL group (the time to good view may be quicker, but not to cord placement).  The literature pretty consistently shows that one can achieve a technically good view in less time with VL but the time to ETI is not consistently better across studies (1,2).  
    • For example, this trial showed an average time to ETI of 22.5 sec (18-29.5) with DL compared with 33 sec (27.5-35.5) with VL (Glidescope), which was statistically significant.  This may be in part due to operator familiarity, favoring DL, but I think this point is still valid.
    • A meta-analysis in the Canadian Journal of Anesthesia demonstrated a statistically significant difference, favoring VL, in achieving a good view of the cords; however, there was no statistically significant difference in time to ETI between DL and VL. 
  • VL is a technology/electricity dependent process.   I grew up in an area of the US where natural disasters may leave a community without electricity for a month and leave buildings/one's house in ruins.  I've spent a fair amount of time in South Asia where these situations are more like a way of life.  Many areas of the world are resource limited and may have frequent power outages and limited funds for this equipment.  

(Cox's Bazaar, Bangladesh, 2010)

Take home?
Best said by Dr. Seth Trueger @MDaware on Twitter:  "VL/DL = belt + suspenders. and real time training. and supervisor midaz"  


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  •  Video-laryngoscopes in the adult airway management: a topical review of the literature Acta Anaesthesiologica Scandinavica Volume 54Issue 9pages 1050–1061, October 2010 

  • Groeben H.
  • Expected difficult tracheal intubation: a prospective comparison of direct laryngoscopy and video laryngoscopy in 200 patients.  Br. J. Anaesth.102 (4):546-550

    Note:  I use Glidescope interchangeably with VL at times when talking about personal experience since it's the VL method I have the most experience with.  

    1 comment:

    1. Great post! And thanks for the shout out :)

      2 studies to supplement what you have:
      Walls' group studied the Storz first hiding the screen, then showing it to intubators, and the VL component did improve the view http://www.annemergmed.com/article/S0196-0644(10)00108-3/fulltext

      Levitan has a great study on various VL options and one of the main points is tube delivery problems, which can originate not just from lack of space but also a much steeper angle of approach to the glottis, increased risk of getting caught on tracheal rings, etc http://www.annemergmed.com/article/S0196-0644(10)00560-3/fulltext