Thursday, April 11, 2013

Indulging in Intubation - Lessons for the Novice

The Gist:  Learning endotracheal intubation (ETI) is both a privilege and a risky endeavor.  As patient safety is of the utmost importance, some situations may not be appropriate for novice intubators.  Dr. Minh Le Cong posed a question regarding who should intubate, discussed here, and Dr. David Marcus also has posts on this topic here and here. There are some things, however, that a novice intubator can do to maximize their learning process in an efficient and safe manner.
  • Note:  I'm not an expert and this is not an evidence-based review.  This is essentially a "Tricks of the Trade" post.
Last year, I wrote this post after an anesthesia rotation.  I'm finishing up a final airway elective, both in preparation for residency and as a gift to myself after a month of public health research. I realized I had benefited from many things gleaned from Free Open Access Medical education (FOAM) world.  Here are some things that have made an impressive difference..

My Top 10 List
1.  Know what you're getting into.   Dr. Minh Le Cong has built a #FOAMed airway curriculum.
2.  Do an anesthesia rotation.
  • Allows for controlled, planned control of the airway.  This is part of the PGY-1 curriculum in U.S. EM programs, but it's also helpful as a medical student where one can easily get 40-50+ intubations in a month.  
  • Allows one to see what happens after the tube is secured such as response to pain, duration of medications, ventilator management.  
  • On a non-airway note: excellent for nerve blocks and arterial lines as well.
3.  Verbalize what you see see and do every step of the way during ETI.
  • An attending once told me, "It feels like an eternity when you're not holding the laryngoscope." Attendings get nervous if they can't see what's going on.  Let everyone know when you're "in the vallecula" if you're using a Macintosh blade, when you see cords/arytenoids, or if something (like cricoid) isn't working. 
4.  Know the physiologic responses to induction drugs and laryngoscopy.  Control of an airway isn't just about placing the tube - induction drugs, laryngoscopy, and the patient's underlying medical status do bizarre things to hemodynamics.  When it becomes available, check out the lecture given on the opening day of the Social Media and Critical Care Conference by Dr. Scott Weingart.
  • Post-intubation hypotension (PIH)
    • Heffner et al: 1 year retrospective cohort (~1/2 eligible were excluded) showed that PIH is common (22%, n=66) and associated with respiratory processes and a shock index (HR/SBP) >0.8 prior to ETI.  The percentage is essentially the same as their prior study (23% with PIH; nearly all intubated with etomidate, often referred to as "hemodynamically stable").
    • Another, more heterogeneous study by Green et al, didn't show any clear associations between PIH and medications but demonstrated that patients with underlying respiratory issues are more likely to have PIH and sustained PIH is associated with badness on the mortality front.
  • In the OR, the induction propofol and fentanyl were always backed by sticks of phenylephrine "just in case."  A recent EMRAP episode (subscription required) featured a debate on this concept between Drs. Amal Mattu and Scott Weingart.
  • Laryngoscopy causes stimulation of the sympathetic and parasympathetic innervation to the hypopharynx, larynx, and trachea.
    • Increased heart rate (~30 bpm) and blood pressure (~25mmHg) thought to be due to release of catecholamines secondary to CN IX,X stimulation and renin-angiotensin aldosterone system (1).  
    • Bronchoconstriction due to parasympathetic stimulation (1).
    • Note: Pediatric patients may have bradycardia, pretreatment with atropine in some infants is of controversial utility (1).
5.  Use airway adjuncts.
  • Video laryngoscopy (VL) devices often require a different skill set in passing the tube through the cords. Some institutions have one start with VL before direct laryngoscopy (DL) but in others, this is not routine practice, so get some experience.
  • Mask ventilation.  Practice the two-handed technique, not the inferior E-C taught in BLS (Hart et al).
  • Get a feel for the bougie - it can be surprisingly difficult to induce memory.
6.  Use a combined VL/DL device if you have one available.  
  • Allows attending to visualize structures to augment safety and correct the learner. 
7.  Know your limits. First-pass success in ETI is important, keep this and the patient in mind.  Opportunities may arise when a difficult airway is placed in your hands.  Know when to say no or ask for help.
  • A recent retrospective analysis of ED intubations in Academic Emergency Medicine by Sakles et al demonstrated adverse events (AE) increase with a greater number of ETI attempts.
    • 1st pass success = 14.2% with AE (n=1333; 72.9%)
    • Multiple ETI attempts = 53.1% with AE
    • Note: AEs included esophageal intubation, oxygen desaturation >10% (most common), hypotension, dysrhythmia, laryngospasm, etc.  Some of these are probably more clinically important than others.
  • A multi-center prospective study of n=2616 in Japan by Hasegawa et al demonstrated an adjusted odds ratio of 4.5 (95% CI 3.4 to 6.1) for AE in multiple attempt ETIs.
      8.  Establish an airway plan.  Seemingly easy, straight-forward airways can become surprisingly difficult.  As an attending told me, "the purpose of procedures in Emergency Medicine is to keep you humble."  Stay curious and never assume you've "got it in the bag." The scariest ETIs I've been a part of were unanticipatedly difficult, perhaps, in part, due to lack of preparation.
      • Talk through your plan with the attending/team to ensure you have an appropriate plan, communicate the plan, identify any pitfalls, ensure proper materials, and demonstrate knowledge. 
      • In the ED, even if you plan to do DL, bring the VL device to the bedside.  If DL fails, the back up plan is ready. 
      • Identify and plan for patient co-morbidities such as pulmonary disease, obesity (see video by Dr. Winters, EDexam post, GI bleed, increased intracranial pressure, or trauma.  
      9.  Remember that ETI doesn't end with the passing of the tube.  
      • Ensure your patients have sufficient analgesia on board.
      • Ensure ventilator settings are appropriate to the situation.  For example, some patient populations need longer expiratory times (asthmatics) or higher respiratory rates (DKA, salicylate ingestion, need for CO2 regulation).
      • This EMCrit post has some neat checklists at the bottom to help one systematize post-intubation care.
      10. Avoid hypoxia.
      • Use apneic oxygenation (NODESAT).  If the attendings don't use this, it offers an opportunity for discussion (at an appropriate time, away from the patient's bedside).  
      • Recognize pulse oximeter lag and the limitations of the pulse oximeter, as demonstrated by Dr. Rob Bryant.  
      Note:  some attendings may interpret some of these points as a "sign of weakness," so be prepared and do what's best for the patient.

      References:
      1.  Ron Walls and Michael Murphy.  Emergency Airway Management. 3rd edition. 2008: Philadelphia, p222-229.

        6 comments:

        1. Great Post.
          Don't forget to ramp obese or pregnant patients, or anyone who may be difficult to perform BVM (eg beard, micrognathia) as long as spinal precautions not required, see http://bit.ly/ZcDHYb for tips. You're lucky if you get 40+ intubations/month in your anaesthetics rotation, in Aus it's all LMA's on fasted elective patients! Lastly don't get confused by difficult airway algorithms, which are, well, difficult to remember in a crisis! Have a look at the Vortex cognitive aid for the unexpected difficult airway, it's astonishingly simple and easy to remember when you're looking down the barrel. http://bit.ly/16WRlPy

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          1. Thanks for your comments. Fantastic points. Ramping is a ventilation game-changer that was never taught to me in anesthesiology. There's a link to a presentation by Dr. Mike Winters in the post, but I'm going to update it with the link you provided - that's excellent stuff! Also, I'm a fan of the Vortex. It's not that its not great enough to be a top 10 but I wanted to stick to the absolute basics and I haven't had attending buy-in on this, CricCon, etc...yet, so I have no personal experience with implementation. Perhaps it'll sneak its way into my residency program...

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        2. Awesome post! Love this topic obsessively. Nice compendium of intubation learning pearls.

          I Would echo Andy Buck and add that positioning is key: rev trendel (head of bed 30 deg), ear to sternal notch, face plane parallel to ceiling, head elevation as well as bed height and head of bed patient access are key.

          The airway resources you point to also highlight the "tricks" to first pass success (getting it into your habits to reflexly do ELM, bougie etc in the heat of battle under stress is the goal).

          Using anesthesia rotation to become adept at BMV and LMA insertion is very useful as these are your main backups. OR and VL is a great place to learn the anatomy (cadaver lab is great if one gets the chance!).

          Check out Rich Levitan's Airway Cam website as it has much #FOAMed on airway www.airwaycam.com.

          Finally, being comfortable with some type of emergency surgical rescue technique is good. There are many web resources on this. I've also collected some of this into Storify if you haven't seen it yet.

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        3. Wonderful tips! I'd also second the call for Dr. Levitan's AirwayCam website, and if at all possible taking his course. I was fortunate enough to attend as a paramedic and it was quite invaluable in my own practice.

          I'm definitely in the "talking aloud" camp. "Lips, teeth, tongue, soft palate, uvula, tonsils, epiglottis, positioning the tip in the vallecula, applying ELM, ..."

          My only addition to your list is: SUCTION SUCTION SUCTION. (and if you have more time SUCTION)

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          1. Agree on "suction epiglottoscopy". The yankauer tip can also be used as a probe when airway distortion/ swelling/ disruption/ redundant tissue is an issue.

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        4. Remember to use an ETCO2 device - preferably CAPNOGRAPHY! Diagnostically, it's a gem! You'll know right away if you've intubated the trachea or esophagus and you can get a reading and control their Ph level. "Slap the Cap and look for squares!"

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