Tuesday, October 28, 2014

Surgical Airway, Part Two: Pediatric Translaryngeal Ventilation

And we're back! In our last post, we discussed a number of approaches to the surgical airway, including the traditional "scalpel-hook-tube" method, the Seldinger technique, newer methods using bougies, and homemade/DIY/MacGyver approaches (a shout out to ALiEM's Dr. Andy Neill for sharing his study on emergently using Bic Pens!).  But what about kids?  That's truly a beast of its own, so today is dedicated to our precious we ones.

Clearly stating the obvious here: emergent pediatric airways are much less frequent than those in the adult world, and fortunately surgical airways in children are exceedingly rare.  But you always have to remember that you cannot do a traditional cric on a child. Their cricothyroid membranes are just too small to accommodate an endotracheal tube, and you have an incredible high likelihood of damaging local structures.  A paper we've referenced studied neonatal cadavers and found that in general their CTM's were about 2.8 mm tall, in comparison to the 2.0 ETT, which has an external diameter of 3.0 mm.

The exact cutoff age varies in the literature, anywhere from age five to age twelve.  Generally speaking, if there's a kid, put your scalpel down.  You could theoretically use this approach for adults as well, but they would require the jet ventilator--simply bagging them through the catheter won't generate adequate tidal volumes, and 15 L/min through the jet probably won't cut it either.

What you'll need is generally similar to the needle approach for kids: a 14 G angiocath with a 5 cc saline filled syringe (in a pinch, you can get this out of a central line kit), and some sort of adaptor for BVM (if that's your endpoint).

The big difference now is that you will need a jet ventilator--the system generally includes a hookup to high pressure wall O2 (generally at about 50 psi), tubing, an on-off valve/injector, a regulator, and a Luer lock to attach to your catheter (see below for images).  Is this easily located in your shop?  Best make sure that it is.

You'll start by identifying the laryngeal prominence, moving inferiorally to locate the CTM.  In neonates and smaller children this may be difficult as their laryngeal prominence is not developed.  In these instances, start low and move your finger up the tracheal rings until you've found the CTM.  After cleaning, aim your needle caudad at about 30-40 degrees.  Just like in our previous post, you'll want to aspirate to get air bubbles.  And it should aspirate easily--any resistance suggests you're still in soft tissue.  If your patient is awake (hopefully not), you can inject lidocaine via the syringe to suppress the cough reflex.

After that, just advance the catheter, and remove your needle.  If you're going to be using a bag, toss on your adaptor (usually a 3 mL syringe MacGyvered into a 7.0 ETT adaptor--seen below), and start squeezing.

One big downside to using the standard angiocath is that it can kink relatively easy.  An alternative, if you have it in your shop, is a nonkinking wire catheter, demonstrated here from the Walls text:

As for jet ventilating, you'll need to attach your apparatus and do some adjustments.  To avoid barotrauma, you'll need to reduce the inspiratory pressures to less than 20-30 psi.  This is where an expensive commercial device earns it weight in gold--you'll want a device that can reliably and easily do this quickly. You will want to set your flow rate at about 1 L/min per year of age, and then titrate up 1L/min based on how much chest wall movement you're seeing.  Your control will either be a handle or a button, with several variations depicted below:

Due to their small lung volumes, the jet is generally contraindicated in kids younger than five.  In these incidences, use the bag, ventilating carefully (but against a lot of resistance!) and with age appropriate equipment.

And now, here's your gratuitous Whit Fisher MacGyver video--this one features novel ways to jet ventilate when your equipment is not within grasp (along with some absolute ridiculousness):

As always, these writings on procedurology are for EDUCATIONAL PURPOSES ONLY.  Do your own research, keep calm/carry on, and always do the right thing.  You are the expert, and you are the one who will save a (young) life.

Thank you all for following!  And thanks again to emcurious.com!



Navsa, N. et al  (2005).  Dimensions of the neonatal cricothyroid membrane--how feasible is a surgical cricothyroidotomy?  Pediatric Anesthesia, 15:402-406.

Walls RM, ed. Manual of Emergency Airway Management, Section 2.

Roberts and Hedges' Clinical Procedures in Emergency Medicine, 6th Edition. 
Chapter 6.

Whit Fisher's YouTube Page

Friday, October 24, 2014

Surgical Airway, Part One: Cricothyrotomy

Hey there, super friends! So far, we've managed to settle down into a groove with this whole blog thing with some solid posts about tough, challenging, weirdo, what-the-heck style procedures.  Together, we've made our way through thoracotamies, Blakemores, and lateral canthotomies.  We're bigger men and women in white as a result.

So, I think we're ready to tackle the elephant in the room.  We're ready to battle Voldemort; we're willing to stop Johnny from "sweeping the leg";  we're going to confront the Emperor, and we will NOT turn to the dark side of the Force.  Our archnemesis is calling, and we're not afraid.

That's right guys, we're doing the cric today.

Most providers I've talked to can count the number of cric's they've had in their career on one hand, but they remember every single, bloody detail of theirs, and will continue to do so until the day they die.  And I'm not being glib there.  The cases that lead to crics are always insanely unique; so unique that writing about any of my examples will surely open the medicolegal Pandora's box from hell.  I'll abstain.

Remember your indications, mainly that you cannot oxygenate or ventilate.  If you can't get the tube, but you can successfully place something temporary like an LMA, step back for a second.  If there's an alternative, take it.

Anyway, just like many other things in medicine, there is more than one way to skin a cat.  We will talk of a few, but not all, of the methods here, starting with the most rudimentary.

1.) Traditional Cric.

The motto of this one is: keep it simple, stupid!  You need your knife, you need your hook, you need your dilator, and you need some sort of tube (either a nice trach or a sawed off 6.0 ETT).  That's it!

1.) Find the cricothyroid membrane.
2.) Cut skin vertically 2-3cm--get ready for some bleeding to screw up your view!
3.) Cut membrane horizontally.
4.) Get your hook in the superior aspect before you remove your scalpel.  Also get someone to hold traction on this!
5.) Get your dilator in laterally and rotate it down 90 degrees (the Trousseau's are kind of counter intuitive--squeezing opens them).
6.) Tube in, cuff up, start bagging.

In terms of incision the skin, there is a bit of discrepancy between our generally accepted way of doing these and what is done in the surgery world (i.e., vertically vs. horizontally).  I personally remember taking ATLS and having an older trauma surgeon laugh hysterically in my face when I demonstrated doing the initial incision vertically on a model.  Ignore the haters out there, this is how we do it and that's that.

Here's a very nice demonstration on a cadaver courtesy of the University of Maryland Department of Emergency Medicine:

2.) Seldinger Cric (aka "Melkering It").

I have never seen this one done but I love the sound of it.  For one, my fear of a horribly bloody surgical field is alleviated. However, this option requires a good, confident ability to locate the membrane--this might be a problem if there's significant trauma.

The kits are as simple as you'd want them to be, including your scalpel, wire, 6 mL syringe, 18 G needle w/catheter,  cuffed catheter, and dilator.

Identify your landmarks, and come at the cricothyroid membrane directed 45 degrees caudad.  You'll want to have your syringe loaded with a bit of saline so you can confirm entry into the trachea with air bubbles.  Thread your catheter, and the rest is just as you'd expect it--wire it, incise it, and then dilate it!  Your dilator slides into the catheter, and you'll want to grip them like so as you push them in:

After you've hubbed it, pull out the dilator and guidewire.  You should be good to go.  Here's an incredibly dated looking video from Cook Critical Care:

3.) Bougie Cric.

It's all the rage!  There's a lot of buzz about this one, and rightfully so--some initial data has shown that it is related to higher success rates and less risk of tracheal damage.  And it's quicker!

You need even less for this one.  Your kit will include a No. 20 scalpel, a bougie, a 6.0 ETT, and your finger (you could throw in a hook as well but it's not required).

The procedure: make a horizontal stab with the scalpel at the cricothyroid membrane (yes I realize what I said earlier).  Do it all the way through the skin and the membrane.  Bluntly dissect down with your finger, keeping it in there.  Load the bougie in under your finger.  Slide the tube in.  Bougie out.

Here's some demonstration images majestically taken by AP:

Here's a demonstration from Darren Braude via Scott Weingart's YouTube page:

4.) Crazy MacGyver Cric.

We're entering the world of the unknown on this one, but essentially you resort to this when you're patient is crashing and you essentially have to grab whatever is nearby. 

While I in no way shape or form recommend you try this, the ever brilliant Dr. Whit Fisher has an awesome technique for making a trach needle out of an IV spike (who would have known?):

Just threw it in for the sheer awesomeness of it all.

Pick your poison, but get it right.  Practice makes perfect, and the more times you can simulate a cric, the more comfortable you will be when your number comes up.  Academic Life in Emergency Medicine has a fantastic recipe to make a bleeding model for simulation here: http://www.aliem.com/simulation-trick-of-the-trade-bleeding-cricothyroidotomy-model/.

As always, these wannabe instruction manuals are made for EDUCATIONAL PURPOSES ONLY.  You already know darn well enough that a cric is the last-ditchiest of last-ditch procedures, so don't go getting heroic on us after this one.

Stay tuned!  Next up is the PEDIATRIC surgical airway.....



Robers and Hedges' Clinical Procedures in Emergency Medicine.

Makowski, A. L. (2013). A survey of graduating emergency medicine residents' experience with cricothyrotomy. The Western Journal of Emergency Medicine, 14(6), 654–661. doi:10.5811/westjem.2013.7.18183

Hill, C., Reardon, R., Joing, S., Falvey, D., & Miner, J. (2010). Cricothyrotomy Technique Using Gum Elastic Bougie Is Faster Than Standard Technique: A Study of Emergency Medicine Residents and Medical Students in an Animal Lab. Academic Emergency Medicine, 17(6), 666–669. doi:10.1111/j.1553-2712.2010.00753.x

Nakstad, A. R., Bredmose, P. P., & Sandberg, M. R. (2013). Comparison of a percutaneous device and the bougie-assisted surgical technique for emergency cricothyrotomy: an experimental study on a porcine model performed by air ambulance anaesthesiologists. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine, 21(1), 1–1. doi:10.1186/1757-7241-21-59

University of Maryland Department of EM's YouTube Page

Procedurettes YouTube Page

Scott Weingart's YouTube Page