Filling the Gap

Everyone’s got a theory about what to do in the CICO emergency. Unless the CICO situation is all about kids. Andrew Weatherall goes through a recent review on this arising from the kids’ hospital in Melbourne. 

If you’ve spent a bit of time online you would have noticed a phenomenon that isn’t particular to medical types but is definitely a favourite diversion of that crew. It doesn’t require memes (though they often pitch up). There are no cats required (but then I’m not sure cats are ever really required, they’re just sort of everywhere online).

The conditions that are required to thrive are pretty easy to find though. Just take one example of a ‘babushka niche’ (yes I came up with that and I’m sticking to it now so try to look OK about hopping on board). Like the sort of doll that keeps revealing smaller hideout specialists somewhere inside itself, this is the “small topic inside the subspecialty area” that only the truly obsessive could get worked up about.

The second condition is easy: you need space in the gaps of the evidence for the people in the niche to say “well, I reckon”. That’s all you need to really get people firing. A low visibility health thing and contestable conclusions.

Need an example? How about front of neck options in an emergency airway situation? That’s not a fashion comment on accessories for the urbane anaesthetist to wear somewhere between chin and chest. It’s about the first thing you’ll look for if things are getting really grim.

The key thing is that you can make a pretty logical argument for different options, particularly “scalpel-bougie” and “cannulate and start with the oxygen”. You also can’t find definitive evidence that one technique is better than the other. You can find some evidence that might suggest one course over the other until you pick away at the flaws that mean that suggestion doesn’t really apply to your setting. You won’t find a stone tablet for the barn wall though.

The slightly weird thing is that it’s precisely these sorts of situations where you’ll find some extremely passionate diatribes. Sometimes it’s like people think evidence is born from the fevered loins of loud opinions. Or maybe it’ll erupt from a hot mess of online feelpinions like a Monkey God from a weird old mountain rock egg.

Of course it’s not always that extreme but it certainly takes up many a web archive. Unless of course you’re talking about kids and front of neck access. Once it’s little kids it seems like people pack it, mutter something about APLS and ‘1 litre per year’ and settle for something else …

¯\_(ツ)_/¯

So why can’t CICO in kids get the same debate going?

The State of Play with Kids CICO

OK, let’s not make too many wishes because I’m not sure we really need another online discussion like that. There are probably a couple of really obvious reasons. The first is that CICO situations in kids are really very rare. The vast majority of difficulty with kids’ airways is predictable and it’s pretty rare to find all other options failing.

The other reason is that we’re not really dealing with a situation where there is lots of stuff published. There is pretty much zero evidence and zero gear that is really suitable for kids and it’s hard to disagree too much about nothing I guess.

At my joint we’ve been starting to work through this whole area because we’ve hit one of those times when you need to break apart things that look familiar to see what options there might be. So for a while we’ve been inching towards our best suggestions that we’ll prepare for. It’s been evident to us for a while that the approach will have to rely a fair bit on pragmatism.

Which makes the appearance of this excellent educational review from a team at the Royal Children’s Hospital Melbourne very timely. It puts together a lot of useful information and some very similar thinking in a package with a neat bow.

In the hope that a teaser can encourage you to go and read it in full, here’s just a few highlights.

Experts Struggle With What to Recommend Beyond “ENT Please”

You can understand why. That might work out OK if you’re in a tertiary facility but most kids’ anaesthesia is not performed in big hospitals. Of course that does bring us back to the point that difficult kids’ airways should be predictable so you can make a plan to have more back-up. And getting ENT involved makes sense, particularly in the smaller kids.

Nevertheless, recent stuff from this paper includes quotes like:

“The Delphi Group reached consensus in promoting percutaneous cannula cricothyroidotomy as the first-line technique for emergency airway access in the 1- to 8-year age group, although there was no consensus on whether the transtracheal route could also be used.”

The uncertainty is really well encapsulated in the inability to offer any real recommendation. Even in recommending needle or cannula techniques first, the discussion notes that the cricothyroid membrane is small and difficult to find and close to the mandible making access hard. Direct tracheal access with a needle or cannula is also noted to be difficult because that windpipe is more mobile and more likely to be compressed during the procedure. Surgical cricothyroidotomy isn’t something that you’d think would be easy in the under 1 year old if a cannula is already forbidding.

The review article also covers this area well. The result? The evidence can’t recommend scalpel technique over cannula techniques.

This leads to another key consideration: mindset.

Looking at cases of CICO where rescue wasn’t attempted early enough is a stark reminder that something potentially much worse than choosing a technique with limitations is not getting on and trying to correct oxygenation.

So perhaps a really key consideration in choosing to adopt a particular strategy first is another key element – which technique provides the smallest barrier to people getting on and doing it?

If you promote scalpel techniques for the younger kids and the thought of doing that is just too much for too many staff (be they medical or nursing staff participating), then maybe you’re setting that rare patient up for a big fall.

Scalpel Techniques May Not Transfer Well to Kids

The studies that have been done were in adults and pretty heterogeneous. People extrapolate from small studies of elective cannula cricothyroidotomy where oxygenation was actually successful but there were complications from the cannula to say it might not be a good option to break out that cannula. Those cartilaginous structures that help provide protection with scalpel techniques for nearby tissues in adults don’t apply in kids. The evidence sort of isn’t evidence.

 

Anatomy Is Not Your Friend

It wasnt in uni either. OK that’s just me. But do you think you’d be stressed in a real world CICO situation in a small kid? I would be, so I wonder how easy it would be to identify this anatomy?

Screen Shot 2016-07-16 at 1.09.52 AM copy

Not big.

Even if you do, the larynx in the smallest ones is more anterior, that jaw could be in the way. Can you get the angles right to approach that airway with your cannula?

“That’s OK,” you say. “I’ll just extend the neck to provide that access.”

Cool. Except the review points out that in neonates and infants full extension of the head and neck still might not be enough to access the cricothyroid membrane and you might be forced to approach the trachea. But the more distal you are the higher the rate of failure. Ace.

10522247883_8e47b7bd22_o

I guess the anatomy could be worse.

A Cannula Is A Complex Choice

The authors here suggest a 16 G cannula as small enough for neonates and infants and large enough for adults. However, the smaller the cannula the more you have to compress the trachea to get that cannula in there. Remembering that studies using these sorts of techniques (sometimes in animals but still relevant) show rates of posterior wall injury over 40% so that is a real thing to think about.

So the choice from this team was 16 G because it removes the need to think about what you choose (though they suggest thinking about 18G for specialty small people units).

Jet Ventilators Are Scary

Other groups have supported things like the Manujet in the 1-8 year olds but given the risks of unfamiliarity, the ability to dial up big pressures and the absence of clearly defined suitable pressures in kids it seems … not ideal. The authors here suggest either the Enk Oxygen Flow Modulator or the Rapid-O2 Insufflator (there’s lots of details in the paper). That said, I think there’s probably still scope for a better device for kids as quicker feedback if there’s obstruction to the cannula or airway would be ideal. Done in a safe fashion with slow rates, a focus on chest rise and plenty of time for expiration this adds up to a reasonable option.

Who Needs Equipment?

Probably us. As established by Coté and Hartnick, most of the equipment out there actually doesn’t work for the younger kids anyway.

For more examples, this paper has detailed descriptions relating to scalpel techniques and percutaneous cricothyroidotomy/tracheostomy techniques. It’s way beyond the scope to go through that in this little post but there is a recurring theme is pretty obvious – the equipment isn’t quite fit for purpose. Airway catheters are not quite the size you want, or the percutaneous kits aren’t quite the size you want. It’s close but not quite there. Maybe this argues more strongly for the techniques not limited by the available kit when you’re in the rescue phase. Back to the cannula I guess.

CICO

The kit from the paper in its clear-panelled glory.

More Research Is Needed

That much is pretty obvious. I’m really glad they said this too because we’re right in the middle of a project that we really hope might help with researching airway techniques for kids as well as education for clinicians. And while I am busting to spill the beans we’re not quite at that stage.

I can say that it is somehow related to digging for small mammals in South Africa, ionising radiation and fancy talcum powder but more than that and I’d get in trouble.

 

So I would go and read this paper. It should stimulate a lot of thought and comes with a thorough description of where they ended up (call ENT, cannula as first rescue option, scalpel with a preference for an oxygenating bougie next).

And I promise to get back to you when we’ve finished digging up fossils.

 

Notes:

That paper again is this one:

Sabato SC, Long E. An institutional approach to the management of the ‘Can’t Intubate, Can’t Oxygenate’ emergency in children. Pediatr Anesth. 2016;26:784-93.

You might also like to look at this:

Black AE, Flynn PER, Smith HL, et al. Development of a guideline for the management of the unanticipated difficult airway in pediatric practice. Pediatr Anesth. 2015;25:346-62.

And the Coté thing is this one:

Coté CJ, Hartnick CJ. Pediatric transtracheal and cricothyrotomy airway devices for emergency use: which are appropriate for infants and children? Pediatr Anesth. 2009;19:66-76.

That image is from flickr Creative Commons and is unchanged from Bill Gracey’s post.

And don’t forget comments and things you can share are greatly appreciated. As are follows if you are into that.

 

 

Did you scroll all the way down here? Good for you. You could reward yourself by going and looking at this fantastic thing on the brilliance of Chuck Jones, Warner Bros animator. It can’t all be about medicine.

 

 

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3 responses to “Filling the Gap

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