An opportunity for a quick post to point to a new publication with something useful on drowning. From Dr Alan Garner.
Unfortunately we attend a number of paediatric drownings in the Sydney area every year. Many recover well. Some do not. Some do unexpectedly well. We have had a patient who was GCS 3 at our arrival and asystolic on the monitor make a full recovery. Most children in this situation however either die or are severely impaired.
This brings us to a vital question – when is it reasonable to stop resuscitation? Well, here’s some evidence to help inform the chat.
The Dutch Study
Over at the BMJ a new paper has just hit the screen:
This study is a nationwide observational study in the Netherlands of children with cardiac arrest due to drowning. The authors have put together ten years of data collected in a country with more than 30 million people. It seems unlikely we’ll see a bigger study.
The study indicates that no child resuscitated for more than 30 minutes had a good outcome. There were good outcomes in those resuscitated for less than 30 minutes.
This matches our experience. Our patient with the GCS 3/asystole combination and a subsequent good outcome had a return to spontaneous circulation while still on scene.
The other point of interest is that it is from an environment where water temperature is presumably a fair bit colder than the coastal fringes of Australia, but the results would appear to be similar.
It would appear that discontinuing resuscitation after 30 minutes in those with no neurological improvement or stuck in asystole is a reasonable practice.
Dr Andrew Weatherall returns to stuff about paediatric airways, a bit of a companion to an earlier post with some practical tips.
There are some things you’re taught from a very young age to believe in. Then it turns out it’s just plain wrong. Santa Claus. The Tooth Fairy. The Public Holiday Numbat. (Well, the last one might be specific to my upbringing.)
And in medicine there are plenty of examples those too. Oxygen is always good. You can’t manage trauma without a cervical collar. Then of course there’s pretty much everything about the paediatric airway. As if managing kids didn’t come with challenges anyway, we all get to work with information that is just plain wrong.
And there’s no mistaking that clinicians find paediatric airways difficult. The staff from Royal Children’s Hospital Melbourne have recently published a sizeable prospective study of emergency department intubations. This is from a big, clinically excellent tertiary kids’ hospital receiving 82000 patients in their ED every year. In 71 intubations across a year (only 71!), 39% had adverse events (most commonly hypotension in 21% and desaturation in 14%) and the first pass success rate was 78% (only 49% had a first pass intubation with no complications).
Now lots of things will contribute to those figures. But at least part of pondering that has to be making sure we understand what we’re dealing with.
It points out that some of the classic teaching on the paediatric airway come out of a 1951 report by a Dr Eckenhoff. This includes the issues of the position of the larynx, the shape of the epiglottis and the funnel-shaped airway. Actually, to really trace the story, you have to start a little earlier.
It’s 1897. Waistcoats aren’t ironic yet. Pipes aren’t an affectation they’re an expectation. Jack the Ripper is part of shared memory, not fevered historical narratives. And Bayeux was making casts of the airways of dead children. 15 casts actually in kids aged 4 months to 14 years.
Taking measurements of the circumference of the airway at the glottis, cricoid level and trachea, the cricoid ring was noted to be narrower than other parts of the airway (the topic of the shape of the airway wasn’t mentioned). This is the work that led to the idea that kids under the age of 8 had a conical larynx, with the cricoid ring as the narrowest point.
Consider for a second the qualities of plaster poured into a distensible tube. Wait, it’s not entirely distensible because the cricoid can’t distend. Is it maybe possible that the plaster may have distorted the anatomy? I’ll leave that with you for a bit.
This suggestion of the conical airway made its way into Eckenhoff’s later paper (though with a specific note that cadavers may not represent the living accurately). There were also some descriptive points raised:
The larynx moves down from the C3-4 level in the neonate to C4-5 in the adult (I’ve always been under the impression this move is brought about both by the need to phonate properly for speech and the loss of the need to breathe and breastfeed at the same time, but this point doesn’t feature in airway descriptions and I’m happy to be corrected).
A stiffer and more “U” or “V”-shaped epiglottis with an angle to the anterior pharyngeal wall of around 45 0 rather than lying close to the base of the tongue.
A case report of a 2 year old with airway complications thought to be related to an inappropriately sized tube, feeding the idea of uncuffed endotracheal tubes in kids under the age of 8.
All these points that form part of so much teaching lead to another question – would such a descriptive effort get a run in modern publishing?
Newer Tools Means Better Understanding
The answer of course is probably not. Of course you can only use what you have and it’s absurd to judge Eckenhoff (or Bayeux) for their accuracy against modern modalities. All we can do is revisit our thinking when new information becomes available.
We now have the significant advantage of radiological techniques (CT or MRI) and bronchoscopy to evaluate airways in children who aren’t dead. Again the Tobias article goes into more details but there are some key things to take from this modern literature:
In spontaneously breathing and muscle relaxed patients, the cricoid was not the narrowest part of the airway. That honour belongs to the vocal cords.
There is no change in the ratios of the cross sections over age – the cricoid doesn’t start relatively smaller and enlarge by the time you hit 8.
The cross-section looks like an ellipse (there’s more distance between the anterior and posterior bits than the two side bits).
What should we do then?
Well for starters we should probably settle the tube choice thing. This is just more support for the argument to use a cuffed tube. For starters, the old “leak” test seems pretty dubious when you could be snug against the lateral walls but still leaking around the anterior or posterior areas. And I’m guessing no one has had their “leak accuracy assessment” externally audited.
It makes more sense to use an appropriately sized cuffed tube with the cuff pressure kept < 20 cm H2O. There’s now fairly convincing evidence that appropriately used cuffed tubes don’t cause big issues in recovery. Better ventilation, better monitoring, less flows and gentler tube material in contact with the mucosal wall. Makes sense.
What you can’t do is ignore the cricoid. It is still an unyielding bit of the anatomy and anyone can turn a high volume-low pressure cuff into a high volume-high pressure cuff – the difference is a couple of mL. And swelling in an airway that starts with a much smaller cross-sectional airway still means less margin for flow obstruction.
So choose the right tube, use it safely and you can get on with things.
While We’re At It, Let’s Forget One Blade to Rule Them All
Seeing as we’re talking about things that aren’t things, you may have also come across the idea that you should use a straight blade for the smaller kids (say, kids under 2). I’ve mentioned elsewhere that I think this is baloney but here’s a little bit of evidence.
Varghese and Kundu have published something on exactly this issue. 120 kids aged from 1-24 months had laryngoscopy (once anaesthetised and given muscle relaxation) with either a Miller or Macintosh blade, and then crossed over to the other type of blade. (Note they used both with the tip in the vallecula.)
The findings? The views were pretty much the same. The rates of difficulty were about the same. In fact, it’s a pretty beige set of numbers where being beige is actually as cool as things could be.
Some where the view wasn’t so great with a Macintosh had a better view with the Miller blade. Some went in reverse. The message though is a pretty resounding “same, same”.
So there’s just some truths that needed revisiting. There are no funnel-shaped airways. The airway isn’t round. There’s not one correct blade for the under 2s.
I still resent having to give up on the Public Holiday Numbat though.
Here are the PubMed links for those mentioned in this post.
I don’t do DIY. This is partly because in the same way I wouldn’t expect a carpenter to have a crack at fixing their kids’ bones in preference to seeing an orthopod, I think it makes sense to use professionals.
It’s also because I’m just not that great at it. Anything I did make would end up looking like something trying to squeeze itself into the shape of the thing it is sort of supposed to be. And I’m fond enough of my family to want to protect them from the risks of my own handiwork.
Anyway, I do paediatric anaesthesia. I get to spend more than enough time trying to make things that aren’t quite right for the situation fit in with what I need. Why DIY at home when you have to DIY at work?
Making Things Fit
The problem with paeds practice is that kids are sometimes kids and sometimes little adults and often forgotten in research. Or if not forgotten put in the category of “the ethics and logistics of that will be so painful I’d rather remove my spleen via my auditory canal”. And in trauma care we’re also dealing with total numbers that are lower than is the case for adults.
So what we end up with is lots of extrapolation from adult data and lots of retrospective studies sprinkled with the occasional fairy dust of a small case series. Then we have to try and mash those leftovers together to come up with a plan for a very specific situation.
An example: how about tranexamic acid in trauma?
Making It Up
Following on from CRASH-2 and MATTERs, what to do in the younger generation is an obvious question. A big prospective study in kids after trauma would be perfect. And a pipe dream.
So if you turn to the literature what you see is a large number of people trying out archery on summer camp and hitting many, many different targets while all shooting vaguely in the same area.
To corral some of them in one spot, take the review by Faraoni and Goobie looking at antifibrinolytics in non-cardiac surgery in kids. All of the following values are listed as loading doses in the scoliosis and craniofacial groups: 10, 15, 20, 50, 100 and 1000 mg/kg with infusions anywhere from 1 mg/kg/hr up to 100 mg/kg/hr. In the scoliosis patients there are total numbers of up to 80 patients and slightly baffling figures suggesting total blood loss is decreased but transfusion requirement pretty much the same. Or that in the craniofacial surgery group it seems like probably there might be slightly less blood loss and transfusion needs.
But in paediatric cardiac surgery there might be more seizures too, even though the overall safety profile looked pretty good. Nothing definitive though. Such clarity.
So now the job is to consider how to take this magnificently imperfect evidence and apply it to a specific and different clinical scenario, trauma.
The Royal College of Paeditrics and Child Health and the National Paediatric Pharmacists Group Joint Committee had exactly this challenge back in 2012. It’s the intellectual equivalent of trying to catch pancake batter. Messy.
Ultimately they chose what they termed the pragmatist’s option – 15 mg/kg loading (up to 1 g) over 10 minutes then an infusion of 2 mg/kg/hr. Maybe enough to do something, but with a homeopathic infusion so you were unlikely to get complications. Entirely rational in the absence of evidence too.
But what if there was another approach?
What they didn’t have access to was some recent data out of the UK military Afghanistan experience in Camp Bastion. TXA had become standard for adult trauma patients under certain conditions after the release of CRASH-2 and both editions of MATTERs. These sort of treatment centres don’t just receive adults though and they must have been wrestling with what to do in smaller patients.
What they describe is another type of pragmatic approach. Rather than any adjustment they just did what they were already doing. Tranexamic acid in a 1 g dose for all comers and more on the basis of medical assessment (though it looks like no one got another dose).
This gets past lots of problems, particularly with getting accurate weights or ages and the need to learn different treatment regimes. It also comes with a certain amount of glee, not because you’re sort of saying “kids are just little adults” and you know that would break plenty of people. You’re actually saying “kids are adults”. If you say that 3 times while drawing a pentagram in a circle of candles, somewhere a paediatrician will be woken with a pain between their shoulder blades.
They describe a breakdown of 66 patients under 18 getting TXA and 700 without TXA. Having severe abdominal or extremity injuries and showing evidence of severe metabolic acidosis were significant predictors that TXA would be used. TXA use was independently associated with reduced mortality but no great difference in packed red blood cell/fresh frozen plasma transfusion ratios. Intriguingly in those getting a large volume transfusion, receiving TXA was associated with greatly improved neurologic status at the time of discharge (now that opens up a need for more work). They didn’t note an increased risk of thromboembolic complications (but they probably don’t have the numbers to be sure about that).
Overall, we’re talking about kids with an average age of 11 so using the equation of (3 x age) + 7, the weight might be about 40 kg (though I’m not certain if the weights might be a bit less than algorithms from developed countries). That would mean a starting dose averaging round 25 mg/kg.
The Other Extra Bit
That 2014 review also mentions an additional titbit that’s a little useful. Some pharmacokinetic work has been done in patients with craniofacial surgery patients and it appears that an upfront dose of 10 mg/kg then an infusion of 5 mg/kg/hr is optimal for establishing appropriate drug levels. This is far more useful information than cardiac surgery pharmacokinetics where additional considerations of dilution by bypass circuits, potential for pre-existing cyanosis and a variety of other factoids make it hard to draw comparisons. So 10 mg/kg might be enough initially but the subsequent infusion should probably be more than a scattering of holy water (as in more than 2 mg/kg).
The Bottom Line
We’re still stuck with not enough information about paediatric patients. Will there be a bigger study in paeds trauma soon? Probably not. But we can say with more confidence than before that doses that are pretty big seem to be OK.
So what would I do now? I’d modify the pragmatic plan and go with a 20 mg/kg loading dose (or 0.2 mL/kg of our current stock) and once in hospital I’d go with an infusion of 5-10 mg/kg/hr.
And I’d still hope someone is going to try to build a better shack.
Dr Andrew Weatherall does prehospital doctor stuff but spends lots of time serving the somnolent god of anaesthesia in a tertiary paediatric hospital. He has particular interests in cardiac, thoracic, trauma and liver transplant anaesthesia and is trying to be a PhD student in his spare time. You can also find him as @doc_andy_w
Little creatures have the potential to cause significant stress. It’s true of spiders. It’s true of parasites. And for many medicos, it’s true of paediatric patients. All too often, the experienced clinician confronted with the alien life-form of a kid goes through a rapid medical devolution, retreating to the almost foetal uselessness of a medical student confronted for the first time by having to do a procedure they’ve only read about.
It’s entirely reasonable to feel less comfortable with stuff you don’t do all the time. In fact, it’s healthy to step up a level of vigilance to make sure no little point in care is forgotten. The risk is that the heightened awareness can flip over to downright anxiety. Even experienced clinicians can sometimes forget that they are really good at what they are about to do and let little things compromise their success.
Managing the paediatric airway is a case in point. It is different. There are all those annoying calculations to remember. Everything feels the wrong size. The things that should be easy, like bag-mask ventilation, seem unusually clumsy. It’s as if someone managed to switch your shoes onto the wrong feet and then asked you to run.
When doing time in the paediatric theatres we frequently have experienced clinicians dropping by to brush up on their paediatric airway skills. From an observer’s point of view, there are little technical things that crop up repeatedly and cause grief. They are also the sort of technical hitches that distract from the mental process of getting the job done. If these little things were addressed, the prospect of the paediatric airway should be no more daunting than the prospect of participating in a yawning competition at the local retirement village lawn bowls competition.
So here, in no particular order, are the commonest practical things I see clever people forget:
A Light Touch
True paediatric patients are not big. Unlike the momentarily moribund wildebeest of adult medicine, they do not require brute strength. Airway management starts with good bag-mask technique and that should be easy (I am making the assumption that they don’t have the sort of condition that makes people widen their eyes when flicking through the ‘big book of syndromes’).
All too often those who do medical stuff in big people seem to want to subdue the small scruff of a paediatric patient with the big unwieldy shovels they refer to as ‘hands’. In smaller kids, it is really hard to apply good bag-mask technique if you try as you would in an adult, with a digit behind the angle of the jaw and other fingers arranged along the mandible.
Try this one – lay your middle finger gently across the soft tissue just where the neckline starts to head up to the chin (yep, right in the midline). Gently stretch the skin up to the jaw line with that middle finger (almost like you’re pushing the little ridge of skin up to the chin). Now add the mask with your index finger and thumb holding it to the face as per normal. You should have an open airway. That’s all the effort it takes (if that’s as clear as mud, let me know and I’ll try to produce a better version).
Smaller kids desaturate quickly. Whether or not you’ve done nasal prong oxygenation, you should feel at liberty to gently provide ventilations while waiting for the muscle relaxant to reach “apparent serenity now” efficacy.
Know Your Equipment
If you are going to use different equipment it pays off to know the details of the kit. This seems really obvious, but all too often the occasional paediatric airway specialist gets so focussed on the other bits of getting the job done they take the equipment stuff for granted and things get messy at some point after everyone thinks crunch time has been and gone.
Here’s an example. Observe the photo of two different kids endotracheal tubes. The one on the bottom is a bit more custom-designed for kids. Another popular brand up top looks pretty much like a down-sized adult endotracheal tube.
When you look closer, you might notice that the one on the bottom has an obvious black line where the tube is intended to line up with the cords. If you place it there, the tip of the tube is usually in a good spot, and the distance between cuff and cords is actually a fair bit.
Now look at the one on the top by comparison. The cuff ends around where that black line is. So if you place this one with the cuff a bit beyond the cords, you have successfully achieved lung isolation (kudos to you). Sometimes in bringing it back to where both lungs benefit from the cool breeze generated by your relieved bagging, the cuff could be sitting in the cords. Bugger.
Knowing which one you carry (or should carry) matters. Same goes for choice of laryngoscope (and the resultant changes in positioning the patient). Speaking of which …
Keep an eye on the forest
You get handed a straight-blade laryngoscope to intubate a child (the fact that I’d probably choose a curved blade in pretty much every paeds patient is an entirely separate rant). Your job is to get a view on laryngoscopy that permits successful intubation. Your job is not to pick up the epiglottis. Do not confuse a popular choice for during the intubation with your daily KPI.
If placing the tip of the blade in the vallecula is what works, do that and put the tube in.
Use Cuffed Tubes
Shouldn’t we be choosing uncuffed tubes? Really? Just because you prefer harder to manage ventilation with a high chance of needing to change the tube entirely? Or are you a staunch supporter of tradition in medicine? Even where that tradition was established because the perished rubber endotracheal tubes with their low volume high pressure cuffs made of rubberised sandpaper were causing complications?
Seriously, just use cuffed tubes (and check the cuff pressure regularly). That way you get to do it just the once before the high fives rather than trying to figure out how to calibrate the ‘leak’.
Noses are for other doctors
There is no need for all endotracheal tubes in paediatric patients to be nose snorkels. A secure airway is the goal, and that is best done with a quick oral intubation. The number of doctors I see who seem to have the impression that neophyte airways means nasal airways in all circumstances never ceases to astonish.
So there’s just 6 quick tips to get the practical bits sorted. Is it absolutely exhaustive? No, but these are things I keep seeing (so you can grade the level of evidence as “stuff I see heaps and heaps that I thought I’d mention”). If you’ve got others (or disagree) I’m always all ears.
The aim is to help anyone get to the natural state of things – where ill kids needing intubation aren’t the scary ones. It’s healthy 3 year olds drinking red cordial at a party that inspire true fear.
This post is meant as a chance to share stuff seen through observation. If anyone is keen, I can follow up with the broader rant with the working title of “the variety of ways all that stuff about paediatric airways turns out to be kind of rubbish”, or the “choose the cuffed tube” rant in full.