Category Archives: intubation

Airway, intubation, Prehospital Trauma

Just because you can …

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With a couple of new papers landing that touch on the issue of how you provide and measure quality care around airway management, Dr Alan Garner returns to point at big animals that are bad at hiding.

Two new airway papers have come across my desk in the last couple of weeks and I now wish I had waited a bit longer before putting up the last post on first look intubation as a quality measure.

So where to start? Well how about a place where everything is apparently big? Yes, there’s a bit of work just out of Texas which sheds further light on that first look intubation story so that’s where we’ll land.

Chasing Quality

It sounds like they have used RSI for a while but undertook a quality improvement project to try and reduce their peri-intubation hypoxia rate.  The project involved introducing a bundle of interventions described in the paper as “patient positioning, apn[o]eic oxygenation, delayed sequence intubation, and goal-directed preoxygenation”.

The paper provides copies of the protocol for intubation pre- and post-bundle intervention in the on-line appendices so I might just go through them here to see what they did differently.

The first thing is there was an emphasis on positioning in the bundle, specifically head up a bit and ear-sternum positioning.  Lots of goodness here that I strongly support.

The second measure they mention was apnoeic oxygenation.  However looking at the pre- and post-bundle policies it is evident that they used it in both time periods.  In the before period it ran at 6L/min till the sedation was given then it was turned up to 15L/min.  In the post period however it was run at “MAX regulator flow” after the ketamine was administered.  I don’t know about the O2 regulators in Texas but to me this does not sound like they changed anything significant.  I will come back to apnoeic oxygenation later.

For pre-oxygenation in the pre- bundle period they used a NRB mask (with nasal prong O2 as above) in spontaneously ventilating patients (and arrested patients were excluded) but in the post- period the pre-oxygenation had to be by BVM with two handed technique to ensure a tight seal plus PEEP.  More goodness here that warms my heart.

Delayed sequence intubation in this study refers to administering 2mg/kg of ketamine then maximising preoxygenation for at least 3mins prior to administration of the muscle relaxant.  I don’t think this is necessary in all patients but this was the policy in the bundle.

The last thing they did was “goal-directed preoxygenation”.  This refers to having a SpO2 target >93% for at least 3 minutes during the pre-oxygenation phase after the ketamine had been administered.  If they could not achieve >93% the patient was managed with an LMA or BVM and transported.  I think this represents sensible patient selection in that it removes the high risk of desaturation patients from the process.  When you look at the results you need to keep this patient selection in mind. However I agree that in their system this is a reasonable approach to ensure patient safety for which the managers should be applauded.

Show Me The Money

Yes let’s get to that money shot:

Table

I have been banging on about peri-intubation hypoxia being far more important than first look intubation rate for a while now and this data shows really clearly why.

There is no significant difference in this study in either first look or overall success rates pre and post the bundle but the hypoxia rate fell by a massive absolute 41%!  The 16% decrease in bradycardia emphasises just how much difference they made.  The managers of this system and their staff alike both need to be congratulated for this achievement as this is something that really matters.  And the first pass and overall success rates give no clue!

It really is time to drop first look as a quality measure and move on.  You could look at this paper and start wondering if it might even be worth dropping overall success rate too, which is an interesting thought.  Their policy favoured patient safety over procedural success rates by abandoning the attempt if the pre-oxygenation saturations could not be raised above 93%. It looks like it is working out well for the patients.

Oh, Back to Oxygenation

I promised I would come back to the apnoeic oxygenation issue.  I know the authors state that it was part of their bundle, but it was used in the pre- bundle period as well.  Hence there is no data here to support it’s use.

All three randomised controlled trials of apoeic oxygenation in the ED and ICU contexts (see the notes at the end) have now failed to find even a suggestion that it helps (check those notes at the end for links) and there are no prehospital RCTs.  My take is that it is time to move on from this one too and simply emphasise good pre-oxygenation and good process when the sats start to fall – or never rise in the first place like this group did so well.

Overall a big well done to the Williamson County EMS folks and thanks for sharing your journey with us.

Moving Right Along

The other paper comes out of London, where the ever-industrious HEMS group have published a retrospective review of their database over a 5 year period (from 2009-2014). They were looking for adult trauma patients they reached with an initial noninvasive systolic blood pressure of 90 mmHg or less (or where a definite reading wasn’t there, those with a central pulse only) and with a GCS of 13-15.

This gave them a total of 265 patients (out of a potential 9480 they attended). 118 of those underwent induction of anaesthesia out there beyond the hospital doors (though with exclusions in analysis they end up with 101 to look at) and the other 147 (that number dropped to 135 on the analysis) got to hospital without that happening.

Now the stated indications for anaesthesia listed are actual or impending airway compromise, ventilatory failure, unconsciousness, humanitarian need, patients unmanageable or severely agitated after head injury, and anticipated clinical course.

Now given that the inclusion criteria includes patients having a GCS of 13-15, it seems like both unconsciousness and those really impossible to handle after head injury are likely to be pretty small numbers in that 101. Even airway compromise, ventilatory failure and humanitarian need seem like they’d be not the commonest indications in that list that would apply to this patient group, though they’d account for some.

I guess it’s possible the patients were all initially GCS 13-15 on the team’s arrival but deteriorated en route, though I just can’t sift that out from the paper. Plus if that was the case it seems like you’d say that.

The Outcomes

In their 236 study patients, 21 died and 15 of those were in the ‘received an anaesthetic’ group. The unadjusted odds ratio for death was 3.73 (1.3-12.21; P = 0.01). When adjusted for age, injury mechanics, heart rate and hypovolaemia the odds ratio remained at 3.07 (1.03-9.14; p = 0.04).

Yikes, sort of.

What To Make of That? 

I guess we should make of it that … things you’d expect to happen, happen? Intubating hypotensive patients and then adding positive pressure ventilation in the prehospital setting is potentially risky for patients for a variety of known pharmacological and physiological reasons that the authors actually go into.

So the question is why embark on such a procedure where you know the dangers in detail? You’ve have to really believe in it to end up wiht 101 cases to follow up.

It feels like there’s an elephant in the room to try and address by name. I wonder if it has something to do with a practice I observed while working in the south-east of England 8 years ago. It relates to that last category “anticipated clinical course”.

james-hammond-347179-unsplash
Hovering elephant heads. They’re real.

The concept here is that if you figure the patient is going to be intubated later on in the hospital, you might as well get on and do it. Except the data here suggests that, much like you’d expect, you probably shouldn’t get on and channel your inner Nike marketing script.

Just because you can does not mean you should.  This paper really drives this home though it doesn’t really seem to come straight out and say it. It does pass the comment that “Emergency anaesthesia performed in-hospital for patients with cardiovascular compromise is often delayed until the patient is in theatre and the surgeon is ready to proceed.” Perhaps the problem isn’t using the phrase “anticipated clinical course”. It might be that you just have to remember that the anticipated course might best contain ‘risky things should probably happen in the safest spot’ in the script.

Compare and Contrast

The process of undertaking emergency anaesthesia because later the patient might require emergency anaesthesia is pretty much the complete opposite of the approach from the Williamson County EMS folks. They erred on the side of patient safety and withheld intubation if it was associated with unacceptable risk.

This paper demonstrates that emergency anaesthesia in patients with a high GCS but haemodynamic instability is associated with higher mortality.  We should probably be glad the authors have made this so apparent, because this is probably as good as we’re going to get. We’re not going to get a randomised controlled trial to compare groups. No one is allowing that randomisation any time soon making this another example of needing to accept non-RCT research as the best we’ll get to inform our thinking.

Patients with hypovolaemia due to bleeding need haemorrhage control. The highest priority in patients with that sort of hypovolaemia would seem to be getting them to the point of haemorrhage control quicker. And delaying access to haemorrhage control (because the prehospital anaesthesia bit does add time in the prehospital setting) when the patient has a GCS of 13-15 doesn’t seem to prioritise patient safety enough. Patients probably need us to adjust our thinking on this one.

That seems like common sense. The retrospective look back tells us pretty conclusively it’s a worse option for patients. And now it’s up to us to look forwards to how we’ll view those indications for our next patients. And “anticipated clinical course” probably just doesn’t cut it.

 

Notes:

That hovering elephant head was posted by James Hammond in a Creative Commons-like fashion on unsplash.com and is unchanged here.

How about all those things that got a mention above that you should really go and read for yourself?

Here’s that whole bundle of care paper out of Texas:

Jarvis JL, Gonzales J, Johns D, Sager L. Implementation of a Clinical Bundle to Reduce Out-of-Hospital Peri-intubation Hypoxia. Ann Emerg Med. 2018;doi:10.116/j.annemergmed.2018.01.044 [Epub ahead of print]

Those RCTs of apnoeic oxygenation in critical care environments mentioned are these ones:

Caputo N, Azan B, Domingues R, et al. Emergency Department use of Apnoeic Oxygenation Versus Usual Care During Rapid Sequence Intubation: A Randomized Controlled Trial (The ENDAO Trial). Acad Emerg Med. 2017;24:1387-1394.

Semler MW, Janz DR, Lentz RJ, et al. Randomized Trial of Apnoeic Oxygenation during Endotracheal Intubation of the Critically Ill. Am J Respir Crit Care Care Med. 2016;193:273-80.  

Vourc’h M, Asfar P, Volteau C, et al. High-flow nasal cannula oxygen during endotracheal intubation in hypoxemic patients: a randomised clinical trial. Intensive Care Med. 2015;41:1538-48.

And that paper on the hypotensive, awake prehospital patients scoring an anaesthetic is this one:

Crewdson K, Rehn M, Brohi K, Lockey DJ. Pre-hospital emergency anaesthesia in awake hypotensive trauma patients: beneficial or detrimental? Acta Anaesthesiol. Scand. 2018;62:504-14.

 

 

 

 

 

 

 

 

 

Airway, intubation, Paediatrics

Old School/New School – Updating Classic RSI

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Respect for the classics doesn’t mean being stuck with them. Here’s a refresher on why you might not want to do RSI like they used to by Dr Andrew Weatherall. This one is a cross post picked up from the paeds anaesthesia site he chips in on, www.songsorstories.com 

Everything in medicine needs the occasional reboot. I mean not as often as Hollywood thinks we need to reinvogorate a superhero franchise but at least every now and then. Sometime that’s because we learn new things (cross reference here). Sometimes it’s because our perception of what is the biggest risk changes (more on that in a second). And sometimes we suddenly realise that the original reason something became fixed practice might not have been a thing in the first place.

Which brings us to RSI, a classic so many of us have grown up with.

What is this thing?

The story of RSI starts with excellent intentions (and for this version of events I’m leaning heavily on this review by the excellent Thomas Engelhardt). In this case the idea was to come up with a safer way to get the snorkel in the all important windpipe as quickly as possible to try and minimise the risk of things that should stay nestled in the gastrointestinal tract might find their way to the lungs.

And you can understand why. Serious aspiration can, sometimes, be deadly. The first piece of the puzzle was written up by Morton and Wylie way back in 1951 who described where with the patient sitting up the anaesthetist would give intravenous barbiturate then muscle relaxant and rapidly intubate them. A rapid sequence of induction and intubation. So really it’s RSII.

8 years later a description emerged of a thiopental/relaxant/40-degree head-up tilt foot-down tilt. It wasn’t for another 2 years that cricoid pressure popped up (thanks Sellick) although interestingly it included not just a bit of pre-oxygenation but also some bag-mask ventilation prior to putting the tube in.

It was another 2 years before the other classic bit of RSII became popular, with an exhortation to avoid bag-masking because of the perceived risk for gastric insufflation and hence regurgitation.

A classic technique derived from a series of “what abouts” and “I reckons”. I mean, you wouldn’t read about it. Except you just did.

That’s not to say that medicine doesn’t have space for a bit of logical derivation of good ways forward. It might just suggest that the whole approach is open to a refresh.

Re-evaluating the Likely

If the technique was designed to prevent aspiration, maybe we should start with looking at how likely this event is in a setting a bit more modern than 1951. In 1999 the epic writing team of Warner, Warner, Warner, Warner and Warner looked at 56138 patients under 18 having procedures (elective or emergency) over 12 years to see just how big this problem was. This covered 63180 procedures.

The time frame for defining aspiration was entry into the operating room until 2 hours post-anaesthetic. To score the label there had to be direct identification of bilious secretions or particulate matter in the tracheobronchial tree or new X-ray findings after an episode of regurgitation.  A total of 24 patients met the criteria.

11 of those were emergency cases so the rate in that group was 1 in 373 compared to 1 in 4544 in the elective cases. 21 of the 24 were around induction. 15 of the 24 had no symptoms develop despite the aspiration. 5 of the other 9 did need respiratory support of some kind and 3 of them needed ventilation for more than 48 hours. Well the paper says that but actually describes ventilation for 18 days, 14 days and 33 days in those cases.

And there’s the rub. It’s really very impressively rare. But then when it goes bad, the downside can be very, very down.

So fine, let’s prevent the bad thing. We’d better get on with the classic old RSII, right?

Remembering the Even More Likely

The problem with being so rigorously focussed on avoiding pulmonary aspiration that you do things like not help the patient breathe, is there are other basic functions that don’t get looked after so well. Like oxygenating.

Gencorelli et al looked at episodes of desaturation during RSI while describing the classic drugs/cricoid/no ventilation technique. Across 1070 children included they reported a 3.6% rate of desaturation to 89% or below (1.7% of the patients being in the under 80% group). Not surprisingly the under 2s were more likely to have a desaturation.

These rates are low of course and certainly lower than in some other areas of practice. Reports from emergency departments have indicated desaturation rates anywhere from 14% to 33% (with the latter reporting rates of desaturation of up to 59% in the under 2s).

So amongst the various things we’re trying to do to prevent the 1 in 400+ event are we at risk of failing on another key thing. You know? The oxygen provision thing.

What’s the alternative?

Neuhaus and team subsequently described very well their approach to RSII, which they badged as cRSII (where the “c” is for “controlled” not some other “c” word like “cheese” which wouldn’t make sense anyway but would be a good reminder that cheese is great).

They key features for them (putting to the side “lots of preparation”):

  • 20 degrees of head up (though they say only for the over 2s)
  • Suction any NG in situ.
  • Give the drugs.
  • Avoid cricoid pressure (with a few exceptions).
  • Provide gentle facemark ventilation with peak pressures of 12cmH2O.
  • Neuromuscular monitoring to ensure the muscle relaxant has really, really worked.

This last point makes a heap of sense as active regurgitation is a problem created by airway instrumentation when you don’t have adequate anaesthesia and paralysis.

cRSII
It’s a big list.

Talk is cheap though, what were their results?

They report on 1001 patients They had a moderate hypoxaemia (89-80%) rate of 0.5% and a severe hypoxaemia (< 80%) rate of 0.3% and the 8 patients this represents had a median age of 0.8 years. They had 1 patient with regurgitation but no evidence of aspiration.

That’s pretty impressive.

Putting it Together

So if we accept that we should really try and optimise oxygenation, and that the risk of this is higher than the risk of aspiration then we have to accept that modifications to that original technique are reasonable. What are a few steps for practically putting it together?

1. Assess that risk of a full stomach

It might well be that we’re going to avoid cricoid most times, but there are still a few situations where that risk of aspiration is probably higher. In the Neuhaus paper they suggested achalasia, Zenker diverticulum or post-colonic interposition patients (done for oesophageal replacement) always need cricoid.

It certainly seems worth having heightened concerns in the patient with significant increases in intra-abdominal pressure.

2. Everyone sits up

Why wouldn’t you have a bit of head up? It makes sense if you’re avoiding passive regurgitation and is a good position for pre-oxygenation, facemark ventilation and intubation. I’m not quite sure why some authors have suggested the under 2s shouldn’t be head up. This is a routine option.

3. Have that suction handy

Goes without saying maybe, but I’m saying it.

4. Pre-oxygenation, but not with distress

Yes you want to pre-oxygenate. And most times you can talk kids through that and get a full 3 minutes in. Some kids will only get more distressed with oxygenation though, and insisting on pre-oxygenation only guarantees distress. Given that you’re going to apply gentle face-mask ventilation, it’s rare you need to go to the wall on this one.

And while I’m there what about apnoeic oxygenation? Well, as discussed in this post, the evidence that’s available in kids isn’t so persuasive as to suggest it should be routine. The stuff that has been done showing extended apnoeic time actually followed effective pre-oxygenation with face-mask ventilation. So as we’re going to put that tube in quickly after the same sort of effective face-mask ventilation, extending apnoeic time for minutes seems not that clinically relevant.

5. Cricoid yes or cricoid no?

Again this is a judgment call. I know plenty of anaesthetists who still prefer to start with it but with a low threshold to remove it. I’m more likely to mostly err on the side of not using it, except for those high risk of aspiration patients.

If you are going to use it, it is worth noting that, particularly in infants, the trachea is quite often more prone to distortion by cricoid pressure than you realise. Doing flexible bronchoscopy work you’re sometimes asked to manipulate the airway and I’ve seen the whole trachea get substantially compressed and distorted by seemingly innocuous manipulation. Distort it enough and you can increase the resistance to air going in and out enough to make it easier to get down to that stomach.

In addition, as covered very nicely in this review, cricoid relies on the alignment of trachea and oesophagus and the evidence is that in kids < 8 years old 45% had displacement of the oesophagus so you’d be unlikely to get compression of the oesophagus even with perfectly delivered cricoid (at least on the CT scanning mentioned).

So for the very high risk ones I’d tend to start with it (well start with it once I’m sure the kids won’t react to it going on), but that leaves almost everyone where I would’t be too concerned. And if it is on, I’d be quick to take it off if it was impeding either view or tube passage.

OLYMPUS DIGITAL CAMERA
Maybe I included this picture of an echidna because they have a reputation for being good at waiting and not because it’s a prickly situation.

6. Wait

We’re going to take our time with face-mask ventilation and maintain oxygenation. So where’s the extreme rush getting the tube in? Being too obsessed with that step, even though you’re achieving oxygenation, is a way to end up instrumenting the airway while the patient is only lightly anaesthetised or inadequately provided with paralysis. What was that thing we’re preventing again? The regurgitation thing that’s worse if we get going while the kid is lightly anaesthetised? Oh, right. Slow down.

The description suggests using a nerve monitor. I can’t say this is routine myself, but once the muscle relaxant is onboard I do publicly note for the team I’m working with how long we’ll be waiting on the clock before we start trying to intubate. (“The clock says 09:30 now. Once it ticks over to 09:32, we’ll start with the intubation.”)

I then remind everyone that this will take an unnervingly boring period of time and they might want to come up with a good joke to fill the time.

7. Ventilating

Yes, this is a thing that’s necessary because kids desaturate quickly. Particularly the younger ones. Achieving gentle face-mask ventilation relies on really good technique with the bag in hand. Plus it’s very therapeutic to gently squeeze that bag.

7. What about parents?

This one also needs an assessment of what might help and what won’t. For lower risk kids, as a paediatric anaesthetist doing it regularly, I’d be comfortable having them along. But if it was the sort of case that was likely to be difficult, or if I was back at the training junior doctor stage, there’d be no dilemma for me. I’d tell the parents that they wouldn’t be coming in. Having them alone to help their child relax (not always a guaranteed result of having parents in) has some advantages. But the prime job is safe management of the peri-induction period. And that might mean less people around.

 

So those are the simple things that have shifted over the course of my time in the big wide medical world. It’s a realignment of the priorities in a way that makes the ‘R’ in ‘RSII’ look smaller and smaller so that the oxygenation is placed at the top of the tree.

Put together though it’s a reboot worth endorsing. I mean the 60s just weren’t that great, surely?

 

Notes:

How many bits that are really important aren’t covered here? There must be some. So leave a comment. We’ll all learn.

And if you like the post and other things around the joint, maybe throw your email in the relevant spot so you’ll get an email each time a new post pops up.

This post is a cross-post from another site that this Weatherall bloke works on called Songs or Stories. It’s about paediatric anaesthesia.

That echidna pic came from flickr’s Creative Commons area and is unchanged from Duncan McCaskills’s post.

Now to the literature, because going to the direct papers is always rewarding.

That review by Engelhardt where he makes it clear what he thinks is this one:

Engelhardt T. Rapid sequence induction has no use in pediatric anesthesia. Pediatr Anesth. 2015;25:5-8. 

The paper by the anaesthetic equivalent of the Brady Bunch or something I assume is this one:

Warner MA, Warner ME, Warner DO, Warner LO, Warner JE. Perioperative Pulmonary Aspiration in Infants and Children. Anesthesiol. 1999;90:66-71. 

The benchmarking study is this one:

Gencorelli FJ, Fields RG, Litman RS. Complications during rapid sequence induction of general anesthesia in children: a benchmark study. Pediatr Anesth. 2010;20:421-4. 

The emergency department studies mentioned in passing for their demonstration of high rates of desaturation are these ones:

Long E, Sabato S, Baby FE. Endotracheal intubation in the pediatric emergency department. Pediatr Anesth. 2014;24:1204-11.

Rinderknecht AS, Mittiga MR, Meinzen-Derr J, Geis GL. Kerrey BT. Factors Associated with Oxyhemoglobin Desaturation During Rapid Sequence Intubation in a Pediatric Emergency Department: Findings from Multivariable Analyses of Video Review Data. Academic Emergency Medicine. 2014;22:431-440. 

That paper looking at controlled techniques in kids is this one:

Neuhaus D, Schmitz A, Gerber A, Weiss M. Controlled rapid sequence induction and intubation – an analysis of 1001 children. Pediatr Anesth. 2013;23:734-740.

And that other review is this one:

Newton R, Hack H. Place of rapid sequence induction in paediatric anaesthesia. BJA Educ. 2016;16:120-3.