The core job when you reach for general anaesthesia is to provide a general lack of awareness. So what about when it doesn’t work?
The person making the coffee sort of has to make the coffee right. I’m pretty sure newsreaders serve the primary function of reading the words about the news. Near as I can tell Rob Schneider films are all about inflicting pain. So much pain.
Anaesthetists had better make sure people are actually comfortable when they have that procedure. Plus safe of course. That’s really the job. And when it comes to kids’ anaesthesia it’s more common to deploy general anaesthesia to make sure that the experience is OK which means awareness is very much the enemy.
But how much can we really know about whether we need to be worried about this? Is it a real world problem at all?
What do we know?
Awareness gets plenty of coverage. Take the whole of NAP5 for example. It makes sense that it’s a big deal too because the sequelae for people who experience it. You’d expect that to be true for kids too, so everyone would be trying to wrestle this beastly thing down, right?
Except for this, like so many things, we don’t have a whole lot of information. Comparatively anyway. It’s just the latest example of a thing that gets less attention in paediatrics. To which I guess we can ascribe our usual excuses: the numbers in kids are harder to chalk up when you’re doing research, it’s harder to explore ideas like this in kids, ethics clearances are a bit more of a hurdle…. does that cover it? Boring but necessary disclaimers done.
There is some stuff out there though because people do look. So let’s start with the simple stuff.
What are we talking about?
For the rest of the time in this post we’ll be talking about the version of awareness where it’s pretty definitive that the kid involved was actually aware of a thing that happened because the account fits. There is some sort of explicit recall of events or things that happened that are apparent on questioning or retelling.
I mention this because there have been descriptions over the years of implicit recall. This would be events where there is a change in behaviour after the anaesthetic or some other apparently telltale sign that some sort of awareness event happened, but the patient can’t actually clue you in any other way.
The kids’ literature just doesn’t seem to go with that, and it’s hard to see how you’d sift that out. So let’s keep it explicit. The awareness stuff that is.
How common is it?
Common. And not common.
Yes. Both. Sort of.
The reason I offer up the non-answer is that defining incidence of awareness in this setting is a lot about how you choose to establish that awareness happened.
Some of the studies that explore awareness in kids modify the Brice questionnaire. That original series of questions comes out of a study from 1970 (which I guess means they were doing the actual research on awareness at the same time as self-awareness was big business in the summer of love… but there’s a hairy hippy tangent not to imagine too much). The questions in the Brice questionnaire are pretty straightforward: what are the last and first things you remember, was dreaming a thing during it, and what was the worst bit (plus, wait, also the next worst bit)? Modify those for the dinosaur-fanatic to surly teenager demographic and you have your standard approach to exploring awareness.
When you approach it this way you come up with a version of the number 1. Let’s say 1 in 136ish. That’s the number a pooled analysis of a series of cohort studies came up with. The range of ages in the original studies that contributed to the analysed 4486 cases was 3-16 and that 1 in 136 equates to a rate of 0.74%. That’s not a small number when you remember that the rate in the general adult population (not the high risk one) is quoted as 0.1-0.2%.
Maybe that’s too direct though. When NAP5 came around there was a whole chapter on awareness in kids. For that one they were relying on self-report and only included cases never reported to a health professional before. They uncovered a total of eight reports of certain/probable or possible awareness occurring while the reporter was a kid (there were 24 reports in total but a bunch of them were classed as unassessable). That gave them an estimated incidence of around 0.002%. That makes the 1 number closer to the 1 in 60,000 range.
What do the cases have in common?
Here is my short summary for this answer:
Authors in this area seem to want to try and find associations but with the numbers included in the reports I sort of wonder if they’re searching to pad the publication.
Take NAP5. The reports that came out were sometimes from a long way back. One in the “unassessable” category reached back 62 years. In the more certain group, 5 reports were within a year and the other 3 were many years later.
The full group of reports were sometimes from a period of time where the ‘Liverpool technique’ (meaning very serious neuromuscular blockade, lots of opioid, nitrous oxide but none of those crazy volatile things) was in vogue.
Of the 5 probable and 3 possible cases, all had IV induction but with a range of thiopentone, propofol and ketamine. Half had sevoflurane, two had isoflurane, one had halothane. Two had some pain/paralysis sensations to report. 5 of the 8 had nitrous oxide. 4 had neuromuscular blockade, two didn’t and in two it wasn’t clear if they did or didn’t. For 5 cases it was during induction, twice it was during maintenance and for one it was during emergence.
How do you make a pattern of that?
In the pooled analysis where they came up with an incidence of 0.74% they’re still only looking at 33 cases in total. So when they say that their multivariable analysis points at use of nitrous oxide and insertion of a tracheal tube as risk factors, it feels like a stats trick rather than something to hang your hat on.
Does it even matter?
One point of interest is that most authors seem to think long-term distressing psychological sequelae are less common in kids with awareness than adults. That’s one of the explanations given for the discrepancy between self-report and direct questioning. But then in NAP5 they also wonder if the discrepancy is because it’s so overwhelmingly distressing that it gets buried. But then they don’t really draw any conclusions as to whether distress is a thing.
Phelan et al did try to follow up patients where awareness was previously identified. They got a response rate of just over 50% and couldn’t find anyone with symptoms of post-traumatic stress. That response rate dropped them from 7 potential cases to 4 though.
This is exhausting. Some of those unassessable cases in NAP 5 did report significant distress though (and the unassessable bit was partly due to the lack of corroboration available decades after the initial event).
From a pragmatic point of view, let’s just assume that there are some kids who will end up with scars. If we can avoid awareness (which we want to do anyway), then we can have the not scarred future.
But what do we do about it?
So now that we’ve established we don’t really know enough to know what we know about it, what should we do about it?
A little while back one of the authors of the NAP5 section, the good Michael RJ Sury, did a review on the topic that appeared in Pediatric Anesthesia. The “what should we do” section ends up leaning very heavily on ‘here’s the recommendation for adults so I guess…. that??’
That probably comes across not quite right because it’s all pretty pragmatic. Like “give a good anaesthetic” pragmatic. But for the purposes of listing, here it is:
1. Give enough of the things that prevent awareness
Assuming clinical condition allows it, actually give things that stop awareness at doses that are appropriate (remembering that there’s that period where kids need relatively higher MAC amounts than adults. This step also requires that you monitor delivery appropriately. For volatiles that’s appropriate agent monitoring. For TIVA, thinking about your doses but also being able to monitor the manner in which you deliver the agent (like being able to see the cannula site) are both important.
Interesting sidenote that none of the cases of reported awareness graded as “probable or possible” had inhalational induction. Again, not big numbers but maybe the more definite clinical state once you’ve got to anaesthesia than the dose per kg-dependent one actually helps you out.
2. Be appropriate with other things
Giving plenty of the things to block pain (e.g. opioid or via regional approaches) is sensible. Some of the patients in all of the studies report pain as being a significant problem and the more nociceptive stimulus, the more anaesthetic agent you appear to require to drop your chance of awareness.
Also, use muscle relaxant only as you need to (patients being able to produce reflex movements is thought to be a protective factor against being light) and then make sure you appropriately reverse at the and.
3. What about monitoring?
As mentioned above, it’s worth not forgetting that movement (which is generally from a spinal reflex) can be an effective monitor. Sign like heart rate, pupils and blood pressure aren’t reliable enough. In Sury’s review the suggestion is that processed EEG monitoring might have a role (but it’s not exactly pushy about it) as a step at the end of all these other monitoring steps to affirm your sense that you’re in a good place and that probably particularly applies when using TIVA. It is not suggested that an available value be used to drive the dosing.
4. What about if you think your patient might be aware?
Some in the broader NAP5 audit reported that a calming voice that seemed understanding is actually helpful. So if you think there’s a chance, start talking.
What about when you do all that but now there’s someone reporting awareness?
Well bugger. The Sury review reproduces the diagram for adults and in the absence of things developed specifically for kids that seems about right.
The key steps break down to this:
1. Meet up with the patient (and their family)
The purpose of the meeting is to spend most of your time listening. Take in all the details and just accept that they are describing their experience and that it’s genuine. Expressing regret that it happened is kind of important too. It’s also suggested that you consult with a local psychology type person.
2. Analyse the story
You want to figure out if this falls into the probable/possible group. So check the details, check with other staff who were at the operation and see if there’s anything in the notes or on the chart that might help interpret it.
You also want to get a second opinion on that analysis.
3. The Support Phase
Initially you want to check if there are signs that the event has had an impact. The big things to look out for are flashbacks, nightmares, new anxiety or depression. Making contact 2 weeks down the track to see if any of those signs are still there is also really important (and obviously once you describe this as part of your plan, you have to follow through).
If there are signs that there’s been an impact at 2 weeks, it’s time for a formal referral to local psych-type services.
And that’s it. A thing that makes us all worry, that we don’t know the incidence for in kids, that we think we can prevent if we just do normal more … normally and for which the follow-up is a bit disturbingly vague.
The end result appears to be that you can reassure kids and families that is uncommon to have issues of awareness. And there are not special tricks needed to try and prevent it in kids compared to adults. You just give an anaesthetic.
And give thanks that it’s not as painful as a Rob Schneider movie.
Hi there. Did you like this post? Did you know there are other posts? Or that you could just get an email when a post drops? Well maybe consider that. Or do some sharing. If you like, of course. No pressure.
Meanwhile the image was just one of the Google DeepDream things that went around when that horror show became apparent. It was at a few different news sites.
Now, the cohort study thing is this one:
Now the NAP5 report is here and if you go to Chapter 15 you’ll be able to download the one about kids:
The follow-up for post-traumatic effects paper is here:
And that Sury review is this one: