OK, there’s been a break. Sometimes you need those. Let’s get back into it with a look at something tricky – big orthopaedic operations in kids with cerebral palsy.
There are some things where the name tells you exactly what it is. A mudskipper pretty much skips through mud. A blackbird is pretty black. Acme really did make giant rubber bands.
Cerebral palsy is not such a term. It describes a variety of permanent but non-progressive syndromes and the resulting range of categories is immense. There is also a range of settings in which patients with cerebral palsy might need an anaesthetic, some more common than others.
Sometimes those operations are sizeable and children with cerebral palsy can represent a real challenge for the keen anaesthetist. So to start to touch on this complexity, perhaps we could look at just one tricky type of case and try to take away some general lessons to use on another day.
So why not multi-level surgery?
It’s not about deep surgeons…
Well, the surgeon may be a unique and complex individual who does indeed have multiple levels to their personality. It is instead the case that we’re talking about surgery at multiple levels of the lower limbs – think up near the hip/pelvis, around the knee or down at those feet. It’s at least a couple of those levels and may include components of soft tissue work (muscles and tendons and the like) and bony realignment or other rejiggery to improve the patient’s gait or posture or to deal with pain.
So that’s pretty big surgery in challenging patients who need a lot of care and will need a lot of analgesia. It’s made extra challenging by the all too frequent presence of osteopenia in these kids. So how about we get into those particular challenges?
All the associated things…
Cerebral palsy is hugely variable in its presentation and comes with a long list of common associations. There are specialists who wrestle with this their whole professional lives so it’d be fair to say this is going to be the most fleeting of descriptions but maybe it’s worth working through a few of the body systems.
Cerebral palsy of course comes with many different subtypes. While it’s good to know the particular subtype for the child you’re looking after, be that spastic or dyskinetic or ataxic, the reality is that there can be lots of overlap and the features can change over time. Clever neurology or paediatrics types can work hard on this sort of classification. What is more useful is to establish with the child and whoever looks after them what this means for their functional abilities and limitations.
The first key point here is to establish really simple things: how does this child communicate? Is there any intellectual impairment? How would you be able to assess discomfort or other perioperative things that will be really important? Are there any behavioural elements to be aware of and how does this child feel about the whole healthcare experience? Any carer is rapidly going to become a very important part of the anaesthetic team.
It also makes the GMFCS grading (that’s Global Motor Functional Classification System of course) quite useful. It looks like this (this being for the 6-12 year old age group as it changes with age):
Level I – Walks without limitations.
Level II – Walks with limitations.
Level III – Mobilises with a hand-held mobility device.
Level IV – Self-mobility with significant limitations; may use powered mobility.
Level V – Transported in a wheelchair.
You can see it’s already pretty involved. On top of that around 45% of patients will have some form of seizure disorder. Vision and speech can also be impaired, as can speech. Really if the neuro stuff was all there was to worry about, you would still be very busy.
Of course it’s not.
It wouldn’t be an anaesthesia post without more focus on pain than you might get from other sources on CP. Pain is reported by anywhere between 50 and 75% of patients with CP. In 25% it proves limiting. Understanding how your patient makes it clear they are in pain is obviously extremely important.
Disordered sleep is another common finding. It can look like anything from the classic behavioural issues of kids to altered circadian rhythms, hypoventilation, or other airway issues. A good sleep history turns out to be pretty important.
The Respiratory Stuff
Chronic lung disease is a significant contributor to the morbidity and mortality associated with cerebral palsy. This may be due to recurrent aspiration and associated pneumonia (neither of which is helped by the sialorrhoea often seen due to difficulties managing normal salivary output). Scoliosis may be associated with a picture of restrictive lung disease. Respiratory muscle dysfunction can contribute to difficulties clearing secretions.
All in all, a thorough respiratory assessment needs to be a high priority.
The Gut Stuff
Up to 90% of kids will have significant GI symptoms. This can be any of chronic constipation, reflux disease, abdominal pain or swallowing issues. These are also a big part of nutritional issues and the respiratory function picture.
The Urinary System
Anywhere up to 60% of children will have some sort of urinary issue. This includes all manner of issues with sensing bladder fullness and controlling voiding. It comes with an increased rate of urinary infection. It might not seem the most pertinent to anaesthesia, but can significantly impact on quality of life during routine hospital care and deserves some planning.
Are you exhausted yet? This is one of the other truisms of looking after kids with CP – it’s time consuming to get on top of it. So if we’re gong to do our job and consume that time, what are the particular issues for anaesthesia?
Cold, Low and Slow
Let’s start with the complications that are more likely. These would be important things to be ready for. Wass et al back in 2012 published something pretty useful here. They looked at 800 patients having all sorts of surgery and specifically searched for one of the following potential adverse events: airway obstruction, aspiration, bronchospasm, delayed emergence, hypotension, hypothermia, laryngospasm, neuropathy, pneumonia, reintubation, seizure or stridor. That’s quite a list.
So what did they find?
Well the guts of it is in this figure:
Cold, low and slow (to wake). The first two alone made up around 80% of the total complications seen. It’s worth noting though that this study actually included adults, though there were fewer of these than kids and that overall you were more likely to have a complication if you were an adult (with a rate of 72.1%) than a kid (58.2%).
Let’s go into each of these a little more then:
For this work hypothermia was defined as anything under 35.5 degrees Celsius. This patient population have altered thermoregulation which is not a great mix with the operating room environment. Lee et al had a look at similar things in their study, and the risk of hypothermia was higher with long operations [falls over incredibly shocked] but also in older paediatric patients, if the GMFCS level was higher and when it was hip surgery that was involved. Given that hypothermia is associated with increased wound infection, coagulation system effects and even cardiac events (more relevant to older types) then it’s probably worth thinking about.
Wass et al defined hypotension as something lower than 20% of the preoperative blood pressure. They propose the possibility that hypotension might be a common event due to increased sensitivity to anaesthetic agents or blunted central responses to haemodynamic changes. They have not much to back this up of course. It reads more like they have to try and have a swing at it because they weren’t really set up to explore the cause further.
The other most common issue was delayed emergence. At least part of this is probably due to hypothermia in some patients, but it is more than that alone allows for.
Many of those other complications seen are within the realm of what you’d expect. The exception to that might be seizures, though of course these patients often have seizures as part of what they live with.
Let’s make a plan …
So now we get to the practical part of this multi-level surgery anaesthetic. The nature of a blog post is it won’t necessarily encompass everything, nor is it likely to be exactly how everyone would do things. That comments section is open for everyone to add their top tips or remind me of the bits I was too dopey to include. Here are some practical starters though:
1. Assess your patient for now and later…
Up above there is the bit covering all the many, many things you will have to consider. Trying to write down exactly how to do each of those is well beyond the scope of a post you should be able to read in a few minutes. The key question is always “is there anything we can optimise before this surgery needs to get done?” In this setting a lot of that will be about current (vs usual) respiratory status, current seizure control where relevant and whether there are reversible nutritional things to consider (like iron-deficiency anaemia as an example).
One key element is assessment around pain issues for your patient before the surgery (given the high rates of chronic pain) and how they express discomfort and pain if there are challenges to communication created by motor delay or speech challenges. A rookie error is to assume that limitations in those areas mean the patient can’t understand everything you say. Receptive abilities may be very excellent even while the ability to then express themselves can be really compromised.
So the general rule of “start with the kid” is indeed, a good point to commence. In those patients where it is tricky to figure out how much of what you’re saying is understood by your patient, or where you are finding it hard to understand the response then parents and carers become super important.
Personally I find “how do you go about talking with [X] about things like soreness?” is a really good way to understand the way forward. Likewise “what should we look for if we’re trying to see if [X] might be sore?” is really useful. Of course then you need to make sure everyone else looking after your patient while in hospital also knows that information.
2. The Pain Plan
Multi-level surgery is the sort of surgery where regional analgesia has a lot to recommend it. You could do this with either a caudal or epidural approach with an infusion to follow for the days after. For most true multi-level surgery, there will be enough different areas covered that infusion catheters covering an individual nerve probably aren’t going to be adequate.
Even epidurals may be challenged if you’re covering the foot and ankle region, all that area around the knees and right up to the pelvis. I’ve even heard of some institutions where they place two separate epidurals to cover lower lumbosacral areas and the higher pelvic dermatomes. I have to say I’m a fairly simple character and have always stuck with just the one.
Now, a full discussion of epidural analgesia is obviously not what we’re here for. Assuming that all the appropriate consent and preparation steps have been covered though here’s one suggestion amongst the many possibilities that seems a fair place to start.
- Place that epidural after the patient is under anaesthetic.
- You can try some modification for position depending on which particular areas are being operated on, but it’s hard to pick up whether L4/5 vs L2/3 is going to make a huge difference for most. I haven’t seen evidence to cover that particular question. In is good.
- Once it’s in situ, use it for the operation obviously. This also helps minimise the amount of anaesthetic agent required.
- Keep running an infusion afterwards. At my local institution, most anaesthetists use bupivacaine 0.125% with fentanyl 2 mcg/mL added. The infusion rate typically starts at 0.2-0.4 mL/kg/hr (at least until patients are more adult-sized).
- Think about additives – I know plenty of anaesthetists who will also add clonidine to the epidural plan. This is partly about better analgesia, though some also tell me that maybe it helps reduce muscle spasms. But the pain is a definite thing. Some, but not all, will bolus with something around 1 mcg/kg during the operation. The infusion dose is then, for most patients, 1-2 mcg/kg/day. Keeping in mind that there are some concerns about sensitivity to agents/hypotension/sedation in this patient group it seems to sensible to consider starting at the lower end of that range, calculated as “lower end of that range for my starting rate infusion”.
- There’s a quick rough calculation for this. If you want 1 mcg/kg/day, you divide 8 by the mL/kg/hr rate. If you want it to be 2 mcg/kg/day, you divide 16 by the mL/kg/hr rate. Trust me it works. As long as your infusion bag is 200 mL.
- For an example, let’s imagine you had a 24 kg patient, and you were going with 0.3 mL/kg/hr of epidural solution as your infusion. Let’s say you want 1 mcg/kg/day of clonidine in the infusion. Nominally with 8/0.3 you’d end up with ‘please add 26.666666667 mcg of clonidine’. So let’s call it 30 mcg. In 200 mL of the solution that’s 0.15 mcg/mL.
- At 0.3 mL/kg/hr you’re actually programming 7.2 mL/hr. Which means in 1 hour the patient receives 1.08 mcg of clonidine. Which means in a day they get 25.92 mcg. Which brings us back to about 1 mcg/kg/day. Easy, right?
For your overall pain plan of course, you don’t want to forget the other agents. Paracetamol and NSAIDs are worth including in most cases. Opioids may be required, though hopefully not while the epidural is in action. Novel things like gabapentin might be a consideration, though they can be associated with a bit of sedation.
3. The Warming Plan
Given that very high risk of hypothermia, and an operation that involves a lot of exposure to the outside world, this requires a lot of attention. Warming should start as early as possible, even in the preoperative area. Warm the theatre, at least until the surgeons are actually next to the patient with scalpel in hand, and make sure there is forced air warming throughout the period where all the procedures at the start are happening. Add in some fluid warming and you might just get close.
It’s worth noting that the warming measures may need to continue in recovery and I’ve certainly seen hypothermia develop a bit later on the wards. There are also some things we don’t usually think of as warming measures that can help. Just one example is in the patient who has overnight feeds for nutritional reasons. The metabolism that goes with that feed is it’s own warming measure.
4. Planning for Haemodynamics
Some means of getting in a decent amount of fluid is important, though vascular access can be challenging. These operations can be associated with blood loss so a group and hold is a reasonable thing to have done and it’s reasonable to consider invasive arterial monitoring. At this stage there doesn’t seem to be much evidence on whether antifibrinolytics might have a role for these operations, though it is creeping into local practice. Dosing is a thorny topic already covered here, so we’ll move right on.
Different clinicians I’ve worked with choose either to have bolus vasopressors ready (locally that’s metaraminol) or maybe even an infusion for the duration of the anaesthetic. The aim is to keep it within the ‘20% of original BP’ range.
5. Minimise the Agents
There is some suggestion on the basis of studies with BIS that patients with cerebral palsy may need less of the agent to achieve the sorts of values folks usually target. Given the known issue with delayed emergence, and really the general principle that you don’t want to use more than you need, attention should be at least paid to how much of your anaesthetic agent you’re using. This will be helped by a regional approach to analgesia.
6. Where to Next?
Another very important point is choosing the right location for post-operative care. This will be very much a local decision based on what particular wards are happy to manage post-operatively, and the ratio of nursing staff to patients. Respiratory considerations, including sleep apnoea, might well push you to choose a higher acuity area.
There’s just the start of a very big topic. All it needs is a comprehensive assessment, planning for haemodynamic challenges, preparation for bleeding, aggressive warming, multimodal analgesia including regional approaches and appropriate postoperative planning including for respiratory issues.
This ended up being a long post, but there is heaps more that you could include. If there are super important points you have to share about looking after kids with cerebral palsy, please chip in. Also feel free to correct any errors you can see. Everything here, is just a suggestion of course and has to be interpreted in an individual’s context. It’d be great to hear about your context.
Now, how about the reading?
A lot of the general medical stuff actually came from UpToDate.
I found these papers pretty useful when it came to the anaesthesia.
Wass CT, Warner ME, Worrell GA, et al. Effect of General Anesthesia in Patients with Cerebral Palsy at the Turn of the New Millennium: A Population-Based Study Evaluating Perioperative Outcome and Brief Overview of Anesthetic Implications of This Coexisting Disease. J Child Neurol. 2012;27:859-66.
The propofol dosage one is here:
Saricaoglu F, Celebi N, Celik M, Aypar U. The evaluation of propofol dosage for anaesthesia induction in children with cerebral palsy with bispectral index (BIS) monitoring. Pediatr Anesth. 2005;15:1048-52.
There’s also a bit in this one:
Hey, you got all the way to here. Maybe you deserve to listen to some awesome music on tape. Different tape.