Should we stop looking at first look intubation rates?

A brief note: I get to do the editing duty this week (Dr Andrew Weatherall that is) and I could not let it pass without a word of tribute to Dr John Hinds. I had only had the chance to learn from the good Dr Hinds via his online presence. It was a big presence. 

As one who did not know him personally, I can only reflect that he demonstrated many of the best qualities of a passionate doctor and that his passing, far too soon, has revealed many of the best qualities of his colleagues. 

Just in case you needed another reminder, you could watch him in action here, or read good words by @Eleytherius here, or sign a really worthwhile petition to deliver a vision for a better prehospital service for patients in NI here. 

As to this week’s post, Dr Alan Garner has a post on looking for the right outcomes so we’re doing the right thing for our patients. 

Can’t see the wood for the damn trees

As part of their intubation quality program many services now report their first look intubation rate. We have been doing so for a couple of years now. This looks like a really good thing to do. We know that more than one attempt at intubation is associated with greater incidence of serious adverse events in critically ill patients, and the more attempts the more likely those adverse events become (reference 1).

Therefore a strategy of aiming for first look success is probably a good idea, a strategy that my own service employs. So this should be a good thing to report as a quality measure too. Indeed why would you not? After all, the more attempts, the worse things get right?

Well wait a minute …

First let’s have a think about why we would report it. Is it telling us something that actually matters?

The outcomes that really matter are did they die or end up with hypoxic brain injury. The process issues that really matter are did they get hypoxic or have a cardiac arrest during the intubation process. There are other hard complications/process issues you can measure too like aspiration with unnecessary additional ventilator days, or even did you break their teeth.

First look intubation tells us none of these things. It does not tell us if the patient became hypoxic, aspirated or even arrested. Yes it is associated with lower incidence of these complications but it does not tell you if the complication actually occurred.

And what if emphasising first look intubation rate as a quality measure shifts the focus in the wrong direction? Could you risk making the risk of hypoxia higher?

Am I losing the plot here? Let’s go back to first principles.

The outcomes that really matter are death and hypoxic injury. I don’t think anyone is going to argue these should be avoided. Fortunately the incidence of these is pretty low so we tend to use surrogates for these things instead, things like the incidence of hypoxia or hypotension/bradycardia during intubation. These are pretty direct measures reflecting outcomes that matter.

First look intubation isn’t an outcome. It’s not even a surrogate for an outcome – it’s a surrogate for a surrogate of an outcome. My concern is that surrogates for an outcome, rather than the actual outcome can lead you way up the garden path. The MAST suit again comes to mind. The patient’s BP went up so it had to be a good thing surely. Of course when someone finally did a decent study on the outcome that really mattered, mortality, it was trending to worse not better.

Although there are no randomised controlled trials showing hypoxia to be bad for you, the circumstantial evidence is pretty overwhelming so I agree this is not quite like the MAST suit situation. However in using first look intubation as a quality measure we are now reporting a surrogate for a surrogate of the outcome that actually matters. I.e. we are reporting first look as it is associated with lower rates of hypoxia because lower rates of hypoxia are associated with lower rates of death and brain injury.

This is a risky game and recent audits of my own service show why. For the past year we have had a monitor that records the vital signs every 10 seconds and we download the data at mission end and attach it to the record. I have been going through these records to see what our rates of peri-intubation hypoxia actually are.

First thing I need to say is that our first look intubation rate so far this year is 100%. However we did have a couple of episodes of significant hypoxia.

My concern is that by reporting the first look rate, we draw attention to it and we send the message to our teams that this is the thing that we think matters. So better to press on a little bit longer even though the sats are falling to make sure I nail that tube first time!

What was the big picture again? [via Jarod Carruthers on flickr under CC 2.0 and unaltered]
What was the big picture again? [via Jarod Carruthers on flickr under CC 2.0 and unaltered]
Why are we reporting a surrogate for a surrogate? I have really accurate data from the monitor on the peri-intubation hypoxia rate, hypotension, bradycardia and arrest. Why report a surrogate for these things that might actually encourage our staff to focus on the surrogate and cause an episode of hypoxia, bradycardia, hypotension etc.

It remains important to emphasise optimising conditions for the first intubation attempt as that appears to have lower complication rates. However it is a means to an end. We should emphasise the outcomes (or at least the surrogates with only one degree of separation from that outcome) that matter. Why report a surrogate for a variable when you have the data to report the actual variable?

Some services like our own are now reporting 100% first look intubation rates, but no one is yet reporting 0% peri-intubation hypoxia rates. Aim for first look intubation as that appears to be a smart strategy, but tell your people it is the hypoxia that matters by making that the centre of attention in your reporting.

What do we mean by hypoxic?

Another thing I have been forced to look at is the definition of peri-intubation hypoxia. I had intended to use the definition of hypoxia used in many of the studies on this subject:

“Desaturation was defined as either a decrease in SpO2 to below 90% during the procedure or within the first 3 minutes after the procedure, or as a decrease of more than 10% if the original SpO2 was less than 90%.” (reference 2, see also 3-5)

I excitedly opened the data file of our first patient that we had intubated when we got our shiny new monitor a year ago to see what had happened. It was easy to identify the timing of intubation from the capnography data as we routinely pre-oxygenate our patients with a BVM device with the capnography attached. The sats pre-induction were a steady 90%, for 2 readings they were 89% (20 seconds) and then climbed to 98% when ventilation was commenced. So according to this definition we had a desaturation!

I don’t think anyone would claim a fall in SpO2 of 1% is clinically significant. It is also less than the error of the measurement quoted by the manufacturer of the oximetry system. This set of circumstances is not going to occur that often but it does not make sense to classify this case as a desaturation. We have therefore modified our definition to:

“Desaturation is defined as either a decrease in SpO2 to below 90% (minimum change at least 3%) during the procedure or within the first 3 minutes after the procedure, or as a decrease of more than 10% from the pre-intubation baseline if the original SpO2 was less than 90%.”

So what should we be reporting?

Thomas reported that each subsequent attempt at intubation was associated with an increased risk of hypoxia, aspiration, bradycardia, cardiac arrest etc. If we have the data on these variables then why not report them directly instead of reporting the surrogate for them. For hypoxia I would suggest our slightly modified definition above.

As for other variables why not use the definitions from Thomas’ paper?

Bradycardia HR <40 if >20% decrease from baseline
Tachycardia HR >100 if >20% increase from baseline
Hypotension SBP <90 mm Hg (MAP <60 mm Hg) if >20% decrease from baseline
Hypertension SBP >160 if >20% increase from baseline
Regurgitation Gastric contents which required suction removal during laryngoscopy in a previously clear airway
Aspiration Visualization of newly regurgitated gastric contents below glottis or suction removal of contents via the ETT
Cardiac arrest Asystole, bradycardia, or dysrhythmia w/non-measurable MAP & CPR during or after w/in intubation (5 min)


For the physiological definitions Thomas includes percentage change from baseline like we do with the hypoxia definition. This acknowledges that these are critically ill patients and often have deranged physiology before we start. These definitions can therefore be used in the real world in which we operate. If we all adopted these definitions we could meaningfully compare ourselves with Thomas’ original paper and with each other.

And as for us…

We are seriously thinking about ditching the reporting of first look intubation rate. It is not telling us what really matters – and we can’t get better than our current 100% rate anyway. Despite this we are having occasional episodes of hypoxia and other complications, and it is possible that the rate of these complications are being exacerbated by emphasising first look.

We are therefore looking at moving to the much more comprehensive set of indicators used by Thomas (along with our modified hypoxia definition). This will demonstrate to our team members the factors that we think really matter, because we measure them and report them externally.

You could argue that the only way to achieve 0% hypoxia is to accept that we are not going to have a 100% first look intubation rate. I for one would gladly give up our 100% first look rate if in doing so we achieved 0% hypoxia. I don’t yet know if this is achievable but I have some ideas. Those who walk the quality & patient safety road with me know that we might never arrive, but that should not deter us from the journey.

Anyone coming?



1 . Thomas CM.   Emergency Tracheal Intubation: Complications Associated with Repeated Laryngoscopic Attempts. Anesth Analg 2004;99:607–13. [Full text.]

  1. Anders Rostrup Nakstad MD, Hans-Julius Heimdal MD, Terje Strand MD, Mårten Sandberg MD, PhD.   Incidence of desaturation during prehospital rapid sequence intubation in a physician-based helicopter emergency service. American Journal of Emergency Medicine (2011) 29, 639–644


  1. Reid C, Chan L, Tweeddale M. The who, where, and what of rapid sequence intubation: prospective observational study of emergency RSI outside the operating theatre. Emerg Med J 2004;21:296-301.


  1. Omert L, Yeaney W, Mizikowski S, et al. Role of the emergency medicine physician in airway management of the trauma patient. J Trauma 2001;51:1065-8.


  1. Dunford JV, Davis DP, Ochs M, et al. Incidence of transient hypoxia and pulse rate reactivity during paramedic rapid sequence intubation. Ann Emerg Med 2003;42:721-8.

Sandpits, Better Eyes and New Monitors – Can NIRS work for prehospital medicine?

This is part 2 of a series (part 1 is here) on trying to study near-infrared spectroscopy in the prehospital setting by Dr Andrew Weatherall (@AndyDW_). Can NIRS work? No one can be sure but here’s one approach to getting some data we can actually use. 

A while back I did a post where I pointed out that when you get sold technology, there’s a whole history behind the machine that goes beep that means it’s probably not what you’re told. And the example I used was near-infrared spectroscopy tissue oximetry.

That was partly because I’m involved in research on NIRS monitoring and I’ve spent a lot of time looking at it.  Like every time I look carefully in the mirror, there’s a lot of blemishes that I miss on a casual glance. I also don’t mind pointing out those blemishes.

So that post was about all the things that could get in the way – light bouncing about like a pinball, humans being distressingly uncatlike, comparing monitors that are might be apples and aardvarks rather than apples and apples and basing your whole methodology on assumptions of tissue blood compartments. Oh, and maybe you can’t get sunlight near your red light.


The thing is, I really want to answer that original question – “How’s the brain?”

So enough of the problems, can we find some solutions?

Actually I’m not certain. But I can say what we came up with. It’s a plan that involves sandpits, hiding numbers and finding better eyes. Oh, and changing the design of monitors forever and ever.


Playing in Sandpits

Our first step was to try and figure out if NIRS technology could even work in the places it wasn’t designed for. Not near the cosy bleeping of an operating theatre monitor where the roughest conditions might be inflicted by a rogue playlist.

We figured that the first issues might be all the practical things that stop monitors working so effectively. And we already knew that in the operating suite you often needed to provide shielding from external light to allow reliable measurements.

So we asked for volunteers, stuck sensors to their heads and took them driving in an ambulance or hopped on the helicopter to do some loops near Parramatta. It gave us lots of chances to figure out the practicalities of using an extra monitor too.

And we learnt a bit. That we could do it with some layers of shielding between the sensors and the outside world. That the device we tested, though comfortable next to an intensive care bed was a bit unwieldy at 6 kg and 30 cm long to be carried to the roadside. Most importantly that it was worth pushing on, rather than flattening everything in the sandpit and starting again.

Early engineering advice included "just put a tinfoil hat on everyone to shield the sensors". I just ... I ... can't ... [via eclipse_etc at Flickr 'The Commons']
Early engineering advice included “just put a tinfoil hat on everyone to shield the sensors”. I just … I … can’t … [via eclipse_etc at Flickr ‘The Commons’]

Hiding Numbers and Getting Out of the Way

The next thing that was pretty obvious was that we couldn’t set out to figure out what NIRS monitoring values were significant and at the same time deliver treatments on the basis of those numbers. We needed to prospectively look at the data from the monitor and see what associations were evident and establish which bits in the monitoring actually mattered for patients and clinicians.

Of course paramedics and doctors tend to like to fix stuff. Give them a  “regional saturation” number which looks a little like mixed venous oxygen saturation while the manufacturer (usually) puts a little line on the screen as the “good-bad” cutoff line is a pretty good way to see that fixing reflex kick in. So to make sure it really is a prospective observational study and we’re observing what happens in actual patients receiving their usual treatment we ended up with a monitor with none of the numbers displayed. Better not to be tempted.

It was also obvious that we couldn’t ask the treating team to look after the NIRS monitor because they’d immediately stop doing the same care they always do and occasionally (or always) they’ll be distracted by the patient from being as obsessive about the NIRS monitor as we need for research.

So recruiting needs a separate person just to manage the monitor. On the plus side this also means we can mark the electronic record accurately when treatments like anaesthesia, intubation and ventilation or transfusion happen (or indeed when the patient’s condition obviously changes). It’s all more data that might be useful.

Getting Better Eyes

One of the big problems with NIRS tissue oximetry so far seems to be that the “absolute oximetry” isn’t that absolute. When you see something claiming a specific number is the cutoff where things are all good or bad, you can throw a bucket of salt on that, not just a pinch.


Maybe this much salt. [via user pee vee at Flickr's 'The Commons']
Maybe all of this salt. [via user pee vee at Flickr’s ‘The Commons’]
The other thing is that to pick up evolving changes in a dynamic clinical environment is difficult. What if it isn’t just the change in oximetry number, but the rate of change that matters? What if it’s the rate of change in that number vs the change over the same time in total haemoglobin measurements, or balance between cerebral monitoring and peripheral monitoring at the same time? How does a clinician keep track of that?

What we might need is a way of analysing the information that looks for patterns in the biological signals or can look at trends. The good news is there’s people who can do that as it’s acutally a pretty common thing for clever biomedical engineers to consider. So there are some clever biomedical engineers who will be part of looking at the data we obtain. When they have spare time from building a bionic eye.

My bet is that if NIRS monitoring is ever to show real benefits to patients it won’t be only by looking at regional saturation (though we’ll try that too). It will be the way we look at the data that matters. Examining rapidly changing trends across different values might just be the key.


Thinking About the Monitors We Need

Let’s imagine it all works. Let’s assume that even with all those hurdles the analysis reveals ways to pretty reliably pick up haematomas are developing, or the brain is not receiving enough blood flow, or oedema is developing (and there are other settings where these things have been shown), there’s still a big problem. How do you make that information useful to a clinician who has a significant cognitive load while looking after a patient?

For each NIRS sensor that is on (3 in this study) we’ll be generating 4 measurements with trendlines. The patient is likely to have pulse oximetry, ECG, blood pressure and often end-tidal capnography too. Putting together multiple bits of information is an underappreciated skill that highly trained clinicians make a part of every day. But it adds a lot of work. How would you go with 12 more monitoring values on the screen?

Yes Sclater's lemur, that's 16 monitoring values to keep track of. [via user Tambako the Jaguar at flickr]
Yes Sclater’s lemur, that’s 16 monitoring values to keep track of. [via user Tambako the Jaguar at flickr]
So before we can take any useful stuff the analysis reveals and free clinicians to use the information, we need to figure out how to present it in a way that lets them glance at the monitor and understand it.

How should we do that? Well it’s a bit hard to know until we know what we need to display. My current guess is that it will involve getting clever graphics people to come up with a way to display the aggregated information through shapes and colours rather than our more familiar waveforms (and that’s not an entirely novel idea, other people have been on this for a bit).

So then we’d need to test the most effective way to show it before finally trying interventional studies.

This could take a bit.

And that is a story about the many, many steps for just one group trying to figure out if a particular monitor might work in the real world of prehospital medicine. There are others taking steps on their own path with similar goals and I’m sure they’ll all do it slightly differently.

I hope we end up bumping into each other somewhere along the road.


Notes and References:

Here’s the link to our first volunteer study (unfortunately Acta Anaesthesiologica Scandinavica has a paywall):

Weatherall A, Skowno J, Lansdown A, Lupton T, Garner A. Feasibility of cerebral near-infrared spectroscopy monitoring in the pre-hospital environment. Acta Anaes Scand 2012;56:172-7.

If you didn’t look on the way past, you should really check the video of Prof. Nigel Lovell introducing their version of a bionic eye. It’s pretty astonishing and I can’t quite believe I get to learn things from him.

It’s the very clever Dr Paul Middleton who was first author on a review of noninvasive monitoring in the emergency department that is well worth a read (alas, another paywall):

Middleton PM, Davies SR. Noninvasive hemodynamic monitoring in the emergency department. Curr Opin Crit Care. 2011;17:342-50.

Here’s the PubMed link from a team taking a preliminary looking tissue oxygen monitoring after out-of-hospital cardiac arrest:

Frisch A, Suffoletto BP, Frank R, Martin-Gill C, Menegazzi JJ. Potential utility of near-infrared spectroscopy in out-of-hospital cardiac arrest: an illustrative case series. Prehosp Emerg Care. 2012;16:564-70.


All the images here were via flickr’s ‘The Commons’ area and used without any modification under CC 2.0

Studies in Blood from Iran – A Quick Review

We all want to stop bleeding. Here’s a quick review from Dr Alan Garner of a paper coming out of Iran that looks at haemostatic dressings. 

Hatamabadi HR et al. Celox-Coated Gauze for the Treatment of Civilian Penetrating Trauma: A Randomized Clinical Trial. Trauma Monthly. 2014;20:e23862. dii: 10.5812/traumamon.23862

There is not a lot of data on haemostatic dressings in the civilian context and human data from the military context is not randomised for obvious reasons. It is therefore nice to see a RCT on this subject in humans. In the study they compare the time to haemorrhage control and amount of haemorrhage in stab wounds to the limbs between 80 patients treated with Celox gauze versus 80 patients treated with normal gauze.

The study is from an emergency department in Tehran and is pragmatic in design. There are some limitations of the study worth mentioning. It was open label, and the amount of bleeding was measured simply by the number of gauze squares used. Weighing the gauze would have been a more accurate way to estimate ongoing blood loss.

The details of how the gauze was applied isn’t that clear. To be effective the gauze needs to be packed into the wound against the bleeding vessel. Was the Celox used in this way to maximise the chances it would work? I can’t tell from the paper. Oh, and the company provided the product for the trial.

Perhaps the biggest puzzle in the design is that patients with really significant haemorrhage (those requiring transfusion) were excluded from the trial. This is the group where you really want to know if the stuff works. You could theorise that this group of patients may have trauma coagulopathy and the method of action of Celox (being by electrostatic attraction and independent of clotting factors) might be particularly useful and a bigger difference between groups may have been found. I guess that will have to wait for another day and another trial that someone works through ethics.

Acknowledging all of this, there was a significant difference in the time taken to achieve haemostasis and the amount of ongoing bleeding with the Celox gauze looked superior by both measures.

This suggests that it remains reasonable to use these products as evidence continues to point to efficacy. Of course these agents are not a magic bullet and all the other principles of haemostasis need to be applied as a package, including urgent transport to a surgical facility.

Research That is Positive When It Is Negative

This weeks post is the first in a series touching on some of the challenges when you start researching technology for the prehospital setting (or anywhere really). Dr Andrew Weatherall (@AndyDW_) on why some monitors aren’t the monitors you’re sold. 

I am new to the research game. As is often the case, that brings with it plenty of zeal and some very rapid learning. When we first started talking about the project that’s now my PhD, we set out wondering if we could show something that was both a bit new and a positive thing to add to patient clinical care.

It didn’t take long to realise we’d still be doing something worthwhile if the project didn’t work one little bit.

Yep, if this thing doesn’t work, that would still be fine.


Simple Questions

I’m going to assume no one knows anything about this project (seems the most realistic possibility). It’s a project about brains and lights and monitors.

It came out of two separate areas of work. One of these was the prehospital bit of my practice. All too often I’d be at an accident scene, with an unconscious patient and irritated by the big fuzzy mess at the middle of the clinical puzzle.

“How’s the brain?”

Not “how are the peripheral readings of saturation and blood pressure against the normative bell curve?” Not “how are the gross clinical neurological signs that will change mostly when things get really grim?”

“How’s the brain?”

At the same time at the kids’ hospital where I do most of my anaesthesia we were introducing near-infrared spectroscopy tissue oximetry to monitor the brain, particularly in cardiac surgery cases.

The story sounded good. A noninvasive monitor, not relying on pulsatile flow, that provides a measure of oxygen levels in the tissue where you place the probe (referred to as regional oxygen saturation, or tissue saturation or some other variant and turned in to the ideal number on a scale between 0 and 100) and which reacts quickly to any changes. You can test it out by putting a tourniquet on your arm and watching the magic oxygen number dive while you inflate it.

Except of course it’s not really as simple as that. If you ask a rep trying to sell one of these non-invasive reflectance spectroscopy (NIRS) devices, they’ll dazzle you with all sorts of things that are a bit true. They’re more accurate now. They use more wavelengths now. Lower numbers in the brain are associated with things on scans.

But it’s still not that simple. Maybe if I expand on why that is, it will be clearer why I say I would be OK with showing it doesn’t work. And along the way, there’s a few things that are pertinent when considering the claims of any new monitoring systems.


A Bit About Tech

Back in 1977, a researcher by the name of Franz Jöbsis described a technique where you could shine light through brain tissue, look at the light that made it out the other side and figure out stuff about the levels of oxygen and metabolism happening deep in that brain tissue. This was the start of tissue spectroscopy.

Now, it’s 38 years later and this technology isn’t standard. We’re still trying to figure out what the hell to do with it. That might just be the first clue that it’s a bit complicated.

Of course the marketing will mention it’s taken a while to figure it out. Sometimes they’ll refer to the clinical monitors of the 1990’s and early 2000’s and mention it’s got better just recently. They don’t really give you the full breadth of all the challenges they’ve dealt with along the way. So why not look at just a few?

  1. Humans Aren’t Much Like Cats

Jöbsis originally tested his technique on cats. And while you might find it hard to convince cat lovers, the brain of a cat isn’t that close to a human’s, at least in size. (As an aside, I’m told by clever bionic eye researchers the cat visual cortex actually has lots of similarities with that of humans – not sure that explains why the aquarium is strangely mesmerising though).

He also described it as a technique where you shone the light all the way across the head and picked up the transmitted light on the other side. But even the most absent-minded of us has quite a bit more cortex to get through than our feline friends and you’d never pick up anything trying that in anything but a neonate.

So the solution in humans has been to send out near-infrared light and then detect the amount that returns to a detector at the skin, on the same side of the head as you initially shone those photons.

When you get handed a brochure by a rep for one of these devices, they’ll show a magical beam of light heading out into the tissues and tracing a graceful arc through the tissues and returning to be picked up. You are given to believe it’s an orderly process, and that every bit of lost light intensity has been absorbed by helpful chromophores. In that case that would be oxy- and deoxyhaemoglobin, cytochromes in the cell and pesky old melanin if you get too much hair in the way.

See? Here's the pretty version that comes with the monitor we're using in the study? [It's the Nonin EQUANOX and we bought it outright.]
See? Here’s the pretty version that comes with the monitor we’re using in the study? [It’s the Nonin EQUANOX and we bought it outright.]
Except that’s the version of the picture where they’ve put Vaseline on the lens. Each one of those photons bounces eratically all over the place. It’s more like a small flying insect with the bug equivalent of ADHD bouncing around the room and eventually finding its way back to the window it flew in.

So when you try to perform the underlying calculations for what that reduction in light intensity you detect means, you need to come up with a very particular means of trying to allow for all that extra distance the photons travel. Then you need to average the different paths of all those photons not just the one photon. Then you need to allow for all the scattering that means some of the light will never come back your way.

That’s some of those decades of development chewed up right there.

  1. Everyone Looks the Same But They Are Different

So that explains the delay then. Well there’s another thing that might make it hard to apply the technology in the prehospital environment. Every machine is different. Yep. If you go between systems, it’s might just be that you’re not comparing apples with apples.

That particular challenge of calculating the distance the light travels? Every manufacturer pretty much has a different method for doing it. And they won’t tell you how they do it (with the notable exception of the team that makes the NIRO device who have their algorithms as open access – and their device weighs 6 kg and is as elegant to carry as a grumpy baby walrus).

So when you read a paper describing the findings with any one device, you can’t be 100% sure it will match another device. This is some of the reason that each company calls their version of the magic oxygen number something slightly different from their competitor (regional saturation, tissue oxygenation index, absolute tissue oxygen saturation just to name a few). It might be similar, but it’s hard to be sure.

Maybe that's harsh. Could a walrus be anything but elegant? [via Allan Hopkins on flickr under CC 2.0]
Maybe that’s harsh. Could a walrus be anything but elegant? [via Allan Hopkins  on flickr without mods under CC 2.0]
  1. When “Absolute” Absolutely Isn’t Absolute

You get your magic number (I’m going to keep calling it regional saturation for simplicity) and it’s somewhere between 60 and 75% in the normal person. The thing is it hasn’t been directly correlated with a gold standard real world measurement that correlates with the same area sampled.

The NIRS oximeter makes assumptions about the proportions of arterial, venous and capillary blood in the tissue that’s there. The regional saturations are validated against an approximation via other measures, like jugular venous saturation or direct tissue oximetry.

On top of that all those “absolute NIRS monitors” that give you a definite number that means something? No. “Absolute” is not a thing.

It’s true the monitors have got much better in responding to changes quickly. And they’ve added more wavelengths and are based on more testing so they are more accurate than monitors from decades past. But they can still have significant variation in their readings (anywhere up to 10% is described).

And they spit out a number, regional saturation, that is actually an attempt to take lots of parameters and spit out a number a clinician can use. How many parameters? Check the photo.

This is from an excellent review by Elwell and Cooper. [Elwell CE, Cooper CE. Making light work: illuminating the future of biomedical optics. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 2011;369:4358-4379.]
This is from an excellent review by Elwell and Cooper. [Elwell CE, Cooper CE. Making light work: illuminating the future of biomedical optics. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 2011;369:4358-4379.]
  1. The Practical bits

And after all that, we reach the practical issues. Will sunlight contaminate the sample? Can it cope with movement? Do you need a baseline measurement first? Does it matter that we can only really sample the forehead in our setting?

All the joy of uncertainty before you even try to start to research.


So why bother?

Well the quick answer is that it might be better for patients for clinicians to actually know what is happening to the tissue in the brain. And acknowledging challenges doesn’t mean that it isn’t worth seeing if it’s still useful despite the compromises you have to make to take the basic spectroscopy technique to the clinical environment.

But even if we find it just doesn’t tell us useful stuff, we could at least provide some real world information to counter the glossy advertising brochure.

There are already people saying things like,

“You can pick up haematomas.” (In a device that just tells you if there’s a difference between the two hemispheres.)

“Low regional saturations are associated with worse outcomes.” (But that’s probably been demonstrated more in particular surgical settings and the monitoring hasn’t been shown to improve patient outcomes yet.)

“You can even pick up cytochromes.” (In the research setting in a specially set-up system that are way more accurate than any clinical devices.)

All of those statements are a bit true, but not quite the whole story. The other message I extract from all of this is that all this uncertainty in the detail behind the monitor can’t be unique to NIRS oximetry. I have little doubt it’s similar for most of the newer modalities being pushed by companies. Peripherally derived Hb measurements from your pulse oximeter sound familiar?

After all this it’s still true that if we can study NIRS oximetry in the environment that matters to us we might get an exciting new answer. Or we might not. And sometimes,

“Yeah … nah.”

Is still an answer that’s pretty useful.



This is the first in a series. The next time around, I’ll chat about the things we’re trying in the design of the study to overcome some of these challenges.

If you made it this far and want to read a bit more about the NIRS project, you can check out the blog I set up ages ago that’s more related to that (though it frequently diverts to other stuff). It’s here


Working with Standards that are Forgetful – Australian NSQHS Standards and Retrieval Medicine

In times where external standards are increasingly applied to health services, where does retrieval medicine fit in? Dr Alan Garner shares his insights after wrestling with the Australian National Safety and Quality Health Service Standards process. 

In Australia, national reform processes for health services began in the years following the 2007 election. Many of the proposed funding reforms did not survive negotiation with the States/Territories but other aspects went on to become part of the Health landscape in Australia.

Components which made it through were things like a national registration framework for health professionals. Although the intent of this was to stop dodgy practitioners moving between jurisdictions, the result for an organisation like CareFlight was that we did not have to organise registration for our doctors and nurses in 2, 3 or even more jurisdictions as they moved across bases all over the country. Other components that made it through were the national 4 hour emergency department targets although I think the jury is still out on whether this was a good thing or not.

NSQHS copy

Other Survivors

Another major component to survive was the National Safety and Quality Health Service Standards. The idea is that all public and private hospitals, day surgical centres and even some dental practices must gain accreditation with these new standards by 2016. The standards cover 10 areas:

  • Governance for Safety and Quality in Health Service Organisations
  • Partnering with Consumers
  • Preventing and Controlling Healthcare Associated Infections
  • Medication Safety
  • Patient Identification and Procedure Matching
  • Clinical Handover
  • Blood and Blood Products
  • Preventing and Managing Pressure Injuries
  • Recognising and Responding to Clinical Deterioration in Acute Health Care
  • Preventing Falls and Harm from Falls

Are these the right areas? Many of the themes were chosen because there is evidence that harm is widespread and interventions can make a real difference. A good example is hand washing. Lots of data says this is done badly and lots of data says that doing it badly results in real patient harm. This is a major theme of Standard 3: preventing and controlling healthcare associated infections.

Here is a visual metaphor for the next segue [via]
Here is a visual metaphor for the next segue [via]

What about those of us who bridge all sorts of health services?

So what about retrieval? We are often operating as the link between very different areas of the health system. And we pride ourselves on measuring up to the highest level of care within that broader system. So do these apply to us? Did they even think about all the places in between?

Well, whether these Standards will indeed be applied to retrieval and transport services remains unclear as retrieval services are not mentioned in any of the documentation. CareFlight took the proactive stance of gaining accreditation anyway so that we are participating in the same process and held to the same standards as the rest of the health system.

So when we approached the accrediting agency, this is what they said: “Well, I guess the closest set of standards is the day surgical centre standards.” We took it as a starting point.

Applying Other Standards More Sensibly

This resulted in 264 individual items with which we had to comply across the ten Standards. And we had to comply with all standards to gain accreditation – it is all or nothing. However as we worked through the standards with the accrediting body it became clear that some items were just not going to apply in the retrieval context.

A good example is the process for recognising deteriorating patients and escalating care that is contained in Standard 9. There are obvious difficulties for a retrieval organisation with this item as the reason we have been called is due to recognition of a patient being in the wrong place for the care they need. This is part of the process of escalating care. It would be like trying to apply this item to a hospital MET team – it doesn’t really make sense.

With some discussion we were able to gain exemptions from 40 items but that still left us with 224 with which to comply. Fortunately our quality manager is an absolute machine or I don’t think we would have made it through the process. There’s take away message number one: find an obsessive-compulsive quality manager.

It took months of work leading up to our inspection in December 2014 and granting of our accreditation in early 2015. Indeed I am pleased to say that we received a couple of “met with merits” in the governance section for our work developing a system of Carebundles derived from best available evidence for a number of diagnosis groups (and yes I’ve flagged a completely different post).

So yes or no?

Was the process worth it? I think independent verification is always worthwhile. As a non-government organisation I think that we have to be better than government provided services just to be perceived as equivalent. This is not particularly rational but nevertheless true. NGOs are sometimes assumed to be less rigorous but there are plenty of stories of issues with quality care (and associated cover-ups) within government services to say those groups shouldn’t be assumed to be better (think Staffordshire NHS Trust in the UK or Bundaberg closer to home)

As an NGO however we don’t even have a profit motive to usurp patient care as our primary focus. The problem with NGOs tends rather to be trying to do too much with too little because we are so focused on service delivery. External verification is a good reality check for us to ensure we are not spreading our resources too thinly, and the quality of the services we provide is high. The NSQHS allow us to do this in a general sense but they are not retrieval specific.

Is there another option for retrieval services?

Are there any external agencies specifically accrediting retrieval organisations in Australia? The Aeromedical Society of Australasia is currently developing standards but they are not yet complete.

Internationally there are two main players: The Commission for Accreditation of Medical Transport Systems (CAMTS) from North America and the European Aeromedical Institute (EURAMI). Late last year we were also re-accredited against the EURAMI standards. They are now up to version 4 which can be found here. We chose to go with the European organisation as we do a lot of work for European based assistance companies in this part of the world and EURAMI is an external standard that they recognised. For our recent accreditation EURAMI sent out an Emergency Physician who is originally from Germany and who has more than 20 years retrieval experience. He spent a couple of days going through our systems and documentation with the result that we were re-accredited for adult and paediatric critical care transport for another three years. We remain the only organisation in Australasia to have either CAMTS or EURAMI accreditation.

For me personally this is some comfort that I am not deluding myself. Group think is a well-documented phenomenon. Groups operating without external oversight can develop some bizarre practices over time. They talk up evidence that supports their point of view even if it is flimsy and low level (confirmation bias) whilst discounting anything that would disprove their pet theories. External accreditation at least compares us against a set of measures on which there is consensus of opinion that the measure matters.

What would be particularly encouraging is if national accreditation bodies didn’t need reminding that retrieval services are already providing a crucial link in high quality care within the health system. There are good organisations all over the place delivering first rate care.

Maybe that’s the problem. Retrievals across Australia, including all those remote spots, is done really well. Maybe the NSQHS needed more smoke to alert them.

For that reason alone, it was worth reminding them we’re here.



Risky Business – Weighing Things Up

The excellent Dr Paul Bailey returns to provide more practical insights from the bit of his work that involves coordination of international medical retrieval. This is the second in (we hope) a recurring series which started here

Greetings everyone, it’s a pleasure to be back for the long awaited second edition of this humble blog. Looking back at my first foray into this unfamiliar world I’m pretty happy with how it reads and I think that it worked out well. If any of you have questions, I’m happy to participate in a bit of to and fro in the comments section.

Where to from here? I thought we might talk about risk. It’s hard to know exactly where to start, but it is fair to say that there are clinical risks, aviation risks, environmental and political risks – and there are probably more but I can’t think of them right now.

Aviation risks are the domain of our pilot colleagues and it’s extremely fair to say that they do a great job. One of the reasons that flying is so safe overall is that pilots specifically (and the aviation industry more generally) take risk very seriously. This might well have something to do with the personal consequences to the pilots of getting it wrong, I’m not sure.

When was the last time, for instance, that the nurses or doctors amongst you had to consider your fatigue score whilst working for a big hospital? What is the mechanism by which you might stop work when you consider yourself impaired or too tired to work any longer? Random drug testing at work anyone? If you’re a doctor or nurse, not likely, unless you are also working in aviation. See what I mean?

Whilst on a job the clinical team are considered part of the crew and whilst it is certainly within our job description to point anything out to the pilots that looks odd – it is up to the pilots to get us there and back safely. One of the Gods of CareFlight said to me once that it was his considered opinion, having been in the game a while, that if the pilots don’t want to go somewhere – for whatever reason – then neither does he. I reckon that is a pretty good rule of thumb.

What about medical risk?

Preparing for an international retrieval, the risk assessment starts straight away. From the Medical Director’s chair, we attempt to have a clinical discussion with SOMEONE close to the patient, usually a doctor or nurse in the originating hospital. This can be difficult – sometimes there are language issues; sometimes standards of care might be different to what we are used to; sometimes it’s just the time of day. How many people would be able to give a comprehensive medical handover at short notice in your hospital at 02:30?

We can also discuss the case with a nurse or doctor from the assistance company as an alternative. Sometimes it is even possible to talk to the patient or their relatives and in fact this is often the best source of up to date information.

It's a pretty long hallway you're looking down to assess the patient.
It’s a pretty long hallway you’re looking down to assess the patient.

In a similar way, patients’ clinical condition can change in the substantial lead time between the activation of a job, your arrival at the bedside and the eventual handover of the patient to the next clinical team.

In the world of international medical retrieval, if the patient is still alive by the time you get there, it is likely that they are in a “survivors” cohort already and will very likely make it to the destination hospital intact. If death was considered imminent, it is unlikely the assistance company would go to the lengths of setting up an international medical retrieval. Sepsis is probably the grand exception to this rule – patients who are septic have progressive illnesses that are not improved by being shaken up in the back of an aircraft.

The summary is that sometimes the information is incomplete, may be in fact be wrong in spite of the best efforts of the Medical Director, or may well have been correct at the time but things have moved on. It’s best to keep an open mind about what you are going to.

Ways to Ruin a Dinner Party – Bring Politics and the Environment

Easy to understand in some ways, and hard to define on paper are the environmental and political risks associated with international medical retrieval.

Some locations are potentially dangerous on a 24/7 basis and it can be a matter of choosing the “least bad” time of day – eg daylight hours – for you to be on the ground, and to make that period of time as short as possible – eg by arranging the patient to meet you at the airport. Sometimes the situation will require the assistance of a security provider. Port Moresby would be an example of a location where any or all of the above statements are true.

Different standards apply in some locations and it can, for instance, be necessary for all fees and charges associated with a patient’s hospitalisation to be paid prior to their departure. Retrieval team as bill settlement agency.  Indeed, sometimes these fees can be very complex and quite difficult to understand. The hospital administrators may not be sympathetic to your timeline with regards to pilot duty hours and a strong wish to depart.

Some counties in our region have relatively new or potentially unstable political situations and this might come into play from time to time. East Timor is a perfect example. It is also possible to find yourself in the thick of a countries political situation in the event that a government official or politician becomes unwell and requires evacuation to a location with a higher standard of medical care.

Just one example - expect the unexpected.
Just one example – expect the unexpected.


So the risk is there, what do you do?

In the end, it is not possible to control for everything that could go wrong on a retrieval. The essentials are to be well trained, have the right equipment with you (it’s not much use back at the base), work with good people all of whom are doing their jobs properly and keep an open mind about both the clinical and logistical situation as the case progresses.

So here are some principles we try to follow from the coordinators end:

  • We will not send you to an uncontrolled situation.
  • We will endeavour to have you flying in daylight hours wherever possible.
  • We will do our best to give you a comprehensive medical handover prior to departure and discuss things that might go wrong.
  • The pilots undertake to get you and the patient there and back safely.

And my suggestions for those on the crew?

  • It is vital to maintain situational awareness and to understand that the world of international medical retrieval is fluid and things change – you don’t have to like it but you do need to respond.
  • Good communication is essential – within the clinical team, between the clinical team and the pilots and between those on the mission and the coordinator (not to mention the local organisers). Good communication is your best friend and keeps you, your team and the patient safe.

Until next time …

Examining the Hairs on the Yak – A Good Chance for More Chat

One of the good things about research that has its own issues, is that there is lots of scope to learn from the things about it that are good, as well as those that aren’t so great. The nice thing about ongoing comment is it gives even more chances to explain why a researcher might make certain choices along the way. Every question in research has more than one way of approaching some answers. Dr Alan Garner returns to provide even more background on this particular study, which has already generated some interesting conversation and a follow-up post

It’s an excellent thing to be able to keep having discussion around the challenges related to both conducting and interpreting a trial.  These things always bring up so many valuable questions, which deserve a response. So this is not going to be quick, but I hope you’ll have a read.

Lots of things changed between the time this trial was designed and now. Standards of care change. Systems, processes and governance models change. Indeed, in this trial standard care changed underneath us. We completed the protocol and gained ethical and scientific committee approval for this study during 2003.

The world was a different place then – at the start of 2003 George W Bush was US President and Saddam Hussein was still running Iraq. There is no keener instrument in medicine than the retrospectoscope particularly when focused 12 years back. Would I have done things differently if I knew then what I knew now – absolutely. Does the trial have hairs? Looks like a yak to me and I don’t think we are pretending otherwise.

Asking Questions

Did we ask the right question? The question was pragmatic. Add a doctor and with them comes a package of critical care interventions that were not routinely otherwise available in our standard EMS system. A number of cohort studies had previously looked at exactly this question and more studies have asked it since. Even papers published this month  have examined this question although the issue often overlaps with HEMS as that is how the doctors are frequently deployed.

I might segue slightly to address dp’s question as well which overlaps here. Is it the procedures that the team performs or the person performing the procedures that matter? Dp suggests that a better study design would be to have them all use the same protocols then we compare doctors with non-doctors. Such a randomised trial has actually been done although it is a long time ago now – 1987. It is one of the classic Baxt and Moody papers and was published in JAMA.

Patients were randomly assigned to a helicopter staffed by a flight nurse/paramedic or a flight nurse/emergency physician. The flight nurse and emergency physicians could perform the same procedures under the same protocols including intubation, chest tubes, surgical airways and pericardiocentesis. By TRISS methodology there was lower mortality in the group that included the doctor and the suggestion was this might be related to how they judged the necessity for intervention, rather than technical skill. This study is well worth a read. They note that the outcome difference might have been removed if the nurse/paramedic team was more highly trained but where does this end? We then move into the question of how much training is enough training and this is an area that I think is still in its infancy. Each time you do some research your prompt a whole lot of extra, usually interesting questions.

All That Methods Stuff

Anyway, back to this paper. All analyses presented in this paper were pre-specified in the statistical analysis plan. Although the protocol paper was not published till 2013, the statistical analysis plan (SAP) was finalised by the NHMRC Clinical Trials Centre in August 2010, more than a year prior to follow up of the last recruited patients. Copies of the SAP were then provided to the trial funders and NSW Ambulance at the time it was finalised in 2010. Along the way we have presented data in other settings, mostly at the request of interested parties (such as the Motor Accidents Authority who specifically requested analyses of road trauma cases) and in retrieval reviews. This is why there has been the opportunity for extra public scrutiny by experts like Belinda Gabbe. And public scrutiny is a good thing.

And Standard Treatments?

I’m very happy to provide some reassurance that this study did not rely on junior doctors being put through EMST/ATLS and then sent out to manage severe prehospital trauma patients. Rather the trial protocol states that treatment was according to ATLS principles. In 2003 there was no other external standard of care that we could cite for trauma patient management that was widely and internationally recognised.

The specialists had of course all completed EMST/ATLS but they were also all critical care specialists in active practice in major trauma centres in Sydney with ongoing exposure to severe trauma patients. The average years of prehospital trauma management experience held by this group of doctors at the beginning of the trial was more than 12 years each. They operated to those high level of treatment standards, with regular reviews of management to make sure this was current best practice over the life of a trial that ended up being longer than we hoped.

Other Dimensions of Time

And time wasn’t a friend. Recruitment was indeed slower than planned. This is a common problem in prospective trials. Our estimates of how long it would take to recruit the required sample size were based on a written survey of the major trauma centres in Sydney in 2003 to determine how many unconscious adult blunt trauma patients they were seeing each year. This was reduced to 60% to reflect the fact the trial would recruit for only 12 hours each day (although during the busiest part of the day) and the time needed to recruit was then estimated at 3 years. We in fact planned for 4 years to allow for the fact that patients usually disappear when you go looking for them prospectively. This of course is exactly what happened but to a greater degree than we planned.

I agree it would have been nice to have the results formally published earlier. We did present some results at the ICEM in Dublin in June 2012. It is interesting to note that Lars Wik spoke immediately before me at this conference presenting the results of the CIRC trial on the Autopulse device. This study was finally published online in Resuscitation in March 2014, more than three years from recruitment of their last patient and this trial did not include a six month neurological assessment as HIRT did.   Getting RCTs published takes time. Given we did have to perform six month outcome assessments I don’t think we were too far out of the ball park.

Quokka copy 2
To keep you going, here’s a quokka who looks like he’d be up for a chat too. [Via Craig Siczak and unchanged under Creative Commons.]

Randomising in Time Critical Systems

Just to be sure that I really have the right end of the stick on the question of excluding patients after randomisation I ascended the methodology mountain to consult the guru. For those that don’t know Val Gebski he is Professor and Director, Biostatistics and Research Methodology at the NH&MRC Clinical Trials Centre in Sydney. He was our methodology expert from the beginning of planning for the trial.

When I reached the mountain top I had to leave a voice message but Val did eventually get back to me. He tells me excluding patients post randomisation is completely legit as long as they are not excluded on the basis of either treatment received or their outcome. This is why he put it in the study design.

These are essentially patients that you would have excluded prior to randomisation had you been able to assess them properly and of course in our study context that was not possible. The CIRC study that I have already discussed also adopted this approach and excluded patients that did not meet inclusion criteria after enrolment.

Prehospital studies where you have to allocate patients before you have been able to properly assess them are always going to have these kind of difficulties. The alternative for a prehospital RCT would be to wait until you know every element of history that might make you exclude a patient. How many of us have that sort of detail even when we arrive at the hospital?

Extra Details to Help Along the Discussion

The newly met reader might also like to know that the call off rate was about 45% during the trial, not 75%. This is not different to many European systems. If you don’t have a reasonably high call off rate then you will arrive late for many severely injured patients.

And of course the HIRT study didn’t involve “self-tasking”. The system randomised cases on a strict set of dispatch guidelines, not on the feelings of the team on the day. This process was followed for nearly 6 years. There was not a single safety report of even a minor nature during that time. Compliance with the tasking guidelines was audited and found to be very high. Such protocolised tasking isn’t inherently dangerous and I’m not aware of any evidence suggesting it is.

It’s reassuring to know that other systems essentially do the same thing though perhaps with different logistics. For example in London HEMS a member of the clinical crew rotates into the central control room and tasks the helicopter using an agreed set of dispatch criteria. This started in 1990 when it was found that the central control room was so poor at selecting cases, and it resulted in the call off rate falling from 80% to 50%. The tasking is still by a member of the HEMS team, they just happen to be in the central control room for the day rather than sitting by the helicopter.

A more recent study from last year of the London system found that a flight paramedic from the HEMS service interrogating the emergency call was as accurate as a road crew assessing the patient on scene. This mirrors our experience of incorporating callbacks for HIRT.

The great advantage of visualising the ambulance Computer Assisted Dispatch system from the HIRT operations base by weblink was the duty crew could work in parallel in real time to discuss additional safety checks and advise immediately on potential aviation risks that might be a factor.

To consider it another way, why is the model safe if the flight paramedic is sitting at one location screening the calls but dangerous if he is sitting at another? What is the real difference between these models and why is one presumably a safe mature system and the other inherently dangerous?

More Mirrors

I agree that the introduction of the RLTC to mirror the HIRT approach of monitoring screens and activating advanced care resources (with extension to a broader range) was a good thing for rural NSW. However they did activate medical teams into what are very urban areas of Sydney who were neither a long way from a trauma centre nor was there any suggestion they were trapped. Prior to the RLTC the Ambulance dispatch policy for medical teams was specifically circumstances where it would take the patient more than 30 mins to reach a trauma centre due to geography or entrapment. Crossover cases obviously didn’t explain the whole of our frustrating experience of recruitment, but it was one extra hurdle that finally led us to wrap recruitment up.

You can’t bite it all off at once

In a study where you collect lots of data, there’s no publication that will let you cram it all into a single paper. So there are definitely more issues to cover from the data we have. This includes other aspects of patient treatment. So I will be working with the other authors to get it out there. It might just require a little bit of time while we get more bits ready to contribute to the whole picture.

Of course, if you made it to the end of this post, I’m hoping you might just have the patience for that.

Here’s those reference links again: 

That Swiss paper (best appreciated with a German speaker). 

The Baxt and Moody paper.


The earlier London HEMS tasking paper.

The latter London HEMS tasking paper. 

Same, same? Actually different

More of the operational data from the Head Injury Retrieval Trial has just been published. By luck more than anything else this has occurred within 24 hours of the publication of the main trial results which you can find here.

Some operational data about systems used in the trial has already been published. A key part of HIRT was a dispatch system where the operational crew were able to view screens with case information as they were logged to spot patients who may have severe enough injuries to warrant advanced care. They could then use the available information or call the initiating number for further details. If the available information matched the criteria for consideration of an advanced care team, the randomisation process then swung into action. The whole idea was to streamline the process of activation of an advanced care team to severely injured patients.

A study looking at this dispatch system in the context of identifying severely injured children has already been published here. This study compared the trial case identification system with the Rapid Launch Trauma Coordinator (RLTC) system in NSW. When the trial dispatch system was operating the paediatric trauma system in Sydney performed significantly better than when the trial system was not available. This was a combination of the dispatch system and the rapid response capability of the trial HEMS. The speed and accuracy of dispatch was a key component however.

So what’s this new paper about?

In this new paper we had the opportunity to explore the HIRT data set to look at the times it took various team models to treat patients and get them to the hospital, and then through the ED to CT. The data is unique as far as I know as we had the unusual situation of two physician staffed services operating in parallel sometimes being dispatched to the same patients.

You can find the paper here.

Getting to a CT scanner in a more timely fashion than this was a way of tracking patient progress through their care. [via]
Getting to a CT scanner in a more timely fashion than this was a way of tracking patient progress through their care. [via]
First comment is that this appears to confirm some European data that physician teams do not significantly affect prehospital times when compared with paramedics although the intubation rate is much greater. Papers such as that by Franschman from the Netherlands make interesting comparisons with this paper. The Dutch Physician staffed HEMS system closely mirrors the HIRT rapid response system in time intervals (and many other factors too). The fact that we have such similar results half a world apart suggests some generalisability of the data.

So are there some differences?

This study did show some differences between the physician teams in those time markers through the patient pathway. It’s worth making a couple of comments that might help to interpret that data.

This is not about individual performance but about systems. There were doctors and paramedics who worked across both systems. Their times followed the pattern of the system they were operating in on any given day.

If you look in the study discussion, the two physician HEMS systems are quite different. The Greater Sydney Area (GSA) HEMS forms part of the State ambulance helicopter system. It has to be all things to all people all the time. They have a wide range of tasks including interfacility transports, hoisting operations, ECMO and IABP transfers etc and they may potentially be tasked anywhere in NSW and perhaps up to 100nm off the coast. By necessity they are multirole and they have to be able to respond to any of these mission types when the phone rings without any notice.

The rapid response HEMS system that was set up for the trial is not constrained in the same way. It is a specialist service where every mission follows the same basic pattern. This data indicates that it is very, very good at doing one thing. Indeed as far as I am aware the scene times for intubated patients are the fastest achieved for a physician staffed HEMS anywhere in the world, even slightly faster than the published data from the Netherlands. The price of specialisation however is that this service cannot perform the range of tasks that the multirole GSA HEMS undertake.

Put simply the services are not interchangeable. The data indicates that the specialist rapid response model will arrive at patients first compared with the multirole GSA HEMS model anywhere in the greater Sydney area, except at the extreme edges of their operating range where rural bases may be faster, or within a couple of km of the GSA HEMS Sydney base.

The differences also apply to scene times where the HIRT rapid response system had scene times of half that or less observed in the GSA HEMS teams, even when confounders such as entrapment and requirement for intubation were considered. We speculate on some reasons for this such as the relative team sizes for the two operations. There may well be advantages in highly familiar teams. There is certainly some evidence for this in other areas of medicine.

What do we make of this?

Overall however I think specialisation is the key. If we again compare the HIRT rapid response model to the Dutch physician staffed HEMS system the similarities are striking. Like the HIRT system, the Dutch only perform prehospital cases, they only operate within a limited radius of their operating base (including urban areas) and they do not have hoists. Like most European HEMS they have small team sizes. And their times are remarkably similar to that achieved by the HIRT HEMS system in our study. It is all about how the services are structured and their role definition which makes them good at what they do.

There are clear implications for the task allocation system in Sydney from this data.

The current pattern of tasking appears to allocate physician teams primarily on who is closest. This allocation only makes sense if the two teams are interchangeable in capability. This is very clearly not the case. The two systems are quite different. The relative strengths of each service should be taken into account in the dispatch policy so that patients will get the most rapid and most appropriate response possible given their location and clinical condition.

The patient doesn’t care who started out closer. They want the service they need for their situation. The different strengths of the two services should form a complimentary system that ensures the fastest and highest quality care to patients, whether they are on the roadside, already in a smaller hospital, at the base of a cliff or on a ship off the coast.

What about dispatch?

The evidence from this study combined with the previous study on the Sydney paediatric trauma system also indicates that the HIRT case identification system significantly outperformed the RLTC in both speed and accuracy.

The trial case identification system operated for nearly 6 years without a single report of any type of safety incident, even of a minor nature. Once the RLTC came into being in 2007 the RLTC and HIRT systems operated collaboratively to identify severely injured children and ensure a speedy response. When HIRT identified a paediatric case, they checked with RLTC who retained tasking control to ensure that there was no additional information or competing tasks that might affect the dispatch decision. In this way Ambulance retained central control and oversight of the system and a double up of tasking to paediatric patients was averted. This would seem to be the ideal system with patients benefiting from the increased speed and accuracy of the parallel case identification process when the HIRT and RLTC systems were operating together, but Ambulance retaining central control so that competing tasks could be balanced. The HIRT dispatch system was however discontinued in 2011 when the last patient was recruited into the trial.

The practical difficulties of applying this level of sophistication to resource allocation, given the sheer volume and variety of demands on the centralised despatch system, need to be acknowledged. Nevertheless it might be time for a rethink.

Here’s those references again:


The comparison of dispatch systems in paeds patients.

The times paper.

The Dutch study.



HIRT – Studying a Non-Standard System that Ended up as Standard

There’s always a bit of extra reflection you can’t include in the discussion of a research paper. Dr Alan Garner reflects more on some of the challenges of doing research in prehospital medicine. 

The main results of the Head Injury Retrieval Trial have now been published on-line in Emergency Medicine Journal. We have paid the open access fees so that the results are freely available to everyone in the spirit of FOAM. This was an important study that was eagerly awaited by many clinicians around the world.

The summary from my point of view as the chief investigator: an enormous opportunity wasted.

It is now nearly ten years since we commenced recruiting for the trial in May 2005. Significant achievements include obtaining funding for a trial that was ultimately to cost 20 million Australian Dollars to run. I am not aware of another prehospital trial that has come anywhere close to this. Hopefully this is a sign that prehospital care is now seen as worthy of the big research bucks.

In the subsequent ten years world events have helped to drive increasing investment in prehospital trauma research, particularly conflicts in Iraq and Afghanistan and the perception that there were many preventable deaths.   The US government has become a big investor in prehospital research that might lower battlefield mortality. The Brits on the other hand typically made some assumptions based on the evidence they had and got on with it. Higher levels of advanced interventions during evacuation as exemplified by the British MERT system in Afghanistan seem to be associated with better outcomes but the evidence is not high quality.

I am the first to acknowledge that randomised trials are inherently difficult when people are shooting at you. Most prehospital care is not quite that stressful but there remain significant barriers to conducting really high quality prehospital research. Taking the evidence you have and getting on with it is a practical approach but it is not a substitute for meticulously designed and executed high quality studies. Such studies often disprove the evidence from lower level studies. We all bemoan the lack of good data in prehospital care and recognise the requirement for better research.

When you’re only left with signals

The Head Injury Retrieval Trial taken in this context really is an opportunity wasted. There is a strong signal in the as-treated analysis of unconscious trauma patients that there is a significant difference in mortality associated with physician prehospital care. The Intention to treat (ITT) analyses was not significant however.

The potential reasons for the lack of difference in the Intention to Treat group is really best appreciated by looking at the difference in intervention rates in Table 2. Both treatment teams (additional physician or paramedic only) could intubate cold so we only report the rate of drug assisted intubation. This was by far the most common physician only intervention, and the one we have been suspecting to make the most difference to head injured patients. When you look at the rates receiving this intervention it was 10-14% in the paramedic only group due to the local ambulance service sending their own physician teams in a good percentage of patients, compared with 49-58% in the treatment group. If this really is the intervention that is going to make the difference, our chances of demonstrating that difference are not great unless the treatment effect is absolutely massive.

When the system you study changes

The Ambulance Service in NSW decided two and half years into the trial that they considered physician treatment to already have sufficient evidence to make it the standard of care. They partially replicated the trial case identification system to enhance identification of patients that they believed would benefit from dispatch of a physician (there’s more detail in the HIRT protocol paper).

This is not the first time that such a thing has happened. In the OPALS study of prehospital advanced life support in Canada in 2004 the original study design was a randomised trial (Callaham). It was however done as a cohort study owing to the belief of paramedics that it was unethical to withhold ALS despite absence of proof of its efficacy. We bemoan the lack of evidence but belief in the efficacy of established models of care make gathering high quality evidence impossible in many EMS systems. NSW has proved to be no exception.

Sydney remains a good place to do this work of course.
Sydney remains a good place to do this work of course.

Where are we then?

So where does this leave Sydney? I think a quote from Prof Belinda Gabbe best sums up the situation. Prof Gabbe is a trauma researcher from Monash who has published much on the Victorian trauma system and was brought in as an external expert to review the HIRT outcome data during a recent review of the EMS helicopter system in New South Wales. Her comment was:

“As shown by the HIRT study, physician staffed retrieval teams are now an established component of standard care in the Sydney prehospital system. The opportunity to answer the key hypothesis posed by the study in this setting has therefore been lost and recommendation of another trial is not justified. Future trials of HIRT type schemes will therefore need to focus on other settings such as other Australian jurisdictions, where physician staffed retrieval teams are currently not a component of standard care”.

The only jurisdiction in Australia with enough patients to make such a study viable that does not already use physicians routinely is Victoria. Such a study would be particularly interesting as the recent randomised trial of paramedic RSI from that state found absolutely no difference in mortality, the area where the HIRT trial indicates there well may be a difference. Any potential trial funder would want some certainty that history would not repeat itself in the standard care arm however.

In NSW though, the question of whether physician care makes a difference to patient outcome is now a moot point. It is now the standard of care – HIRT has definitively demonstrated this if nothing else.   All we can do now is determine the best way of providing that care. We have more to publish from the data set that provides significant insights into this question so watch this space.


In case you missed them above:


The HIRT Protocol Paper

Callaham M.   Evidence in Support of a Back-to-Basics Approach in Out-of-Hospital Cardiopulmonary Resuscitation vs “Advanced” Treatment. JAMA Intern Med. 2015;175(2):205-206. doi:10.1001/jamainternmed.2014.6590. [that one isn’t open access]

A Bit About Paeds Trauma for Those Who Do A Bit of Trauma

This is a post put together by Dr Andrew Weatherall as background preparation for a talk at the SPANZA Paeds Update from March 14, 2015. This is an update for the occasional paeds anaesthetist. It’s not about covering it all but hopefully there’s a few useful points in there to prompt a little thought and discussion.

For lots of people who do a bit of paediatric care, there’s a bit of nervousness around little people. It’s a bit disproportionate to the numbers of actual cases of course because paeds trauma is not common. In fact, rates are slowly going down.

There is also a common paediatric conundrum to deal with – what do you do with adult evidence? This is because overwhelmingly trauma literature deals in the bigger, smellier version of Homo sapiens.

So the challenge is to provide a refresher on something that is getting less common for most of us, using evidence for other patients.

This might be easier with a story, weaved from a bit of experience and not that much imagination.

Crash copy

The Call Comes In

You get a call from the emergency department that they are expecting a paediatric patient from a crash, not too far from your hospital out on the far edges of the city. The road speed limit is around 80 km/hr and they have a 6 year old child who was sitting in the rear right passenger seat, in a booster seat. He’s probably too small for this booster seat. It doesn’t look like he was well secured.

The child was initially GCS 12/15, with a heart rate of 145/min, BP 85/58, a sore right upper quadrant, and a deformed right upper leg. Initially SpO2 was 96% but is now 100% on oxygen.

Where Should They Go?

Of the schools of thought (big kids’ centre vs place where they do lots of trauma but not lots of kids), NSW has gone for the hospitals with the pretty waiting rooms.

Probably the most relevant local research on the topic is from Mitchell et al. who looked at trends in kids going to paeds trauma centres or elsewhere. They found kids getting definitive care at a paeds trauma centre had a survival advantage 3-6 times higher those treated at an adult trauma centre.

There are issues with this. Mortality as a sole marker when you’re only discussing about 80 kids across 6 years may not be the most reliable marker of quality care. You only need one or two cases to shift from one column to the other to significantly skew the picture.

Possibly the more significant finding was the delay created by making that one stop. Stopping at another hospital (even within the metropolitan area) delayed arrival at the paediatric trauma centre by 4.4-6.3 hours. Early discussions to transfer obviously need to become a priority.

In NSW, the policy is now for ambulance officers to go directly to the paeds trauma centre if it’s possible within 60 minutes. Unless they don’t think they’ll get there.

The impact on the doctor working outside the kids trauma centres is two-fold:

  • There’s less paeds trauma to see.
  • The paeds trauma you do see will be the bad stuff.

Great mix.

The room with the international colour coding of "kids bay"
The room with the international colour coding of “kids bay”

At Emergency

So the patient, let’s call him  Joe, arrives. For the sake of discussion I’m going to assume he did come to the paeds trauma centre, but there’s a whole separate (possibly more interesting) scenario you could think through where he goes to a smaller metropolitan hospital.

Joe arrives with an IV cannula in place and Hartmann’s running. He has a hard cervical collar in place. His GCS has improved to 14/15 (he’s closing his eyes but he seems a little scared) but his heart rate is now 155/min and his BP is 78/50. Peripheral oxygen saturations are still 100% on oxygen (they were 96% off oxygen). He is sore and tender in his right upper quadrant just like they promised. That right femur does look broken. There’s also a lump on the right side of his head, towards the front just on the edge of the hairline.

The New Alphabet

We all remember the alphabet, whether  first drummed in by the fluffy denizens of Sesame Street, or mostly embedded by a trauma course. A then B then C.

Anyone working in trauma knows this is only the older version. So 1900s. The trauma alphabet now has a bunch of variations (C-A-B-C,  MH-A-B-C, choose your edit) to highlight the need to think about arresting blood loss early.

A lot of this shift in thinking is surely related to the vast amount of knowledge gained in managing trauma from military conflict where stopping haemorrhage is one of the most effective things you can do to save lives.

The causes may be different (especially in kids), but some of the thinking can be transferred.

This makes sense not just because bleeding is not great for patients. It’s also because many of the measures required to stop it take more than a couple of minutes. Not so much in the case of tourniquets or fancy dressings that make you clot. Things like surgery, or interventional radiology, or blood product management.

If you’re an occasional paediatric trauma practitioner, there’s a few points worth remembering if you’re going to elevate the importance of haemorrhage control, even while getting the other stuff done:

  • Find the blood early – better rapid diagnostic options, particularly ultrasound, need to be deployed early to figure out where blood loss might be happening.
  • Decisions need to support stopping bleeding – if the patient is bleeding, it is more than a bit important to progress continually towards making them not bleed. This is particularly relevant to arranging radiology and surgery as quickly as possible where indicated.
  • Transfusion – bleeding patients don’t need salty fluids. They need blood. And given what we know about acute traumatic coagulopathy, they probably need it in a ratio approaching 1:1:1 (red stuff: plasma:platelets).
  • Give TXA – after CRASH-2 and MATTERs, tranexamic acid has also made it to kids. A fuller discussion is over here (and there’s also the Royal College of Paediatrics and Child Health thing here though as I mention in that other post, I think they’ve got the doses not quite right).
Set 1 from The Children's Hospital at Westmead Massive Transfusion protocol (obviously, check local policies).
Set 1 from The Children’s Hospital at Westmead Massive Transfusion protocol (obviously, check local policies).


And here's the next delivery pack. (And check it out in full context, don't just rely on this screengrab.)
And here’s the next delivery pack. (And check it out in full context, don’t just rely on this screengrab.)

Joe is Getting Better

Ultrasound confirms some free fluid in the abdomen. The fractured femur is reasonably well aligned but you’ve started warmed blood products early. Joe is responding to his first 10 mL/kg of products with his heart rate already down to 135/min and a BP of 88/50. Respiratory status is stable. GCS is 15/15 and you’ve supplemented his prehospital intranasal fentanyl with IV morphine. 

You decide to go to the CT scanner to figure out exactly what is going on with the abdominal injury. Once around there Joe vomits and starts to get agitated. CT confirms a right front-temporal extradural haematoma. As he’s deteriorating you head up to theatres. 

photo 2

Now I’m going to assume anyone reading this is pretty happy with an approach to rapid sequence induction with in-line stabilisation to manage spinal precautions (not that we’d have a hard collar anyway, because those are on the way out in the draft ILCOR guidelines). We’d all agree on the need for ongoing resuscitation. I’ll also assume no one is going to stop the surgeons from fixing the actual problem while you mess about getting invasive arterial blood pressure measurement and a central line sorted.

What would be nice is some better evidence on what are the right blood pressure targets.

What BP target for traumatic brain injury?

Still, the best the literature can offer is a bit of a ¯\_(ツ)_/¯

If you look at this review from 2012 the suggestions amount to:

  • Don’t let systemic mean arterial pressure go below normal for age.
  • It might be even better to aim for a systolic blood pressure above the 75th percentile.
  • If you do have intracranial pressure monitoring and can therefore calculate cerebral perfusion pressure, then aim for > 50 mmHg in 6-17 year olds and > 40 mmHg in kids younger than that.

Hard to escape the thought we need more research on this.

The Rest of Joe’s Story

Everyone performs magnificently. Joe’s extradural is drained. His femur is later fixed and his intra-abdominal injuries are managed conservatively. The next most important thing might just be that you remembered to give him good analgesia.

Not Forgetting the Good Stuff

I might have some professional bias here, but I think remembering analgesia is just as important as the rest of it. Studies like this one suggest surprisingly high rates of PTSD symptoms even 18 months after relatively minor injury (38% though it was a small study). Although the contributors to PTSD are complex there is some evidence (certainly in burns patients)  that early use of opioid analgesia is associated with lower rates of PTSD symptoms.

This stuff matters. A kid with PTSD symptoms is more than just an anxious kid. They are the kid who is struggling with school, struggling with social skills and generally struggling with the rest of the life they were supposed to be getting on with. Pain relief matters.

So it is worth prioritising good analgesia:

  • Record pain scores as a vital part of the record.
  • Block everything that is relevant (no child with a femur fracture should have an opportunity for a femoral block of some description missed).
  • Remember treatment as analgesia (don’t just leave the fracture like you found it, for example).
  • Give rapidly acting,titratable drugs as a priority with regular checks of efficacy.
    • For example, fentanyl 5 mcg/kg in a 10 mL syringe gives you 0.5 mcg/kg/dose if you give 1 mL at a time. Do this and reassess every 3 minutes.
    • Likewise, ketamine 1 mg/kg in 10 mL provides a dose of 0.1 mg/kg each time you give 1 mL (though some would say you should use midazolam to offset dysphoria too).
    • Don’t forget novel options – methoxyflurane anyone?

The Wrap

Paeds trauma may not be as common, but it needs to be done to the same high standards we expect of trauma care anywhere. Most of the stories in resuscitation are well worn tales. But there are a few things to really take away:

* Think about doing everything to stop bleeding early.

* More blood for resuscitation, but more sensibly too.

* Never forget pain relief.


And with any luck, most of this is already old news.


Postscript: Just after I put this together, the always excellent St Emlyn’s blog put up something covering the latest changes to APLS teaching. To my immense relief a lot of it is the same. It’s worth checking out.

After the postscript: This isn’t designed to be too prescriptive and everything should be figured out in local context. Obviously any thoughts anyone has to share would be very welcome.