Tag Archives: trauma

The Deal with Seals

Greg Brown returns to look at an important thing relevant to first responders (and lots of other people really) – the sucking chest wound. 

We’ve all been there – sitting through some kind of “first aid” training and having some kind of “first aid trainer” speaking authoritatively on some kind of “first aid style” topic. If you are like me you’ve used your time productively over the years and perfected what my wife refers to as “screen-saver mode” – it’s that look on your face that tells the instructor that you are listening intently, often supplemented by the insertion of “knowing nods” or head-tilts, but in actual fact you are asking yourself “if I was able to collect all of my belly button lint over a 12 month period and spin it into yarn, I wonder if I could make enough to abseil off London Bridge?”

Don’t get me wrong – I reckon effective and accurate first aid training should be a mandatory part of having a car / bike / truck / bus licence. More appropriately trained people should mean faster recovery rates for most injured people (and less work for overstretched first responders).

It’s just that sometimes first aid trainers teach stuff based on ‘we reckon’ or ‘that’s how we’ve always done it’ rather than evidence or knowing it works in the real world. This post is about one of those things.

“What is a sucking chest wound?”

In the Army questions come in a few different shapes and sizes. A popular one is “there is only one obscure answer you should have guessed I wanted”. Trust me, the muzzle velocity of your primary weapon is 970 metres per second.

Another popular one is “the question that should be about one thing, but is actually to demonstrate a quite tangential point”.  Like,

“What is a sucking chest wound?”

For an army instructor the answer is not what you are thinking right now. It is “Nature’s way of telling you that your field craft sucks and everyone can see you and now you got shot”.

Let’s Go With the Medical One

We’re going to go with the alternative, more medical one. A sucking chest wound is defined as air entering the thorax via a communicating wound that entrains air into the space between the lungs and ribs more readily than the lungs can expand via inspiration through the trachea.

This is about pressure differentials – in order to inhale, the lungs must generate a relative negative pressure such that air can be sucked into them via the trachea. But if you make a big communicating hole in the trachea, that might become a pretty big highway for air to enter the space with the negative pressure.

The communicating hole does need to be pretty big. Depending upon which textbook you read, this hole needs to be a minimum of a half to three quarters the diameter of the trachea. Also, the patient needs to be undergoing relative negative pressure ventilation (or, in simple terms, breathing spontaneously). If they are being artificially ventilated (which requires positive pressure) then the pressure inside the lungs will be higher than the pressure on the outside of the body; the result is that air will be forced out of the intra-pleural space (or thorax) by the expanding lung (as opposed to being entrained into the thorax via the hole in the chest).

Are sucking chest wounds really that bad?

Well, yes. They suck in fact.

A sucking chest wound creates what is known as an open pneumothorax. Let’s consider the option where that hole does not seal on expiration. We’ll get onto the also very annoying sealing with a flap version in a bit.

In this slightly not so annoying case, the patient will have a ‘tidalling’ of air in and out of this communicating hole. The effect? Respiratory compromise, increased cardiovascular effort and reduced oxygen saturations. Patient satisfaction? No, not really. Death? Maybe – depends on what other injuries exist and the ability of the individual to compensate. See Arnaud et al (2016) for more details.

But if this communicating hole were to seal itself on expiration then you now have an open tension pneumothorax. Sounds bad; IS bad.

In such a case, each time the patient breathes in they will entrain air through the communicating hole in the chest wall (that whole “negative pressure” thing in action). But when they breathe out, instead of having that additional intra-pleural air tidal outwards, the flap will seal it in place; each time they breathe in, the volume of trapped air will increase and you’ll end up with the tension bit.

How much air is required? Well a randomised, prospective, unblinded laboratory animal (porcine) trial conducted by Kotora et al (2013) found that as little as 17.5mL/kg of air injected into the intra pleural space resulted in a life-threatening tension effect.

Actually, that’s a fair bit of air…for those of you who are lazy and don’t want to do the math, that’s 1400mL for an 80kg person. But remember, any tension pneumothorax (open or closed) is progressive – each time you breathe, more air is trapped; therefore, it doesn’t take long to reach crisis levels.

“But are they common enough for us to be worried about?”, I hear you asking. The short answer is yes – in fact, the long answer is also yes.

Kotora et al (2013) reviewed the statistics from the Joint Theater Trauma Registry regarding contemporary combat casualties with tension pneumothorax and found that they accounted for 3 – 4% of all casualties, but 5 – 7% as the cause of lethal injury.

“Yes, but I don’t live in a combat zone…”, I hear you say. I have two responses:

  1. Good for you; but also,
  2. According to Littlejohn (2017), thoracic injury accounts for 25% of all trauma mortality. And sure that stat is for all forms of thoracic injury and a sucking chest wound is but one of those but there’s a neat article by Shahani which sums up the incidence nicely and it turns out you should give this some thought.
The Table
We even saved you some time by grabbing the relevant image.

So, your field craft sucks – now what?

Now that we know that sucking chest wounds are both possible and bad, we should probably discuss treatment.

Some History

Back in the mid 1990’s, Army instructors were very big on rigging up a three-sided dressing. Unwrap a shell dressing, turn the rubbery-plastic wrapper into a sheet and tape three sides down with the open bit facing the feet to allow blood drainage.

And, in an astonishing turn of events, everyone I’ve met who tried this confirmed it didn’t really work that well.

In that Littlejohn paper they make reference to the fact that by the 2004 ATLS guidelines (which are not usually that quick moving), it was being written unblock and white that there was no evidence for or against the three-sided dressing option. It was done because it sounded good in theory, but the evidence wasn’t there.

Now to the New

Actually, not that new. Chest seals already existed.

These chest seals (at that time the Bolin produced by H & H Medical, and the Asherman produced by Teleflex medical) included one-way valves to allow for the forced escape of trapped intrathoracic air and blood. basically they took the impromptu three-sided dressing and made it a ready-made device in the form of an occlusive dressing with an integral vent.

But did they work?

Yes and no.

On a perfectly healthy (albeit with a surgically created open pneumothorax) porcine model with cleaned, shaved, dry skin they sealed well and vented air adequately.

However, once the skin was contaminated (dry blood, dirt, hair etc) the Bolin sealed much better than the Asherman. And if there was active blood drainage too (such as in an open haemo-pneumothorax) then all bets were off. Both vents clogged with blood and ceased to work. Sure, you could manually peel the seal back and physically burp the chest but if you did so the Bolin became an un-vented seal and the Asherman was as good as finished (i.e. it wouldn’t reseal). But hey, at least you had sealed the communicating hole and in doing so stopped entraining air.

“Is this the best you can do?” you may be asking. Well to be honest, since the vents didn’t work for more than a breath or two most people decided that the vents were pointless. The outcome was that we all decided to forget about the vents and just seal the wound. That way, assuming that there was no perforation to the lung, this open tension pneumothorax (aka sucking chest wound) became a routine, run of the mill, plain old pneumothorax. And if there were signs of tensioning (e.g. increasing respiratory distress, hypotension, tachycardia….) one just needed to peel back the seal and manually burp the communicating hole thus relieving the pressure. Use a defib pad – those bad boys stick to anything! Problem solved….

Or how about a newer idea + research?

In 2012 the Committee on Tactical Combat Casualty Care (CoTCCC) started questioning the efficacy of contemporary practices regarding the placement of chest seals on sucking chest wounds. It had already been accepted that the current vented chest seals had ineffective vents, so practice had changed from using a chest seal with an ineffective vent to simple, “soldier proof” unvented seals and burping them as required. Surely there had to be a better way…?

Kotora et al (2013) decided to test three of the most readily available vented chest seals in their aforementioned randomised, prospective, un-blinded laboratory animal (porcine) trial: enter the Hyfin, Sentinal and SAM vented chest seals.

What they found was that all three were effective in sealing around the surgically inflicted wounds and in evacuating both air and blood. Thus, in 2013, CoTCCC changed their recommendations back to the use of vented chest seals.

But there were still some questions:

  1. Once life gets in its messy way, do they seal (or at least stick to skin)?
  2. Are all vent designs equal?

To answer question 1, Arnaud et al (2016) decided to evaluate the adhesiveness of the 5 most common chest seals used in the US military using porcine models. What they found was that the Russell, Fast Breathe, Hyfin and SAM all had similar adherence scores for peeling (> 90%) and detachment (< 25%) when tested at ambient temperatures and after storage in high temperature areas when compared to the Bolin. The researchers admitted, though, that further testing was required to assess the efficiency of the seals in the presence of an open tension haemo-pneumothorax.

In response to question 2, Kheirabadi et al (2017) tested the effectiveness of 5 common chest seals in the presence of an open tension haemo-pneumothorax (again, on porcine models). Essentially, there are two types of vent: (i) ones with one-way valves (like in the Bolin and Sam Chest Seals), and (ii) ones with laminar valves (like in the Russell and Hyfin Chest Seals). Their question was: do they both work the same?

What they found was that when the wound is oozing blood and air then seal design mattered. They found that the seals with one-way valves (specifically the SAM and Bolin) had unacceptably low success rates (25% and 0% respectively) because the build-up of blood either clogged the valve or detached the seal. By contrast, seals with laminar venting channels had much higher success rates – 100% for the Sentinel and Russell, and 67% for the Hyfin.

The Summary


  1. Sucking chest wounds are bad for your health.
  2. Sealing the wound is good.
  3. If the seal consistently allows for the outflow of accumulated air and blood, then that’s even better.

Therefore, now that we know all of this, one’s choice of chest seal is important. At CareFlight we use the Russell Chest Seal by Prometheus Medical (and no, we’re not paid to mention them we’re just sharing what we do). Why? Because it works – consistently. Both for us and in all the aforementioned trials.


The premise of this addition to the Collective is that you’re a first responder. That being the case, use an appropriate vented chest seal on a sucking chest wound.

However, you still need to recognise that the placement of the seal does not automatically qualify you for flowers and chocolates at each anniversary of the patient’s survival – you still need to monitor for and treat deterioration. Such deterioration is likely to include a tension pneumothorax for which the treatment is outside of the scope of most first responders (other than burping the wound).

If you are a more advanced provider then your treatments might include the performance of a needle thoracocentesis, or perhaps intubation with positive pressure ventilation and a thoracostomy (finger or tube).

In essence, know the signs and symptoms then master the treatments that are inside your scope of practice. (Or you could enrol in a course…such as CareFlight’s Pre-Hospital Trauma Course or even THREAT… OK that was pretty shameless.)

Meanwhile we’d love to hear:

  1. What chest seal do you use?
  2. Why?
  3. How does it go?

Or you could just tell us what other things you think suck.

Could be the leafy green thing. Could be a person maybe.


We’re not kidding about hearing back from you. Chip in. It only helps to hear other takes.

You could also consider sharing this around. Or even following along. The signup email thing is around here somewhere.

That image disparaging all things Kale (or kale) is off the Creative Commons-type site unsplash.com and comes via Charles Deluvio without any alterations.

Now, here are the articles for your own leisurely interrogation.

If you’re time poor and will only read one, make it this one by Littlejohn, L (2017). It’s “Treatment of Thoracic Trauma: Lessons from the Battlefield Adapted to all Austere Environments”. 

Another great one (albeit somewhat longer) is by Kheirabadi, B; Terrazas, I; Miranda, N; Voelker, A; Arnaud, F; Klemcke, H; Butler, F; and Dubick, A (2017). It’s “Do vented chest seals differ in efficacy? An experimental evaluation using a swine hemopneumothorax model”.

An oldie but a goodie is this one by Kotora, J; Henao, J; Littlejohn, L; and Kircher, S (2013). It’s “Vented chest seals for prevention of tension pneumothorax in a communicating pneumothorax”.

To round it out, take a squiz at Arnaud, F; Maudlin-Jeronimo, E; Higgins, A; Kheirabadi, B; McCarron, R; Kennedy, D; and Housler, G (2016) titled “Adherence evaluation of vented chest seals in a swine skin model”.

Podcast #4 – Another Side

Straight back with another podcast and with the same guest, Dr Blair Munford. 

This time Blair has a very different type of story to share.

Please have a listen and consider sharing. Or if you like the site consider signing up to get emails when posts hit.

Anyway, here’s the various ways to get the podcast.

Right click and choose save as to download the podcast. (That’s control-click if you’re on a trusty Mac.)

Of course you could just find the podcast over at iTunes here.

Or the rss feed is here.


There’s a chance that something about Blair’s story might make you want to help someone, somehow. If that’s the case either drop a message in the comments or email at careflightcollective@gmail.com and we’ll follow up.

In this episode all the music is by Broke for Free and available via Creative Commons at the Free Music Archive.

The image is by Justin Luebke and was uncovered at unsplash.com


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.