Tag Archives: evidence based medicine

Auckland HEMS prehospital blood transfusion – coming soon to a helicopter near you

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Bloody hell.

Pretty much summarizes the severe traumas that define the essence of our trade.

And sometimes, the answer to critical bleeding is to give blood.

We are grateful to our colleagues at Sydney HEMS, who advise: “blood is provided to transfuse patients with life-threatening bleeding after meticulous attention to hemorrhage control.”

Auckland HEMS is poised to begin providing prehospital blood as part of our bundle of critical clinical interventions. We are fortunate to collaborate with the New Zealand Blood Service and with our local District Health Board to provide this service. http://www.nzblood.co.nz

Herein, please find our training video. We welcome your feedback.

Our draft Blood SOP is undergoing usability testing with our clinical teams. Once finalized, we will share this for FOAM.

This is an unsystematic review of the current literature. A few themes are emerging:

1. There is now evidence of survival benefit in the military and in the civilian literature.
2. Beyond packed red blood cells, services are also exploring the use of plasma, and of whole blood.
3. Pouring in blood is frivolous without meticulous hemorrhage control.
4. If we are to forge strong links in the chain of trauma survival, these critically ill patients must move quickly to definitive care. We are working with our local trauma centres to move seamlessly from out of hospital into ED, Resus, Operating Theatres and Critical Care. Please share your experiences with us.
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Dr Chris Denny, Auckland HEMS Medical Director
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(Auckland HEMS team members click HERE for access to the draft SOP)
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References:

Pretrauma Center Red Blood Cell Transfusion Is Associated With Reduced Mortality and Coagulopathy in Severely Injured Patients With Blunt Trauma

Prehospital blood transfusion in the en route management of severe combat trauma: a matched cohort study

Initial UK experience of prehospital blood transfusion in combat casualties

The effects of prehospital plasma on patients with injury: a prehospital plasma resuscitation

The feasibility of civilian prehospital trauma teams carrying and administering packed red blood cells

Prehospital Transfusion of Plasma and Red Blood Cells in Trauma Patients

Emergency whole-blood use in the field: a simplified protocol for collection and transfusion

Blood Far Forward–a whole blood research and training program for austere environments

Australian Patient Blood Management Guidelines

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…and for simulation purposes, here is a blunt force trauma scenario:

An unidentified surfer discovers the hazards of being caught inside at a notoriously shallow reefbreak during the biggest swell in two years..

The benefits of HEMS – more evidence!

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This post was prompted by two new studies about the benefits of HEMS. For those of you with short attention spans, I’ll give a one-liner on each study then describe them more thoroughly later on.

  1. U.S database study: among severely injured trauma patients (Injury Severity Score >16), HEMS is associated with improved survival rates 
  2. Dutch database study: Reduced mortality among polytrauma patients especially those with abnormal vital signs

The debate surrounding the benefit of patient-oriented outcomes for HEMS is nothing new.  In much of the world, HEMS (helicopter emergency medical services) includes physicians on board the helicopter though in North America often HEMS clinicians are advanced care paramedics. In each country, different models exist and as a result extrapolating findings to our setting is difficult.

One of our BK's that we fly at ARHT

One of our BK’s that we fly at ARHT

It’s easy to imagine that that HEMS (with or without a physician on board) benefits our patients. We bring highly trained clinicians to a scene where we can perform advanced interventions and then rapidly transport the patient to hospital for definitive care. However, studies have demonstrated variable results regarding patient outcomes with HEMS. These differences are undoubtedly affected by the variability amongst HEMS systems around the world. Each HEMS group operates with different thresholds for activation, variable relationships with the local land EMS and then there are a range of geographic and patient characteristics that will affect patient outcomes.

I mentioned above two recent studies that provide additional evidence into the benefits of HEMS. I’ll focus on the Dutch study from the European Journal of Emergency Medicine primarily. They included a consecutive cohort of trauma patients that either HEMS or land EMS responded. It’s not  They used some fancy statistics to calculate lives saved due to HEMS response. It would have been nice to have a more detailed description about their setting as it would allow for more robust comparisons to other centres. It should be noted they had <5% penetrating trauma in their population. It’s unclear how this impacts the statistics but likely critically ill patients who suffered penetrating trauma should be transported to hospital quickly since operative management is likely to be required. They also intubated a large number of their patients when HEMS was on scene (58%). This number was quite surprising. In our setting, we would intubate <10%. Again, whether they have an standard operating procedure or set of criteria for intubation – it would have been good for some discussion about this.

They had fairly reasonable scene times as well. While I don’t think scene times are as important as sometimes they’re made to be especially when necessary interventions are being performed, they at least didn’t spend hours on scene! Interestingly, when we compare the EMS vs. HEMS pre-hospital time there was a 7min difference (42min vs 49min). This is almost entirely accounted for by the extra 7 min that HEMS spends on scene. The authors describe short transport times which suggests that if there truly is a HEMS survival advantage then this isn’t the result of faster transport.

In the U.S study, which has a very different EMS system, they found survival benefit among the most seriously injured trauma patients. I believe there weren’t physicians part of the U.S HEMS model but they probably had advanced care paramedics. Unfortunately the study doesn’t describe the system well. Nonetheless, again using some statistics to account for injury severity, HEMS in the U.S appears to benefit sick patients with altered physiology. It is challenging to interpret U.S data as there’s considerable heterogeneity and financial drivers for HEMS use.

Ultimately we need more prospective data that isn’t fraught with the challenges of using retrospective data – each of these above studies suffer from these limitations. However, there is an emerging trend that HEMS benefits severely injured patients and more importantly, this could be independent of the transport time benefits. This is growing evidence that HEMS is not just an expensive, fast taxi service. Instead, improved patient outcomes may be the result of better clinical expertise brought to the scene.

Does every patient who gets pre-hospital needle decompression need a chest tube?

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The authors of a recent study tried to answer this question. The authors evaluated patients who got needle decompression in the field using prospective, observational methodology (though I wonder if truly prospective given the lack of data). Anyways, they noted that in their population very few patients (5/52 decompressions) escaped without requiring a follow-up chest tube. Only 1/15 penetrating trauma patients did not get a chest tube.  A few important questions remain including how many of the needle decompressions actually reached the pleural cavity or the technique used for decompression (appears later in Q&A that it was probably anterior axillary line). 

The authors conclude to have a low threshold for chest tube insertion based on CXR however, not shockingly a CT chest will provide more information. This study certainly doesn’t support withholding a chest drain if needle decompression is performed in the field. There was a nice suggesting by another surgeon who commented they leave all the needles in place during CT scan to see if it actually reached the pleural cavity. For the stable patient that doesn’t need immediate intervention, this is probably sound advice. Wait for the CT then make decision based on clinical and radiographic data.

There should probably be further study on this topic but for now, this is all we have! Here’s the abstract below.

Is routine tube thoracostomy necessary after prehospital needle decompression for tension pneumothorax? KM Dominguez et al. Am J Surg 2013; 205(3): 329-332 

BACKGROUND:

Thoracic needle decompression is lifesaving in tension pneumothorax. However, performance of subsequent tube thoracostomy is questioned. The needle may not enter the chest, or the diagnosis may be wrong. The aim of this study was to test the hypothesis that routine tubethoracostomy is not required.

METHODS:

A prospective 2-year study of patients aged ≥18 years with thoracic trauma was conducted at a level 1 trauma center.

RESULTS:

Forty-one patients with chest trauma, 12 penetrating and 29 blunt, had 47 needled hemithoraces for evaluation; 85% of hemithoraces required tube thoracostomy after needle decompression of the chest (34 of 41 patients [83%]).

CONCLUSIONS:

Patients undergoing needle decompression who do not require placement of thoracostomy for clinical indications may be assessed using chest radiography, but thoracic computed tomography is more accurate. Air or blood on chest radiography or computed tomography of the chest is an indication for tube thoracostomy.

A medical student’s perspective at Auckland Rescue Helicopter Trust

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For those of you who might have missed a few posts on here, you may not realize that HEMS has picked up a straggler along the way. I am a 5th-year medical student interested in pre-hospital and retrieval medicine, as well as anything high-stress and involving trauma and emergency. My role down at the base is to help out the HEMS doctors with setup of simulation scenarios, as well as keeping the simulation equipment and all our training packs stocked and ready to go. I am also keen to learn from everyone at the base on topics ranging from pre-hospital ultrasound to flying on instrument flight rules (IFR), as well as trying to convince myself and all the paramedics that one day I will be able to do a full-extension pull-up. Watch this space.

Today we unveiled our beautiful new manikins from Laerdal by using them in a simulated scenario on beta-blocker overdose.  We recruited the duty crew from the base, with the understanding that if a job came in they could easily leave the simulated scenario and go. We set it up as if the patient was in a remote medical centre after being retrieved by on-site paramedics from her home. The crew arrived to find a paramedic (yours truly) with the patient who had HR 30-35, bp 70/40, sats 97% on air, and RR 16/min. She had also had a 4-second period of asystole en route to the medical centre.

The team moving the patient onto the stretcher - ready for transport. Pads in place and ready for anything! Picture is a bit blurry because the team was moving with such efficiency & speed!

The team moving the patient onto the stretcher – ready for transport. Pads in place and ready for anything! Picture is a bit blurry because the team was moving with such efficiency & speed!

The remote control of the new manikin allowed us to simulate the heart rate and resps, whilst still maintaining fidelity of the scenario. This manikin also has the ability to moan, cough and respond yes or no, meaning the GCS could be fairly adequately ascertained. We used a sim technique we call ‘veining’ for cannula placement, which involves taping IV extension tubing up the arms of the manikin using skin-like tape with a cannula in the ACF, and then attaching an empty saline bag to the tubing to act as a reservoir. This allowed the participants to push drugs and run fluids, again preserving the fidelity of the scenario. We also used a piece of software called SimMon (for iPad), which can be set up to look like a regular monitor and will make appropriate noises when remotely controlled from iPhone (including that sweat-inducing desaturation beep). Our manikin can generate heart rhythms on our cardiac monitors but we use SimMon technology to supplement O2 saturation and blood pressure values.

The manikin with "veins" taped along the arms. It allows for actual IV starts and fluid administration. Everything is collected into the empty 1L NS bag.

The manikin with “veins” taped along the arms. It allows for actual IV starts and fluid administration. Everything is collected into the empty 1L NS bag.

This scenario utilized many things that I’m coming to realise are important in in-situ simulation. Firstly we used the duty crew, meaning that we didn’t have to get anyone to come in on their days off. But also that if a call came in for a job, our crew remains operational and can respond to that at any moment. So this makes our training highly efficient.   Secondly, this scenario was run on-site, including in the back of the chopper itself. Again excellent for fidelity and also for practicing techniques in a confined space. We are also vigilant about our labeling of training gear with bright red tags to ensure nothing from our training gear gets mixed with operational equipment.. A debrief time is equally as important as scenario-time, and this can be hard to facilitate if everyone disappears halfway through!

As a student, I found this scenario enlightening from both a simulation and medical point of view. I did some reading around beta-blocker overdoses and I found an excellent review about the use of high-dose insulin. Insulin has an increased inotropic effect on the heart, and clinical experience has shown that this has beneficial effects on patients who have overdosed on beta- and calcium-channel blockers. It’s also relatively cheap, readily available, and the dose to remember is easy – 1IU/kg bolus, then follow with 1-10IU/kg/hr infusion. Of course glucose needs to be monitored and a D5 infusion should be run whilst giving the insulin, and may need to be continued for up to 24h after the insulin has stopped. Monitoring the potassium is equally important, but remember the hypokalaemia is more due to cellular shift than overall potassium loss. There isn’t much data on the use of insulin in pre-hospital settings for such overdoses but it likely could be used during long flight times like inter-facility transfers. During our debrief, the clinicians felt it was more important to initiate early transport than high-dose insulin therapy in the field. But the discussion is pertinent and worth having.

All in all today was a good day for learning some key simulation techniques and some good emergency medicine. And apart from that, I managed to ask at least 14 irrelevant questions and steal 2 coffees, a yoghurt and half a banana from the lunchroom. So really a most successful morning.

Rossi Holloway

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Full-text pdf for the reference above can be found here (secure area limited to ADHB staff only – ADHB has online subscription access to this journal via the Philson Library at the University of Auckland School Of Medicine)