Newest addition to the ARHT simulation equipment!

Sim and Choppers

One of my medical education interests is looking at how we train and practice rarely performed procedures. For these situations, simulation offers an excellent method of training. The challenge, however, is recreating the fidelity of such situations since many rarely performed procedures are quite invasive.  Often we’ll start the training with a task-trainer like model and then progress to a full size manikin. Task-trainers are simulation models specifically designed for one type of procedure. 

In emergency and pre-hospital medicine, the cricothyroidotomy is among the most invasive, time critical yet rarely performed procedures. In addition to the potential technical challenges of this procedure, the decision to perform a cric might be even more difficult.  Identifying a “can’t intubate, can’t ventilate” scenario and then to “pull the trigger” may be one of the hardest cognitive leaps we face in resuscitation.  For example, last week, in the  Auckland emergency department we ran an…

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

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

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)

Inattentional Blindness – does this apply to pre-hospital medicine?

A recent study (not sure if it’s been published yet but will be soon) studied the ability of radiologists to accurately identify abnormalities on a CT scan. We’re talking board-certified, full fledged radiologists! I can’t take credit for coming across this paper – check out @TechnicalSkillz, ED physician in Toronto who tweeted the link. He has a real interest in cognitive biases and medical decision making. Anyways…I digress.

gorilla CT scan

This image was presented to radiologists after they were told to look for abnormalities including lung nodules. Do you see the abnormality? Don’t worry…you don’t need to be an expert at reading CTs…it should be obvious!

24 radiologists examined this image and 20 were not able to identify the gorilla in the upper right corner! 20/24 didn’t see it! that’s unbelievable. They’re so focused on looking for other things that they glazed right over it. Using eye tracking technology, the reserachers were able to show that impressively 12 looked directly at the gorilla but still they didn’t see it!

This concept of inattentional blindness (or perceptual blindness) is

failure to notice an unexpected stimulus that is in one’s eyesight when other attention demanding tasks are being performed (Wikipedia)

I think this happens not infrequently in pre-hospital medicine and the emergency department. How many times does the patient turn out to have an entirely different presentation from what we hear over the radio call out or what’s written on the triage note. Right from the beginning we’re biased by the what we hear…it may be the local clinic calls with “a 73yr old with pneumonia”. Maybe there’s some shortness of breath to reaffirm this diagnosis but just as the radiologists were looking for nodules, we might be looking for pneumonia and miss the pneumothorax because we didn’t find out the patient fell earlier today. It could have been obvious if we just auscultated the lungs more closely but because we were thinking about crackles, we didn’t anticipate there would be absent breath sounds.

I think we’re especially vulnerable in the pre-hospital setting to inattentional blindness. We receive limited and often wrong information. Add that to time pressures to reduce scene times and it’s very easy to succumb to such cognitive biases.  We must implement cognitive checks to ensure that diagnoses are not missed. Standardized approaches to common presentations can help to ensure that critical diagnoses are considered regardless of the presentation. Efforts to ensure strong team communication will also enhance diagnostic abilities – maybe someone else on your team saw something you didn’t but failed to mention it.

Awareness of pitfalls around diagnostic errors must extend to pre-hospital clinicians. This will help us identify those gorillas! Check out some of the work by Pat Croskerry who’s a world leader in medical decision making, cognitive biases and diagnostic error (plus he’s Canadian, so he must be great!). Please note, the author of this post is Canadian which may be the reason for this conflict of interest!