POTD: Trauma Tuesday - Vasopressors in hemorrhagic shock

Background pathophysiology:

Hemorrhagic shock is initially driven by a sympatho-excitatory phase attempting to compensate for acute blood loss and is characterized by vasoconstriction, tachycardia, and preserved MAP. The hypotension that subsequently follows is a result of decreased sympathetic nervous system activity from a physiologic exhaustion of endogenous catecholamines (norepi, epi) and other adjuncts (angiotensin II and vasopressin).

The traditional teaching:

The objectives of hemodynamic resuscitation in trauma is to restore adequate intravascular volume with a balanced ratio of blood products, correct pathologic coagulopathy, and maintain organ perfusion. The use of vasopressors has been traditionally discouraged in this setting as several studies have demonstrated that it leads to adverse outcomes and increased mortality risk. Permissive hypotension is advocated based on limited data that lower SBP and MAPs will result in improved mortality. Note that ATLS does not recommend the use of vasopressors currently.

Vasopressin as the pressor of choice for trauma?

The truth is that the optimal arterial blood pressure target for resuscitation of hemorrhagic shock patients is unknown. There are no studies that have come up with a concrete goal. In order to avoid increased mortality, we have shied away from using vasopressors as adjuncts in trauma resuscitation, but we know that intuitively, persistent hypotension and hypoperfusion are associated with worse coagulopathy and organ function. Thus, it would seem prudent to reconsider this all-or-nothing strategy for something more nuanced. In one of the landmark papers that demonstrated poor outcomes from early vasopressors by Sperry et al, vasopressin was the only vasopressor that was not associated with increased mortality.

In 2019, the AVERT-Shock trial demonstrated that vasopressin administration may improve blood pressure and perfusion without worsening blood loss or increasing mortality. Vasopressin has a direct vasoconstricting effect on V1 receptors but also increases the sensitivity of the vasculature to circulating catecholamines. This is why it is often used as a second-line agent in critical care settings. Theoretically, vasopressin may augment the effects of the limited endogenous catecholamines circulating when a body is in hemorrhagic shock and avoid the deleterious effects of adding exogenous ones.

However, note that this study included a much larger proportion of penetrating trauma compared to blunt trauma, potentially limiting generalizability. While it demonstrated a robust clinical difference, it was underpowered to show a statistically significant difference in mortality. Ultimately further investigations are needed, but this paper provides a great jumping off point into how we may reach for a more balanced approach to trauma resuscitation that may include both blood products AND vasopressors when the blood products alone do not seem to be restoring perfusion.

References

https://rebelem.com/avert-shock-vasopressin-for-acute-hemorrhage/

https://emcrit.org/wp-content/uploads/2022/04/Vasopressors_in_Trauma__A_Never_Event_.13.pdf

A. Sims et al., “Effect of Low-Dose Supplementation of Arginine Vasopressin on Need for Blood Product Transfusions in Patients With Trauma and Hemorrhagic Shock: A Randomized Clinical Trial,” JAMA Surg, Aug. 2019.

VOTW: Pediatric Skull Fracture

This week’s VOTW is brought to you by the UST~

A 9 month old female infant was brought into the Pediatric ED two days after a fall from a high chair. The infant vomited once after the fall but was otherwise acting normally since then. The patient was brought to the ED 48hrs after the fall for a boggy left parietal scalp hematoma. The patient had a normal physical exam apart from the hematoma.  A POCUS was performed which showed...

Clip 1 shows an oblique disruption in the cortex of the skull, indicative of a fracture. The bones have an “overlapping” appearance. A hypoechoic hematoma is present overlying the fracture.

Image 1 shows the same fracture with relevant structures labeled.

Image 2 shows a cortical disruption in the skull of the same patient, but this one is a cranial suture

Sutures and fractures look the same! How do I differentiate them?

• A suture can be followed all the way to a fontanelle.

• Sutures are present symmetrically - scan the contralateral side if unsure

• Fractures may appear irregular, jagged or displaced.

• Sutures generally have an “end-to-end appearance” (image 2)- the cortex stops, there is a small space, and then restarts.

• A fracture is likely to have an overlying hematoma.

Image 3. More examples of sutures

Image 4. A review of the anatomy of sutures and fontanelles

How to perform the study

1. have a parent or assistant stabilize the child’s head, especially if they are squirmy

2. use a linear high frequency probe and a lot of gel, especially if there is hair

3. warm up the gel (put the gel bottle in your backpocket) which might make it less uncomfortable for the patient

4. scan the area of swelling in two orthogonal planes and look for disruptions in the cortex

5. scan the area around the hematoma as well- the fracture may not be directly under the hematoma

Clinical Decision Making

There is limited data on the use of POCUS for diagnosing pediatric skull fractures.

•  When performed by EM Physicians, POCUS for skull fractures has sensitivities ranging from 67% - 100% and specificity of 85% - 100% (1)

•  The presence of a skull fracture increases the likelihood of intracranial injury by four-fold (2)

POCUS for pediatric skull fractures might be most useful in the borderline case- for example a child who has an occipital/parietal/temporal scalp hematoma but otherwise looks great in the ED. Using PECARN you decide that you would rather observe this patient than subjecting the patient to radiation +/- sedation. If you decide to perform a POCUS, the absence of a skull fracture might be reassuring to you (and the family) and support your shared decision to observe the patient. The presence of a skull fracture might raise your concern for intracranial injury and change your decision about imaging. 

For a patient with a high pre-test probabiltiy for underlying pathology a negative POCUS should not be used a rule out test.

It might also be useful seeing a depressed or complex skull fracture as this may expedite imaging and specialist consultation.

More research is needed to define the role of POCUS in clinical decision making and how we might be able to integrate it with clinical decision rules like PECARN.

Happy Thanksgiving!

Your Sono Team

1. Alexandridis G, Verschuuren EW, Rosendaal AV, Kanhai DA. Evidence base for point-of-care ultrasound (POCUS) for diagnosis of skull fractures in children: a systematic review and meta-analysis. Emerg Med J. 2022 Jan;39(1):30-36. doi: 10.1136/emermed-2020-209887. Epub 2020 Dec 3. PMID: 33273039; PMCID: PMC8717482.

2. Kuppermann N, Holmes JF, Dayan PS, et al.. Identification of children at very low risk of clinically-important brain injuries after head trauma: a prospective cohort study

Wayne Pneumothorax Tray

I wanted to do a little blurb about the pigtail kit at Community. I often find that we as providers become pretty comfortable with what we know and uncomfortable with any tools we haven't used before. Back in July, I had to do a chest tube at Community, and the kit was totally different (and rest of the procedure was completely different because of this). This kit is not saldinger technique, and doesn't require use of needles (though you still should use lido obvs). I was initially confused when I was looking at the kit, and so wanted to write this out in case you face the same!

The kit comes with a 14Fr pigtail, trocar, long blade that goes in trocar (looks like a hollow bore needle, but isn't!), 11 blade, tubing, three way stopcock, and one way air valve. The main difference from the pigtail kits that we're used to, is there is no guidewire and no needle! Meaning, you're not going in with the needle first. 

Essentially, you will end up inserting the pigtail with trocar and long blade in one piece, into the incision site. The trocar is placed in a larger fenestrated hole towards the end of the pigtail.

The steps for the procedure include;

1. Confirm the location, fool (pick the side with the pneumo, and do it in the triangle of safety)

2. Prep the site with chlorhexadine

3. Anesthetize the site with lido

4. Get sterile

5. Drape and re-prep (you could probably prep once, but I'm a little OCD)

6. Combine the pigtail, trocar, and long blade as shown in image

7. Make your incision above the rib with the 11 blade

8. Taking the combined long blade, in trocar, in pigtail - insert at your incision, aimed towards the lung apex

9. Remove the long blade once you pass the resistance of the pleura

10. Advance the trocar and pigtail, before removing the trocar and continuing to advance the pigtail to the desired depth (usually around 15-20 cm)

11. Suture the pigtail in place and place a dressing over it

12. Attach the tubing with the one way valve or to a pleurovac

Now for those of you that may read this and say "omg, I'm not trying to just stab someone," well, you are not alone. Others have commented the same. And if you are so inclined to place this pigtail using saldinger technique, that is still possible. You will need to crack open a central line kit and pillage the needle, syringe, and guidewire. The trocar in the Wayne Pneumothroax tray is hollow bore, and the guidewire can still be fed through that. Hope this was helpful!