POTD: Cryoneurolysis? What is that?

Welcome to a very exciting POTD inspired by our research extraordinaire and pain management expert Dr. Sergey Motov!

He recently enlightened me on the topic of cryoneurolysis as a pain management modality, and my first response was: what is that? So let's learn together!

What is it?

The use of cold temperature to treat pain using nitrous oxide contained within the cryoneurolysis probe/cannula. Nitrous oxide enters a low-pressure chamber at the end of the cryoneurolysis probe, which causes a precipitous decline in temperature. This decline in temperature leads to axonal injury and analgesia at the intended site. Because cryoneurolysis relies on axonal injury for analgesia, pain control can be achieved for weeks to months. 

For our surgical colleagues, this may be done with direct visualization of the nerve in the OR. For the EM folks, this can be done using an ultrasound-guided approach with a percutaneous cryoneurolysis probe. 

What's the evidence?

A systematic review by Cha et al. (2021) noted that cryoneurolysis may be useful for chest wall pain after surgery or trauma, however many studies are of low quality, and more research is needed. Similarly, a case series published by Wang et al. (2024) showed promising results for cryoneurolysis as pain management after rib fractures. 

Other preliminary data suggest efficacy in pain control following total knee arthroplasty, rotator cuff injuries, limb amputations, and lower limb burn injuries. 

However, as previously mentioned, many studies are not the highest quality (lots of case reports and case series) and more research is needed. But, so far the results are promising!

What's the downside?

Because analgesia can be achieved for weeks-months, this modality is less useful for nerves that have both motor and sensory function, as it can impair someone's motor function for a long time. 

Other potential side effects are similar to those of nerve blocks, including bleeding, infection, and (longer than intended) nerve damage.

Also - this requires a specialized cryoneurolysis probe to do, so you'd potentially be limited by the resources of your practice setting.

Is this helpful for us in the ED?

Much of the literature that has come out about cryoneurolysis has been from our surgery and anesthesia colleagues. However, given that nerve blocks are becoming more and more common in EM (and certainly in the Maimo ED), doing ultrasound-guided cryoneurolysis can certainly be a pain control modality that EM providers can do. 

Given that a lot of what we see in the ED relates to pain, cryoneurolysis can be an additional pain control option for patients that require long-term pain control. Many of the studies are reporting multiple weeks of pain control after cryoneurolysis. If you're giving pain control after surgery or trauma, the hope is that maybe after the weeks of cryoneurolysis wear off, the patient's injury/surgery will have healed enough that their pain will be tolerable. 

Also, given the public health push to reduce routine opioid use, cryoneurolysis can aid us in providing another option to patients who are in pain. 

In conclusion...

Cryoneurolysis is an old technique that has newly become a feasible pain management option in the era of modern cryoneurolysis probes and ultrasound-guided nerve blocks. While more research is needed and more training is needed for EM providers, this may be an up and coming option for longer term pain management. 

References:

John J. Finneran IV & Brian M. Ilfeld (2021) Percutaneous cryoneurolysis for acute pain management: current status and future prospects, Expert Review of Medical Devices, 18:6, 533-543, DOI: 10.1080/17434440.2021.1927705

Cha PI, Min JG, Patil A, et al. Trauma Surg Acute Care Open 2021;6:e000690.

Finneran Iv JJ, Gabriel RA, Swisher MW, et al. Ultrasound-guided percutaneous intercostal nerve cryoneurolysis for analgesia following traumatic rib fracture -a case series. Korean J Anesthesiol. 2020;73(5):455-459. doi:10.4097/kja.19395

Gabriel RA, Seng EC, Curran BP, Winston P, Trescot AM, Filipovski I. A Narrative Review of Ultrasound-Guided and Landmark-based Percutaneous Cryoneurolysis for the Management of Acute and Chronic Pain. Curr Pain Headache Rep. Published online July 4, 2024. doi:10.1007/s11916-024-01281-z

Wang S, Earley M, Kesselman A, et al. Percutaneous Cryoneurolysis for Pain Control After Rib Fractures in Older Adults. JAMA Surg. Published online August 7, 2024. doi:10.1001/jamasurg.2024.2063

Ilfeld BM, Gabriel RA, Trescot AM. Ultrasound-guided percutaneous cryoneurolysis for treatment of acute pain: could cryoanalgesia replace continuous peripheral nerve blocks?. Br J Anaesth. 2017;119(4):703-706. doi:10.1093/bja/aex142

POTD: What type of blood transfusion do I order?

This POTD was inspired by a CED that we recently did on a level 1 trauma in the ED. Special shout out to RN Mel Besett for answering some of my questions I had about this topic.

The trauma case went something like this...an EMS note was called, stating that a man had stabbed himself in the abdomen with a kitchen knife. He was tachycardic, BP was stable, GCS 15. 

When the patient arrived, he was noted to have HR of 120-130s, BP initially 130s systolic. eFAST positive for free fluid in the RUQ. Throughout the trauma, he remained tachycardic and his BP started to trend downwards - SBP 130s...then 120s...110s...100s. 

It was decided that the patient should receive a blood transfusion, but...what type of blood should we order? How emergent was this?

Let's dive into it. There's a few different types of blood transfusions we can initiate in the ED:

Regular, cross-matched blood:

- For patients who are stable enough to wait. Typically, with waiting for the T&S, requesting blood, and starting blood, this could take more than 1-2 hours. 

- Requires 2 type and screens in the chart - if patient has a previous one in their chart, you can order just 1 

- Blood transfusion consent on Taylor Health

Emergent blood:

- Can take 10-15minutes depending on if there is someone available to run to the blood bank and back. Otherwise, the blood bank will have to send the blood through the chute, which can also take around that amount of time

- Requires a "Emergency Blood Transfusion Request" on Taylor Health

- Also requires patient consent. If patient is unable to be consented, requires 2 attending consent. 

"Cracking the fridge":

- There is a fridge in resus 51 stocked with pRBCs, platelets, and plasma

- Charge RN has code to the fridge

- The fridge also has whole blood (which is all the elements combined), but only the trauma attending can call for whole blood from the fridge

Massive transfusion protocol (MTP):

- At least 6 units of blood, comes from the blood bank

- If starting MTP, typically we start giving units of blood from the fridge, then call for MTP from the blood bank 

To end the case, given the patient's BP was declining, he was taken emergently to the OR. Because the OR was ready and patient couldn't wait ~10-15 minutes for emergent blood to arrive, he received his first unit of blood from the fridge while being transported to the OR. 

POTD: Procedural sedation for ortho reductions

This POTD was requested by one of our sim fellows and new attendings, Vishnu Muppala, who wanted to know what the literature was on different medications for procedural sedation, particularly for orthopedic reductions (fractures/dislocations). So let's dive in.

To start off, let's talk about procedural sedation. There's a few agents that we commonly use in the ED.

The doses and pros/cons of each are nicely summed up in this table from our very own Reuben Strayer:

(https://emupdates.com/emergency-department-procedural-sedation-checklist-v2/)

The above link also has a bunch of info on how to set up for a procedural sedation and what to do if things go wrong.

But today, we're diving into the literature on which one is best for orthopedic procedures. In my experience, our ortho colleagues often times want us to use midazolam, but we often want to use propofol or "ketofol", which is a mix of ketamine and propofol. So is one better than the other?

In a 2015 RCT from Hatamabadi et al., they examined the safety profile and the time it takes from induction to fully awake (aka probably good for dispo) between propofol vs midazolam. In this study, it was found that the safety profile was similar between the two, but propofol had a significantly shorter time from induction to awakening. 

In another RCT (Taylor et al., 2005), propofol was compared with midazolam/fentanyl in shoulder dislocation reductions. Again in this study, propofol was found to have shorter time to awakening. Also, this study found that propofol led to easier shoulder reductions and fewer reduction attempts. There was no statistically significant difference between their safety profiles. Another point for propofol!

One last RCT I found compared a combination of ketamine and propofol to a combination of midazolam and fentanyl (Nejati et al., 2011). In this study, the ketofol group had lower perceived pain compared to the midazolam/fentanyl group. In this study, both groups had similar sedation time and safety profiles. 

However, in the only systematic review I could find comparing the two, there was no difference in safety nor in the effectiveness between the two (Holh, et al., 2008). Of note though, they could only find 4 RCTs looking at effectiveness, and only 2 of them were graded as "good" by the authors. Also, this wasn't specifically for ortho procedures but for all procedural sedations. So maybe not the best sample for our clinical question. 

My conclusions that I gathered from this quick lit review is that is seems like propofol is more effective, takes less time for the patient to wake up, and (ketofol) leads to less pain than midazolam. Both medications, in the purposes of these RCTs, seem to have similar safety profiles. However, as with many things, more data is required to make a stronger conclusion.

Resources:

Hatamabadi HR, Arhami Dolatabadi A, Derakhshanfar H, Younesian S, Ghaffari Shad E. Propofol Versus Midazolam for Procedural Sedation of Anterior Shoulder Dislocation in Emergency Department: A Randomized Clinical Trial. Trauma Mon. 2015;20(2):e13530. doi:10.5812/traumamon.13530

Taylor DM, O'Brien D, Ritchie P, Pasco J, Cameron PA. Propofol versus midazolam/fentanyl for reduction of anterior shoulder dislocation. Acad Emerg Med. 2005;12(1):13-19. doi:10.1197/j.aem.2004.08.039

Nejati A, Moharari RS, Ashraf H, Labaf A, Golshani K. Ketamine/propofol versus midazolam/fentanyl for procedural sedation and analgesia in the emergency department: a randomized, prospective, double-blind trial. Acad Emerg Med. 2011;18(8):800-806. doi:10.1111/j.1553-2712.2011.01133.x

Hohl CM, Sadatsafavi M, Nosyk B, Anis AH. Safety and clinical effectiveness of midazolam versus propofol for procedural sedation in the emergency department: a systematic review. Acad Emerg Med. 2008;15(1):1-8. doi:10.1111/j.1553-2712.2007.00022.x