Central Line

Episode Number: 158

Episode Title: PECS Blocks and Nomenclature

Recorded: April 2025

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VOICE OVER:

Welcome to ASA’s Central Line, the official podcast series of the American Society of Anesthesiologists, edited by Dr. Adam Striker.

DR. ADAM STRIKER:

Welcome to Central Line. I'm Dr. Adam Striker, your editor and host. Today, I'm joined by Dr. Christine Vo, who sits on the editorial board of ACE or Anesthesiology Continuing Education. As many of you know, we we occasionally do an episode highlighting a theme or an issue that the current issue of ACE tackles. Today, she's here to talk to us about pecs blocks and importantly, about nomenclature and regional anesthesia. So let's get right to it. Dr. Vo, thanks for joining us today.

DR. CHRISTINE VO:

Thanks for having me.

DR. STRIKER:

Before we get into the actual topic, do you mind introducing yourself a little bit to our listeners, just maybe talk a little bit about your path, your role, your work with ACE, how you got into it.

DR. VO:

I'd be happy to. So I'm Dr. Christine Vo, a general adult anesthesiologist and associate professor at OU Health in Oklahoma with a strong focus on education, regional anesthesia, and point of care ultrasound. I currently serve on the ACE Editorial Board, which is a premier resource providing concise, high yield educational content for anesthesiologists. And in my role, I collaborate with colleagues from across the nation to review and develop content that covers emerging techniques, clinical pearls, and evidence-based updates and reviews in anesthesiology. My path into regional anesthesia began during residency, where I became particularly interested in ultrasound guided techniques and their impact on perioperative outcomes, and since then, I've been actively involved in teaching residents and medical students, as well as anesthesiologists at the ASA, with an emphasis on refining their skills in regional blocks and ultrasound guided procedures and POCUS.

DR. STRIKER:

Excellent. Well, let's start off with maybe going through a brief history on pecs blocks for those who may not be as familiar, what they are and what they're used for. And also a little bit about how they have evolved over time.

DR. VO:

Yeah. So the pecs blocks or pectoral nerve blocks, they were first described by Dr. Rafael Blanco in 2011, so not too long ago. And this was a technique that was an alternative to thoracic epidurals and paravertebral blocks, particularly for breast surgery analgesia. The initial technique, now known primarily as the pecs one block, involves an injection of local anesthetic between the pectoralis major and minor muscles to target the lateral and medial pectoral nerves. And this provided analgesia primarily to the pectoral region. And then shortly afterwards, the pecs two block was introduced. And this was an expansion of the original pecs one blok, where it included the addition of a second local anesthetic between the pectoralis minor and the serratus anterior muscles. And so this modification allowed for coverage of the lateral branches of the intercostal nerves T2 through T6, the intercostal brachial nerves, and the long thoracic nerve. And this provided broader analgesia for procedures such as mastectomies and axillary lymph node dissection. And so the pecs one is a single injection between the pectoralis major and minor, and then the pecs two actually includes the pecs one in that second injection. Yet many physicians continue to believe that the pecs two block consists of a single deep injection, and that's where clarification was needed. And so over the past decade, these text blocks have gained widespread use due to their efficacy, simplicity, and low risk of complications. And they've also evolved to become part of multimodal analgesic strategies for thoracic and breast surgeries, reducing opioid consumption and enhancing recovery.

DR. STRIKER:

There's a couple aspects of that that I do want to tackle. Let's leave the nomenclature aside for just a second, because I do want to delve into that for a few minutes. But before that, let's talk about the efficacy of fascial plane blocks in general and the advantages and disadvantages compared to what most of us would consider the more traditional regional anesthetics prior to ultrasound.

DR. VO:

Yeah. So fascial plane blocks, which includes those PECS blocks, have definitely grown in popularity due to their simplicity, their safety profile, and their effectiveness in providing regional analgesia without the risks that are typically associated with neuraxial techniques like epidurals and paravertebral blocks. And so the advantages includes the low complication risk. So unlike epidurals, fascial plane blocks avoid the risks with the sympathectomy and resultant hypotension, or spinal cord injury, or even a spinal hematoma. And it's pretty simple to do. So with the use of ultrasound guidance, these fascial planes are easily visualized, making the blocks a lot more accessible even for our less experienced practitioners and learners. They're able to relatively pick up this skill easily. And then the literature shows it's helped contribute to reduced opioid consumption. So when used as part of the multimodal analgesia approach, these blocks can significantly reduce perioperative opioid requirements in the side effects and complications associated with opioids. However, every pro has a potential con, so there are some disadvantages with these fascial plane blocks. Of note is just the limited duration, especially as a single shot injection. It's definitely a shorter duration than our epidurals unless you do thread a catheter and you place a continuous infusion. There is variable efficacy, so these fascial plane blocks definitely help with somatic pain relief. But they are less effective for visceral pain. So there is limited use for them particularly in intra abdominal or pelvic surgeries. And then there's always the possibility of anatomic variability amongst patients. And so the spread of local anesthetic can be inconsistent which may affect that blocks reliability.

DR. STRIKER:

So is the efficacy variable because of the particular user or simply because of the nature of the fascial plane block itself, as you alluded to with the spread of the anesthetic.

DR. VO:

Yeah, I would suggest both. So as you gain more experience, just like with any type of procedures, the efficacy increases. But then also you have to take into account potential for scarring or septations that may limit the spread of these local anesthetics. And then also the local anesthetic choice depending on potency and volume, how much it can actually spread.

DR. STRIKER:

And if you can generally compared to paravertebral or epidural for instance on a one for one basis, comparing the efficacy, forget the safety profile for just a second. Are the fascial plane blocks as effective, or are they as effective as part of a multi-modal? Or are they maybe slightly less effective but the benefit really comes in when you take in the risk profile as well?

DR. VO:

I would say the latter is probably the most accurate representation of fascial plane blocks. As I alluded earlier, it more so also helps with the somatic pain. And so if a component of the patient's pain is visceral in nature, then a lot of these fascial plane blocks don't necessarily work as well. I mean, there are some blocks that, um, theoretically could spread to the paravertebral space, like the erector spinae block. But again, that can be variable too. So when you take into consideration the risk stratification associated with neuraxial blocks and their complications, this is a viable alternative for patients as part of a multimodal analgesic plan. Definitely. And you especially nowadays with patients on a lot of these antiplatelets and anticoagulation medications, these fascial plane blocks offer additional options for our patients. Whereas in the past we may have been limited with not being able to provide an epidural.

DR. STRIKER:

Sure. Yep. Well, let's go ahead and turn to the nomenclature aspect of this. Now, I think everybody recognizes that if we're all on the same page when it comes to classifications or nomenclature, that's a good thing. And standardizing communication is always a good thing. What's the issue here?

DR. VO:

Yeah. So standardizing nomenclature and regional anesthesia is definitely essential for consistency in clinical practice in education and research. And so when different institutions or even clinicians use inconsistent terminology for essentially the same block, it creates confusion and it impairs communication. And so this heterogeneity of language can result in inconsistent reporting. So in research that inconsistent terminology actually makes it harder to compare outcomes or even perform meta analysis. And from the standpoint of billing and coding, there are challenges when you have varying names for the same procedure because that can complicate documentation, billing and potentially reimbursement. And then looking at it from the standpoint of trainees, it's a struggle when you have conflicting names for identical techniques. And this leads to uncertainty or even misapplication. And so ultimately standardization promotes clarity. It improves patient safety. And it streamlines documentation, education.

DR. STRIKER:

Well give me some examples. Like some common blocks that are not consistently labeled.

DR. VO:

Yeah. So like so for the abdominal wall blocks there was the quadratus lumborum block where it was type one, type two or type three. Now they've come to the consensus that it's now identified by its location relative to the actual muscle. So anterior posterior lateral. Even from that standpoint the lateral quadratus lumborum block can be mixed with the posterior tap lock. And so from that standpoint that can be very confusing. And so having some consistency in the language overall helps everyone.

DR. STRIKER:

How does this apply to the pecs one and pecs two blocks.

DR. VO:

Yeah. So there are two main issues with the pecs block. For one, you know, there are many practitioners that still considers the pecs two block as a single injection between the pectoralis minor and the serratus anterior muscle. Whereas when it was first described, the intent was to actually include both the pecs one and pecs two. And so essentially there is a mis naming of the block or misrepresentation of the block by what we're calling it nowadays. And so the proposal is to name the pecs one and pecs two historically in relation to where the injection is. So an inter pectoral pain block for pecs one and a pectoral serratus plane block or pecs two, respectively.

DR. STRIKER:

Now, is the nomenclature issue more of a problem with the fascial plane blocks when it comes to the regional anesthesia umbrella as a whole?

DR. VO:

That's a great question. This original question that I drafted for the ACE program actually came from a recent publication, relatively recent, actually published in 2021. And it highlighted the fascial plane blocks. Now, in relation to other types of blocks, there is a consensus just yet. So I can't speak to that.

DR. STRIKER:

Well now if I understand this correct. There is a consensus group that has aimed to standardize nomenclature for some of these blocks. Is that correct? Tell us a little bit about that.

DR. VO:

Yeah. So this was actually done back in 2020. And they published a consensus guide in 2021 that comprised of leading experts in regional anesthesia. And these experts were both academic and private practice anesthesiologists. Coming from North America, Europe, Asia, and Australia. And they represented varied theoretical and clinical practices. And so these guidelines were published with the hope to standardize the nomenclature specifically of fascial plane blocks. And their goal was to create a unified language that accurately reflects the anatomical targets of each block. And this is critical for consistency and clarity, which in turn this can serve to improve the dissemination of these regional anesthetic techniques for patient benefit. And their focus in this consensus guideline was on abdominal wall blocks, paraspinal, and chest wall blocks. And so their hope was to reduce variability in terminology and improve clarity in the literature.

DR. STRIKER:

And what ultimately was the result?

DR. VO:

The key takeaways there, so blocks should be named according to the fascial plane and targeted nerves, and not necessarily by arbitrary terms. There should be clarity in documentation, so standardized names enhances consistency in clinical documentation and research publications and billing, and their goal was to improve education so that trainees would benefit from more clear and uniform terminology, and thus reducing confusion and enhancing learning outcomes. And ultimately, this was for the broader adoption of these blocks. And so despite the consensus, adoption still is slow, and many practitioners still use older names out of habit. And even the pegs block, um, they weren't able to reach a strong consensus, which in this guideline was greater than 75%. And so they were about there at 73%. But even amongst our experts, there is some heterogeneity.

DR. STRIKER:

Well, And as I imagine now that the performance of these blocks are becoming more and more prevalent, that this work is just becoming more visible, more important, just because it's affecting so many practitioners now, as opposed to when when they started this work. Right.

DR. VO:

Right. And I mean, it's been four years now since it was published. And it's just very interesting to me how slow it is to be adopted with this new nomenclature, given the fact that so many of us incorporate fascial plane blocks in our practice. It's just important to get the word out there and talk about it more.

DR. STRIKER:

Well, like you're doing here. Well, before I let you go, I just want to give you a chance to talk a little bit more about your work with ACE, maybe what you really enjoyed about your role, and what do you wish our listeners understood a little bit more about the ACE program?

DR. VO:

Yes, I would love to. Um, serving on the ACE editorial board has been incredibly rewarding. One of the highlights is collaborating with a team of passionate educators, and we come together to create concise, high yield content that is immediately applicable to clinical practice. When drafting questions and engaging in active discussions with fellow colleagues, it helps to keep me up to date on clinical practices across the country. And believe me when I say discussions, they can get pretty heated, but it's all in good faith. We want to ensure that we are publishing a high-quality product for our members. And what I'd like listeners to know is that the ACE program and booklets, they're more than just a review tool. It's a resource for lifelong learning, and we're very purposeful in curating content that reflects both emerging trends and core anesthesiology principles, and we hope to make it a valuable reference even for experienced practitioners. And so I'd like to encourage listeners to explore the breadth of topics covered. As the Ace program continually evolves, we listen to your feedback and we hope to address the changing landscape of anesthesiology practice.

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DR. STRIKER:

Excellent. Well, Dr. Vo, thanks so much for joining us today.

DR. VO:

Thank you so much for having me. This was a pleasure.

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DR. STRIKER:

And for our listeners, if you would like more information on the Ace program, please visit asahq.org/ace. And don't forget to tune in again next time to Central Line. Take care.

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