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BackTable / VI / Article
Acute Limb Ischemia: Rutherford Classification, Imaging Techniques & Essential Labs
Melissa Malena • Oct 4, 2023 • 318 hits
Acute limb ischemia (ALI) presents unique challenges for the clinician, not only in diagnosis but also in determining the optimal course of treatment. ALI requires clinicians to take an in depth patient history, lab work, imaging and an intensive physical exam to determine the most appropriate treatment protocol for each case. The rutherford classification for acute limb ischemia separates patients into four groups based on ischemia severity and provides a general guideline for interventional treatments. Along with the Rutherford classification guidelines, the emergent level of each case should also play a role in management decisions. Treatments for acute limb ischemia include heparinization, surgical interventions such as arterial thrombectomy and embolectomy, and amputation in the most severe cases.
Interventional radiologist Dr. Alexander Ushinsky provides an in-depth look at his protocol for working up acute limb ischemia, covering physical examination, Rutherford classification, imaging, and labs; and how these various factors influence which treatment is most appropriate for the acute limb ischemia patient. This article features excerpts from the BackTable Podcast. We’ve provided the highlight reel here, and you can listen to the full podcast below.
The BackTable Brief
• Rutherford classification for acute limb ischemia provides a grade to gauge urgency in coordination with pulse examination and physical assessment of the limb. Bedside Doppler examination can also offer immediate insights.
• The Rutherford classification system serves as a primary guide in clinical decision-making. Rutherford 3 patients, showing complete paralysis of the foot, are generally not taken for embolectomy or thrombectomy. Rutherford 1 or 2A patients might be considered for endovascular therapies. Rutherford 2B patients present a challenging gray zone, with decisions influenced by available technology and practitioner experience.
• Essential labs include coagulation parameters, CBC, and chemistry panel. Lactate levels may indicate severe tissue loss. Historically, CTA has been heavily relied upon for imaging, but ultrasound can be crucial, especially in patients with severe calcific, small vessel disease.
Table of Contents
(1) Comprehensive Workup of Acute Limb Ischemia
(2) Rutherford Classification for Acute Limb Ischemia Treatment
Comprehensive Workup of Acute Limb Ischemia
In describing his typical workup of acute limb ischemia, Dr. Ushinsky highlights the importance of a detailed patient history, with a keen eye on the temporality of the ischemia, the presence of underlying peripheral vascular disease, and the potential for coagulopathic processes. Clinicians are urged to discern between true ALI and worsening chronic limb ischemia, a distinction that dictates urgency and mode of treatment. The clinical exam, with emphasis on sensory and motor evaluation, plays a pivotal role alongside bedside Doppler assessments. Furthermore, Dr. Ushinsky stresses the importance of adequate lab work, including coagulation parameters and kidney function, as well as the reliance on Computed Tomography Angiography (CTA) over Magnetic Resonance Angiography (MRA), especially in emergent settings. The discussion punctuates the imperative of informed medical decisions, particularly with anticoagulation considerations, as timely and apt intervention can be the difference-maker in ALI management.
[Dr. Alexander Ushinsky]
I think that when we are assessing the history of the patient, some important things to consider are whether they do have underlying peripheral vascular disease and trying to assess the etiology of why this patient may have developed acute limb ischemia. Making sure they don't have atheroembolic disease or something else that would require cardiology consultation, maybe considering whether they may have some coagulopathic process going on or are prone to clotting that may need to then follow up with a hematology referral.
The first thing is to take the patient's history and assess those risk factors. The other thing is the temporality of the limb ischemia. There are not infrequent cases where we are called for acute limb ischemia. When you actually speak to the patient yourself or the fellow speaks to the patient, you can ascertain that this is more on the worsening chronic limb ischemia, which you would treat sometimes less urgent fashion but it's certainly different.
Getting the medical history of the patient, like we discussed, getting the temporality of the symptoms. Always want to assess the progression of symptoms to see if the acute limb ischemia is getting worse. I tend to have my fellows try to grade the patient's face on the Rutherford classification acute limb ischemia grading, meaning assess their degree of sensory loss and their degree of motor weakness.
Then the other thing on the physical exam is obviously a pulse exam and an exam of the limb. The patient have immobile, paralyzed woody limb, or does the patient just have some subjective sensory loss but otherwise can wiggle their toes? That is a massive inflection point in how I determine to manage the patient.
[Dr. Chris Beck]
Going back to the physical exam, I don't know if you considered an extension of the physical exam, but do you guys Doppler the leg?
[Dr. Alexander Ushinsky]
Yes, we'll certainly get bedside Doppler.
[Dr. Chris Beck]
Oh, I didn't know. Sometimes you can just carry them around. Some places you just grab one off the IR wall and pop over. Cool.
[Dr. Alexander Ushinsky]
We usually do it, and they'll usually be at the bedside if the patient's in the emergency department. We have little carry totes with the Doppler and a little bit of gel for the fellows, definitely. The expectation is the fellow or myself if I'm going out there to the community hospital, we'll Doppler the leg. I will say that for the chronic limb ischemia patients, it can be difficult at baseline. It depends on what the patient's baseline vessels like. For those that have very calcified vessels, it can be very difficult to find those signals.
[Dr. Chris Beck]
Before we get into imaging, any lab work that's important to know ahead of time?
[Dr. Alexander Ushinsky]
Certainly all of the coagulation parameters, a normal CVC, and a chemistry panel to look at their kidney function. If you're really concerned about a pretty severely affected limb, you could start looking at lactate or other markers of tissue loss really, but if it's getting to that degree, there may not be much intervention that you can offer but certainly need to assess that.
[Dr. Chris Beck]
Moving from labs to imaging, I wanted to get your idea of how does ultrasound fall into the role of, like, how important is that for your practice and for your pre-procedure workup?
[Dr. Alexander Ushinsky]
Separate from the question of being able to Doppler, just pedal pulses or popliteal pulse. I would say that historically, I've relied a lot on CTA. I will say that, and we actually had a recent case of this where the patient just had so much severe calcific, small vessel disease and tibial disease that it was very hard to make out much of anything on the CTA below the knee.
In those patients, I think there's a really important role for a good duplex ultrasound from a vascular lab that can do a good exam to see the vessels and evaluate the weight forms if they're present.
[Dr. Chris Beck]
You touched on it, CTA versus MRA, prefer CTA.
[Dr. Alexander Ushinsky]
I think CTA is more readily available, especially in the on-call setting. I think getting a high complexity like a twist MRA is pretty difficult to do in an ER at 3:00 in the morning to get a good exam. The images that can be generated on a Monday at 8:00 AM are really nice, but it's very difficult in an emergency setting. The time commitment for that type of exam if someone who may have an emergent condition, a limb-threatening condition can be sometimes limiting.
[Dr. Chris Beck]
Absolutely. All right. Anything else I missed as far as workup goes? We did HMP, we did labs, imaging, anything else?
[Dr. Alexander Ushinsky]
The only thing I'll say is a lot of the patients are already on medication reconciliation, both for inpatient ordered meds and for outpatient medications, whether the patient's already on anticoagulation if they have not been put on anticoagulation and there's a high index of suspicion. Those are all important things to assess because actually, mobilizing your forces, and if the patient needs an intervention, bringing them for intervention may take some time and making sure that the patient's appropriately, medically treated, if nothing else is paramount.
[Dr. Chris Beck]
Will you guys go ahead and fill that gap as far as the medical treatment? You guys will haptenize them more?
[Dr. Alexander Ushinsky]
Definitely, especially in the community hospitals with the consultant being asked the question or order the exam, order the CTA, order the heparin drip or the Lovenox if the patient's not a good candidate for a heparin drip for whatever reason. In the university hospital where there are resident teams, we'll make the recommendation for whichever anticoagulation is appropriate for the patient if they haven't already received it from the referring provider.
[Dr. Chris Beck]
That's good. You guys are getting your fellows well-trained, right?
[Dr. Alexander Ushinsky]
In our practice here, we've had a very clinically-oriented practice for many years. We were the primary site for the attract trial for venous lysis and we've had an emitting service for a long time as well. Our fellows are generally very comfortable in terms of all aspects of inpatient management and interacting with the inpatient side of the hospital and the referring providers from hospital medicine or cardiology or whomever.
[Dr. Chris Beck]
That's just a way of things from here on out. I graduated eight years ago, and the IRS that are coming up now, they're just a new breed of super docs. Thank you for training these guys up and getting everyone, but you're kind of the ilk-like. Four years ago you were in fellowship, right?
[Dr. Alexander Ushinsky]
Yes, exactly right.
[Dr. Chris Beck]
That's awesome.
[Dr. Alexander Ushinsky]
It's definitely been the culture here for a long time. In retrospect, I hope that the fellows appreciate it. It's definitely burdensome to have to drive in at 3:00 in the morning to see a patient on call. It sounds luxurious to our colleagues who spend the night in the hospital three nights a week, but it becomes important, especially if you want to treat patients of any complexity or be involved in the medical decision-making for a patient.
[Dr. Chris Beck]
That's right. Patient prep, you've seen the patient, you've gone through the workup and you think this is a patient who needs to move on to intervention. The category is patient prep and we can start off in a couple areas, but one of the easy things to knock out is antibiotics, sedation level. Where do you stand on these things with these patients?
[Dr. Alexander Ushinsky]
If you'll allow me before we get into patient prep, one thought.
[Dr. Chris Beck]
Of course, Sasha. You're the guest. Of course, you can do whatever you want.
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Rutherford Classification for Acute Limb Ischemia Treatment
In the evaluation of patients with acute limb ischemia, Dr. Alexander Ushinsky emphasizes the need for accurate patient dichotomization: those amenable to intervention like revascularization and those beyond limb salvage. The critical determinant often hinges on clinical presentation, graded on the Rutherford classification system. Notably, patients with complete foot paralysis (Rutherford 3) are typically unsuitable for embolectomy or thrombectomy, while those with lesser symptoms might benefit from endovascular approaches. The rapid evolution of thrombectomy technology has broadened the scope of treatable patients, while the risk-benefit calculus of intervention continues to evolve as well. Collaborative decision-making, especially with vascular surgeons, becomes paramount in these complex cases to ensure optimal patient outcomes.
[Dr. Alexander Ushinsky]
The one thing I wanted to add is when you assess the patient, I feel like in acute limb ischemia, there is some dichotomization of the patients to those that would benefit from an intervention, meaning a revascularization of some kind, whether that is embolectomy, bypass, thrombectomy, endovascularly, and those that have really lost any salvageability of that limb.
That's something that I stress for my fellows when they evaluate the patient. There's a spectrum, and sometimes we may choose to take on a patient for thrombectomy who is a borderline candidate, the chance of success is somewhat low, but I think that's important for folks who are going to be consulted to evaluate these acute limb ischemia patients, is to also recognize those patients that are not salvageable because, for example, putting a lysis catheter in an elderly patient to try to save an unsavable limb and risk having a catastrophic hemorrhage probably is not worth it.
To have a good sense for those patients that are not a good candidate, the high Rutherford grade patients is important. We're still, I think, learning which techniques lend themselves to the middle Rutherford 2B patients. The patients who have a pretty threatened but maybe somewhat salvageable limb, and which techniques are suited for those patients and which aren't in my experience. I'm sure we'll talk about it coming up, but the jury's still out on what the best treatment for some of those patients are. We're not clear.
[Dr. Chris Beck]
Can you talk about maybe some of the risk-benefit things that you're rolling around in your mind as far as like, how do you tease apart the patients who are unsalvageable from salvageable? We won't ping you to it, but what are some of the things that you consider that push you into one category or the other?
[Dr. Alexander Ushinsky]
A pretty high demarcation of paralysis is the most clear designation. A patient who's Rutherford 3 has complete paralysis of their foot or a portion of their foot, I would not take for embolectomy or thrombectomy procedure in my lab. On the other hand, a patient who's Rutherford 1 or Rutherford 2A, I certainly would consider offering some endovascular therapy for.
I don't personally perform surgical embolectomy, but maybe a candidate for those practitioners who do. The area where I have struggled with sometimes is that Rutherford 2B group, the patients who are starting to have a little bit of extensive sensory loss and now some mild motor deficit. If you had asked me this question three or four years ago when all I had to offer was lysis catheter placement, those patients I would say probably will not benefit.
To be honest with you, I really distinctly remember a patient who I lysed in that context, had a little bit of toe paralysis, pretty extensive sensory loss, did an excellent lysis, great angiographic outcome, three-vessel runoff, patient lost her foot later that afternoon by amputation because we took too long with that approach.
After that, I told myself I'm not going to offer lysis for those patients anymore, but now with some of the newer technologies that you and I we'll talk about in the thrombectomy space, I would consider offering something about percutaneous thrombectomy-type procedures for those patients, at least consider it.
[Dr. Chris Beck]
One of the exciting things about this topic is how just your practices can change with new technology, and it's really driving what we can do and what patients we can treat. Actually, you did touch on something that I did want to talk about is, how do you work with other specialties. You mentioned embolectomy, how do you guys coordinate care between patients who have reasonable practitioners may differ on whether it's an interventional case versus a surgical case?
[Dr. Alexander Ushinsky]
It can be difficult sometimes because not only is it a question of surgical versus interventional, but it's what each particular provider is comfortable offering.
[Dr. Chris Beck]
Right. Yes, Exactly.
[Dr. Alexander Ushinsky]
I think especially when the referral comes to us from the vascular surgeon who's asking us if we'll consider an endovascular approach or a lysis catheter placement, becomes a slightly more straightforward discussion because it's two professionals who know what the other does. In that case, it's just a discussion of what am I comfortable offering versus some of my partners in our group may not routinely use some of the thrombectomy devices that are on our shelf and are more comfortable with lysis catheter placement.
What is the vascular surgeon who's making the referral comfortable offering? For example, some may not consider embolectomy in disease tibial arteries, or the patient may not have a distal target for bypass or a suitable conduit. It becomes a more nuanced discussion with those types of folks. When the referral comes from the emergency department or internal medicine hospitalist, then I'm able to lay out what I think is offerable for my endovascular approaches.
If I feel like the patient's not a good candidate for those, then I would ask them to engage our surgeons for consideration of some of the options they may have. After a discussion comes down to the fact they don't have anything different to offer, then the patients usually return to me if I feel comfortable or if I feel that they're a candidate for some of these endovascular approaches that I can offer.
[Dr. Chris Beck]
Is it a good collaborative relationship with vascular surgery or cardiology or whoever it might be that is in this space?
[Dr. Alexander Ushinsky]
I think in general, we have a fair relationship with them. We have good discussion about these types of patients when the referrals come through. Sometimes there can be some disagreement, especially when there's overlap. I think that now we have a pretty good relationship with the current surgeons in our hospital, and those folks are pretty collegial and we can have a discussion about what we think is the most appropriate treatment.
Sometimes there's a little overlap in terms of who saw the patient initially, because we do have some complimentary treatments, and who would offer the same treatment one versus the other. Some of the vascular surgeons in our hospital do offer lysis catheter replacement. When the consult comes through and it's someone who has done lysis catheter in the past, and then there's a discussion of, do you do this procedure? Do you need me to do it, and things like this? That can happen with a lot of these procedures.
Podcast Contributors
Dr. Alexander Ushinsky
Dr. Alexander "Sasha" Ushinksy is an interventional radiologist and assistant professor with Washington University in St. Louis.
Dr. Christopher Beck
Dr. Chris Beck is a practicing interventional radiologist with Regional Radiology Group in New Orleans.
Cite This Podcast
BackTable, LLC (Producer). (2023, April 24). Ep. 315 – Arterial Thrombectomy [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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