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Free Flap Surgery in Head and Neck Cancer: Strategies for Success
Julia Casazza • Feb 21, 2024 • 32 hits
Caring for free flap patients requires attending to the medical needs of cancer management while simultaneously mitigating the risk of postoperative complications. Chief among these complications is free flap thrombosis, which can irreversibly compromise transferred tissue when not caught early. Strategies such as frequent “flap checks” and a low threshold for OR take-backs help mitigate these surgical risks. Keep reading to learn more about how microvascular reconstructive surgeon Dr. Eli Gordin cares for free flap patients.
This article features excerpts from the BackTable ENT Podcast. We’ve provided the highlight reel in this article, but you can listen to the full podcast below.
The BackTable ENT Brief
• In head and neck cancer cases requiring microvascular reconstruction (“free flap surgery”), performing two-team surgery reduces anesthesia time and risk of surgeon fatigue.
• Surgical antibiotic prophylaxis should include Ancef for cutaneous operations, Unasyn for mucosal operations, and culture-directed antibiotics for chronic wounds.
• The most important portion of any free flap surgery involves the securement of the vascular anastomoses. Before connecting vasculature, surgeons should rinse with heparinized saline solution. Spasmodic vessels can be treated with papaverine, a phosphodiesterase inhibitor.
• Hourly flap checks, performed by nursing, assess the viability of transferred tissue in the first 72 hours following surgery.
• If there is any concern for flap compromise, the solution is to return to the OR immediately. Irreversible microcirculatory damage occurs after less than six hours of ischemia.
Table of Contents
(1) Intraoperative Management of the Free Flap Patient
(2) Securing the Microvascular Anastomoses
(3) The Importance of Flap Checks
(4) Returning to the OR
Intraoperative Management of the Free Flap Patient
In cases of two-team reconstruction, Dr. Gordin waits for the ablative team to remove the tumor before harvesting the free flap. Doing so allows him to know definitively what size flap will be needed. Once harvested, he determines the flap inset before sewing the anastomosis. Intra-operatively, he keeps the volume of crystalloid transfused under five liters. Antibiotic coverage depends on the nature of the surgery: for cutaneous operations, he gives Ancef, for mucosal, Unasyn, and in the cases of chronic wounds, culture-directed antibiotics. His hemoglobin transfusion target is 7.5-8.
[Dr. Gopi Shah]
Intra-op, tell me the sequence of, and may vary, maybe case to case or what your day is like, but in terms of the harvest, and then when you come back to put the flap in. Tell me about that. How do you harvest or prepare the donor site and are you able to do it at the same time that ablation is happening or do you wait until they're done, or?
[Dr. Eli Gordin]
Depends on the case. If it's thigh flap cases, generally you can do the vast majority of the harvest without committing to the size of the actual skin paddle. That's more difficult to do with forearm and fibula cases. Usually, we want to make the reconstruction no larger than it has to be because they end up having a skin graft in those donor site locations when it comes to forearm and fibula. Usually, for those two locations, I'll wait until the resection is done, but then they still usually have a neck or two to do and we can get the harvest done while we're waiting for frozens and waiting for them to complete the neck dissections.
For thigh reconstructions, I'll just start pretty much immediately unless I have something else going on in a different room. For scapula, it's challenging to simultaneously work, any of the subscapular system like lat or serratus or scapula, because the arm has to be up and extended. You can do it, but everybody is uncomfortable. I usually just wait until they're completely done to start doing any of those subscapular system flaps.
…
[Dr. Eli Gordin]
For the entire case, we try to stay below 5 liters of crystalloid for the entire case. Not specific to the harvest but part of our time out when we're discussing antibiotics. Usually, we're doing just Ancef for cutaneous cases and we're doing Unasyn for mucosal cases. Then if it's some sort of chronic wound situation, we might be doing something different based on cultures. As far as pressors, some people are pretty adamant that they don't want to use pressors on any free flap cases.
From my perspective, I think there's sufficient evidence. There's not that much evidence for most things in microvascular reconstruction, but for pressors, it seems like there are a decent number of studies at this point, including meta-analyses that show that using pressors at normal, reasonable doses do not adversely affect the flap outcomes. I just tell anesthesia, "Look, we need to use pressors." If the patient is euvolemic and they're still not maintaining adequate blood pressure, then I'd rather that they give them some pressors as opposed to start flooding them with fluids.
For blood transfusions, we usually use around eight as a cutoff. There is a little bit of a upper limit to what you want the hemoglobin to be, just theoretically speaking in terms of blood viscosity. If you're going to be transfusing, it's not like we would intentionally blood-let a patient to get them below nine. Unless there's some sort of medical reason to transfuse them, we certainly wouldn't do it for anything that's above nine just because of viscosity issue and therefore flow.
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Securing the Microvascular Anastomoses
The “critical portion” of any free flap surgery comes when the vascular anastomoses are made. Whether to begin with the venous or arterial anastomosis is up to the surgeon. Rinsing vessels with heparinized saline prior to securing anastomoses reduces the risk of thrombosis. If affected vessels are small or spasming, papaverine, a phosphodiesterase inhibitor, is a helpful adjunct. Dr. Gordin usually makes the venous anastomoses by utilizing a coupler so that he can remove the arterial clamp sooner. Though patient anatomy ultimately determines the surgical plan, he prefers to have multiple veins draining the flap when possible. He then sews the arterial anastomosis using a 9-0 silk suture with a curved taper needle.
[Dr. Gopi Shah]
Let's talk about when you're under the microscope. Do you do the artery first and then the veins? Does it matter which one you do?
[Dr. Eli Gordin]
It doesn't really matter which one you do. I usually end up doing the veins first just because-- There's not really any reason. It’s just my custom, I guess, to some extent, you have to have the clamp on the artery a little bit longer, if you do the artery first. It's nice, in my mind, to have the clamp on for as little time as possible just so it maybe causes slightly less injury to the vessel. It really just depends on how the vessels are lying, and which is more superficial, and which is more deep, and what seems like it'll just be easier to access and do first. That's really the main determining factor…
[Dr. Ashley Agan]
Do you have a strong preference for having more than one vein? Do you usually have multiple?
[Dr. Eli Gordin]
Yes, I do all the veins that are there. I acknowledge the fact that you probably only need one vein and it maybe does not add anything. That being said, I did have a situation years ago where there was a flap that ended up getting congested, like late postoperative course, post-op day 9 or 10 or something like that. We took her to the OR. The veins were thrombosed. We ended up taking down one of them and we flushed TPA through it. We managed to get it going.
I can't remember, but I remember being happy about the fact that I had two veins and the one I ended up just sacrificing at that point. That was one situation that ever happened that actually felt beneficial to have two veins. I'm not saying that it's really something that you need to do. Plenty of people just routinely do one vein, but my feeling is that it takes five minutes to put a coupler on, so I just couple all the veins.
There are times when there've been three veins in a fibula and I've just coupled all three because it's just easy to do and I just sleep a little better at night. Then there's also a contrary school of thought that's like, "Well, if you only do one, then the flow is higher through the veins, therefore you're less likely to get thrombosis because you have a higher rate of flow through the vein. I don't know. It probably doesn't matter, but I just do two.
The Importance of Flap Checks
Post-operative management of free flap patients focuses on risk mitigation and early identification of thrombosis. Most institutions have a standardized free flap protocol that outlines the management of these patients. In general, following surgery, all patients spend 72 hours in the surgical ICU, where nursing performs flap checks once an hour. Each check assesses skin color, edema, temperature, and Doppler signal. If any of these parameters are abnormal, the next step is to scratch the flap with a needle. A flap that fails to bleed is ischemic, suggesting arterial thrombosis. A flap that bleeds progressively darker red blood suggests venous thrombosis. In either case, nursing staff should notify the on-call team immediately, as OR take back is warranted.
[Dr. Eli Gordin]
We're trying to create a document that's both tells people what happens on each day, post-operative day, and things to look out for when preparing for a case and pre-op preparations and things like that. Then also filling in the rationale behind different things and all kinds of stuff like who might be appropriate to decannulate and how you decide if somebody is maybe ready to start PO intake or capping their trach or whatever. There's just a lot of background information in there too. It's not all just day-to-day do this at this point in time.
As far as flap checks, we do Q1 hours for almost 72 hours. We have them go to the ICU. We don't have an intermediate or a step-down unit, unfortunately. Q1 hour checks can't be done on the floor. They can do Q4 hour, I believe is the most frequent checks that they can do…
[Dr. Ashley Agan]
What does that entail, Eli? Is that just them Dopplering the stitch, or what are you asking?
[Dr. Gopi Shah]
They document the color, the warmth?
[Dr. Eli Gordin]
Everything. As long as it's visible, then flap check entails looking at the flap. Does the color look normal? It should just look like normal, healthy skin. Unfortunately, a lot of times the flap is more pale than the surrounding tissue, especially when it's coming from the leg and it's going to the face or the thigh. It's pretty pale relative to the face. It's always going to look pale relative to the surrounding tissue, but it's really more of a change than anything else. Whether it looks pale, extra pale, whether it starts looking purple, which might be a sign of congestion—
Edema, like I mentioned, is pretty normal and flaps, especially perforator-based flaps, they tend to get pretty edematous slowly over the course of the first three days. That's the peak I think is around day three. Then it starts slowly tapering off again, but a sudden change in flap edema or swelling that might signify hematoma under the flap or hematoma in the neck or wherever else.
The temperature is not the easiest thing to assess. A lot of time the flap does feel more cool relative to the surrounding skin, but you palpate it. You feel the temperature, you feel the general turgor or just how tight it feels. It again should feel pretty normal, but it does get swollen. Then the Doppler check. Usually, we have some degree of donor site extremity checks too. Just doing the same thing with the hand. If it's a forearm, just look at the hand, and especially thumb and forefinger, which are the distal most in the circulation.
If you're getting your circulation from your ulnar artery now and you have no radial artery, making sure that the cap refill and sensation and motor are all intact on the donor site, and there's no evidence of compartment syndrome developing. Then if there's any concern, then they call our resident team, and then the residents would assess. If they agree that there's something questionable on the flap check, then the next step is to scratch it or stick it with a needle, depending on your preference.
Usually I take a scalpel and just make a tiny little, paper cut depth thing, just through the epidermis and barely into the dermis. Not anything that needs to be sutured up, but just a little-- Literally, it looks like a paper cut. I just find that easier to ascertain whether or not there's blood return than if you stick it with a little needle, then you look at the blood, and if it's not bleeding, then obviously that's concerning for ischemia. If it's bleeding real dark red blood that comes out extremely quickly, then that's concerning for venous congestion because you have backflow of blood into the flap. Then there's everything in between, which is usually where it is. Then you're trying to figure out what you should do at that point.
Returning to the OR
Dr. Gordin advises returning to the OR if there is any concern whatsoever for flap viability. Once the affected area is opened up, surgeons can assess for clots using hand-held Doppler or the “strip test.” When a clot is detected, it should be removed and the vessel repaired. Potential causes of thrombosis include technical (suturing) errors and unidentified hypercoagulable states. Regardless of the cause, compromised flaps must be caught early due to the “no-reflow phenomenon,” a point after which ischemia causes irreversible microcirculatory damage. This tends to occur after six hours for skin, and faster for muscle or viscera.
[Dr. Ashley Agan]
When you're going to the OR to troubleshoot, what does that look like? Are you taking down your anastomosis? Can you get an idea of how it's doing just by looking at it or I’m Dopplering it? What does it look when you're doing that OR take back?
[Dr. Eli Gordin]
You can get a sense of how it looks like. If you open the neck and it looks normal, after you've been doing it for a little while, you can get a sense for what a normal artery looks like. If there's a clot, usually, there's a bit of a discoloration, a purpleness. Arteries are usually white light pink shade. It gets a discoloration usually when there's a clot in there but depending on the wall thickness of the artery, you may or may not see that.
Certainly, you would see when you have a pedicle, and it's flowing properly, especially in cases where it's geometrically curving or looping on itself, you don't want to have it kinked, but sometimes we create a gentle curvature in the pedicle, so that it's going to where it needs to go, but not kinking, but then the whole thing expanding as it pulsates. It's not just rocking back and forth, which is more indicative of there being some obstruction and you're just getting a transmitted pulsation appearing thing from the fact that it's attached to a vessel that at some point does have some flow in it until that flow hits the obstruction.
You can just look and see whether or not it's expanding. You can Doppler it. If the neck is open, then you're able to lift the pedicle up and Doppler it with air underneath it such that you're not potentially picking up the signal of a deeper artery, which you can if you're just Dopplering it while it's flat against the neck. For the vein, likewise, you can probably more easily tell when there's a clot inside a vein because it's a thinner-walled structure, and then you can palpate a vein a little bit more easily. You take your little micro jeweler forceps and you can palpate artery, palpate vein. You can feel when there's a clot in there, especially for the vein it's pretty obvious most of the time.
You can do what's called a strip test, where you take two jewelers and you just gently you hold. For the vein you would be holding towards the flap upstream of where the venous drainage is coming from and then you milk with the other pickup. You draw your hand down towards the anastomosis and then you let go of the first one. You try and see whether or not there's venous blood passing through that area.
Then if you're not sure, then you have to take it down or cut a side branch. Sometimes there's little side branches that you clipped when you're doing the harvest, and then sometimes you can cut one on the artery and see whether or not there's brisk blood pulsatile arterial blood shooting out of the side branch or likewise with the vein and look for appropriate venous bleeding, but again, if you can't tell or you're not sure then the next step is you just have to take it down.
Unless it's a very late failure from venous thrombosis in which case the entire thing is clotted off, usually it's one or the other. In my experience, it's most commonly been the artery. Unless it's a late complication because of fistula or infection that affects everything, then you don't necessarily have to take down the vein. You might just take down the artery and the clot is going to be right at the anastomosis.
Unless there was some injury to the vessel downstream of the anastomosis, it's pretty much right there, so you just cut right next to your suture line or through your suture line you can just see the clot, pull it out, and then try and figure out why the clot happens because that's really the next step. Are we going to be able to salvage this? How long has it been? How long do we think it's been since we really detected the ischemia and what we need to change? Why did this happen? Is it a patient intrinsic factor? Do they have some hypercoagulable state that we missed or was it a technical error, which is oftentimes, especially early in your career is usually what it is.
Podcast Contributors
Dr. Eli Gordin
Dr. Eli Gordin is an otolaryngologist, head and neck surgeon, facial plastic surgeon, and assistant professor with the department of otolaryngology at UT Southwestern in Dallas, Texas.
Dr. Ashley Agan
Dr. Ashley Agan is a practicing ENT and assistant professor at UT Southwestern Medical Center in Dallas, TX.
Dr. Gopi Shah
Dr. Gopi Shah is a practicing ENT at UT Southwestern Medical Center in Dallas, TX.
Cite This Podcast
BackTable, LLC (Producer). (2023, September 12). Ep. 128 – Free Flaps 101 [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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