Category: skunk works

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bypass complications graft infection mycotic aneurysm open aneurysm surgery peripheral aneurysm pseudoaneurysm skunk works techniques

EIA pulldown transposition: another way to treat infected common femoral pseudoaneurysm

Patient with infected femoral pseudoaneurysm, skin necrosis, about to blow

A surgeon from Nepal posted a case of a ruptured common femoral pseudoaneurysm infected from IV drug abuse on LinkedIn. The comments centered around typical textbook responses which were:

  1. Ligate, debride, obturator bypass
  2. In situ bypass with femoral vein +/- sartorius flap
  3. Rifampin soaked graft or crypreserved allograft
  4. Ligate only

My preferred treatment is #2, in-situ bypass with harvest of adjacent deep femoral vein. I never liked that procedure because in general in these patients, everything bleeds. Then I had a thought -how about if you mobilize the external iliac artery in the pelvis over its entire length and pull it out from under the inguinal ligament to sew to the femoral bifurcation or SFA? That is, when you enter the pelvic retroperitoneum to gain proximal control:

The external iliac artery is usually redundant and elastic in young people

You mobilize the external iliac artery from the iliac bifurcation to the inguinal ligament, detaching the inferior epigastrics as a last step. And then you pull it out from under the inguinal ligament, and anastomose it to the femoral bifurcation or the SFA.

The mobilized external iliac artery is pulled down to reach normal femoral artery. The distance x is the length of CFA that needs replacing

This makes sense because in young people and those with AAA and minimal atherosclerosis, the external iliac artery is both redundant and elastic, making it suitable for a pull down transposition. But then, how do you know as you mobilize the artery in the pelvis that you have enough to pull down?

Pythagoras figured that out two an a half millenia ago. If you measure the straight line distance from iliac bifurcation to the takeoff of the inferior epigastric arteries, you get the straight line external iliac artery distance. The length of the common femoral artery which is the excess EIA length needed, is assigned the value x. Then the height of the stretched artery off the line between the iliac bifurcation and the inguinal ligament will determine how much extra artery you have.

Taking these values, I did some maths.

The solution for h, the height, is highlighted in yellow below. (note, the variable x in my notes is half the length of CFA, l is half the length of EIA, ie. 2x is CFA length).

Creating a spreadsheet for CFA lengths from 2 to 6cm and EIA straight distances of 5-10cm, the ratio of height H to CFA length varies from a minimum of 0.7 to maximum of 1.7 with an average of 1.1. That means the majority of the time, if you get 1.5x the length of CFA height off the pelvis, you should reach.

If you are short, you can detach the profunda and mobilize the SFA, pulling upwards, then reattach the PFA. Though this is entirely a thought experiment, there is no reason why it should not work. As with most things, I predict that it already has been done!

The advantages are using autologous tissues and leveraging the natural anatomy. There is a cost benefit in that OR time is shorter with less time for venous harvest and avoiding grafts, patches, and devices. The patient would avoid ischemia as would happen in the staged repair. The disadvantage is when you are short, but if you mobilize the appropriate amount (height off pelvis at least 1.5x the CFA length) you should be okay. The more curvature and tortuosity seen on 3DVR recontstruction and absence of significant atherosclerosis would predict feasibility.

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Commentary cost innovation ECMO opinion skunk works techniques type b aortic dissection ultrasound vascular lab visceral malperfusion

5 innovations, 4 years and how cost innovation must save healthcare

At CCAD, during my 4 years here as chief of vascular surgery, I had the privilege of working with excellent colleagues in a world class facility in an amazing and generous host nation. Over that time, our operative case volumes grew rapidly (figure below) as we proved our worth.

Our unique situation as both a main campus of Cleveland Clinic and a startup in 2015 with a fraction of the systems already in place at Cleveland made innovation a necessity. When making do became making great, we achieved the world class results as we were tasked to do. I count 5 off the top off my head in vascular, but there are many more that we do every day, contributed by all the team members. It is in the Cleveland Clinic’s DNA, from its origins century ago in the vasty fields of wartime France, this systemic mission to make things better. I think a lot of how our founders worked from necessity near the trenches in operating theaters within tents, sleeping on rough cots, thousands of miles from Cleveland. It is working in a startup hospital here, a stunning facility endowed by the Emirate of Abu Dhabi, that I realized that practical innovations were the lifeblood of hospitals in times past, and that it continues to have meaning when lives are saved. In a world where costs, not ideas, will, or skills, limit the availability of healthcare, cost innovation will play a large role in its salvation.

Innovation #1: Debranching Thoracoabdominal Aortic Aneurysm

The thoracoabdominal aortic aneurysm (TAAA) is the most challenging operation to do either with open or endovascular approaches because of the complications associated with the procedure including bleeding, kidney failure, spinal cord ischemia, and death. You really can only get good by doing a lot of these regularly, as it brings with it precious experience for the OR, ICU, rehab, and floor staff. The patients with TAAA presenting to CCAD do not always have the opportunity to travel to one of the acknowledged aortic centers (with which each of the faculty here have close ties), and we must offer results that match those other centers. To me, the biggest hassle and source of complication with an open TAAA repair is the drying up of bleeding at the end of the case, the result of long visceral clamp times. Long procedure time prolongs the case and exposes the patient to a more turbulent and prolonged recovery and higher risk.

Endovascular repair with branched or fenestrated stent grafts offers one solution in avoiding the thoracoabdominal exposure and long procedure times. Unfortunately, a significant minority of patients do not have the anatomy for endovascular approaches. We have the skills, staffing, and facilities to offer both approaches, but are handicapped by low volume. Review of our volumes show that aortic aneurysm disease is dwarfed by diabetic circulatory problems. So to offer these patients the same results with open aortic surgery as the patients I had at main campus in Cleveland, I had to cheat a bit by rearranging the deck. How so? By turning the highwire act of thoracoabdominal aortic aneurysm surgery and turning into a deliberate walk on a low balance beam. By debranching the visceral branches from the graft one by one, the visceral ischemia time is minimized (video) or largely eliminated.

I discussed this with Dr. Niranjen Hiremath, our aortic trained clinical associate and like all things in medicine, a similar concept was applied by his mentor, Dr. Matalanis in Australia, to the aortic arch. We have performed two of these and both patients survived and are doing well, including the most recent one with a hybrid extant 2 repair. We published the technique after the first case in Journal of Thoracic and Cardiovascular Surgery (figure below, reference 1). I also presented the first case on this blog (link). More gratifying are the reports of adoption of this technique around the world. The patients come out of the operation without the torrent of coagulopathic bleeding seen with the traditional technique.

Innovation #2, The Vascular Lab in Every Patient’s Room

One of the things that happened early in my tenure was realizing how limited the tools available for vascular assessment were for non vascular caregivers. Both the physical examination with pulse palpation and pulse Doppler examination are challenging to master and usually fail to answer the simple question: is there enough perfusion? The absence of a pulse or Doppler signal in the hands of a non-vascular caregiver is an inconstant thing, and various projects have been undertaken that do not specifically address the triage gap that vascular surgery has compared to cardiology for chest pain. Not all chest pains are referred to cardiology. Only those those patients who pass the screening test of EKG and serum troponin levels are referred. My first inclination was to budget for pulse volume recording machines to be located in the ED and ICU’s of the hospital, but it was not a simple solution and would require stretching the limited vascular lab staff. Then it dawned on me that the toe waveforms offered a solution. On the PVR machines, the toe waveforms are captured by transmitting red laser light through the nail of the toe. A receptor captures a waveform (figure below) that is reflects the passage of blood that absorbs that red light.

This is in fact the identical technology in a pulse oximeter which has extra circuitry to calculate an oxygen saturation. I was not interested in the saturation, but rather the waveform. It turns out, for all practical purposes, the waveform given by pulse oximeter units is qualitatively the same as that given by the pulse volume recorder’s digital plethysmograph (figure below).

So now, when I get a phone call from the ED that a patient has no DP or PT pulse, I ask the caller to place a pulse oximeter with a waveform trace on the patient’s second toe (or nearest extant toe). I then ask, is there a waveform? The presence of a waveform, no matter how dampened, means the patient does not face acute ischemia, and can safely wait until the morning, avoiding a drive in the middle of the night (figure below, severely dampened waveforms).

an abnormal DPPG captured with a hospital ICU pulse oximeter

We are validating this with a study that has completed data collection and hope to present this simple test to a broad audience. This is something akin to having a point of care vascular lab study that can answer a simple question: is there blood flow at the level of the toes? The finer points of “how much blood flow” can be answered by formal testing but that keen absence of broad vascular assessment skills among healthcare providers and absence of a simple test like an EKG for MI will feel less sharp, particularly because of the near universal availability of a pulse oximeter with waveform display throughout most hospitals.

Innovation #3: Assessing for Visceral Malperfusion before Surgery for Aortic Dissection

The typical scenario for a sad ending is this: a patient undergoes emergency surgery for an ascending aortic dissection. The operation ends in the middle of the night. The morning labs show a lactate of 10 which had been rising since the end of the operation from a high borderline level of 2. The urine output also dropped to zero. The patient remains intubated and has palpable femoral pulses, but now has a distended abdomen full of bowel gas, and is unable to report pain. The decision is made to get a CTA on top of the ones the patient received preoperatively which nearly guarantees permanent renal failure and need for hemodialysis. The descending aortic portion of the dissection is noted to be causing a malperfusion of the SMA and left renal artery, and there is pneumatosis of the small bowel through transverse colon which are resected after revascularization. The patient recovers with a jejunostopy and lifelong TPN and hemodialysis. This sad scenario is what I thought about when I was asked to assess a patient intraoperatively without a femoral pulses after an aortic dissection for possible visceral malperfusion. The question was if CT with contrast was indicated. Having an RVT credential (I’m old), I frequently do my own scans, and have found under general anesthesia, the abdomen is easy to scan well. The patient is typically prepped from neck to toes for the operation, so sliding in with an abdominal probe was simple. It is possible to get excellent windows on the visceral segment abdominal aorta with long axis and short axis views of the celiac axis, SMA, renal arteries, and iiac and lower extremity arteries (figure below).

At CCAD, the patients also get a TEE, and the arch and descending thoracic aorta is well visualized. That first patient underwent a femorofemoral bypass for the lower extremity malperfusion, and I found that the left renal artery had obstruction, but the right did not. The patient was reassessed at the end of the case and good visceral perfusion was seen at that point. I realized I was onto something, and whenever possible now for ascending aortic dissections, myself or the vascular tech is called to evaluate the visceral and lower extremity arteries at the beginning of the case, avoiding contrast studies. We are submitting the experience as an abstract for the STS conference.

Innovation #4: Retrograde tibial artery distal perfusion cannulas for ECMO

This past year, ECMO has been lifesaving for many patients facing cardiovascular collapse from COVID and other conditions. Once the cannulas go in, a hypoxic patient in heart failure has a chance at recovery. The drama of the moment causes the caregivers to overlook the fact that up to 10 percent of patients without a distal perfusion cannula will develop leg ischemia, and that after 6 hours, irreversible will occur leading in neuromuscular death and limb loss. This has happened for two patients transferred for care this year. The problem is that the skill of placing a antegrade femoral artery distal perfusion cannula in the proximal thigh is not always present, and the ability to judge perfusion is degraded with ECMO flow. While older patients on ECMO may have significant arterial disease, young patients generally do not, and I saw that as an opportunity for simplifying the distal perfusion cannula by placing a 5F micropuncture sheath into the dorsalis pedis artery (figure below).

The distal perfusion cannula is in the dorsalis pedis artery

This provided sufficient flow to avoid limb loss in a series of patients on which we published a technical article (reference 2) and presented. The retrograde access of these supericial vessels is within the technical envelope of most intensivists and cardiologists, those who most frequently place emergency ECMO cannulae. It was gratifying to catch up with one of my first patients who walked in with both legs, having undergone a heart transplant while bridged with ECMO.

Innovation #5: Park Clamp Used in Thoracoscopic and Laparoscopic Surgery

The Park Clamp (link) is a circular compressor that is intended to compress bleeding tissues allowing for suturing within the circle. I invented this while at main campus, and missing it sorely, had two custom made at the prototyping facility at Cleveland Clinic and shipped into CCAD. It is particularly useful in venous bleeding during spinal exposures, redo groins around the profunda, and retroperitoneal tumor resection. Dr. Redha Souilamas, chief of thoracic surgery (image above) found it particularly useful in thoracoscopic pneumonectomies, when staple line bleeding is encountered on the pulmonary artery (image below).

Pulmonary artery staple line bleeding controlled, ready for suturing.

In laparoscopic surgery, it is possible to introduce the compressor via a small incision and this will allow for laparoscopic suturing of a vascular injury in a bloodless field. I was able to resect an IVC tumor thrombus with Dr. Waleed Hassen using this device to achieve hemostasis. The critical feature of the Park Clamp, lacking a manufacturer, is that we made it ourselves in our own hospital.

Conclusion: a modest proposal or how cost innovation will save health care

Inventions and innovations exist in a vacuum unless they are implemented, and this requires the will to accept the possibility of a better way. You should never be satisfied with the status quo if there is harm to be reduced. There has to be buy in from everyone involved or you get the situation I had when I was a PGY-2 in 1995 in the ICU. Being the surgical ICU resident, I was called nearly hourly to change the dressing on a patient with HIV and necrotizing pancreatitis with an open abdomen. There was over a liter an hour of exudate soaking the dressings and pads, making it a nightmare for the nurses. After a third round of this and feeling it would interrupt lunch, I came upon a plan for covering the wound with lap pads, overlaying a chest tube, and sealing everything with an Ioban. With the chest tube to negative pressure via a Pleuravac, the calls to change the patient’s dressing ceased, and the nurses no longer hand to change the bedding hourly -bedding that was soaked with HIV positive exudate. I was very pleased about this until I was stat called to the director’s office. I was given the dressing down of my life -how dare I experiment on his patient and didn’t I think that placing a suction on the transverse colon would result in a fistula? I hung my head in shame and took down the dressing. Of course, readers will know that this preceded the VAC dressing by about a decade, and negative pressure wound therapy is now a multi-billion dollar industry. What it teaches me to this day is that progress only happens when success is actually seen by everyone, but also there has to be buy-in from the stakeholders -the people who bear responsibility for any bad outcomes -fistula and death in the case of this proto-VAC dressing. Without convincing everyone, there is no success, and the invention goes off to die.

The fact is, one time early in my tenure here at CCAD, we ran out of negative pressure pumps, and I placed this chest tube/Pleurevac dressing on a patient with a large groin wound that was leaking high volumes of exudate and lymph. After two days, when a VAC pump became available, the patient’s groin turned out to be clean and granulating and it came to me that the next great leap in innovation is low cost innovation.

Cost Innovation, to name it, is using what is available, sometimes repurposing, or at others, dialing back the clock, to replace costly things that threaten to break a hospital’s finances while maintaining quality. It was only a few generations ago when hospitals were self contained communities. Rather than use peel packs of disposable gowns and drapes, there were tailors, seamstresses, and launderers making and maintaining the same. The Mayo Clinic was making its own insulin after discovering it and gave away the recipe out of concern for ethics -out of believing it is wrong to profit from a life threatening condition. We have the technology and capacity to make low cost endoscopes and reprocess them -possibly undercutting current costs by a factor of a thousand. We slaughter millions of hogs and cows annually, but harvest no heparin from them in the US. Laser CNC cutters, 3D printers, and enthusiastic makers have proliferated and could make every item that we currently open from a peel pack, use once, and discard into landfills -one only has to look at the cottage industry of face shields and hand sanitizers that bloomed last year during the pandemic. Pharmacists are fully capable and trained to manufacture custom pills and compound salves and solutions by the gallons if only if they are allowed to, saving hospitals millions in cost of medications sold in blister packs and tiny tubes and bottles. Stents can be printed in-house, and stent grafts can be custom made (link). Every town or city has tradespeople who can work stainless steel, plastic, and glass, or make and program custom computers -it is a short jump to making medical equipment at scale in your hospital.

Cost innovation is the only way out for the inflationary cost cycle that has throttled healthcare throughout the world. We have become a world where healthcare is delivered out of peel packs and million dollar investments to perform single procedures is considered normal and desirable, almost to the point of thinking people as coming in disposable peel packs. When I watch shows about hospitals a century ago, such as The Knick, I don’t guffaw at the old-timey medical stuff. I see a fervent environment of innovation in purposeful communities of specialized workers within hospital walls. We need to return to such practicality if we are to break out of the plastic peel pack.

References

  1. Hiremath N, Younes H, Aleinati T, Park WM. Open repair of extent-III thoracoabdominal aortic aneurysm using a modified branch-first technique. JTCVS Tech. 2021 Mar 13;7:29-31. doi: 10.1016/j.xjtc.2021.03.014. PMID: 34318197; PMCID: PMC8312144.
  2. Göbölös L, Hogan M, Kakar V, Raposo N, Sänger S, Bhatnagar G, Park WM. Alternative option for limb reperfusion cannula placement for percutaneous femoral veno-arterial ECMO. Perfusion. 2021 Mar 26:2676591211003282. doi: 10.1177/02676591211003282. Epub ahead of print. PMID: 33765883.
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skunk works techniques Technology Uncategorized

Distraction free writing used to be the norm with technology

IMG_0645

Distraction Free Writing: Portable, Disconnected, AA Battery Powered

Distraction free writing has been a buzzword. It used to be the norm with computers by their limitations and design to focus you on writing. Today, technology is increasingly put in front of you to entertain and distract. The problem for students and writers is that your computer and phone are gateways to music, video, and communication in ways that were only dreams twenty years ago. The key elements of distraction free writing are a decent keyboard, extended battery life, simple interfaces, lack of connectivity, and   absence of party line operators. Each of these elements formed the core of our computers back in the 1980’s, when computers were rarely networked, they were all monochrome, and your words were all that you saw. This desire is driving the market for distraction free writing software and hardware, but you can find ways to create your own portable distraction free writing tools without dropping a fortune. And distraction-free writing is also intrusion-free -something to consider in today’s shifting privacy boundaries. At the end, the best distraction free options may be in reconsidering decades old devices that may be picked up cheaply used or at greatly reduced prices for new. Most current devices are made to last about a thousand recharges, and struggle with purposeful obsolescence. You may find that there are many fine older options that will suit your writing needs while greatly increasing your productivity while avoiding costs.

Consider the keyboards we had back in 1985. They were all mechanical spring keyboards which made a nice click sound. Writing was a tactile pleasure. This was in contrast to the membrane based keys seen on games and toys, and mistakes like the PCjr. You see them today as controls for microwave ovens. The moving keys send a message of accomplishment to your brain. Despite this, flat keyboards with no physical component  are still being thrown up to see if they would stick. The smartphone keyboard on the first iPhone killed the physical ones on Blackberry and the Treo’s after all. Manufacturers are still experimenting with flat keyboards such as on the latest Yoga Book’s e-ink keyboard, and the upcoming Microsoft Surface Duo devices.

IMG_0649
flat screen based keys like on the latest Yoga Book takes some getting used to

These software and touch display based keyboards rely on spelling correction and ultimately constant connectivity to minimize error. The push for ultra-portability means dispensing with the original mechanical keyboard which was descended from electric typewriters like the IBM Selectric. This resulted in the terribly mushy, mass produced keyboards introduced in the 1990’s, getting ever worse. The high point of this design viewpoint was introduced in the 2015 MacBook and recently retired in the 2019 Macbook Pro when Apple realized everyone hated typing on superflat keys meant to accommodate flatness over functionality. There is a welcome movement back to reasonable keyboards. I would even claim that the persistent life and value of the Thinkpad line is the focus on the keyboard that remains preserved after IBM sold it to Lenovo. The new-old keyboard on the 2019 MacBook Pro 16’s are a concession to the realization that typing is a core function of these machines.

There is a push back as writers, office workers, and gamers have created a market for mechanical keyboards. These are usually Bluetooth connected devices, and typically paired to tablets for writing. Unfortunately, separate keyboards connected to tablets are not as portable as a laptop.

QWERKYwriter is a retro mechanical keyboard for tablets but try taking that onto an airplane

I would argue that laptops are not as portable as they could be. The Freewrite (link) was designed with writers in mind as an update to electric typewriters with cloudbased file management and an e-ink display with days of battery life on a single charge. I almost bought one but the small display and the relatively bulky size kept me from springing. I have ordered a Freewrite Traveler (link) which is their mini-laptop version, but since I ordered one last spring, it has remained vaporware with its delivery date pushed back from summer 2019 to spring 2020.

Battery life is a sore point for me. Laptops are now expected to be wonderful if they exceed 8 hours of battery life, but I remember that the original portable computers like the Radio Shack 100 series could go days on AA batteries. Writing appliances were introduced in the 80’s including electric typewriters with single line LCD displays and single file memory which would allow you to compose and edit. I had such a device from Japan in high school that had a four line LCD display, built in thermoelectric (fax paper) printer, and battery life that went several days on 4 AA batteries.

By using computers and smartphones, which function as portable televisions and multi-function, shopping kiosks which use Watts of power, the trade off is battery life and constantly worrying about plugging in for a recharge. We forgot the days of battery life and are happy with 8 hours. The battery power bar is terribly distracting for me and I tend to stop working to find an outlet to recharge when it inevitably drops and when my productivity is nearly always highest. If I’m traveling, this means carrying the power brick, another injury to this one who remembers AA battery powered writing tools.

In 2017, the Samsung Galaxy Note 7 was famously recalled after spontaneously combusting and were banned from airplanes. All Lithium batteries must now be hand carried. Just recently, I was told while checking in that Apple Macbooks could not be turned on during flight because of heating issues. This is a consequence of the greatly increased energy densities of Lithium cells and their chemical volatility. AA batteries and their nickel metal hydride (NiMH) rechargeable variants suffer from no such problem.

Even with great battery life, you have to remember most of that power, and therefore bulk and weight of the Lithium batteries is devoted to painting vivid colors on the screen, communicating via radio signal to the world, and keeping dozens of apps updated on your activities, and not to writing.

The Lithium battery which can power a car because of its energy density is overkill if all you want is to write. The modern computer operating systems, Windows, MacOS, iOS, and Android, are all over-powered for the simple act of preserving words. Consider the lowly text file to a modern Word file. The text file for a novel might take kilobytes of memory, but the same Office Word file is measured in megabytes -thousands of times bigger. Try emailing a fully formatted Word file through your corporate firewalls if it exceeds your company’s limits on attachment file sizes. The size and complexity of information that is exchanged burns power. Compare that to the notes you might write onto paper. The few microcalories used to power your neurons and move pencil on paper, the motor and optics circuitry processing the information at a speed suitable for your ape brain.

My friend and early mentor, Professor David Tilson, refused to relinquish his DOS based word processor even well into the Windows era. And I understood. The monochrome and monotype letters forced you to look at the words and not the style of the words. While I admire Steve Jobs, and his introduction of fonts to our everyday lives, the ability to shape the look of your writing intrudes on its composition. Monochrome does not mean monotonous, and modern distraction-free software efforts like IA Writer embrace simplicity. The emergence of dark mode is another effort at rolling back the clock. When you enable it for your iPhone, it reaffirms the utility and critical need for focus and simplicity. Do you need millions of colors or just letters on a simple background? While you can change the color setting of your laptop screen or your writing software, the ultimate in monochrome experience is an e-ink display.

The e-ink display is what you see on Amazon Kindles. Originally meant for low power usage, high contrast functions like in store signs, e-Ink is currently used for e-Readers, although there is a niche market for e-ink based displays and tablets which do offer the low power hi contrast display perfect for a focused writing work station – you can find them on Amazon and eBay. Unfortunately, because these e-Ink tablets are run typically on Android, there is no escaping the internet on these, and because they do so, their battery lives are not that much different from standard tablets. What the we need is for Amazon to gift the writers of the world with Bluetooth or wired keyboard functionality to their Kindles and offer a text writer that can be synced to their cloud..

What the we need is for Amazon to gift the writers of the world with bluetooth or wired keyboard functionality to their Kindles and offer a text writer that can be synced to their cloud.

The constant need for connectivity drives software and hardware inefficiency. Writing requires intimacy and privacy. Just as you cannot write while engaged in a shouting match with someone, you cannot write with notifications of arriving messages, pictures, and videos. I cannot write while watching a movie or listening to certain music, but all of these distractions are baked into the function of modern computers and smartphones. This uses up battery life. The devices are in a race to maximize the battery and screen size at the cost of purpose and meaning aside from commerce.

Party line operators were a feature of the early telephone systems. Your locality was serviced by an operator that routed your calls and inevitably your conversations were open to intrusion both intentional and unintentional. When all your work is kept on a cloud server, it really is no different. And it isn’t that hackers that may take all your work. My generation grew up with the Cold War, and its dark tales of thought crimes and writers imprisoned for samizdat -ideas forbidden by a state entity. In a time when your social media is a subject for governmental and not just consumer interest, returning to off line options is something to consider seriously. The meaning of party line operators is in this context wholly changed.

The one feature of cloud based options is the convenience of accessing it across all of your devices. But are you really going to be writing on your iPhone, then on your desktop, then on your laptop, then from an airport kiosk? Your file can be lost during the sync process or changed to a competing version from another computer you were working on. And goodbye work if you get hacked or if your cloud service shuts you down or out. While you write, you have to keep a local version and back up to a nonvolatile storage option.

Not connecting to the internet saves you battery life. It also frees you from taking deep YouTube dives into funny cat videos or answering emails or Facebook posts. The stillness you need to just write is difficult to achieve with a modern laptop, tablet or smartphone. It can be attained with these older devices which people in the know still value decades after they left their boxes. I suggest these options if you are thinking of trying a focused writing appliance (a typewriter!).

Option 1: King Jim Pomera DM100  (link) is best described as a writing appliance designed in Japan adapted for the English speaking market. It is a sleek thin portable that allows one to type words unencumbered by internet. The files on it can be transferred to another computer by Bluetooth, and to smart phones by QR code which is cool. It runs for days on AA batteries, and has a backlit monochrome LCD screen. It is priced on th high end at 392.61, but receives the best rating on Amazon which to me is a 4.5. I never come across 5 star reviews that aren’t fake. One reviewers comment that the keyboard is cramped and takes getting used to. It can be used as a Bluetooth keyboard and stand for iOS devices.

Option 2: Neo 2 Alphasmart Word Processor with Full Size Keyboard,, Calculator

The Alphasmart Neo2 (link) was the last of a line of writing appliances put out by a pair of former Apple engineers who wanted to provide affordable word processing options on a full mechanical keyboard. The Neo2 is the most available and apparently the most usable, allowing one to type out hundreds of pages and transfer to a computer via USB connection. The screen is an LCD screen like on a calculator. The killer feature on this device is nearly forever battery life on AA cells. It has a rabid following of professional writers who appreciate the pared down experience for productive writing. It achieves that perfect 4.5 star rating. This is for a device discontinued in 2007 and sells for about 40-50USD in used condition. Reviewers rave about turning it on and instantly being able to type without bootup, and avoiding distraction by email, notifications, social media etc.

Option 3: Psion Series 5MX

The Psion Series 5MX represented the apex of portable computer design in the late 1990s. It was a computer made from the ground up from circuits, hardware, operating system, and apps by British engineers and it was a thing of beauty. Made in the late 1990’s, this device’s killer features, long battery life via AA cells, ultraportabiity, and lack of easy internet access puts it in a separate class. Not everyone like the keyboard, but I have long been able to type on it without difficulty with average to large sized hands. I had one during residency in the 1990’s and it followed me into fellowship. Before EHR, I composed full consultation notes and H&Ps on it and filed them on my password protected CF drive for later retrieval and update for frequent flyer patients. I picked up a pair of these for about 90USD from the Netherlands, but the going priced varies from about 70 to 200USD for a used one in good condition. New ones pop up but they go for nearly their original price -they are that good. I suspect I got a deal because they were Ericsson MC218, a Swedish licensed clone.

It has a compact flash drive, and with the save as text file function in the built-in word processor which works fast and reliably, it is possible to back up to a nonvolatile memory (the CF drive) and transfer to a regular computer. The one caveat is that the maximum size of CF drive it will see seems to be 128mB -that is megabytes which is hard to find. In certain older industrial machinery, instructions are uploaded via CF cards of these size, and so these cards are available on Amazon. Or look in a drawer for an old unused CF card.

I wrote this post on the Psion, and never once looked at emails, social media, or Youtube.

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I wrote this post on the Psion, and never once looked at emails, social media, or Youtube.

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acute limb ischemia aortoiliac occlusive disease (AIOD) innovation limb salvage PAD skunk works techniques ultrasound

The shunt as temporary bypass -a modest proposal

The rise of cardiopulmonary bypass life support has also given a rise to the need to keep large, obstructive cannulas in femoral arteries. ECMO cannulas are often kept in for days, and it is not uncommon to discover limb ischemia and infarction relatively late. This can be avoided by placing a distal perfusion cannula to shunt blood to the leg early in the ECMO process. The ECMO cannulas have a convenient side port to send a little flow to a 6F sheath placed in the femoral or popliteal artery. This is an established technique (reference 1, sketch below), and it works despite the modest flows achieved because it does not take much to keep the leg alive. These patients are not walking, nor are they need to heal leg wounds, so just enough blood flow means something just a little more than what they get when the common femoral artery is completely occluded by the life support cannulas. What is fascinating to me is that these shunts can pptentially help to save limbs when used as temporary extracorporeal bypasses when definitive vascular surgical care is not immediately available.

brachial to femoral shunt sketch

 

When I was a medical student, I took on a research project after my first year where I had a Langendorff preparation of a rat heart (below).

langendorff prep in MRI
an isolated, perfused, beating rat heart placed in a superconducting magnet for NMR spectra acquisition 

My project was to take a rat heart and keep it alive, beating, and even working, through a perfusion apparatus and place this inside a superconductive magnet to obtain Phosphorus nuclear magnetic resonance spectra -intracellular metabolism data including concentration of ATP, intracellular pH, and ATP/ADP ratio. While the project was successful -I am quite proud to have been the only person at Columbia to have successfully acquired NMR-S data with living beating heart, I moved on to other interests and took away this concept: with oxygenated, glucose enriched, isoosmolar fluid perfused at arterial pressure, any organ can be kept alive, possibly indefinitely, including a brain which only recently others have found possible (reference 2) in reputable scientific circles, but the the Nature publishing Yalies were scooped by the Simpsons decades ago (below), and maybe Mary Shelley centuries before,

simpsons head

This is the simple idea. Revascularization is keeping the target vascular bed alive by delivering oxygenated blood. With a shunt, it could be little, it could be a lot, but it certainly is better than zero, and even a little can buy you time.

The breakthrough that I had was several years ago, a patient arrived from another hospital with an Impella pump which did not have a side port like an ECMO cannula. It is a large catheter that augments cardiac output and in the patient that I was asked to see this patient as their leg was cold and pulseless. Their cardiac output was very poor, and they were sustaining an augmented systolic pressure in the 90’s. There was no way to get this patient to the operating room for a revascularization of any sort. It did strike me that the patient had the misfortune of having catastrophic heart failure in the absence of significant athersclerosis and had normal brachial arteries. After discussing the ramifications with the ICU and family, I placed a brachial artery 5F cannula, and connected it to a 5F sheath I placed in the superficial femoral artery below the occlusive common femoral sheath (figure below). A doppler on the tubing connecting the two cannulas confirmed flow and the patient’s left hand maintained a pulsatile oximetry waveform. The leg pinked up and eventually there was a signal in the foot. This managed to perfuse the leg which did better than the patient who succumbed to multiorgan failure from heart failure. The leg did great.

Which leads me to these thoughts. Most hospitals are good at diagnosing large vessel occlusion via CTA. Most hospitals have doctors who can place arterial lines with ultrasound guidance. In the instance of aortoiliac occlusion or femoral occlusion from thromboemboliem, time is a critical limiting factor to limb salvage. Many hospitals do not have vascular surgeons. Many hospitals transfer these patients with a heparin drip but in the ischemic condition. Transfer arrangements may take hours. Why not ameliorate this situation by having an appropriate physician -an anesthesiologist, an intensivist, an EM physician, place an ultrasound guided radial or brachial arterial line, connect to arterial line tubing to a dorsalis pedis arterial line. Tape it all down on the patient after confirming flow (crude sketch below). This would be better than the three extra hours of ischemia the patient gets hit with on transfer. No one would transport a donor kidney without adequate perfusion and protection, but dying legs get transferred all the time with established warm ischemia. If done well, it might turn an emergency procedure into an urgent, semi-elective one. Have the vascular surgeon video conference in to confirm the absence of blood flow and appropriateness of temporary shunting.

radial to dp shunt
radial artery to dorsalis pedis artery shunt

If we are to live in  a world with less vascular surgeons, then the radius of survival has to be extended with use of technology and simple ideas such as this. Comments are welcome.

Reference
1. Foltan M, Philipp A, Göbölös L, Holzamer A,
Schneckenpointner R, Lehle K, Kornilov I, Schmid C, Lunz D. Quantitative assessment of peripheral limb perfusion using a modified distal arterial cannula in venoarterial ECMO settings. Perfusion. 2019 Mar 13:267659118816934. doi: 10.1177/0267659118816934.

2. Vrselja, Z., Daniele, S. G., Silbereis, J., Talpo, F., Morozov, Y. M., Sousa, A. M. Mario, S., Mihovil, P., Navjot, K., Zhuan, Z. W., Liu, Z., Alkawadri, R., Sinusas, A. J., Latham, S.R., Waxman, S. G., & Sestan, N. (2019). Restoration of brain circulation and cellular functions hours post-mortem. Nature, 568(7752), 336–343.

Categories
AAA EVAR hybrid technique mycotic aneurysm ruptured AAA skunk works techniques training

The Hands of a Surgeon

My partner, Lee Kirksey, Vice-Chair of Vascular Surgery, just got a paper on-line (link) about the curiously increasing volume of open surgical repairs we were experiencing from 2010-2014 at the Cleveland campus of the Cleveland Clinic. When I joined in 2012, my impressions at that time were mostly the paucity of straightforward EVAR cases that I had seen in private practice, and the high prevalence of stent graft explantation, infected aortic grafts, and open aortic aneurysm repairs (OAR) for juxtarenal and thoracoabdominal aortic aneurysms for nominally high risk patients. My TAAA muscles had atrophied during my years out of fellowship and I eagerly took the opportunity to recruit the help of my partners and scrub in on these cases with Pat O’Hara, Jean Kang, Dan Clair, Ezequiel Parodi, and Lee Kirksey. It is without any shame that I sought out not just extra expert hands, but interrogated these experts for different ideas and approaches, and absorbed feedback. At the time, I was ten years removed from graduation, a full-fledged vascular surgeon who thought he could do any operation put before him. I cannot imagine the thoughts churning through the head of a recent graduate faced with the choice of taking on an open aortic operation with only 5 cases under their belt, referring the case on to the regional tertiary center, or trying to McGyver an endovascular solution. I contributed probably about 35-50 cases to this paper, but the outcomes were a collective effort. Even today, I will run cases by Sean Lyden, Christopher Smolock, or Lee, if only for the company and gossip.

“We explain this distribution of cases as a function of several factors: a unique, broad regional quaternary referral practice whereby patients with complex aneurysmal disease are referred to our institution; an institutional practice evolution resulting from a critical analysis and understanding of EVAR failure modes that lead to explantation, thus generating a different perspective in the EVAR vs open decision-making process; a parallel high-risk IDE fenestrated graft study; a historical willingness to accept all physician and self-directed patient referrals (ie, a willingness to manage more complex cases); and a published expertise in the area of EVAR device explantation with an annually growing volume of commercial device removals” -from El-Arousy et al.

Reading through that paper, I have come to the conclusion that the increasing open aortic volumes at the Cleveland campus has as much to do with the ongoing retirement of experienced surgeons regionally as it does with the ability to attract these cases. Loss of these surgeons has a cascade effect like losing a species in an ecosystem. The operating rooms forget where the OMNI retractor is because nobody asks for it anymore. The ICU’s are no longer familiar with the ebb and flow of the postoperative open aortic operation. The floors lose institutional memory of the care of these vascular patients as the stent grafts and interventions go home within 48 hours, sometimes the same day.

If you were a vascular surgeon born before 1970, your approach to the scenario of the ruptured abdominal aortic aneurysm may differ substantially from that of surgeons born after the Carter administration. Most of my cohort, Gen-X and older, feel comfortable applying some betadine, opening the belly and placing a clamp. Those younger than us have told me they feel more comfortable putting up a large balloon and deploying a stent graft. In this generation, it is normal to call a general surgeon to decompress the abdominal compartment syndrome and manage the abdominal vacuum dressing. For our generation, the giant industrial robot arms and 80 inch monitors creates a barrier to the problem at hand, and gathering all the extra staff after hours and on weekends requires the logistical skills of a wedding planner.

We prefer an operating table, a willing anesthesiologist, a cooler full of O-neg blood, Prolene and a graft, strong suction, and an extra set of hands. The data suggests either method is equivalent in outcome, but I would argue that depending on the circumstance, there is an optimal method for that patient and you have to have the ability to do either open or endovascular or some hybrid combination. Unfortunately, it is clear that open vascular surgery is year over year diminishing, and and it might not be so great when we start rupturing our aneurysms.

The open approach is preferred because we got good at it by doing a lot of these cases. Your hands -it becomes natural to change the course of the disease and the fate of the patient with your hands. One of the things you lose with a wire based approach is the tactile feedback from the organ that you are treating. Yes, there is a subtle feedback from the flexible tip of a Glidewire, but that’s missing the point. The thing that is rarely considered with open surgery is the tactile aspects of operating.

Your fingers are your point of care ultrasound. As an intern, one of my earliest tasks was reaching in through a 2cm incision with my index finger, feeling for what I would describe as a rotten shrimp, and delivering it out by hooking my distal phalanx around its base. Adhesions were rubbed like money between finger and thumb to judge if you could bovie through it. If you felt a sliding sensation, it was mucosa to mucosa and you looked for another spot to cut. Into my fellowship which could be called the triple-redo, no-one else wants to do-, difficult vascular operations fellowship, the pulse or the plaque felt under the finger would guide me to carve away scar tissue from blood vessel, visualizing the feedback from the fingers. In a rupture, with the belly under a dark mire of blood, there is no seeing, only feeling. Your hands reach into the lesser sac or transverse mesocolon and strangle the aorta -your fingers while clamping, feel and avoid the caudate lobe, the NG tube in the esophagus, and split the crura of the diaphragm like a pick pocket. Once the pulse returns as anesthesia refills the tank, you scratch free the aorta with your thumb and forefinger, then slide the jaws of the aortic cross clamp over your fingers and against the spine and clamp. This takes about 60 to 90 seconds (link).

When a patient is bleeding out, this is the way to control the bleeding. In practice, no amount of rehearsing for getting a patient into a endovascular suite, getting airway and access, swinging in the industrial robot arm, and getting everyone into lead aprons, sending up wire, placing a 12F sheath and an aortic occlusion balloon, will be satisfactorily smoothly and efficiently as a STEMI or STROKE alert. The rAAA is for most hospitals, unless you are in Seattle, a once in a while occurence. Many more people can find a scalpel and an aortic clamp than they can find a 32 inch aortic balloon, a stiff exchange length wire, and a 12F sheath.

When a patient presents with a slowly bleeding, contained rupture, there is time to assemble the teams required for an endovascular repair, and for opening and decompressing the abdomen, for anesthesia to get IV’s, central lines, arterial lines, and order crossmatched blood. One has the time to get and review CT scans and choose grafts. One can even do things backwards, debranching after securing the leak (link) with a stent graft. The luxury of time should signal to you that the endovascular option is the preferable route, as all the advantages of minimally invasive repair are possible. Rural hospitals sending patients two hours by ambulance or arranging for a helicopter -this is the great filter through which those likely to survive make it into the endovascular suite. These patients do great with EVAR, because everything moves more or less like a routine elective EVAR.

The setting up the operating room for tackling rAAA is quite simple. Keep everything nearby. Nothing should ever be stored out of sight, retrievable only by arcane codes whispered in the ears of people down in the basement or across the street. Amazon gives itself a day to get that gadget to you, but the rupturing patient does not have the time to have a 28mm stent graft ordered by looking up a Lawson number, finding the materials person in the faraway room to find it, running it over a city block. The stuff has to be next to the OR. Every scenario is unique, and the best planning is assuming no one person knows where everything is but everything is close at hand -major vascular sets, retractors, C-arm, cell saver, stent grafts, open grafts, balloons, cardiopulmonary bypass -every gewgaw is few steps away. The inventory is what you see, because if you can’t grab it, it does not help the hemorrhaging patient.

If you are a vascular surgeon born after 1980, it is likely that you may have trained in a 0-5 residency and all the old people harumphing about the old ways seem biased. Rather than being rational about their awful upbringing, the old people seem to suffer from Stockholm Syndrome, turning from victims of a harsh and brutal system inherited from the original, Halsted, a cocaine addict, to willing collaborators now mooning about the good old days of every other day call and 120 hour work weeks.

There might be a growing suspicion about advocating for open surgery when fewer people can perform it. One of the truisms of surgery is if only one surgeon claims to be able to do a rare operation with great results when everyone else abandons it, like venous valve surgery or robot assisted mastectomies, it can mean that surgeon might be uniquely talented or shamelessly selling something. It is a shame that open vascular surgery is devolving into that category of arcana, like the Jedi. I have no doubt that the last open vascular surgeon will be a reclusive, bitter, wild eyed hermit like Luke Skywalker was in episode VIII, if we let it get that far.

Bald eagles were saved from extinction. The methods of species reclamation may be what is needed to save open vascular surgery. Financial metabolism drives behavior, and there must be recognition of the time and dedication required to perform good open vascular surgery in the form of increased RVUs and reimbursement. The surgeons retiring in their mid 60’s with straight backs and steady hands need to be incentivized to stay around and coach the next generation in the ways of the Jedi. Call it the master surgeon designation. Every 0-5 graduate needs to focus on getting 100 leg bypasses, 50 carotid emdarterectomy, and 25 open aortas within the first five years of practice with a master surgeon if they did not get this experience during training. Like dead Jedi, it would help even if they were just virtually present, shimmering on Facetime in their (bath)robes to go over planning and approaches, but being physically present and reimbursed for it would make the most sense.

There is always self service in any human activity. One mildly prominent vascular surgeon that I have come across is famous for saying he did not have a vascular fellowship because he did not want to train his competition. It is easy for the fifty somethings to sit and proffer their open skills and profit from its scarcity but it goes against decency to not pass on this collective body of hard won knowledge and skills. There must be stewardship of this great thing we do, this honorable and treasured endowment.

Of the concrete ways we are trying is creating a network of advanced open surgery capable surgeons regionally organized by Martin Maresch, capitalizing on social media and electronic communications. Here at CCAD we are in the organizing phase of a vascular residency, and I very fortunate to have Houssam Younes join us as he shares my interest in surgical education and open vascular surgery. We are contemplating a non-accredited fellowship. We have general surgery residents coming through our service as well as medical students.

One of my mentors told me, “I can train a monkey to do cardiac surgery,” as he was training me to do cardiac surgery. And he was right. The final comment I have is you have to demystify surgery, take away the Instagram perfection, the romance, and list in practical terms the toolkit of maneuvers that form the component parts of all operations and propagate it. Let us not kid ourselves. The technical skills of surgery can be taught to anyone. The Mayo brothers were performing surgery as teenagers before medical school. The knowledge and experience and judgement -that varies as much as people vary and we have a curriculum for that, but the physical acts of surgery need to be taught starting at the medical school level. Standardized drills and exercises need to be created so that proficiency can be metered.

“The individual per trainee OAR volume did not decrease during this period. In the training program, the use of “component separation” (separation of each
operation into discrete, instructionable steps that facilitates trainee mastery) is integral to instruction of open aortic aneurysm repair techniques and permits the
trainee to master all of the technical exposure and repair skills necessary to address and to manage both straightforward and complex aneurysm anatomy. Component
separation is essential to maximize trainee experience across all levels” –from reference 1

Here is my list of things a trainee must accomplish by the time they graduate from a vascular residency or fellowship.
1. Tying knots with gloves on with 6-0 Prolene inside a pickle jar without lifting or moving a 12 ounce lead fishing weight to which the suture is being tied, fast, one handed, two handed, left and right handed.
2. Holding forceps, needle holders, and clamps
3. Correct operation of the OMNI retractor, Weitlander retractor, Balfour retractor, Thompson retractor
4. Incise skin through dermis through correct depth and length with both #15 and #10 blade
5. Open the abdomen through midline and flank incisions and close these incisions
6. Harvest saphenous vein
7. Vascular anastomosis on a table, inside a pickle jar, inside a short Pringle’s can
8. Dissection of adhesions and scar tissue around blood vessels and organs
9. Dissect and expose the common femoral artery via vertical and oblique incisions and close these incisions
10. Dissect and expose the carotid bifurcation, left and right side, and close these incisions
11. Dissect and expose the tibial vessels in various parts of the leg and foot
12. Dissect out the brachial artery at the elbow
13. Dissect out the axillary artery and vein below the clavicle
14. Dissect out the axillary artery and vein from the axilla
15. Dissect out the subclavian artery, vein, and brachial plexus above the clavicle
16. Dissect out the arm veins
17. Dissect out the iliac artery via a lower quadrant pelvic retroperitoneal exposure
18. Dissect out the abdominal aorta via midline laparotomy
19. Dissect out the abdominal aorta via retroperitoneal approach
20. Dissect out the thoracoabdominal aorta via a thoracoabdominal exposure
21. Dissect out the popliteal artery via suprageniculate, infrageniculate incisions and prone position
22. Dissect out the inferior vena cava
23. Dissect out the iliac veins
24. Harvest deep femoral vein
25. Temporal artery biopsy
26. Endarterectomy of carotid, femoral artery, any artery with patch angioplasty
27. Exposure and control of supraceliac aorta, suprarenal aorta for clamping
28. Exposure and control of thoracic aorta
29. Exposure and control of the great vessels via sternotomy and supraclavicular incisions
30. Exposure and control of the vertebral artery
31. Safe removal of vascularized tumors
32. Amputations of digits, legs and arms up to pelvis and shoulder
33. Exposure and control of radial and ulnar arteries
34. Hand surgical techniques of exposing arteries, tendons, and nerves in forearm and hand
35. Plastic surgical techniques of skin grafting and basic rotational flaps
36. Fasciotomy of arms and legs, hands and feet.
37. Exposure and control of celiac axis
38. Exposure and control of superior mesenteric artery
39. Exposure and control of left renal vein
40. Exposure and control of hepatic veins, portal vein
41. Exposure and control of renal arteries
42. Exposure and control of profunda femoral arteries
43. Safe removal of spleen
44. Transabdominal retroperitoneal exposures of the abdominal aorta and inferior vena cava
45. All of the above in a reoperative field
46. All of the above with limited visualization and by sense of feel only
47. Laparoscopic and thoracoscopic techniques
48. Orthopaedic surgical techniques of myodesis, bone grafting, precision osteotomies, infection control, external fixation, spinal exposure
49. Safe resection and anastomosis of bowel
50. Drainage of infection
51. Intensive care of SIRS, MOFS, CHF, Septic shock, postoperative fluid shifts
52. Nonsurgical and surgical management of lymphedema, seromas, and edema
53. First rib resection
54. Spinal exposure
55. Organ harvest and transplantation
56. Planning of complex open, hybrid, and endovascular procedures

Every year, it is apparent that endovascular options suffer from some flaw when outcomes are studied beyond 2 years, but progress will march on in that sphere. It has to. The loss of open capable surgeons to early retirement is accompanied by overapplication of endovascular techniques at least partly due to the lack of knowledge of these open surgical options and achievable good results and partly due to financial incentives. The solution lies in redistribution of reimbursement to open procedures and creation of open surgical fellowships and identifying and empowering mentors who still walk among us.

Categories
imaging opinion Practice skunk works

At the Intersection of Art and Science

tube graft

I taught myself to draw during medical school when I couldn’t figure out the three dimensional relations of structures. I discovered that if you just draw the shading of an object, it pops out in three dimensions. Over the years, I took to carrying little notebooks to sketch out anatomy and proposed operations for patients through this medium. While I found this to be a handy tool that I used only occasionally, since moving to Abu Dhabi, where much of my communicating is done through an interpreter, my drawings carry a much greater weight as direct communication of my thoughts and intentions.

Sketch134215736

Drawing helps the patient and family understand the unseeable. It gives form to words that are often confused like blood vessel, graft, stent, artery, and vein.

sketch1548914407501

What is informed consent when patient’s cannot describe their problems to their friends and relatives what the problem is and what is going to be done about it?

sketch1548482196294.png

I usually draw with the pen in my shirt pocket and some copier paper, but sitting down and doing a proper sketch is soothing and very helpful for me as the surgeon to previsualize the goals that I have to reach during an operation to take the patient across the finish line. During meetings and conferences, I sketch into one of those fancy bound notebooks that I collect.

UNADJUSTEDNONRAW_thumb_4232.jpg
Funny thing is I was doodling during class as a kid, but it was spaceships, not aneurysms.

While pencil and markers do a fine job, the real magic is in using tablet based sketching software, using layers, to build serial images of the steps of an operation.

Sketch252114245.png

I am increasingly tempted to use these images as my operative note, but understanding that words are needeed for billing, I comply. Even so, I find it helpful to put these illustrations on my EMR notes, because it allows everyone to see and understand what I saw and what I did. I leave you with some of my illustrations with attached comments.

sketch1512843604530
Long segment disease stents in their natural occluded state

sketch1548482314177.png

Our best shot

sketch1548482384179.png
The nutcracker

Sketch154211047.jpg
The fractal

auifemfem.png
Hybridized aorto-bi-iliac revascularization

BkjUr9wERNmyk71Mq0sMnQ_thumb_2a60.jpg
Retrieving the unretrievable embedded filter

UNADJUSTEDNONRAW_thumb_270d.jpg
3 step treatment of a type II thoracoabdominal aortic aneurysm

UNADJUSTEDNONRAW_thumb_277b.jpg
Dysphagia lusoria, treated

UNADJUSTEDNONRAW_thumb_27af.jpg
Targets under the ulcer

UNADJUSTEDNONRAW_mini_76c7.jpg
I’m not sure this really works

Sketch296203949
An off pump CABG for a vascular surgeon

sketch1548698417849
Phase 1

Phase 2

Categories
dialysis access skunk works

Enough Flow!

I got a call about a graft fistula that had a stenosis. “Where?” I asked. At the arterial anastomosis, the velocities were high -500cm/s. My next question was, “is there a problem with dialysis?” The response was, “no.” I reassured the caller and then asked what the velocities were in the mid graft. Around 200cm/s.

Which made me pull out a sheet of paper to do some math. I have to confess, after learning higher level math and fluid flow during college, I had to think about it. The question was, for a pipe that goes from 4mm to 7mm in diameter, what is the ratio of velocities in the smaller pipe compared to the larger section?

The diagram above shows the calculations. This makes a lot of assumptions about the fluid that aren’t necessarily true but I went to medical school, not grad school.

The algebra comes out to the calculation that the velocity in the 4mm segment will be 3 times faster than in the 7mm segment. Which is pretty close.

At the end of all this, it struck me that I needed no other more relevant information than the answer to, “is the dialysis going well?” The velocity numbers for the proximal anastomosis aren’t helpful except under the condition “yes, there is a problem with dialysis.”

There is only the Boolean, Dialysis Good, true or false. Enough flow? implies we know the exact number, a magic volume flow number. The problem with focusing on flow is that there is a problem with too much flow. Arteriovenous shunts are like adult ventriculoseptal shunts (VSD). They burden both sides of the heart. It’s like hitching a trailer on a car. Some cars like SUVs are fine for this, but imagine hitching a boat on a tiny car, which what happens to patients with bad hearts and renal failure.

We don’t have many good options in heart failure or severe systemic atherosclerosis than a catheter. Catheters are just awful, but in heart failure, any amount of flow may be detrimental.

I recently saw a patient with no fistula flow, but a patent and aneurysmal segment of cephalic vein fistula remained and inflated with expiration (above). The outside hospital had placed a tunneled catheter in the right internal jugular vein, but it failed to draw enough blood and they had taken to accessing the cephalic vein with a 14g needle and returning the dialyzed blood via the catheter. Here is a case of the nonflow access. The fistula has gone down at the anastomosis several months before -this is rare to have both a widely patent cephalic vein and a closed anastomosis.

The draw from the vein worked well because there was a siphon to the right atrium and on dialysis days, she was fluid overloaded enough to keep the remnant cephalic vein inflated.

The lack of arterial flow meant that return couldn’t happen in the same vein, but imagine if she had the same in the other arm or better, on the thigh.

Which then made me think that a dilated and varicose thigh vein with a patient sitting slightly upright would be fine for access. Why not? And accordingly, in heart failure patients, high venous pressures are the norm especially in the legs when the head is up. Can we make an access for heart failure patients that takes advantage of their fluid overload?

It would work like this. In both thighs, the valves in the saphenous vein are cut using a endoluminal valvulotome, particularly the anterior thigh tributary. Then you wait. The combination of heart failure and bipedalism will result in huge veins. Once the veins are huge, you could make a very small fistulous anastomosis, but I don’t think it would be necessary.

Some people will have large superficial veins that will allow for dialysis access even without a fistula. Crude drawing below if dilated veins created on the thigh.

Knee high stockings, of course.

Let’s agree to call this the Abu Dhabi sump.