The Michigan Vascular Access/MiDRE primer in Vascular Access
Chapter 1 - Introduction to end stage renal disease (ESRD)
A patient on dialysis via a forearm loop graft
End-stage renal disease is a disease entity that currently affects over 400,000 people in the United States, and whose management involves hemodialysis in the majority (>80%) of patients. Nearly every renal failure patient, whether transplanted or choosing peritoneal dialysis (CAPD) will undergo hemodialysis at some time. Systems for providing dialysis care are well established in the United States. Unfortunately, hemodialysis requires passing large amounts of blood through a dialysis filter three times a week: 90,000 to 120,000 milliliters; 90 to 120 liters; or 23.7 to 31.6 gallons over a session repeated three times a week). There is no vein in the human body that can withstand this amount of use without modification.
There are essentially three options that allow for this volume of blood to be drawn from the body, run thought the dialysis machine, and returned to the circulation: (1) a large catheter with two channels can be placed through the skin into one of the major veins with sufficient flow to provide this amount of blood and safely handle its return; (2) a native vein of the patient which has been conditioned by a direct connection with the arterial pressure and flow of an artery to expand, to carry sufficient flow, and to toughen enough to safely and repeatedly handle being punctured by large needles twice a week (called a "fistula"); and finally, (3) an artificial tube connecting an artery and vein, placed under the skin, and also designed to be safely punctured three times a week with large needles (called a graft).
As one can imagine, each of these options requires some alteration of the normal body function, and each carries some risk. Provision of these means is necessary for each dialysis patient, and as each option represents an unstable system prone to failure and complications, there has been much effort and debate escalating recently over how best to provide the safest and most stable option possible. The National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF-DOQI) released a landmark example of evidence-based medicine in 1997 with benchmarks and clinical guidelines. Much of the debate since then has been driven by this effort, with definite signs of quality improvement, and there are organizations existing to help define and drive needed changes (i.e., the Renal Network and its regional branches, the "Fistula First" collaborative, the Controversies in Dialysis Access [CIDA] meeting, the Vascular Access Society of the Americas [VASA] and its biennial meeting, the American Society of Diagnostic and Interventional Nephrologists [ASDIN] and their yearly meeting, journals such as "Seminars in Dialysis", and so on). However, as a surgeon focusing on the care of these patients full-time for over a decade, and as one of the busiest surgeons in this field in my region, my observation is that much remains to be done to achieve the quality levels that we want to see.
(1) The importance of loss of central venous patency
In my opinion, of the three major DOQI guidelines (see above) avoiding or limiting catheter usage to avoid loss of central venous patency is the most important issue in dialysis access, because loss of central venous patency limits or eliminates all hemodialysis options. Catheters can no longer be placed in occluded central veins, and shunts become complicated with unacceptable side effects of venous hypertension. Loss of central venous integrity is caused predominantly by prolonged catheter placement, although pacemakers and AICDs also have major roles, followed distantly by Mediports, PICC lines, common central lines, clavicular trauma and congenital abnormalities.
Right innominant vein occlusion around a right IJ catheter
Since central venous stenosis robs our patients of their options, and as little as three months on a catheter can result in significant central venous damage, it follows that we must get the catheters out as soon as possible. Time on the catheter accumulates with delays in referral or treatment, failures of access creation, delays in maturation to usability, delays due to infiltration or other inability to use an otherwise acceptable access.
This is a central and underappreciated issue, and all other issues reflect back on this. Time on the catheter, and thus loss of central patency, are due to delays in achieving adequate access. Thus, all delays in achieving a non-catheter vascular access for dialysis must be identified, evaluated, and corrected or supervened to achieve the best possible results for the patient. I will discuss the origins of these delays briefly.
(2) Increased time on the catheter due to: (a) delay in referral of the patient to the access team
The DOQI guideline for initiating of access planning is when the creatinine clearance is less than 25 ml/min. It is frustrating to be sent a patient who has been considered "not ready" for surgical referral, but then comes precipitously with a GFR of 9, 11 or 13 and a request for an "AV access as soon as possible". Options that require time may be discarded in favor of a faster graft, or the patient may require a catheter.
Patients are understandably reluctant to have surgery that "I don’t need yet", but this procrastination can be combated by education, introduction to the access team, and familiarity with the system. In addition to basic education about the realities of life on dialysis, early orientation to venous preservation is a key to maintaining their access options. The patients should be sent for a consultation as soon as possible.
Late referral increases the chance that the patient will need a catheter, and for a longer time.
Every picture tells a story in the "Wall of Fame" educational tool
Increased time on the catheter due to: (b) mistakes in access planning
Choosing the right access for a patient is a product of information and experience. Pre-operative venous mapping has been identified as a helpful step in identifying access options. Arterial adequacy is an underappreciated factor. In-office ultrasound is also an essential tool for the access surgeon, and I wish it were more commonly employed. Once the size and patency of the available vessels are known, the available options can be discussed with the patient.
Beyond knowing what ingredients are available, the operator must be able to make the most of those options. Being familiar and adept with direct (sometimes misleadingly called "simple fistulas") and advanced procedures (superficialization and transposition) are key requirements for the access surgeon. Understanding the yield (chance of success), potential requirement for secondary procedures, and time to maturation of each option (wrist fistula versus transposition, for example) are essential if we are to help the patient make an informed choice.
Fistula maturation rates are currently quoted in the 50-60% range. What this means is that 40-50% of fistulas created never become usable. It also means that the patient remains on the catheter all the time that this failed process consumes, and perhaps over and over. It is not unusual for us to be sent a patient with three or four failed access attempts, and with a catheter for a year or more. These patients almost invariably have depleted venous assets, damaged arterial assets, and complicated central venous anatomy.
We see evidence of poorly performed dialysis access operations every week: fistulas created using obviously insufficient arteries, "fistulas to nowhere" in the forearm with no venous outflow, grafts placed under the deep fascia with a good thrill but impossible to cannulate, and poorly performed superficialization and transpositions. Unfortunately, not all bad situations can be remedied.
The experience of the access surgeon is probably the key factor in raising a former 20% prevalence of fistulas to 50 or 60%. Unfortunately, it is a fact that most training programs – general surgical, vascular surgical and transplant – give short shrift to hemodialysis access creation or maintenance. Most of us have learned on the backs of our early patients, and have generally put the learning curve behind us, but it is clear that with an increasing demand and more new providers entering the field, either training must improve, or the burden of the learning curve on the patients will increase.
A good basilic transposition
Not so nice BVT – too short and medial
My own review has demonstrated that the chances of achieving a fistula diminish with each previous access attempt, and with time on the catheter. I have come to the conclusion that the first shot is the best shot, and that first shot should not be wasted.
Increased time on the catheter due to: (c) delay in maturation of fistulas
Maturation of fistulas once created is an important means of making fistulas usable more quickly and getting catheters out. In my practice, once created, the fistula is examined with ultrasound at two weeks and generally at three-week intervals thereafter until ready for cannulation or until a corrective procedure is indicated.
Ultrasound examination by the hands of the surgeon in each and every clinical encounter is key – the ultrasound becomes an extension of the physical examination, and the surgeon can see every variation in size, every stenosis, the depth of the fistula as is courses from the arterial anastomosis to the outflow, branches diverting flow away from the conduit planned for cannulation, the direction of the outflow, and so on.
Steady progress may be tolerable, but delayed maturation in the presence of a dialysis catheter is not. An aggressive follow-up program leading to intervention as indicated may accelerate usability of the fistula, shortening time on the catheter. Procrastination is not a success strategy when the catheter clock is ticking.
Corrective procedures include branch ligation , superficialization, inflow revision or venoplasty.
Increased time on the catheter due to: (d) delay in using the fistula
Once fistulas are judged adequate for release in our practice, an ultrasound-assisted digital photo diagram is created to guide cannulation by the dialysis unit (example attached). This "user’s guide" reduces problems with early cannulation that compromise fistula integrity and demoralize the patient, and aids in getting the catheter out.
Digital photo diagram to guide the unit
Unfortunately, even with the best planned and executed fistula, user errors can prolong time on the catheter by making the access temporarily unusable (severe infiltration) or hasten deterioration and loss (laceration with expanding hematoma or Pseudoaneurysms). In this situation patients become disillusioned, psychologically wed to the catheter, and more prone to long-term complications.
Same arm two days later
Initial cannulation, and cannulation of difficult access should be performed by the true experts in each unit. We have heard from unit administrators that "everyone in our unit is an expert", but the patients tell a different story - of people who don’t listen, people in a hurry, people with wildly varying levels of skill, and rotating casts of characters. I’m telling you, folks, universal expertise just isn’t the reality in most places.
Please be realistic about who is a real expert, and who is not. Instruct personnel to look at the diagrams provided. Treat each problem cannulation as a reportable event, and track performance in a meaningful way. Re-educate poor performers. Identify problem accesses promptly, and sent the patient back for an ultrasound examination and reevaluation. And get the catheters out!!!
(3) Inpatient versus outpatient surgery
Surgeons are frequently asked to see patients for evaluation and placement of dialysis access during their initial hospitalization. I believe that this is rarely essential and that early operation can b actually be harmful: (1) patients and their families are frequently overwhelmed by the unexpected situation and all the new information – a week or two of orientation and an educational office visit can make a big difference; (2) a patient in the acute phase of a serious illness is rarely the best patient for an elective outpatient surgery – two weeks of dialysis and medical optimization can make a big difference; (3) a thorough office ultrasound of a stable patient tends to be better than the bedside exam of an ill patient – I have told patients in the hospital that they had "no fistula options" based on their bedside ultrasound and then found excellent veins for a fistula weeks later in the office; and (4) devoting two hours to driving across town to "meet" a patient is not a good use of my time when patients are clamoring to make appointments in my office – every hospital consult takes the time of four office consultations.
I understand the desire to "get something in" the patient as soon as possible, but offer further points: (1) you will be able to find someone to put that access in, but it’s more important to do something right than to do something right now; (2) the patient who gets a fistula but dies before discharge or withdraws from treatment is not a save; and (3) the non-compliant patient with an IJ permacath, and the non-compliant patient with an IJ permacath and an immature fistula are the same person - still likely to do poorly long-term due to their non-compliance.