Can you tell us about your center?
Barry Bertolet, MD: North Mississippi Medical Center is the largest private rural hospital in America, and has won the Malcolm Baldrige National Quality Award in 2006 and as a system, North Mississippi Health Services, in 2012. We are a regional medical center with 18 cardiologists on staff, cathing around 3500 patients per year, holding fairly steady at doing about 1400 percutaneous coronary interventions (PCIs), and about 800 peripheral interventions per year. We have four cath labs plus a hybrid OR and 3 electrophysiology labs.
Carla Durham, RN: In the cath lab, we have 18 team members, which includes the manager and a charge nurse. The team members are a mixture of radiologic technologists and registered nurses. We staff 4 team members per room during regular hours, and our callback team consists of 4 team members, with at least one being a registered nurse.
Can you describe your patient population?
Dr. Bertolet: One of the maps I often refer to is from the Centers for Disease Control website. It tells you the death rate per 100,000 cardiovascular disease patients, and the colors change from white at the low end to a deep maroon as the numbers rise (Figure 1). It seems like the epicenter of that deep maroon is right over our city of Tupelo. Cardiovascular disease is epidemic in this area. Within the United States, the national rate of death from a cardiovascular illness is about 1 out of 3 to 1 out of 4, and in Mississippi, death from cardiovascular disease is 1 out of 2, applying to men and women. A good amount of this increased cardiac risk is related to obesity. Mississippi has had the distinction of being the most obese state in the nation for about 10 years running. Because of that high obesity rate, Mississippi also has a high rate of diabetes, second only in the nation to Louisiana. With an obese, diabetic population, and people eating Southern cuisine, which often includes fried food, we have an unhealthy population and it is reflected in our cardiovascular numbers for the state.
How did reducing contrast-induced acute kidney injury (AKI) become a focus for your lab?
Dr. Bertolet: We do see a higher number of diabetic patients and worry about their kidneys as a result. North Mississippi Medical Center has an active research program, which is how we were first introduced to the DyeVert System (Osprey Medical, Inc.). We first began to use it in some of the research studies and were impressed, even at the very infancy of this technology, with its ability to decrease the amount of contrast that we delivered to a patient. When you are trying to treat AKI in the cath lab, the amount of contrast delivered to the patient probably plays the biggest role in the outcome of the patient. There have been several experiments looking at other ways to reduce AKI, such as MucoMyst, attempting different intravenous hydration regimens, and sodium bicarbonate. With the exception of making sure that the patient is not dehydrated and limiting contrast load, the rest of these attempts have been proven to be unsuccessful. The premise of the DyeVert system, a device that allows adequate imaging of the coronary vessels while at the same time reducing contrast dye load by about 40-50%, was a perfect fit with our goals.
What are the challenges of treating chronic kidney disease (CKD) patients in the cath lab?
Dr. Bertolet: The first challenge is actually identifying these patients. Unfortunately, I think a lot of doctors, nurses, and nurse practitioners still reflexively eyeball creatinine as an indicator that the kidneys are functioning adequately. But serum creatinine (SCr) as a measure of kidney function is problematic. Let’s say you have a SCr of 1.1, and based on that normal range number you assume the patient does not have kidney disease. But if the patient is actually an 80-year-old lady who weighs 120 pounds, then a 1.1 creatinine indicates a serious kidney issue. So, first we need to make sure we correctly identify chronic kidney disease patients, because they are often incorrectly identified, and that leads to higher incidences of AKI in these patients. One of the big things that Carla has pushed for amongst our staff has been putting mechanisms in place to prospectively identify these patients — not after they went into kidney failure, but before. Education is important.
Carla: All our patients have their estimated glomerular filtration rate (eGFR) calculated in the holding room. If the patient’s eGFR is <60, we use DyeVert on that patient. Before this process, we only really focused on inpatients where chronic kidney disease had been previously diagnosed. We implemented this new process after I attended a conference focusing specifically on AKI (Osprey Medical’s Nurse Tech Symposium). After learning about the importance of AKI, I decided we would calculate an eGFR on everybody and evaluate our results. Everyone downloaded an app from the National Kidney Foundation on their phones that allows rapid eGFR calculations and we placed eGFR calculators on all in-room computers. When the eGFR calculation is <60, we highlight these patients, so we know to automatically use the DyeVert system.
Dr. Bertolet: It was maybe a year ago that we first began to make some of the changes and Carla’s literal “hard stop” prior to putting patients on the table has been in place since about April 2019. Absolutely no one goes on the table without an eGFR calculation. Prior to the implementation of the hard stop, there were people sliding through without a calculated eGFR. Then we would be reviewing cases later, see somebody with an eGFR of 40, and ask ourselves, why didn’t we use DyeVert? We found that a lot of these patients were not correctly identified pre contrast exposure, which is something that is “shame on us.” The new “hard stop” pathway has been superb in identifying patient at an increased risk for AKI prior to any contrast exposure. This process has affected the physicians as well. When I review my patients the night before their procedure, I am not only reviewing the procedure I am going to do and the indications for that procedure, but I am looking at the calculated eGFR in these patients. We prospectively identify patients at risk of an AKI before they even reach the hospital for their procedure. In the past, we were dependent on referring physicians to identify patients with poor renal function. According to previous American College of Cardiology guidelines, we would admit these patients the night before their procedure, administer IV hydration overnight, and cath them the next morning. We depended on the referring physicians to identify the patients who were at risk and on them making the call for the overnight pre-procedure hydration. Yet most of the time, as we have found, these patients are not identified. Another scenario might be that the patient was seen in clinic and had a prior renal function test that looked acceptable. However, at the time they actually undergo a heart cath, that serum creatinine from 6 weeks or 3 months ago may have changed, and that patient may now have significant renal dysfunction when they come in for a pre-op lab prior to a cath.
Was the overnight care of patients undergoing pre-procedure hydration economically sustainable for your center?
Dr. Bertolet: We found out that it was completely unreimbursed care. It came right out of the pocket of the institution and was not billable care that we were providing for the patient. Just from a pure cost perspective, when we put someone in that observation unit and did an IV infusion, it cost the institution $100/hour. If we admitted someone at 6 pm, hydrated them, and did their cath at the very earliest at 8 am, we had 14 hours invested in that patient. That was $1400, cost-wise, that we would not be able to recoup. We learned this the hard way, through a financial analysis after we had been doing pre-procedure overnight hydration for quite some time. I had thought we would be reimbursed if the patient had pre-identified renal disease, but apparently Medicare does not believe that to be an important factor and there is no reimbursement for pre hydration. By bringing in DyeVert, we were able to change our entire pre-treatment protocol. We bring patients in the morning of their procedure, hydrate them with an IV for 2-4 hours pre cath, do the heart cath with DyeVert, and then patients usually undergo a minimum of 3 hours of hydration after the procedure as well. We have taken 14 hours of admission and observation, and basically reduced it to almost nothing, because the patient has to come here and get worked up anyway, so we have perhaps 1 to 2 additional hours invested. If we look at what we spend on the DyeVert device versus what we save in pre hydration, we come out $1000/patient ahead on every patient undergoing this protocol. From an institutional standpoint, the hospital financial administrators love it, because we now have a $1000 savings on every chronic kidney disease patient compared to the cost of our previous protocol. Rather than admitting these patients the night before for hydration, we now hydrate them for a couple hours pre cath, use DyeVert to reduce the contrast load, and hydrate them a few hours post cath while we are doing their observation. Patients have been doing extraordinarily well on this protocol, at a huge cost savings for the institution.
Can you tell us more about the DyeVert system and how it is used in the cath lab?
Dr. Bertolet: The DyeVert is able to smooth the rate of contrast administration, diverting any manually injected excess amount of contrast in order to keep it from going into the patient. As an operator, I get the adequate image I need, but the patient doesn’t get the over-administration of contrast. The amount of contrast reduction delivered to the patient averages at about the 40% mark. With DyeVert, we are able to do heart caths and interventions with very low amounts of contrast in patients who are at high risk of AKI. Not long ago, I did a heart cath on a patient with an eGFR of approximately 20. We were able to do the procedure with 11ccs of contrast using the DyeVert system. This was a patient who, otherwise, after a normal heart cath, would have been in renal failure or would have required dialysis immediately after the cath to pull off the contrast, but did quite well with use of the DyeVert.
Do you set maximum contrast thresholds?
Dr. Bertolet: Yes. We are different than other labs in that I believe we have the lowest threshold. When I worked alongside Osprey Medical to review our research data, we saw that if contrast volume was kept at less than 1.5x the eGFR, no patients developed AKI. Now this is quite different from the rest of the world, where they use 2-3x the GFR. I think that number is way too high, and that is why there is still a large number of AKI cases, when people are “under the acceptable limits.” At North Mississippi Medical Center, we use 1.5x GFR to determine the maximum contrast threshold. If the eGFR is 30, for example, then I am allowed to give 45ccs of contrast. If I can’t do the procedure in less than 45ccs, then it is reasonable for us to stop and bring the patient back another day to complete the procedure, so we don’t overload the kidneys with too much contrast. I think a patient would rather come to the cath lab on two separate days than be on dialysis for the rest of their days.
Carla: The DyeVert also has a monitor that indicates when contrast use is getting near the pre-determined limit. It tells the percentage or how many ccs (mLs) of contrast has been used thus far.
Are there other steps you take to reduce contrast outside of use of the DyeVert system?
Dr. Bertolet: Instead of taking 3 or 4 pictures of the left coronary system, I may only take 2. I am more apt to use a 5 French diagnostic system as opposed to a 6 French system. While there are other things that we certainly can do and want to do in order to benefit the patient, the heavy lifting is done by the DyeVert system.
Have you noticed a reduction in the number of patients developing AKI post procedure?
Dr. Bertolet: Absolutely. Prior to implementing the DyeVert system, our AKI rate was 6.3%. To my knowledge, after implementing the mandatory eGFR calculation, managing to our contrast threshold limits, and utilizing DyeVert on all patients with an eGFR <60, we have had zero patients with an AKI event. I want to reemphasize our patient demographics, with our high diabetic and obesity rates. In obese patients, imaging is more difficult and people often feel the need to give more contrast as a result, and diabetic patients have a higher risk of kidney failure. With the DyeVert system, we can do very good imaging and substantially decrease our AKI rate in a high-risk subgroup of individuals.
Do you have advice for labs who may be interested in reducing their AKI rates?
Carla: Start by doing your homework and learning more about AKI. Do the hard stop and do an eGFR on every patient.
How many minutes does that add to your process?
Carla: Seconds. The staff routinely checks a patient’s lab work pre-procedure as part of the universal protocol for invasive procedures. This time becomes a convenient time to determine the eGFR for that patient. There is not a big learning curve; it is very easy.
Were staff and physicians open to addressing the problem of AKI?
Dr. Bertolet: First, I think we were all shocked by the <60 eGFR patients we were cathing. We seriously underestimated the CKD disease process. The second thing is that I think that physicians have a false sense of security, thinking that if they use <100ccs of dye, that they have done well. I probably haven’t used 100ccs of contrast in any of my cases in a long time. Because these patients are at high risk from the procedure I am conducting, I have been very quick to use DyeVert and use a cutoff of 1.5x eGFR for my total contrast load. If the physician is aware of a contrast restriction, they must consider the necessary steps of a successful cath and maybe even an intervention within contrast load permitted in this setting and in this patient. Anybody can do a procedure with 100 or 150 ccs of contrast dye — and that is really the challenge, to have this threshold out there and stick to that limit. For an institution to be successful, a physician champion is essential. That physician must be committed to lessening the AKI rates at your institution. If nobody cares, nothing changes. If Carla weren’t encouraging staff to calculate the eGFR, it wouldn’t be done as regularly. For physicians, somebody also has to go out there and beat the drum. It takes 3 minutes to set up the DyeVert device! But maybe the doctor says, just forget it, we don’t need it, because I won’t use that much dye — but does he really know how much he will use? By having set protocols, champions on the nursing and physician side who really push AKI awareness, and identifying these patients prospectively so you can do the right things such as pre-hydration and using DyeVert, cath labs can end up with great results for their patients.
Disclosures: Dr. Bertolet and Carla Durham report no conflicts of interest regarding the content herein.
Dr. Barry Bertolet can be contacted at firstname.lastname@example.org.
Carla Durham, RN, can be contacted at email@example.com.