Acute kidney injury (AKI) is a constant battle in the cardiac cath lab. It accounts for the third-highest cause of hospital-acquired renal failure.1 AKI is damage to the kidneys caused by administration of contrast during cardiac procedures, mainly during routine angiograms and percutaneous coronary interventions (PCI). The contrast medium causes vasoconstriction within the renal arteries that can last up to several hours, which results in the kidneys becoming ischemic and a decreased glomerular filtration rate (GFR) that causes a rise in creatinine. This complication adds to the patient’s length of stay and cost accrual to the hospital.
The American College of Cardiology’s National Cardiovascular Data Registry (NCDR) CathPCI registry has a low threshold (rise in serum creatinine of 0.3 mg/dL) for AKI and encourages quality improvements.
Most cardiac patients fall under the high-risk category for AKI. Heart failure, ST-elevation myocardial infarction (STEMI), cardiogenic shock, chronic kidney disease (CKD), age, and diabetes contribute to the higher incidence of kidney injury.2 Over the years, many studies have evaluated ways to reduce AKI. These include the use of acetylcysteine and bicarbonate. These trial results were inconsistent and did not show a significant benefit.1 The POSEIDON trial showed benefit for the use of aggressive hydration,3 which expands the vasculature so that when vasoconstriction occurs with contrast, the kidneys do not become ischemic.
Our facility’s rate of AKI was above the national average. The need to change current processes was apparent. Based on a current literature review, we came up with a 3-part strategy to reduce AKI in the cardiac cath lab. The strategy included a protocol to consistently reduce the amount of contrast delivered during a procedure, changing the contrast medium to a higher quality product, and implementing a hydration strategy for all patients. The Saint Mary’s cardiologists and cath lab staff were all in support of the change and we started tracking patients January 1st, 2019.
Reducing Contrast Use
The first strategy we implemented was to reduce the amount of contrast delivered to the patient. Amit et al demonstrates variation in contrast administration among operators and concludes that reduction is imperative in high-risk patients.4 Through education provided to staff and physicians at our facility, a reduction in excessive contrast administration and unnecessary injections was accomplished. We started at a contrast mean for PCI at 149 mL in 2018, when the national average for contrast use was 126 mL. Over a 3-month period, we reduced that average number to 121 mL per procedure. The strategy followed the “as low as reasonably achievable” (ALARA) method used for radiation safety. The use of power injectors has reduced delivery, but it can also be easy to push the injection button for “puffs” or during catheter engagement. The staff and physicians changed the injects to smaller amounts during engagement of the catheter and set the coronary injections to lower rates. Also, left ventricular (LV) function injections were reduced to 16 mL rather than the traditional 30 mL. We also are a lab that is over 70% radial access for angiograms. The use of radial access has been shown to result in a reduction of the amount of contrast given per procedure.5 Proper acknowledgement and a willingness to change on the part of physicians and staff helped the quality initiative move forward.
In conjunction with lowering the use of contrast delivered per procedure, we created an awareness plan. Brown et al argued that calculating a maximum allowable contrast dose and remaining below that amount will help prevent AKI.6 Other resources used only creatinine and GFR as their source. We created a lab value in the electronic medical record (EMR) (Figure 1) to help show the maximum amount of contrast a patient could receive based upon creatinine and GFR. We decided to go with the more conservative number of GFR x3 to assist in the ALARA initiative of contrast.
This lab value is meant for all staff caring for a patient to understand contrast delivery and trigger a mechanism to help prevent AKI. Any time a creatinine is drawn and resulted, the maximum contrast lab value is shown, with a comment of what Max Contrast signifies. This awareness is for emergency department physicians, hospitalists, cardiologists, radiologists, staff nurses and procedural nurses. All staff can defer stacking procedures that require contrast by delaying or spreading these procedures out over time in order to minimize risk of AKI. A team approach has helped reduce a computed tomography (CT) scan, angiogram and magnetic resonance imaging (MRI) from occurring all on the same day. We started looking at this problem within the cath lab, but quickly recognized that we could shift this initiative as a system issue within the hospital.
The second strategy we implemented was to change the contrast medium. We had been using Omnipaque (iohexol) (GE Healthcare), which is more viscous and has a higher osmolarity than blood (844 mOsm/kg vs 290 mOsm/kg), meaning it can cause a higher rate of renal artery ischemia. Omnipaque is less expensive and provides quality imaging during angiography. The tradeoff was a higher incidence of AKI. A cost analysis showed the incidence of AKI leading to non-reimbursable care outweighed the higher cost of a better contrast medium. Visipaque (iodixanol) (GE Healthcare) has the same osmolarity as blood, allowing it to pass through the renal arteries with less risk of causing ischemia. The other benefit to switching to Visipaque was the 9% reduction in major adverse renal and cardiac events (MARCE).7 A patient who receives hemodialysis because of contrast-induced AKI can cost the hospital more than $25,000 in non-reimbursable costs. The cost of an extra day in the hospital can range from $1500-3000, depending on the level of care and supply usage during the stay. The added cost of contrast was worth the reduction in the number of AKI patients.
The third strategy was to implement a hydration strategy for all patients (Figure 2). While researching this issue, we found that in several studies, patients with normal LV function received their hydration per the POSEIDON protocol.8 Other options were to place central venous pressure (CVP) monitors and adjust hydration accordingly. This option did not appeal to our cardiologists. Patients presenting with heart failure symptoms were not being hydrated due to fear of worsening the heart failure or putting the patient at risk for flash pulmonary edema. The heart failure population is at a higher risk for AKI and these patients were not receiving any IV hydration. To address these concerns, we presented a sliding scale for hydration depending on LV function. This rate adjustment allowed for vasculature expansion prior to the procedure, while minimizing the risk of fluid overload.
The scale is used by cardiology when the decision for cardiac catheterization is determined. For the extreme heart failure cases, a right heart catheterization can be performed to provide more data for volume status and treatment plans. This strategy allowed providers to order hydration according to the patient’s ejection fraction and severity of heart failure. The risk of fluid overload was minimized while adding hydration to this high-risk population.
This 3-part strategy incorporates staff, physicians, and patients to be active participants in the goal of reducing contrast-induced acute kidney injury. In reviewing our 2018 data, we had 22 patients who qualified for AKI per the NCDR registry guidelines. Three of those patients required hemodialysis for a period ranging from several sessions to permanent dialysis. The remaining patients had an increased length of stay ranging from an additional two to seven days. It was clear that this complication added additional burden to the patient due to an increased stay, but also to the hospital, because of increased cost and decreased throughput for other patients. Contrast-induced AKI places a burden on all aspects of the system.
The 3-part strategy started January 1, 2019 and is still in effect today. We collected data from January 1, 2019 through December 31, 2019. We tracked patients through the NDCR who qualified as an AKI because of an 0.3 mg/dL increase in creatinine. We tracked the cost of contrast medium and the amounts being used by each provider to ensure ALARA was being met. In addition, we met as a lab to discuss AKI and set goals to decrease the overall number. This team approach by all staff members was our crucial key to success. Our pre/post cath lab nurses ensured fluids were being administered appropriately before and after each procedure, our physicians and intra procedural staff were measuring LV end diastolic pressure (LVEDP) to address hydration status and decrease injections, and our cardiologists helped educate our hospitalists to address the risks from multiple contrast exams and hydration of heart failure patients. A team approach allowed us to achieve our goal to decrease AKI by 50% in 2019. We had increased our procedural volume by 21% in 2019, but only had 11 patients with AKI as defined by the NCDR. Of these 11 patients, 1 patient had a 2-day increase length of stay, 4 patients had a creatinine increase that was still within normal limits, and the remaining 6 patients had slight increases that resolved on their own and did not require additional interventions. Our facility went from 22 to 11 patients with AKI in a matter of a year. This represents a cost avoidance of over $150K during the period from January to December 2019. Our collaborative goal setting, with all parties working together, made this initiative a success and has changed how we perform angiography. We continue to incorporate this 3-part strategy to further decrease our incidence of AKI not only in the cath lab, but in all areas of the hospital.
Disclosures: Mr. Foust reports no conflicts of interest regarding the content herein.
Trent Foust, MBA, BSN, RN, RCIS, can be contacted at firstname.lastname@example.org.
- Ratcliffe JA, Thiagarajah P, Chen J, et al. Prevention of contrast-induced nephropathy: A randomized controlled trial of sodium bicarbonate and N-acetylcysteine. Int J Angiol. 2009; 18(4): 193-197. doi:10.1055/s-0031-1278353
- Mehran R, Aymong ED, Nikolsky E, et al. A simple risk score for prediction of contrast-induced nephropathy after percutaneous coronary intervention: development and initial validation. J Am Coll Cardiol. 2004; 44(7): 1393-1399. doi:10.1016/j.jacc.2004.06.068
- Brar SS, Aharonian V, Mansukhani P, et al. Haemodynamic-guided fluid administration for the prevention of contrast-induced acute kidney injury: the POSEIDON randomised controlled trial. Lancet. 2014; 383(9931): 1814-1823. doi:10.1016/S0140-6736(14)60689-9
- Amin AP, Bach RG, Caruso ML, Kennedy KF, Spertus JA. Association of variation in contrast volume with acute kidney injury in patients undergoing percutaneous coronary intervention. JAMA Cardiol. 2017; 2(9): 1007-1012. doi:10.1001/jamacardio.2017.2156
- Andò G, Gragnano F, Calabrò P, Valgimigli M. Radial vs femoral access for the prevention of acute kidney injury (AKI) after coronary angiography or intervention: A systematic review and meta-analysis. Catheter Cardiovasc Interv. 2018;92(7):E518-E526. doi:10.1002/ccd.27903
- Brown JR, Robb JF, Block CA, et al. Does safe dosing of iodinated contrast prevent contrast-induced acute kidney injury?. Circ Cardiovasc Interv. 2010; 3(4): 346-350. doi:10.1161/CIRCINTERVENTIONS.109.910638
- McCullough PA, Brown JR. Effects of intra-arterial and intravenous iso-osmolar contrast medium (iodixanol) on the risk of contrast-induced acute kidney injury: a meta-analysis. Cardiorenal Med. 2011; 1(4): 220-234. doi:10.1159/000332384
- McCullough PA, Choi JP, Feghali GA, et al. Contrast-induced acute kidney injury. J Am Coll Cardiol. 2016;68(13):1465-1473. doi:10.1016/j.jacc.2016.05.099