Providers evaluate a number of patient safety considerations before administering contrast media. As automated contrast injectors are increasingly utilized in cardiology departments—replacing the older manifold models—administrators are establishing protocols to lessen the incidence of contrast-associated adverse events, as well as improving the bottom line. Both goals, it seems, are interrelated.
The risks associated with contrast are well-documented, and primarily include contrast-induced nephropathy (CIN) and nephrogenic systemic fibrosis (NSF). CIN is "extremely low risk" for patients with normal renal function, according to the American College of Radiology (ACR), but for older patients—and those with diabetes or other conditions—the potential is greater. NSF has been correlated with gadolinium-based MRI contrast agents in patients with kidney disease.
Some doctors may be firm about their preferred types of contrast. However, most physicians seem to agree on two methods for reducing risk.
"Dye-load and adequate hydration are the only two things that have been consistently shown to reduce the risk of developing contrast-induced nephropathy," says Jason T. Call, MD, a cardiologist at Winchester Cardiology & Internal Medicine in Winchester, Va.
This opinion is supported by various studies assessing the relationship between contrast and adverse events. Contrast volume is a key risk factor for contrast-induced acute kidney injury (CI-AKI) for patients undergoing PCI, according to Jeremiah R. Brown, PhD, of the Dartmouth Institute for Health Policy & Clinical Practice, Dartmouth Hitchcock Medical Center, in Hanover, N.H., and colleagues. The incremental use of contrast beyond the maximum acceptable contrast dose (MACD)—defined as 5 ml times the body weight [kg]/baseline serum creatinine—is associated with greater risk of adverse events (J Am Coll Cardiol Intv 2009;2(11):116–124).
In their analysis of nearly 10,000 patients prospectively enrolled from 2000 to 2008, researchers found that 20 percent of patient procedures exceeded the MACD.
"Patients exceeding the MACD threshold were more likely to be in shock, have two- or three-vessel disease and left main stenosis, and receive more stents," Brown et al wrote. "Patients receiving contrast volumes in excess of the MACD were more likely to have CI-AKI, new onset of dialysis dependent renal failure, cardiac events, bleeding complications, receive transfusions and have a longer length of stay post-PCI. Importantly, their mortality rates also were higher during PCI admissions." Researchers also found that risk-adjusted CI-AKI increased by an average of 45 percent for each category exceeding the MACD.
Certain patient characteristics indicate greater risk for CIN and baseline kidney. Baseline kidney function and diabetes are the two top variables, Call says. If a patient has one of these variables, risk for CIN may increase to 3 to 5 percent, however if he or she has both variables, the risk that the kidneys will be transiently harmed rises to 10 to 15 percent. Additional risk factors include allergies, asthma, and cardiac status, according to the American College of Radiology.
In some situations, the benefits of imaging a patient outweigh the risks associated with the administration of contrast, says says Hani H. Abujudeh, MD, MBA, director of quality assurance in radiology at Massachusetts General Hospital in Boston. If an alternative diagnostic method can produce the desired information in a high-risk patient—such as ultrasound, CT without contrast or an MRI without contrast—that may be better.
Nevertheless, the potential of kidney problems may be a small price to pay for life-saving information. "If contrast results in a diagnosis of a life-threatening condition, then it outweighs the risk of contrast nephropathy," Abujudeh says.
Call concurs, "If we're treating someone's heart attack, you can't stop. It's a life-saving procedure, and you have to accept the risk."
Manifold contrast injectors haven't been pushed out to every clinical setting, but hospitals are increasingly adopting automated systems, which have been shown to reduce the amount of contrast and diminish cost. However, in a recent meta-analysis, Brown and colleagues recommend further research on the association between reduced contrast volume and the risk of CIN.
In their meta-analysis of six studies, researchers found that the use of automated contrast injection significantly