“We are developing protocols for patients who have kidney disease and are undergoing dialysis and need precise, effective doses of recombinant human erythropoietin hormone,” says Chait. The hormone, also known as EPO, manages the production of red blood cells, which, among other things, controls anemia.
Other members of the team include Dr. Michael J. Germain, a nephrologist and the medical director of Renal Transplantation at Baystate Medical Center, electrical and computer engineer Christopher Hollot (Electrical and Computer Engineering) and mathematician Joseph Horowitz (Mathematics and Statistics). Chait, Hollot and Horowitz also run the Control in Biomedical Systems Research Laboratory that develops feedback control methods and tools for biomedical applications.
The new medical protocol, based on the principles of engineering feedback control systems, promises to individualize the EPO dosage for every patient and improve his or her treatment outcomes.
In dialysis patients the amount of EPO produced by the kidneys is inappropriately low for the level of anemia, and so they are treated with recombinant human EPO hormone in order to minimize the need for blood transfusions. Chait notes that current anemia management protocols for administering EPO are more or less “one size fits all” and fail to achieve the desired outcomes for many patients. That is where Chait’s expertise comes in. By utilizing the principles of feedback control systems, his protocols enable medical personnel to personalize the EPO dosage for each patient.
The current management of anemia is unsatisfactory, which prompted the FDA to issue a 2011 warning for chronic kidney disease patients on dialysis stating that "...No clinical trial to date has identified a hemoglobin target level, ESA dose [Erythropoiesis Stimulating Agent], or dosing strategy that does not increase these risks...The lowest ESA dose sufficient to reduce the need for red blood cell transfusions should be used..."
Healthy kidneys normally control the whole complex process of erythropoiesis, which produces red blood cells, but medical science has not yet learned how to duplicate this process.
However, engineers look at erythropoiesis as a closed-loop system, similar to that of a thermostat. When the first electric thermostat was designed 1883 by Warren S. Johnson, it was designed to maintain a desired set-point temperature, despite such variables as the outside temperature, the size of the house or unit, or the climate of the location. In that sense, a closed-loop system can maintain certain engineered goals by using formal feedback control principles to design the controller, which in the case of EPO dosing is called a protocol.
“If you don’t approach erythropoiesis as a closed-loop system, I really don’t think you can expect to achieve desired response,” explains Chait. “Now, erythropoiesis is much more complicated than a thermostat, but the same principles of feedback control apply. The protocol for erythropoiesis has to take into account all the variables and adjust to them.”
Chait adds, “Based on the pilot study, we have seen that we can achieve desired hemoglobin levels with smaller amounts of the drugs. That is believed to be medically beneficial for the patient, and it’s also economically beneficial.”
The end result of a better EPO protocol is improved outcomes for dialysis patients. “One of the main complaints of dialysis patients is fatigue and decreased exercise, even walking, tolerance, which is due in part to their anemia,” says Dr. Germain. “If we could keep their hemoglobin stable, their quality of life would improve.”
College of Engineering News
Image courtesy of Fresenius Medical Care
The new medical protocol promises to individualize the recombinant human erythropoietin hormone (EPO) dosage for every dialysis patient thus improving treatment outcomes.