Rice University seniors design pump to deliver drugs to heart-attack and stroke patients
Like a fine watch, a Rice University student team’s invention will tick and tock to pump lifesaving fluids into heart-attack patients a little bit at a time for hours on end.
The spring-loaded AutoSyP, which regulates the progress of standard syringes, was designed for patients in developing nations who need quick access to a slow and steady supply of medication.
The Rice engineering seniors who call themselves Chemomatic have already won honors for their sub-$400 box; they placed third in the 2013 University of Minnesota Design of Medical Devices student competition earlier this month. But the real payoff will come when their mentors from the University of Texas Health Science Center at Houston (UTHealth) take their device to Fiji for evaluation with heart-attack and stroke patients.
“In a lot of the developing world, there’s a tremendous burden of cardiac disease,” said Dr. Rohith Malya, director of the Division of Global Health at UT Health. “Fiji is the epicenter of it all. They have a death rate from heart attacks about five to eight times that of the United States.”
Malya said heart attacks tend to strike Fijians in their 30s and 40s, much younger than in the Western world. “We think there’s a genetic predisposition to the Western diet being bad for them,” he said. “The Western diet and tobacco came to them about 30 years ago, when they were basically a nation of fishermen and everybody was pretty much healthy.”
Fiji was among the South Pacific nations that declared a pandemic for heart disease at the United Nations in 2011. “It was the first time a noninfectious disease was declared a pandemic for any region,” Malya said. “Basically, the more they live like us in the West, the faster they die like us.”
Malya came to Rebecca Richards-Kortum, director of the Rice 360˚ Institute for Global Health Technologies, and Maria Oden, director of the Oshman Engineering Design Kitchen, for help. They brought the Chemomatic team together last fall.
Rice students Glenn Fiedler, Peter Jung, Lemuel Soh and Kevin Jackson designed their device to run for 24 hours using very little battery power as it delivers a measured dose of drugs or saline to a patient more accurately than an IV drip would. Though it can help treat patients with many needs, the first are likely to be cardiac patients like those under the care of Malya and stroke patients of Dr. Amy Noland, an assistant professor of emergency medicine at UTHealth who also works with the team.
“Myocardial infarctions are ischemic events, clots that develop in the heart, so you use thrombolytic drugs like tPA and streptokinase to break up the clot,” said Jackson, who plans to attend medical school after graduating from Rice. “Both can be used for cardiovascular events. Some strokes are ischemic events, a clot in the brain, and you can use tPA.”
In the Western world, Malya said, hospitals often treat clots with a cathetherization lab used to place angioplasty balloons or stents. “But these machines are expensive, and nobody can afford them but high-level Western hospitals. We’re asking if we can do something using older medicines to get Western-level outcomes. I think we can, and there’s research out there that says we can.”
Fine control of the drug delivery is critical, and the AutoSyP delivers, Jackson said. “Our device accommodates syringe sizes from 5 to 60 milliliters, and the flow rate varies depending on the syringe size. It can be 60 all the way down to 5 milliliters per hour,” he said.
The AutoSyP delivers force to syringes of various sizes through a spring-driven ratchet-and-pawl escapement system, like those found in timepieces. “The idea is to regulate something that wants to unwind quickly,” said Jung, also a future medical student, explaining why the team used a battery-driven stepper motor to disengage the two pawls from the ratchet in turn.
“The spring wants to unwind the ratchet, but it’s opposed by the pawls,” Jung said. “So to knock these pawls up one at a time and allow the release in spring tension, we need to input some energy.”
Every step pushes the syringe plunger a tiny bit forward. A few simple adjustments allow a clinician to adapt the device for various syringe sizes.
They want the AutoSyP to be portable enough to be used in ambulances. “As they like to say, time is tissue,” Jackson said. “The longer you wait (to deliver treatment), the more of it is dying.”
Malya hopes to have one or more AutoSyP prototypes in Fiji for evaluation by health officials within the next three months.
“If this works in Fiji, it’s very expandable to relieve noncommunicable disease burdens in pretty much all of Africa and Southeast Asia,” he said. “If you start at Bangkok and draw a 1,000-mile radius, you cover 30 percent of the world’s population growth. It turns out many of those are middle- or lower-middle-income people who can afford bad things that make them susceptible to heart disease, diabetes and stroke.”