Breathing in a Bag Could Improve Transplantation

iver or heart transplants are fraught with danger long before the body can even think of mounting an immune rejection. The danger stems from a cascade of reactions that begin when donor organs and their oxygen supply first part company. Both the initial lack of oxygen—the ischemia–and the reperfusion as blood flows back into the organs unleash tissue-damaging free radicals.

Until recently, no one knew the extent of damage to the organs, exactly when it occurred or when best to take steps to limit it. But Hopkins pathologist Terence Risby, Ph.D., has found a way to monitor what’s going on that’s both elegant and as straightforward as breathing.

“There’s more to breath than halitosis,” says Risby, whose instrument for analyzing all sorts of oxidative damage is patients’ exhaled breath. Specifically, he collects their breath in plastic bags, then uses gas chromatography to assay minuscule amounts of ethane. “You get ethane,” he says, “when the free radicals react with lipids in cell walls. The more ethane, the greater the damage.”

Risby has shown that damage definitely occurs when organs are being transported, when they’re warmed prior to surgery and, afterward, when blood again surges through them. Further, his animal models show that antioxidants given during surgery greatly protect transplanted tissues.

“The oxidative damage doesn’t just occur during transplants, though,” Risby says. Cardiopulmonary bypasses during heart surgery and temporary blood shutoff during repair of aneu-rysms also do harm. “We think the mild strokes that some people have after bypasses are a direct result of ischemia.”

Now Risby is developing a monitor for ethane that will give an instant readout and extend the technique’s use: “During surgery, we could probe—in real time—what’s going on in a pa-tient’s blood.”

—Marjorie Centofani