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Air Force researchers develop kidney care for austere environments

  • Published
  • By Peter Holstein
  • Air Force Surgeon General Office of Public Affairs
Acute kidney injury is a common side effect of combat injuries. A new device being developed by Air Force researchers from the 60th Medical Group at Travis Air Force Base will treat the life-threatening symptoms of AKI closer to the point of injury, saving the lives of wounded service members.

In Iraq and Afghanistan, about 12.5 percent of casualties develop AKI as a result of their injuries. These injuries are usually not directly to the kidneys, but occur when the kidneys are stressed. Often, they are damaged from blood loss, or from trying to filter blood that has waste products in it due to another injury. One of the most serious outcomes of AKI is hyperkalemia, or unusually high levels of potassium in the blood. This affects 5 percent of critically injured casualties, and is often seen with severe burns, crush injuries or heavy bleeding. Untreated, hyperkalemia can quickly lead to heart problems and sudden death.

Fortunately, there are treatment methods for AKI that prevent these effects. However, they involve bulky equipment and a high volume of special fluid, up to 100 liters in a single day.

“Right now, we can’t push treatment for AKI any farther forward,” said Maj. Ian Stewart, one of the 60th MDG researchers developing the new treatment. “Patients requiring acute kidney care are either evacuated to Ramstein Air Force Base in Germany, or we have a smaller dialysis machine deployed to Bagram Air Force Base in Afghanistan.”

Since most symptoms of AKI take several days to manifest, this process works well for the current conflict. Today’s battlefield care and speedy aeromedical evacuation system gets severely injured patients to these large, sophisticated dialysis machines within one to two days, before they suffer from the life-threatening symptoms of hyperkalemia. But this may not always be the case. To prepare for unknown future conflicts and adversaries, researchers are studying new ways to deliver battlefield care.

“New military doctrine that says we need to be ready to care for patients for a prolonged time at earlier echelons of care, like in a field setting or forward operating base,” said Stewart. “If patients are in-theater longer, they are going to develop AKI. How are we going to treat those patients?”
Maj. Stewart’s team thinks they’ve found an answer, by simplifying the kidney dialysis process so it can be delivered in austere settings.

“We’ve been working to minimize the foot print for acute kidney care, making it incredibly small so that care can be offered downrange,” said Stewart. “We are focusing on the buildup of potassium in the blood that leads to hyperkalemia, which can be fatal in the short term.”

Targeting the earliest and deadliest symptom of AKI allows for a simpler treatment protocol that doesn’t require large amounts of fluid. Using a small, commercially available rapid infuser pump, already common used in military medicine, the researchers run the blood through a new filter to help remove excess potassium before it can cause too much damage to a patient’s kidney.

“We identified items that would be available in relatively austere locations that could take the place of the complicated dialysis machine,” said Stewart. “We repurpose something already there, which removes a huge part of the footprint. We had to develop a small filter, about the size of two soda cans, to filter the potassium, which replaces the need for liters and liters of fluid.”

Working with industry partners, Maj. Stewart’s team is in the initial testing process. The new device must receive approval from the U.S. Food and Drug Administration before it can go into production, but Maj. Stewart is optimistic.

“We have done a fair bit of the early experiments now, and the results have been very encouraging,” said Stewart. “If we face a situation in the future where we can’t evacuate patients right away, we need to have a plan in place to save their lives from conditions like hyperkalemia. Simplifying care for AKI will allow us to project lifesaving capability almost to the front lines.”