GUT CHECK: DARPA says it is studying a new type of injectable foam that molds to organs and slows hemorrhaging. This could help field medics buy more time for wounded soldiers en route to medical treatment facilities.
Image: Courtesy of the Defense Advanced Research Projects Agency (DARPA)
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Despite their best efforts to stabilize abdominal wounds sustained on the battlefield, military first-responders have few options when it comes to stanching internal bleeding caused by, for example, gunshots or explosive fragments. The Defense Advanced Research Projects Agency (DARPA) says it is studying a new type of injectable foam that molds to organs and slows hemorrhaging. This could provide field medics with a way to buy more time for soldiers en route to medical treatment facilities.
The polyurethane foam begins as two liquids stored separately and injected together into the abdominal cavity. One liquid is a polyol, a type of alcohol. The other is made of isocyanates, a family of highly reactive chemicals widely used in the manufacture of flexible and rigid foams. Within about one minute after a medic inserts the liquids at the midline—near the belly button—the mixture expands to nearly 30 times its original volume and then turns solid. It slows or halts hemorrhaging by sealing wounded tissues. Once the patient can get to intensive care, doctors would remove the solid mass and then perform surgery to permanently stop any bleeding.
“Initial battlefield care is provided in austere, often hostile conditions by field medics,” says Brian Holloway, program manager for DARPA’s Wound Stasis System program, which was launched in 2010 to find a technological solution to control internal hemorrhaging. The foam, made by Arsenal Medical, Inc., indiscriminately blocks the sources of the bleeding, almost like a scorched-earth campaign against blood loss.
“We’ve been waiting for this," says Donald Jenkins, trauma director at Saint Mary’s Hospital in Rochester, Minn., and a 24-year Air Force veteran who has spent more than 700 days in combat zones, including in Afghanistan and Iraq. When asked how often he has seen soldiers suffer from abdominal hemorrhaging caused by explosives or gunshot wounds, he pauses and says, “Too many times.”
Arsenal Medical initially developed the foam to serve as a delivery mechanism for another treatment that would differentiate between healthy and wounded tissue, and then stop bleeding by binding only to the wounded portion. Using swine as subjects, researchers induced liver injury by wrapping a wire around the organ during surgery, closing the animal, and then pulling on a portion of the wire that had been left protruding through the skin. They waited 10 minutes between pulling the wire and injecting the two liquids in order to allow the blood to pool inside the body, as it often does in combat wounds.
Researchers were surprised at what they found when they removed the solidified foam. “When we saw the animal models that we had used, we realized that we had solved the [internal hemorrhaging] problem,” says Upma Sharma, lead researcher on the project. The foam reduced blood loss sixfold in those tests, and three hours after the injury the survival rate was 72 percent in the treatment group versus only 8 percent in the control group. Swine are often used as test subjects because pigs have an organ structure very similar to humans.
This particular foam is one of about 1,300 that Arsenal Medical researchers tested as they experimented with variables such as the rate of expansion and the amount of time in which the two chemical precursors became a solid foam. The researchers also had to consider whether or not the foam reacted with other fluids in the body. “We specifically engineered it as a two-part system so it would interact with itself,” Sharma says, explaining that the liquids, once injected, could not have a chemical reaction with other bodily fluids. Some foams also would not work because they could not push against the blood flow or they stuck to the tissue.
Although Arsenal Medical’s foam has a lot of potential, it still needs some work before it is field ready. After the material solidifies, it can cause bruising. In addition, the reaction between the two liquids generates heat, which raises the temperature of surrounding tissue by about 2 or 3 degrees Celsius. Sharma says this temperature increase is on par with a high-grade fever. Some patients might also have an allergic reaction to the foam.
Jenkins points out another potential problem: Pieces of solidified foam could break off inside the body and go adrift in a patient’s bloodstream, eventually blocking blood flow to the legs or lungs. Sharma says the researchers have not seen any evidence of this happening, however.
Nevertheless, Jenkins sees some promise in this new approach to a common problem for field medics, and perhaps first-responders in remote rural areas. “If half the deaths on the battlefield are torso hemorrhaging, and you were able to save 10 percent, would the survivors say it’s worth [the risk]?” he asked. “I’d say yes.”
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9 Comments
Add CommentAbsolutely right direction to go as far as putting money and time into something worthwhile.
Reply | Report Abuse | Link to thisIt's hard to see how the injection of those two liquids to form foam do not violate the first rule in medicine:
Reply | Report Abuse | Link to this"Primum non nuture" - First, do no harm.
Big problem - all that "solid" in the abdominal cavity will make it harder for the operating surgeon to identify small intestinal injuries. And yet even a "tiny" leak releases billions of bacteria - inviting an abscess or sepsis.
Big problem - all that "solid" in the abdominal cavity will be hard to totally remove by the surgeon at the time of laparotomy.
Removing "only" 99% will still leave plenty material for "adhesions" to form. Adhesions are "scar tissue" attachments of the intestine to each other and other structures in the abdominal cavity. Adhesions serve as points where intestines can twist around - causing an obstruction needing surgery to relieve.
This will remain a life-long "curse" that could rear its head at any time, any age.
Big problem - "Isocyanates" are one of the two liquids being injected to form the foam. Clicking on the link above where the term "isocyanates" is introduced, leads to the following information from the Center for Disease Control:
"Isocyanates are powerful irritants to the mucous membranes of the eyes and gastrointestinal and respiratory tracts. Direct skin contact can also cause marked inflammation. Isocyanates can also sensitize workers, making them subject to severe asthma attacks if they are exposed again. Death from severe asthma in some sensitized subjects has been reported. Workers potentially exposed to isocyanates who experience persistent or recurring eye irritation, nasal congestion, dry or sore throat, cold-like symptoms, cough, shortness of breath, wheezing, or chest tightness should see a physician knowledgeable in work-related health problems.
Preventing exposure to isocyanates is a critical step in eliminating the health hazard. Engineering controls such as closed systems and ventilation should be the principal method for minimizing isocyanate exposure in the workplace. Other controls, such as worker isolation and personal protective clothing and equipment may also be necessary. Early recognition of sensitization and prompt and strict elimination of exposures is essential to reduce the risk of long-term or permanent respiratory problems for workers who have become sensitized."
- http://www.cdc.gov/niosh/topics/isocyanates/
Besides the severe peritonitis pain from the injection of the noxious isocyanates, the inflammation likely would cause adhesions resulting in the lifelong risks explained above.
Considering how bad an abdominal wound is, this is great. To many times if the wound is open and the sack broken there is little that can be done than watch the victim die. This is some of the best tools I've seen for a medic on the field. The saddest thing to see is someone trying to put their intestines back in and the amount of pain involved in a wound in that area.
Reply | Report Abuse | Link to thisAlthough I applaud such a development, I prefer not to have war.
Reply | Report Abuse | Link to thisThis would be a last ditch effort to stem massive hemorrhaging, with impending death.
Reply | Report Abuse | Link to thisIf a penetrating wound such as a gunshot is going to cause death within a couple of minutes, and nothing else is available, then this is it.
If you ask the injured soldier, and probably they are unconscious at this point, do you want to accept the risk, or die, he's going to try to survive, and deal with the other complications later.
There are developments for battlefield medics, even remote battle field surgery, performed by a surgeon at a remote location, possibly even on the other side of the world via the internet, using remote manipulators.
Battlefield stretchers are being developed with potential to start IV's and have equipment for performing remote surgery. It's almost a survival capsule.
Much surgery is performed by robotic or remote surgery anyway now.
The idea in battlefield medicine is to stop bleeding, restore volume with blood or plasma expanders to treat shock, and stabilize vital signs until the person can be treated more definitively at a forward based hospital.
Air evacuation has assisted greatly in improving battlefield survival and massive transfusions of platelets have helped to reduce hemorrhaging.
Actually they don't want to raise blood pressure to normal levels, since it will cause even more hemorrhaging.
Techniques developed on the battlefield are being utilized in big city hospitals where gun shot injuries are all to common and actually fatalities have decreased substantially, although gun shot injuries persist at high levels of occurrence.
The treatment with polyurethane foam could have civilian applications as well. Certainly massive injuries occur during vehicle accidents and sometimes hemorrhaging from abdominal injuries is extensive.
Again, the initial treatment of massive injuries is the critical time. If hemorrhaging can be avoided and severe shock avoided, then there is potential for recovery, however if the blood pressure drops below tissue perfusion pressure, then organ failure begins immediately with immediate effects on the brain, within seconds or a couple of minutes, and other organs such as kidneys and liver are not far behind. Shock liver is another very difficult issues in treating critically ill persons and if the kidneys lose perfusion pressure, kidney failure will occur with necessity for dialysis or organ transplant.
Should be able to simply peel the mass loose from the organs - so long as it did not actually encase them.
Reply | Report Abuse | Link to thisSmall bleeders will have sealed on their own - the only worry will be reopening them.
While far from perfect, it IS a step in the right direction. The next step will be to make it biodegradable, and preferably nutritiously absorbable by the body (mights well get some use out of what's dissolving, right?)
As far as allergies go - if I'm going to bleed out before there's a chance of help, or have my intestines rot because of the digestive juices all over everything - I'll take the chance of anaphalactic shock - at least it will be quicker.
As far as the pain goes - with the pain and trauma of that major a wound, likely won't feel the additional agony.
Can see where it would be a right royal pain in the operating room getting that styro out, though - maybe some kind of dissolvant to make it easier?
I like the fact you are looking beyond the battle field. I know the gentleman that would prefer no war probably speaks for all of us or at least those who understand the cost of war. But as a first aid response to what is normally a mortal wound, this has so much merit. The ideal of easily peal able may not be that complicated if there was a way to inject a neutralizer into to gel.
Reply | Report Abuse | Link to thisAnything is better than watching a person try to put their intestines back into their body. You want to help them and you will but the stench, the blood and the crap (literally) is a lot to face in that situation. This is a much healthier approach and probably allows for a better outcome for the patient/victim.
You sound like a surgeon, I was on the other side of the coin with a perforated ulcer and the pain was so intense that anything that offered hope until the surgery is a welcome sight. You did hit on the potential harm from the chemicals, but chemicals do strange things when they mix and often become less of the problem than the wound. Good input on a very serious wound or condition and the pain it induces does not leave the patient very coherent as to options. I know in my case I said no more surgery, I don't recover well. The surgeon easily changed my mind by telling me to enjoy the last 6 hours of my life.
Reply | Report Abuse | Link to thisgreat creation! like an absorbent sponge, not to water, but to blood.. ahh
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