Viewers of the TV program "ER" get a revealing look at the conditions that confront emergency-room personnel who routinely treat gunshot wounds, accident victims, and stabbings. In such a setting, seconds count in the staff's ability to save lives. And it's under such circumstances that materials will play a growing role in improving a patient's chance of survival. Let's start with those essential staples found in any ER--bandages.
|Bandage under development at the American Red Cross combines two clotting agents, fibrinogen and thrombin, that bond with injured tissues to seal a wound.|
Blood suckers. Blood loss through wounds claims tens of thousands of lives each year. Scientists with the American Red Cross' Jerome H. Holland Laboratory for the Biomedical Sciences (Rockville, MD) have teamed with U.S. Army researchers to change that statistic by developing a bandage that clots blood instantly.
The researchers have produced bandages and other dressings that they claim can seal a severe, bleeding wound in seconds with a tough, artificial scab. If the dressings prove effective and safe, they could radically change emergency-room treatment for civilians and soldiers, saving thousands of lives now routinely lost.
Fibrinogen and thrombin, two human blood plasma proteins, hold the key to the bandages' development. Concentrating the proteins at the site of the wound speeds the natural clotting process.
Technical advances in blood work, brought on in part by recent efforts to cleanse blood products that might be contaminated, and the discovery of new ways of isolating fibrinogen and thrombin from each other until needed, opened new approaches to making the clotting dressings. With support from the Army, the Red Cross has guided this effort and is seeking patent rights to bring the clotting ingredients together in several forms.
|Lightweight, waterproof selectively permeable membrane system protects against chemicals, toxins, and microorganisms.|
Most of the effort has gone into a bandage, embedded with the clotting proteins, that a physician can press into a wound and hold in place for a couple of minutes. The researchers have also developed a self-expanding sealant foam that can be propelled into deep wounds or the body cavity to contact internal bleeding sites. A dry spray that could be squirted onto a large, open wound or burned area is also under development.
"This is a revolutionary way of using an old technology," says Dr. Martin J. MacPhee, the principal Red Cross scientist working on the project. "By delivering 10 to 20 times more clotting factor to a wound than is naturally available in the blood, the bandage can stop a gushing hemorrhage with a clot that is much, much stronger than normal." Last year, the Food and Drug Administration approved use of the first such fibrin sealants for surgical procedures.
Working with a team led by Col. John R. Hess of the Walter Reed Army Institute of Research, the Red Cross researchers discovered how to freeze-dry human fibrinogen and thrombin that had been filtered and cleaned to remove most bacteria and viruses. The freeze-dried proteins are then placed on a special backing to form a bandage that can be absorbed by the body if left in a wound.
The processed bandage is sealed in an airtight foil pack to keep out moisture that can activate it, and the pack is sterilized with gamma-ray radiation using a patented process developed by Indico Technologies (Bellevue, WA). This allows the two clotting proteins to be packaged at room temperature without reacting with each other unless moistened. The bandage uses blood itself as the liquid that activates clotting.
Initial tests of the bandage probably will be with surgical patients undergoing operations, such as prostate gland removal, that normally result in heavy bleeding. These tests may be followed by trauma studies, perhaps at centers that treat bloody liver and spleen injuries.
Human trials are about a year away, say the researchers. Negotiations are under way to find a manufacturing partner to make the bandages for the test. If successful, the bandages should receive FDA approval in three to five years. Tests of the fibrin sealant foam are another two or three years away.
Dressed to survive. Another Army project promises to not only save lives on the battlefield but also in the ER. Under development by scientists at the U.S. Army Soldier Systems Center (Natick, MA), the project involves a new generation of lightweight chemical and biological protective clothing based on selectively permeable membrane systems. The technology--a kind of reverse osmosis--also holds promise for protecting ER personnel against harmful viruses, including the AIDS virus.
Two systems are being investigated: an amine-based membrane/fabric system from W.L. Gore & Associates (Wilmington, DE) and a cellulose-based membrane fabric system from Akzo Nobel (Wuppertal, Germany). Scientists Quoc Truong, Dr. Eugene Wilusz, and Dr. Donald Rivin are the brains behind the membranes.
The selectively permeable membrane technology will reduce or eliminate the current use of carbon in chemical and biological (CB) protective clothing, the scientists say. Since carbon adds weight and bulk, the protective overgarments fabricated from the materials are much lighter than their predecessors--51% less hefty than the standard battledress overgarments, and 45% lighter than the Joint Service Lightweight Integrated Suit Technology overgarment now in use.
Moreover, the new clothing launders easily and takes up less space. Thus, the gear should prove to be a big improvement over its forerunner from a logistical standpoint.
Both materials provide protection against highly toxic compounds, including chemical and biological agents. The thin, lightweight, flexible materials also allow moisture vapor to pass through the clothing, providing relief from heat stress through evaporative cooling. And, since the systems are waterproof, they will protect users from wet weather.
Both membrane technologies have undergone successful testing on the Natick lab's Thermal Manikin. Soldiers who have assessed the new ensemble for comfort and durability in limited field tests rate it highly, Truong reports. Extensive field tests of the systems will be conducted this summer.
In addition to use by the military, scientists believe the clothing systems will become valuable assets in the ER, for industrial-chemical and pesticide handlers, and even as a sophisticated filter to separate chemicals from water vapor or other chemicals. "It's ideal for the ER," says Truong, "since it is breathable, lightweight, and filters out all types of viruses and bacteria."
Circulation amplifier. Apply small amounts of electrical current to areas of the body, and that current can move interstitial fluids to encourage blood circulation. Increased blood circulation reduces pain, promotes healing, and diminishes bacterial infection. This, in turn, creates an environment within the wound that allows the body's own healing mechanisms to take hold.
Until recently, however, the only way to apply current to the body was through conductive patch electrodes. These patches normally cover only small areas and are applied to the skin by an adhesive. Although effective, the patch electrodes cannot treat large, complex areas such as hands, feet, knees, elbows, and backs.
|Galvanic stimulation garments increase vascular flow to promote quicker healing and tissue repair.|
Realizing this drawback, the engineering staff of Medical Devices Inc. (Cumming, GA) began development of electrically conductive garments to effectively treat large areas of the body. The company established a development program with Polygenics International (Cary, NC), a specialty knitter, to design an electrically conductive garment. The material had to fit snugly, yet needed to stretch in order to make contact with areas being treated.
The design team tried many iterations, but determined that silver-coated thread blended with highly stretchable nylon offered the best economic solution. The result: CoronaTexTM, a knitted fabric garment electrode. Not only are the garments electrically conductive, but they are also cool, soft, and non-irritating. The knitted electrodes come in many sizes and shapes, including gloves and socks. Moreover, they work with most electrostimulation treatments and microcurrent devices.
"Use of these garments is ideal in the treatment of soft-tissue injuries, diabetic foot ailments, carpal tunnel syndrome, arthritic discomforts, edema, and muscle spasms," says Medical Devices President Kent Kohnken.
To date, the garments have successfully treated sports injuries, replacing the popular cold pack. The garment acts as an internal pumping mechanism to "push" the blood at an accelerated rate to the injury. This action helps drain fluid and reduce swelling.
Jack Guldalian, president of NeuMed (West Trenton, NJ), whose company distributes Medical Devices' garments under the name TheraKnit(R), predicts that the garments will soon make an appearance in the ER in an effort to improve emergency treatments and promote quicker healing. In the future, he says, the garments' pulses and signals will be linked into a virtual-reality system that can more accurately diagnose injuries on the spot.
Double-duty dog tags. The familiar metal dog tag worn by members of the armed forces may soon give way to a rugged plastic tag containing medical records on a memory chip. Data-Disk Technology Inc. (Sterling, VA) developed the new record carrier, called the Medi-Tag(R), with the assistance of DuPont Engineering Polymers (Wilmington, DE). The tag has a rugged outer shell of DuPont Zytel(R) nylon resin, with a flash-memory chip surface-mounted on an integrated circuit inside.
The chip's memory can include information on an individual's complete medical history--x-rays, allergies, medications, dental records, etc. Medical personnel around the world could read and update the record by inserting it into a slot in a standard PCMCIA card reader attached to a personal computer.
"The reliable, long-term protection provided by Zytel nylon is crucial to the tag's reliability as a permanent record," says Data-Disk President Tom Clark.
Data-Disk uses a glass-reinforced grade of Zytel based on nylon 612 polymer. The resin proved well suited for the slow, low-pressure mold filling required to avoid damaging the tag's electronic circuitry. In addition, encapsulation molding techniques developed by DuPont helped Data-Disk achieve a hermetically sealed shell that can withstand dust, fluids, impacts, abrasion, and skin oils.
Clark reports that Medi-Tag has performed well in limited tests conducted by the Department of Defense's Telemedicine Technology Area Directorate (Fort Detrick, MD). The current version of the tag has a 20-Mbyte storage capacity, with 40- and 80-Mbyte prototypes under test. The military reportedly plans to issue a personal information carrier based on this technology to all active and reserve personnel.
However, what really excites Clark are possible civilian spinoffs. He envisions its use in an ER setting to quickly alert medical personnel about possible treatment complications associated with medications or life-threatening medical problems.
For protective clothing:
Protection in combat
Protection against industrial-chemical pesticides
Freeze-dry process for blood-clotting proteins
Amine- and cellulose-based membrane/fabric systems
Meeting strict FDA requirements.
Making certain the material can withstand the harsh chemicals, temperatures, and abuse it will face in a medical/ER environment.
Assuring the material will resist any toxins and microorganisms it will encounter.
Finding the best material supplier at the best price once the product is ready for market.