The tourniquet--the last-resort device used to temper the blood flow to an injury--is almost as old as warfare itself. The Romans reportedly used straps of bronze and leather to slow down bleeding, most often during the amputation of a limb. The early appliances used by Romans have seen surprisingly few design updates (perhaps partly due to a sullied reputation around the time of World War II, when tourniquets were blamed for causing amputations rather than saving lives). So last year, the Portland, Oregon–based design firm Ziba worked with SAM Medical equipment to update the tourniquet.
A standard-issue tourniquet is a belt-like compression device that’s tied around the thigh or upper arm when either limb has been severely injured, or even lost. It stalls circulation from the heart, giving medics time to move and treat a wounded person before they suffer from too much blood loss.
The early 1900s saw one major advancement in tourniquet design: The pneumatic tourniquet, which used an air-inflated cuff to cut off blood flow. This helped prevent a too-tight tourniquet, which could cause skin and nerve damage, among other complications. On the downside, that airflow required a separate portable electronic device. This clunky problem was one of two major insights that drove the Ziba design team to create a lighter device: “You pretty much have 90 seconds to save a soldier’s life,” says designer Niklas Gustafsson. “The most important thing was speed.”
The Ziba team got the tourniquet down to 1.1 pounds (the standard Combat-Ready Clamp used by the military weighs 1.6 pounds). They did this by cutting down on what Gustafsson calls the “nice-to-have padding,” as well as on the amount of Velcro, which, while thought to help secure the device, can actually cause delays and some fumbling by over-sticking to the surface area.
A medic’s pack can weigh up to 40 pounds. “So, it’s crammed in with a lot of stuff. It has to be really lightweight, but it still has to be rigid so it can’t be too flimsy,” Gustafsson says of why they constructed SAM out of a strong yet flexible ballistic nylon material. Incidentally, making the tourniquet lighter also makes manufacturing cheaper: it retails for $350; the Combat-Ready retails for around $760.
Standard-issue tourniquets also have another crucial limitation: They’re only effective when secured around a thigh. In particularly gruesome scenarios, a victim’s entire leg could be lost, or the injury could include a shattered pelvis. Ziba's junctional tourniquet goes around the lower abdomen, and because of a compression device, targets arteries headed toward the legs. Gustafsson describes it as “a small, specially designed inflatable bladder that puts direct pressure on the artery feeding the legs, as opposed to regular tourniquets that encircle and compress the entire limb.” This is the most crucial difference between the SAM Tourniquet and older models: It singles out the arteries, and spares the rest of the tissue and muscle in the leg, which can be unnecessarily damaged.
As mentioned earlier, the tourniquet fell out of favor around World War II, partly due to the risks involved in over- or under-tightening the apparatus. They’ve since come back into the medical community's good graces and were essential to saving lives during the Boston Marathon bombings. “As we began to take a hard look at how to respond to these types of incidents, what became clear was that the sooner you can stop victims from bleeding, the higher likelihood you will have for reducing fatalities,” John Cohen, a senior counterterrorism official at the Department of Homeland Security, told the New York Times.
To make tourniquets as foolproof as possible (and therefore faster to use and more effective) the Ziba team worked with SAM to build a custom buckle with an internal spring mechanism. As the medic pulls on the straps, that mechanism can sense when the compression has reached the optimum 150 Newtons, and then locks. All of this can be done with one hand, making it epitomize what SAM Medical's CEO and founder, Dr. Sam Scheinberg, believes a battlefield device should be: "bomb proof and brain dead."