As the U.S. military prepares for future high-intensity, high-casualty wars, its medics are training to do something they rarely did during the Global War on Terrorism: remove a tourniquet from a wounded soldier.

Not long ago, tourniquet training for most U.S. service members followed a simple, strict guideline: apply one high and tight to the extremities to stop life-threatening bleeding and stop removing it. to advanced medical care personnel.

A modern military tourniquet is a strong nylon strap that is secured tightly around an injured limb with Velcro and then tightened by twisting a small rod until blood flow stops.

In the GWOT era, stopping a service member’s bleeding in the field was the top priority, and the possibility of rapid medical evacuation required few additional considerations. But in large-scale combat operations, where air control is contested, both medical and non-medical troops We may need to find alternative solutions to prolonged tourniquet use to prevent the type of catastrophic damage that can result in organ dysfunction or loss of limbs.

US Army Special Forces training staff told Business Insider that students in their medical journey are increasingly expected to know how to remove them, not just apply them. Troops are ranked on those eliminations, known as tourniquet conversions, and on their ability to teach others to do the same.

“As we see more data on the battlefield of modern conflicts without that golden hour, doctors are now forced to make a decision themselves about when and if they reverse that tourniquet,” said the head of the Army’s special operations medical course, a trauma expert who spoke to Business Insider on condition of anonymity. “If you don’t, you’ll lose that limb.”

Tourniquets are among the most important life-saving tools in a medical kit, according to the Army’s Tactical Combat Casualty Care guidelines, and hemorrhage is the leading cause of preventable death on the battlefield. When in doubt, applying a tourniquet to an injured patient remains a safe decision, the chief said.

But the complexity of Ukraine’s battlefields, where widespread surveillance and attack drones have often made timely evacuation of victims impossible, has shown that this is not always a hard and fast rule.

There, doctors are forced to care for combat casualties for a longer period of time, which requires them Find other ways to control bleeding to avoid the damage that can occur from leaving tourniquets on for too long. Troops in Ukraine have previously told Business Insider that prolonged use has turned injuries that should have been an “easy fix” into life-altering amputations.

When blood flow is restored after prolonged tourniquet use, toxins from damaged tissue can be released into the bloodstream, potentially damaging the kidneys. Ukraine has reported an increase in demand for dialysis among wounded troops who have been on tourniquets for too long. Permanent nerve damage is also a concern.

One of the clearest lessons emerging from Ukraine is the need for more troops to understand tourniquet conversions, said Col. Ken Dwyer, commander of the Army Special Warfare Center and School, which oversees student training.

“I put a tourniquet on to save this guy’s life. But at some point, I need to find a less destructive way to control that bleeding,” Dwyer said. “I have to take that tourniquet off and see if a pressure bandage works or something else works, and try to save that limb.”

Students, including Navy medics assigned to Navy special operations and reconnaissance units and Army medics assigned to the Rangers and Green Berets, are also expected to teach tourniquet conversion to other service members and allied forces, the course head said. (Navy SEAL and Air Force special operations medics attend separate training courses.)

Troops who fought in Iraq and Afghanistan were taught to apply tourniquets, but rarely to remove them; Loosening one too soon can restart massive bleeding.

That approach reflected the nature of the wars the United States fought and its overwhelming air superiority: Casualties were often evacuated by helicopter within the military’s “golden hour” to well-staffed trauma centers, where surgeons and trauma specialists could safely remove the tourniquet.

Evacuating victims in Ukraine is now so difficult and dangerous that ground robots are increasingly being used to evacuate troops, with varying degrees of success. Deploying medical teams for rescue is risky and helicopter evacuations are often impossible.

“The durability of a prehospital tourniquet has been a concern for a long time,” said John Holcomb, a traumatology professor at the University of Alabama who previously directed the Army Surgical Research Institute and served as a trauma consultant to the Army Surgeon General.

But “it was less worrying in Iraq and Afghanistan because we had a very quick evacuation, right? We controlled the air.”

After the chaos of combat, he said, victims arrived at well-lit, well-staffed medical facilities, where providers had the time and resources to reevaluate tourniquets. Even those that might not have been necessary could be removed quickly enough to avoid complications.

Ukraine has forced military trauma experts to reconsider the assumption that victims will quickly receive advanced care.

“When you don’t control the air, when you’ve denied prolonged evacuation, then you put on a tourniquet, if you leave it on for more than two hours, it can cause more problems than the wound,” Holcomb said.

Stacy Shackelford, a professor of emergency medicine and former director of the Army’s Joint Trauma System, called the shift a “180” driven by lessons from Ukraine. “Every person who is trained to apply a tourniquet must also be trained to remove it,” he said.