By David Brown
Monday, November 1, 2010; 5:13 PM
AT BAGRAM AIR BASE, AFGHANISTAN Bleeding to death has always been the chief hazard of war wounds - and the control of bleeding the first task of the combat surgeon. Ambroise Pare knew that 460 years ago.
A French physician who treated some of the first combat wounds caused by firearms, Pare observed in 1550 that when amputating a limb there was less bleeding if blood vessels were tied off with silk thread rather than cauterized with a hot iron. For that and other gentler practices he became known as the "father of surgery."
Pare's professional descendants are still obsessed with bleeding.
The improvements in the care of casualties that have come out of the Iraq and Afghanistan wars almost all involve hemorrhage, the medical term for bleeding. They include better ways to stop it, keep it from restarting, and reverse it by restoring blood to the circulation (an option not available to Pare). They Improvements in treating hemorrhage are the main reason survival of battlefield casualties is so much greater now than in the past.
Data presented at a conference in August revealed that 8.8 percent of the U.S. combat casualties in Iraq and Afghanistan died, either on the battlefield or later of wounds. That compares with 16.5 percent of the Vietnam War's casualties and 22.8 percent of World War II's.
A different analysis compared battlefield injuries that occurred between 2003 and 2006. Those in the later year were more severe on average than those in 2003, but mortality wasn't significantly greater. For the subset of "blast injuries" - the most common cause of trauma - wounds in 2006 were more extensive, severe and likely to take a soldier permanently out of service than those of 2003. But they weren't more likely to be fatal.
The conclusion: Medical treatment has gotten better over the nine-year course of the wars.
Almost none of the improvement is the consequence of new drugs or new devices. Most of it, ironically, involves old technology and old practices that fell out of favor in the past 50 to 100 years and have been rediscovered and improved.
And nearly all of them involve blood.After Mogadishu
The modern focus on battlefield hemorrhage came out of the disastrous military operation in Somalia in 1993 chronicled in the book and movie "Black Hawk Down."
Over a 15-hour period, about 170 U.S. soldiers were involved in a battle in the narrow streets of Mogadishu where they'd gone to capture a Somali warlord. Helicopters crashed, soldiers were trapped and fired on by civilians, and rescuers got lost. More than 100 troops were wounded, 14 died on the battlefield, and four died later at hospitals.
Several years after the event, military physicians analyzed every serious injury and death that occurred. They wanted to learn whether any could have been prevented, or if any of the care had unwittingly led to more casualties.
The analysis showed that bleeding was a huge problem, leading to most of the deaths. Several people bled to death from wounds in places where direct pressure wasn't possible, such as the chest or neck. One person, however, was saved by an improvised tourniquet on his thigh.
"The emphasis on hemorrhage control certainly stemmed from that episode," said John B. Holcomb, one of three surgeons who treated the wounded. "There was a lot of introspection. Frankly, I think the military was ready for a change."
The new treatment strategies weren't all hatched out of the Mogadishu experience. Many were already in development. But Somalia accelerated the process.
The single most important change was the endorsement of tourniquets, ancient devices that for the second half of the 20th century were considered too dangerous to use because extended use can cause tissue damage. The new ones optimize the force distributed across the strap and can be tightened and locked with one hand. Every soldier carries one, and medics carry a half-dozen.
Tourniquets are especially useful in wars where blast injuries, not gunshot wounds, predominate. Many makeshift bombs damage both legs or blow them entirely off. A person whose femoral arteries, the main arteries of the thigh, are both severed will die in about seven minutes. Today, many soldiers with such wounds arrive at the hospital with tourniquets on each leg and all bleeding stopped.
Their usefulness is so obvious that some soldiers here go on foot patrol with them loosely placed on each limb, ready to be tightened. Designers of the next-generation combat dress are trying to determine whether the devices can be built into the clothing, possibly with gas canisters that can be triggered to inflate them.
Military analysts estimate tourniquets have saved the lives of at least 1,000 U.S. soldiers, and possibly as many as 2,000, in the current wars.
Of course, many soldiers suffer wounds in places - such as the neck, chest, abdomen and groin - where tourniquets can't be used. An analysis of "potentially survivable" wounds in soldiers who died after reaching the hospital showed that 80 percent succumbed to hemorrhage, and 70 percent of the time it was from one of those "non-tourniquetable" sites.
A new generation of bandage, called Combat Gauze, may help solve that problem. The fabric is impregnated with kaolin, a powdered clay that stimulates blood clotting. It has proved more effective than clot-forming powders and granules, which often blew away or were washed out by bleeding.
Despite these devices, most soldiers with major trauma lose life-threatening amounts of blood. How medics respond to that condition is the second big innovation in hemorrhage care.
The innovation? Do less than you can and let the body run the show.Simple assessments
Medics are now taught not to worry if a person's blood pressure is as low as 85/40 (normal is 120/80) as long as the patient is alert. People in shock - severe low blood pressure, which causes mental confusion or unconsciousness - get up to a liter of intravenous fluids. Others get a catheter that is capped and can be used later if needed to push fluids into a vein. Gone is the routine hanging of a bottle of fluid, part of the classic visual tableau of battlefield care.
The preference for keeping the blood pressure low in trauma victims - both because they can tolerate it and because raising it can dislodge clots and make matters worse - was well understood in World War I and World War II, according to Holcomb. But by the time of Vietnam, "it seems as if that concept was lost," he said.
In the adoption of an even older practice - one Hippocrates would endorse - medics are told to evaluate a patient's status only by looking at him, talking to him and taking his pulse. Pulse - now taken in the wrist, not the neck, because it's easier to find - is characterized as "absent," "weak" or "normal." On this assessment, lifesaving decisions can be made.Magical powers
The third big blood-related innovation involves what happens in the emergency room's trauma bay and operating room.
In the past, patients in shock were resuscitated with IV fluid, supplemented with red blood cells. Now they're given whole blood or its equivalent in components.
Blood is a mixture of about 45 percent cells and 55 percent plasma. The latter consists of water, sugars, salts and proteins, including the "clotting factors" that trigger a cascade of reactions ending with the formation of a blood clot. As a trauma patient bleeds, those proteins are consumed. If transfusions consist mostly of oxygen-carrying red cells and not enough plasma, bleeding eventually goes out of control.
To prevent that, some military physicians give Factor VIIa, one of the proteins, to people getting 10 or more units of blood in 24 hours. (Such casualties are called "massively transfused" patients.) But there has never been a definitive answer on its effectiveness - and there is not likely to be, because randomized controlled studies, the kind most likely to provide an unbiased answer, are not permitted on the battlefield where the patients cannot give consent.
What does unequivocally work is whole blood.
Whole blood's near magical power to revive trauma patients was recognized on the Western Front in World War I. But when scientists later learned to separate and store blood components - red cells, plasma and clot-initiating particles called platelets - whole-blood transfusions fell out of favor.
But in some situations, where there is no blood bank, using whole blood freshly collected from donors is the only choice. The second battle of Fallujah in Iraq in November 2004 was one of them. Dozens of casualties were massively transfused with whole blood. All survived to be evacuated.
"It was just unbelievable that you could have this kind of success record. It made us stop and ask how this was happening," recalled Donald H. Jenkins, who was a surgeon in Iraq during that Fallujah battle and is now director of the trauma center at the Mayo Clinic in Rochester, Minn.
He and other military doctors later analyzed the experience of soldiers massively transfused at the main military hospital in Baghdad early in the war. The rate of survival was nearly nine times as high for the people who got whole blood (or the equivalent of it in components) as for those who got mostly red blood cells and IV fluid.
Military doctrine now is to give blood in a 1:1:1 ratio of red cells, plasma and platelets. But when surgeons occasionally turn to the "walking blood bank" of registered donors for whole-blood transfusions, they notice an especial benefit.
"It seems like you just give this stuff and it works," said Rodd Benfield, a Navy surgeon now operating at the hospital at Kandahar Air Field. "It's warm, it's fresh and it's blood!"
Replacing blood lost with whole blood or its equivalent in components doesn't just help restore clotting. It also reduces the risk of acute respiratory distress syndrome (a condition first recognized during the Vietnam war, where it was called Da Nang lung) and multi-organ failure. And the fresher it is, the better.
A study done by Holcomb and others showed that in massively transfused patients, mortality goes up if they get blood more than two weeks old. Old red cells don't carry oxygen as well as newer ones, and they don't form as strong clots. Fresher blood also helps reduce infection.
At the hospital here, where grievously wounded patients arrive every day, the goal is to give massively transfused patients blood less than 21 days old.
On a recent night, surgeons were operating on someone who had stepped on a mine and lost both legs at the knee. He'd received 13 units of blood in the appropriate components - about a pint more than an adult typically has in the circulatory system.
The anesthesiologist called for another unit of red cells. When it arrived, a nurse held the bag out for him to inspect.
"That blood is going to expire in four days," he said. "That's garbage."
He sent it back and got a newer one.