How One Doctor Fights the Grim Spectre of Bleeding to Death

Traffic is moving well. I’m in a car with Dr. Sandro Rizoli, somewhere between Toronto and Hamilton, Ontario. There are coolers full of blood in the back seats and trunk. “If someone rear-ends us right now,” Dr. Rizoli says, “they’re going to feel really bad: there’ll be blood everywhere.”

He jokes, but he takes car accidents very seriously in his work as a surgeon. Car accidents are one of the leading causes of life-threatening injuries, what doctors call trauma. Of all the Canadians admitted for trauma each year, 6500 die. It is the leading cause of death for people under the age of 45 in Canada and worldwide.

“Trauma patients die from two things: head injuries or bleeding,” says Dr. Rizoli. Head injuries and brain damage are tough, but “patients that don’t stop bleeding are worse. No matter how well we stitch them up, if they keep bleeding, they won’t get better.”

Dr. Rizoli is the director of trauma research at the Sunnybrook Institute and an assistant professor at the University of Toronto. His research focuses on bleeding and trauma. He is also my dad, which is why I am in the car with him. He needs someone to carry the coolers.

Normally, the body stops bleeding by coagulating. Coagulation is the process that creates scabs, like when you scrape your knee. It keeps you from losing blood, and is the first step in healing.

Trouble is, trauma patients’ bodies do not act normally. Injury and shock can cause patients to become coagulopathic, that is, unable to stop bleeding. The chemical processes involved in coagulation may have trouble because of complications like hypothermia or increased blood acidity. It is also possible that patients have already lost too much blood, and along with it, many of the chemicals and building blocks needed to clot. Without scabs and clots, organs fail and patients die.

In trauma “we have to make most decisions looking at the patient. Problem is, that’s too late,” says Dr. Rizoli. If doctors knew that a trauma patient will become coagulopathic, they could do something about it. “What we need is a warning.”

Searching for the red flag that says: “I can’t stop this bleeding, deep inside of me”

Dr. Rizoli’s most recent work is searching for just that. He and his researchers at Sunnybrook are studying a blood test called thromboelastography (TEG, for short) that may be able to identify coagulopathic patients quickly.

Blood tests commonly used in trauma are not very good at this. “[They] don’t give us enough of the right kind of information.” Dr. Rizoli believes TEG may provide the right kind of information. While other tests isolate certain aspects of blood clotting, TEG uses whole blood and can provide a “big picture understanding” of coagulation.

The mechanics of thromboelastography are reasonably simple. A blood sample is put in a cup. This cup rotates gently, simulating the movement of blood in the body. A small cylinder is lowered into the middle of the cup. The cylinder and the cup do not touch, so that the rotation of the cup doesn’t rotate the cylinder.

Over time, the blood begins coagulating and clots form between the cup and the cylinder. The clots connect them and the cup’s motion begins to rotate the cylinder. By measuring when and how the cylinder moves, it is possible to see how quickly the blood coagulates, how strong its clots are, and how soon they fall apart.

TEG results can tell doctors “not just what’s wrong, but how to treat it,” says Dr. Rizoli. If the time before clotting is too long, patients may be missing the chemical factors that start the process. If the clots are weak, patients may be missing platelets, the building blocks of scabs. If the clots fall apart too quickly, the patient may need drugs to keep them from doing so.

This information could not only save lives, but also blood. Dr. Rizoli tells me about one patient who would not stop bleeding, despite doctors’ best efforts. The patient required so much that the hospital had to re-schedule operations for lack of blood. Identifying and treating coagulopathic patients early may reduce the need for massive blood transfusions later on, reducing the demand for blood.

Calibrating Coagulation

Strangely, this potentially useful test has been around for over fifty years. It was first described by Dr. Hellmut Hartert in 1948, and has been used by anesthesiologists and cardiac surgeons for years.

One of the reasons why taken trauma doctors haven’t already looked at TEG is that it’s been very difficult to carry out quickly and consistently. TEG machines have only recently become practical thanks to computer technology, explains Dr. Rizoli. Computers can graph and calculate much more quickly than trauma docs, who work under a great deal of pressure.

“Still, it’s not perfect. It’s a needy machine.” It needs to be calibrated three times a day. It requires a certain temperature. It has to be in a place where it won’t be bumped, since that could break clots and ruin the results. These things can be controlled in a scheduled operation, but not in a chaotic emergency room.

It is also hard to tell which TEG results are normal and which are a sign of trouble. In heart surgery, doctors can compare results taken during the operation to results from before the operation. Unforeseen differences between them indicate blood problems. “But they see the patient normal and then mess them up. With trauma, they come in already messed up.” There’s no before to compare to. According to an upcoming paper by Dr. Sandro Scarpelini, TEG in trauma “remains scarcely used due to lack of standard techniques and normal values.” If the test is going to be useful in trauma, doctors need a standard to compare their results to.

Which is why we’re chauffeuring three gallons of blood. It comes from 600 trauma patients, collected as part of a large study headed by Dr. Rizoli. The 2200 samples were taken while the patients were being treated at the hospital. Every time blood was required for a test, a sample was also taken for TEG testing.

These TEG tests were carried out very precisely. “We standardized everything,” says Dr. Rizoli. “From the gauge of the needle [used to take the blood], to how many times to shake the bottle, to how long the machine had been left on.” A dedicated technician carried out the tests.

We are taking the blood samples to a laboratory at McMaster University that specializes in blood analysis. In the next few months, they will be examined for traces of the chemicals involved in coagulation and evidence of clots. These results will be matched against the TEG results, as well as patient histories.

“We want to see whether TEG picked up on patients who couldn’t clot.” If it did, the information could be used to establish standards for TEG testing in trauma, and perhaps lead to its use in the trauma centre.

Other researchers are also excited by the potential of TEG. Dr. Kenji Inaba, a trauma researcher at the University of Southern California, has recently acquired a TEG machine. He has been “playing with TEG using pigs’ blood,” and is “just getting comfortable with it.” When he hears of Dr. Rizoli’s study, he’s impressed. He believes that there is “a lot of interest in TEG in trauma,” and that the study will “beat everybody to the punch.”

Dr. Rizoli says that may be, but that there’s still a long way to go. Data is still being collected from patients that have been at the hospital a long time. “There’s a massive amount of data.” It took almost four days just to label all the blood samples. It will be months before the test results and patient histories are matched up and analyzed.

In comparison, carrying those coolers isn’t really so hard.