Stopping the triad before it starts
One of the greatest challenges in treating patients with multisystem injuries is a group of interrelated symptoms, collectively known as the trauma triad of death. The conditions that make up the triad — hypothermia, coagulopathy and acidosis — compound one another in an escalating chain of events that, if untreated, results in irreversible tissue damage and death.
According to Terri A. Elsbernd, R.N., pediatric trauma coordinator at Mayo Clinic in Rochester, Minn., the precipitating factors are hemorrhagic shock, hypotension and resulting hypothermia.
"Up to 66 percent of trauma patients have diminished body temperature," she says. "It doesn't matter what the geographic region is or the time of year, most trauma patients are hypothermic. Resuscitation efforts, including the use of unwarmed fluids and red blood cells, can cause a significant drop in body temperature, too."
Hypothermia is the gateway to the triad because almost all clotting mechanisms are temperature dependent. Cold inhibits the clotting cascade, leading to coagulopathy. Unchecked hemorrhage, in turn, decreases blood pressure and the amount of available oxygen, causing cells to convert to anaerobic metabolism. The resulting release of lactic acid further hinders clotting and cellular function, which leads to decreased cardiac output and even less available oxygen.
"In other words, people become more hypothermic, more coagulopathic and more acidotic in a vicious cycle. And that's what kills patients," Elsbernd says. She adds that all three components of the triad are woven together so tightly that as time passes, it becomes increasingly difficult to separate and reverse them.
Recognition equals prevention
It can also be difficult to recognize shock in the first place, especially in young, healthy, compensated adults. "Don't be fooled by people who are fully alert and oriented," she cautions. "As for children, they can lose 30 percent of their blood volume before their blood pressure drops."
To help detect early signs of hemorrhagic shock, Mayo Clinic now uses the St02 monitor, a device that measures tissue hemoglobin oxygen saturation at the level of microcirculation. Watch Anita Stoltenberg, respiratory care supervisor in the emergency department and trauma intensive care unit, discuss use of ST02 monitors on Youtube.
Serum lactate is another reliable indicator of shock that may be particularly helpful in patients with a significant mechanism of injury but normal vital signs. Base deficit — the amount of base needed to titrate 1 liter of arterial blood to a pH of 7.40 — is used to measure global tissue acidosis. Base deficit testing can be performed at the bedside using a handheld device and a single drop of blood.
Elsbernd recommends that smaller hospitals perform coagulation studies early in their evaluation. Ongoing blood pressure monitoring, pulse oximetry, core body temperature and urine output are all helpful in assessing circulatory status, but Elsbernd cautions that it's important to look at vital signs more globally. "If the patient has only one or two low blood pressure readings, consider the possibility of shock," she says. Then consider what can be done to reverse hypothermia and prevent the downward spiral into the triad. Keep the patient covered, use forced-air warming blankets, increase the temperature in the trauma bay, make sure IV fluids and blood are warm."
She suggests that hospitals lacking resources for adequate rewarming transfer trauma patients who have a registered core temperature below 96.8 F (36 C).
Ultimately, Elsbernd says, keen clinical skills trump everything. "An understanding of the pathophysiology of the triad, as well as rapid recognition and intervention, can decrease mortality," she stresses. "There are so many things nurses can do that will make a huge difference in the outcome for the patient."