A young man crashed his motorcycle at a high speed and is bleeding out despite best efforts by EMS. The odds are clearly stacked against him — after all, traumatic injuries kill more Americans under 45 than any other cause of death.
But what if you could buy this patient more time, time that would allow for surgical repair of the most significant wounds and replacement of the blood volume? That idea was floated 20 years ago in a call for more research on suspended animation, and today, EPR-CAT shows promise for being a real game-changer in lowering the death rate from trauma or rapid exsanguination.
A patient bleeding to death has only a short time for emergency physicians and critical care specialists to stop that bleeding, something they know all too well. “If you have enough time, you could plug the hole and fill the tank back up,” said Hasan Alam, MD, a noted critical care surgeon who is the Norman Thompson Professor of Surgery and the head of general surgery at the University of Michigan Hospital. “But your window of opportunity is limited.”
Figuring out how to lengthen that time took Dr. Alam back to work by pioneering critical care specialist and the “father of CPR,” the late Peter Safar, MD, and thoracic surgeon and retired Army Colonel Ronald Bellamy, MD. (Crit Care Med 1996;24[2 Suppl]:S24.) They proposed using rapid induction of profound hypothermia to allow time — an hour or two, at most — for resuscitative surgery.
“Cooling is one of the most powerful strategies we have available to prolong ischemia time,” said Dr. Alam, who has studied emergency resuscitation in large animals. “We do it all the time in transplant surgeries. But using this powerful technique in the trauma setting is more challenging.”
Cooling in transplant occurs before the heart is stopped, he said, while trauma patients are already in shock and dying when they arrive in the ED. “Will cooling work at that time, or is it too little, too late? What tools and devices should be used? How fast should we cool the patient, and how fast should we rewarm them? There are many questions that we had to address,” he said.
Ready for Prime Time
Laboratory research like Dr. Alam's has helped to provide answers to some of these questions and demonstrated the feasibility of rapidly inducing hypothermia for exsanguinating trauma. Now, it's finally ready for prime time, or at least for a pilot study in humans. The EPR-CAT (Emergency Preservation and Resuscitation for Cardiac Arrest from Trauma) study, led by researchers at the University of Maryland and a team at the University of Pittsburgh, has been in development for quite some time now. Samuel Tisherman, MD, the director of the Center for Critical Care and Trauma Education and the director of the surgical ICU at the University of Maryland Medical Center, said they expected to enroll the pilot cohort of patients in 2010, but the complexities of the study and consent requirements delayed matters.
Dr. Tisherman acknowledged the difficulty of the task at hand, noting that CPR doesn't work if the patient has virtually no blood in his body. “Typically, we open the chest, give blood, and intubate, but very few survive,” he said. “Depending on the institution, the survival rate for trauma patients who suffer cardiac arrest is between five and 10 percent, and the difference is often whether or not people even choose to try.” (Failure rates are skewed by institutions that choose not to attempt resuscitation in extreme cases of massive exsanguination.)
The two centers plan to study 10 EPR-CAT patients in the pilot phase, comparing their outcomes with 10 control patients who meet all the criteria for EPR-CAT but cannot receive it because appropriate personnel are not present. “It's not really feasible to train all your trauma surgeons to do something complex that's going to be done infrequently, even at a very busy place like a shock-trauma center,” Dr. Tisherman said. “So here in Maryland we've trained five surgeons in this procedure, and in Pittsburgh they've trained three. If one of those surgeons is present when an appropriate patient comes in, then we ... do it.”
The EPR-CAT study will enroll patients who have at least one sign of life within the five-minute period prior to ED arrival or in the ED and those who have no response to open-chest CPR with clamping of the aorta or who remain without a pulse for five minutes despite aggressive resuscitative efforts.
Dr. Tisherman said the study will focus on patients who have penetrating trauma, such as stab or gunshot wounds. “That's based upon the known data on trauma patients who have cardiac arrest on whom we do ED thoracotomies. Those with penetrating trauma have a little better chance than those with blunt trauma, partly because it's more straightforward to figure out where the bleeding is, and also because with blunt trauma, it's unknown whether or not there's also a serious head injury. What we're trying to do with this trial is show that it can work in the patients we think have the most chance to benefit.”
Because patients will be unable to give informed consent to participate in the trial and may not have a family member present, the study will be conducted under the FDA-authorized exception-from-informed-consent process that includes opportunities for public comment and a means to opt out of inclusion. Individuals living in the trial communities who do not want to be given EPR-CAT will wear a bracelet similar to a MedicAlert bracelet when the trial is enrolling. “Almost every trauma trial has to go through this process,” said Dr. Alam. “It's slow and cumbersome but the right thing to do.”
Laboratory studies have found that the best way to achieve cooling is to flush a large amount of ice cold saline into the aorta, and the EPR-CAT study will cool patients by 50 degrees below normal, not the six or seven degrees usually employed. “You get the core of the body cold as fast as possible and then just let the blood drain out, operate quickly, and place the patient on full cardiopulmonary bypass,” Dr. Tisherman said. “Since the patient is so cold, that's the only way to restart the heart. So then we start slowly rewarming the patient, reinfuse them with blood, and when their temperature is back to normal, we'll take them off bypass.”
The investigators have found that using the typical tools and devices involved in induced hypothermia for other purposes, such as transplant, is effective. Dr. Alam said they have not developed any exotic devices and use the same pumps, cannulas, and oxygenators that are used every day in cardiac surgery and transplant.
Assuming that the pilot trial and follow-up studies are successful, EPR-CAT could be instituted into a small subset of trauma centers — busy ones, Dr. Tisherman said. “Doing something that takes this kind of effort for only one or two cases a year won't be successful,” he said. “You need interested trauma surgeons and cardiac surgeons and perfusionists who are willing and able to help.”
That said, however, Dr. Alam said his group trained the team at the University of Maryland with a trial run in an animal model, and it took the chief of trauma five minutes to put in the catheters and initiate hypothermia. “It's a complicated procedure,” he said, “but not beyond the skill set of an experienced trauma surgeon. But it would take a few days of training using animal models. You don't want the surgeon to understand only the theoretical and not the practical aspects of the technique.”
Ultimately, EPR-CAT could be a game changer for the trauma death rate. “Right now, our chances of saving patients like this are slim to none,” said Dr. Tisherman. “The patients we are losing right now are usually young and otherwise healthy people, so saving some of the patients we currently can't could really have a major impact.”
Note: Dr. Tisherman and his co-investigator Dr. Patrick Kochanek disclosed that they have a financial interest in EPR and in some of the associated equipment, including special catheters and accessories that have been licensed to EPR Technologies.
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