By Anita Srikameswaran
Pittsburgh Post-Gazette (Pennsylvania)
Copyright 2006 P.G. Publishing Co.
Regional paramedics will soon be testing intravenous fluids, an airway device and altered CPR protocols on some of their most critically ill patients to try to better the odds of surviving trauma and sudden cardiac arrest.
Emergency and trauma researchers from the University of Pittsburgh Medical Center and UPMC Trauma Services, members of the 10-city Resuscitation Outcomes Consortium, will be holding public forums to discuss the studies, which are funded by the National Institutes of Health and other agencies. One will be held in Oakland on Friday.
According to the American Heart Association, 95 percent of people who suffer cardiac arrest will die before they get to a hospital. It kills 900 Americans daily.
If frontline paramedics can’t restart a stopped heart, “I never have opportunity to take care of that patient,” said UPMC emergency medicine specialist Dr. Clifton Callaway. “This is something where paramedics save lives and nobody else does.”
Researchers hope the upcoming studies will show them which rescue procedures will be most effective.
Federal authorities have waived typical informed consent processes because people who will be in the trial could be unconscious or otherwise incapable of agreeing to participate.
Ambulance services in Pittsburgh, Washington, Fayette and Westmoreland counties will be part of the project, as will STAT MedEvac, Dr. Callaway said. Seattle, Milwaukee, San Diego and Toronto are among the cities in the consortium.
One of the studies, led locally by trauma surgeon Dr. Samuel Tisherman, will focus on trauma patients who either have a head injury or are in shock due to blood loss. During initial treatment, paramedics will give them one bag of either standard saline solution; a more concentrated, or hypertonic, saline solution; or the hypertonic solution mixed with a starch called Dextran.
The paramedics will not know which one they will be administering.
Fluids are used to restore blood pressure and circulation, Dr. Tisherman explained. Paramedics currently only give standard saline.
The hypertonic Dextran solution being studied here is already in use in Europe. In cases of head injury, the more concentrated fluids can limit brain swelling and “seem to have beneficial effects on the immune response to trauma,” Dr. Tisherman said.
Lab research and small studies in trauma patients hint that giving hypertonic fluids as soon as possible, instead of switching to them after the patient arrives at the hospital, may be of benefit in the long run.
“They look promising,” Dr. Callaway said. “They appear to reverse shock more quickly and they seem to eliminate some of those delayed effects of shock that may play out in the hospital.”
He is leading the local arm of the second study, which centers on cardiac arrest and has two components.
Cardiac arrest often stems from ventricular fibrillation, in which the heart stops contracting rhythmically and instead quivers chaotically, interrupting blood flow to the body.
If an electrical shock is delivered promptly, the heart could resume pumping normally. That concept has inspired the installation of easy-to-use automated external defibrillators, or AEDs, in public places and other sites.
Paramedics typically don’t witness a cardiac arrest, but must drive several minutes to get to the patient, Dr. Callaway pointed out. By then, a fibrillating heart may be less responsive.
“It’s used up all its energy stores,” he explained. “Defibrillation is less energetic. The most common thing to happen is that rescue shock stops all the electrical activity and the heart is completely silent.”
Lab studies suggest that performing for several minutes the chest compressions of cardiopulmonary resuscitation, or CPR, can re-energize the heart and increases the likelihood of restoring a normal beat with a rescue shock, Dr. Callaway said.
For the last decade, Pittsburgh paramedics have used a defibrillator right away in patients in ventricular fibrillation. In Seattle, though, paramedics perform CPR first and then give a shock.
“We really have no information to say which is better,” Dr. Callaway said. “There is no data to tell us.”
So, the consortium will try to figure it out by assigning ambulances to do either shock immediately or to give three minutes of CPR and then deliver the shock.
Even if bystanders have been doing chest compressions, paramedics will follow the protocol assigned to them, Dr. Callaway said. However, if a bystander has used an AED to deliver a shock, the patient will not be entered into the trial.
The second component of the CPR study involves using a device called an impedance threshold valve, which fits on the tubing between the bag and mask used to deliver air to patients who are not breathing on their own.
When a rescuer pushes down on the chest, oxygen-rich blood is forced out of the heart to the rest of the body, Dr. Callaway explained. When the rescuer’s hands come up and the chest expands, oxygen-poor blood should refill the heart.
But because the lungs are also refilling with air, the heart doesn’t refill as well as it could, rendering the compressions less effective.
“This valve eliminates that,” Dr. Callaway said. “It tries to prevent the air from going back and forth with every chest compression.”
In the study, paramedics will use either a real or dummy valve — they won’t know which — during the resuscitation procedure.
So when the two components are combined, cardiac arrest patients will fall into one of four groups: real valve plus early defibrillation; real valve plus late defibrillation; dummy valve plus early defibrillation; or dummy valve plus late defibrillation.
Trauma and cardiac arrest survivors will be re-evaluated one, three and six months later.
Researchers want to see whether the interventions enable more patients to live through the crisis, get out of the hospital and return home “neurologically intact,” as Dr. Callaway put it.
More than 15,000 people around the country will become participants during the next three years or so, but “the way to get into this study is for something totally unexpected to happen to you,” he said. About 600 patients annually could come from the local sites.
Pregnant women and children are among those who are automatically excluded from the research project, and people cannot participate in both the trauma and CPR studies, Dr. Callaway said. Family members can refuse on the patient’s behalf.
Also, “if people hear about this and they don’t want to be involved with this, they should contact us,” Dr. Callaway said.
For more information about the project, go to www.emsresearch.org or call 412-647-4221. A public forum will be held from noon to 1 p.m. Friday at William Pitt Union in the Assembly Room, 4200 Fifth Ave., Oakland.