Resuscitative Care Gets Second Wind
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| LUCAS mechanical CPR device from Physio-Control. |
Last year, Philips Healthcare unveiled a comprehensive strategy to improve care for patients who suffer a sudden cardiac arrest, beginning with the emergency medical team’s arrival on the scene, through the ambulance ride, to arrival at the emergency department. Additionally, many institutions took up the cause to dramatically shorten door-to-balloon times, resulting in a plethora of data regarding best practices. Experts in the field say there is no one single device or strategy that works best, but it is the combination of many strategies working in concert that helps reduce mortality from sudden cardiac arrest.
The goal for every cardiac arrest patient is to limit damage to the heart, brain, and other vital organs, so the person has as full of a functional recovery as possible. In recent years, researchers have recognized that it is not necessarily the lack of oxygen during a cardiac arrest that causes brain damage. Rather, it is the rapid re-initiation of normal blood flow and delivery of oxygen that triggers a series of metabolic and inflammatory responses, which cause damage on the cellular level.
“We now understand that while return of spontaneous circulation may represent winning the first battle, there is much more that can be done to win the war—that is, to achieve neurologically intact survival,” says Vincent N. Mosesso Jr., MD, an associate professor of emergency medicine at the University of Pittsburgh School of Medicine and medical director of the University of Pittsburgh Medical Center Prehospital Care.
To slow the rapid return of blood flow following a sudden cardiac arrest, most ED’s now utilize hypothermia therapy. There is some debate when it should be started and how it should be delivered, but the consensus is that cooling benefits the return of neurological function in this patient population. Hypothermia therapy can be initiated by EMS at the scene, during transport or at the hospital through intravenous chilled saline or external cooling devices.
The Hospital of the University of Pennsylvania (HUP) has seen some impressive gains in survival and outcomes since adopting a very aggressive use of hypothermia for sudden cardiac arrest patients, according to Benjamin Abella, MD, an assistant professor of emergency medicine at HUP. The hospital, however, doesn’t initiate cold therapy in the pre-hospital setting. “It’s unclear to me whether we need to do it in the field,” Abella says.
Nevertheless, the era of therapeutic hypothermia is here and it’s difficult to justify not cooling patients, he says. Some smaller hospitals may not have the resources to initiate intravenous hypothermia. It can be expensive, ranging from $1,500 to $2,000 for each cooling infusion. Since chilled saline is not approved specifically in post-cardiac arrest, Medicare doesn’t reimbursement for this application. In addition, outlying rural hospitals may not gain overall expertise in treating sudden cardiac arrest patients with only a small number treated per month. One idea is to create regional Centers of Excellence for sudden cardiac arrest patients, similar to what exists for stroke patients (see sidebar, page 30).
“There is a very serious effort underway to determine whether the American Heart Association might wish to come out with a position statement regarding Centers of Excellence for post-cardiac arrest care,” says Joseph P. Ornato, MD, chairman of the department of emergency medicine at Virginia Commonwealth University Medical Center in Richmond and medical director of the Richmond Ambulance Authority. “We’ve clearly seen that there is a learning curve involved in treating this patient population and studies suggest a significant jump in survival occurs when providers handle 40 or more cases per month.”
Early, rapid and aggressive therapy
Virginia Commonwealth University uses a combination of early mechanical CPR and aggressive and rapid intravenous cooling in the field, says Ornato. Patients reach the ideal core temperature in one hour, compared to four or five hours with external cooling. Ornato says they are discharging about 40 percent of patients alive and neurologically intact, compared with a national average below 10 percent.
About a year ago, the center decided to initiate hypothermia therapy during resuscitation, not afterward. EMS personnel also use the AutoPulse mechanical CPR device (Zoll Medical) early in the rescue. Survival rates improved significantly from 2.9 percent to 10 percent after the city of Richmond placed the AutoPulse in every emergency vehicle. “I’m convinced that if you’re going to use devices, you need to use them early and aggressively,” ?Ornato says.
His team looked at the incremental benefits of mechanical CPR over manual. They found that the device showed benefit but only if it was deployed within 10 to 12 minutes after the 911 call. Interestingly, at the same time Ornato and colleagues were having success with mechanical CPR, the randomized controlled ASPIRE trial found a trend toward worse outcomes in those treated with mechanical CPR in the pre-hospital setting (also using the AutoPulse device) compared with manual CPR (JAMA 2006;295:2620-2628). There’s been much debate about the ASPIRE trial’s design and results, but the bottom line for many practitioners is that they will not endorse the use of mechanical CPR devices in the pre-hospital setting without evidence that suggests they have a benefit over manual CPR.
Another integral part of the success with sudden cardiac arrest patients in the city of Richmond, says Ornato, is its use of an advanced computer network to look for geographic and temporal patterns—hourly, daily, weekly, on holidays, etc.—regarding emergency incidences. The computer calculates where—statistically—the next most likely life and death emergency will happen. “The results are uncanny,” Ornato says. “In 90 percent of all calls, our paramedics, who are not at fixed locations, are on the scene within eight minutes or less.”
Max Harry Weil, MD, distinguished university professor and past chair of the AHA Advanced Cardiac Life Support subcommittee, and colleagues at the Weil Institute of Critical Care Medicine in Rancho Mirage, Calif., have designed a miniature mechanical CPR device that weighs less than 5 pounds. Currently available commercial devices generally range from 15 to 35 pounds. “In an emergency out-of-hospital setting, where this miniature device has the most potential, it’s a great advantage for the rescuer to hang it on his belt or have it attached to the oxygen tank typically carried on the back of the first response rescuer so that it is immediately available,” Weil says.
The miniaturized device developed in the Weil Institute, a non-profit research and educational academic center, is pneumatically operated, as are the Life-Stat (formerly Thumper, Michigan Instruments) and the LUCAS device (Physio-Control), while the AutoPulse is battery operated. In an experimental setting, Weil and colleagues found their device was as effective as the Thumper (Resuscitation 2008;76[2]:191-197). Weil admits that persuasive outcomes data do not exist yet for the miniaturized chest compressor (he’d also argue that persuasive data do not exist for any of the devices). However, he expects its size and ease of use, as well as the cost—projected to be at least one-third less than current commercially available devices—to be advantageous.
Intelligent boxes
A mysterious thing has occurred within the last few years, according to Weil. A majority of cardiac arrests now are not due to ventricular fibrillation, which, along with ventricular tachycardia, is the only rhythm for which automated external defibrillators (AEDs) are effective. “More than half of the instances of cardiac arrest cannot be treated effectively with the defibrillator,” he says.
The reason for these changes is a mystery, but some data suggest that it might be related to the drugs prescribed to people with heart disease, and specifically heart failure, according to Weil. These drugs, which include beta-adrenergic blocking agents, statins and calcium channel blockers, tend to make ventricular fibrillation very short lived, which then degenerates into a pulseless rhythm or asystole. “This phenomenon has brought workers in the field, particularly under the auspices of the American Heart Association, to reemphasize the importance of chest compression,” Weil says.
In the meantime, vendors are addressing this problem by developing “smarter” AEDs. Depending on the manufacturer, today’s defibrillators may have an artifact rejection system that minimizes delays and errors in arrhythmia interpretation before making a “shock/no shock” decision; they may coach the user through the entire defibrillator use sequence; they may coach the user through manual chest compressions; and they may allow the entire resuscitation record to be downloaded into a database for review. Weil calls them “intelligent boxes,” to guide both the professional rescuer, as well as the bystander, in attempting to treat cardiac arrest.
The smartest AED by itself, however, will not save anyone. What researchers in post-resuscitation care have learned over the last several years is that there are many factors that go into saving lives. These involve devices such as smart AEDs, therapies such as hypothermia, and strategies such as either becoming a Center of Excellence for post-arrest care or outreaching to your larger neighbor who has the infrastructure in place to provide cutting-edge treatment. Cardiologists, cardiovascular healthcare personnel and hospital executives can stake their claim in this field by taking their resources as far as possible in post-arrest care, and then by reaching out to the community at large to ensure that everyone’s efforts are coordinated.
| Does it pay? |
| Being a Center of Excellence for post-cardiac care is not for everyone. The cost of developing one depends on the volume and the amount of infrastructure and technology already in place. High-volume facilities have shown good outcomes. And there is payback, as patients with atrial fibrillation get an implantable cardioverter defibrillator, Medicare-age patients remain in the system for chronic heart problems and those with coronary disease go to the cath lab for interventions. Several studies, including Merchant et al (Resuscitation 2008;79:398?-403) and Omerovic et al (Circulation 2008;118:S_767) suggest the use of PCI is underused in post-resuscitation care. Sunde et al reported a jump in out-of-hospital cardiac arrest survivors once a post-resuscitation protocol that included emergent reperfusion was implemented (Resuscitation 2007;73:29-39). Hosmane et al concluded that serious consideration should be given to emergent angiography and revascularization, regardless of neurologic status, when resuscitated patients with STEMI are being evaluated in the emergency department (J Am Coll Cardiol 2009;53:409-15). “Economics aside, a comprehensive strategy for post-arrest treatment is the best medical care,” says Benjamin Abella, MD, an assistant professor of emergency medicine at the Hospital of the University of Pennsylvania. |