Hypothermia changes hospitalistsí role in resuscitation by Deborah Gesensway
Published in the March 2010 issue of Today's Hospitalist
Cooling patients who survive cardiac arrest to preserve neurological function is one of the hottest developments in clinical care. And with the field showing signs of tremendous growth in the U.S., some experts say that hospitalists are poised to play a major role. That role, they add, will go beyond the actual cooling of patients and involve follow-up care once patients have been re-warmed.
The therapy has received a lot of attention because the data on neurologic function after resuscitation are so grim. Studies have shown that only between 5% and
"Resuscitation has been one of those orphan fields in medicine for a long time."
ĖDana P. Edelson, MD University of Chicago Medical Center
30% of patients successfully resuscitated after cardiac arrest survive to hospital discharge. Many who survive never regain neurologic function.
Hypothermia has been effective in one out of six cases, with landmark studies finding that cooling patients for 12 to 24 hours decreased the risk of death and increased the chance of a good neurologic recovery. That makes hypothermia by far the best therapeutic option out there.
So why is hypothermia available in only a minority of hospitals? Physicians who have established cooling services say there are a number of start-up hurdles that need to be cleared.
Then there are logistical issues to be hammered out. Should local hospitals try to establish these services, for instance, or would centralized hypothermia centers be a better way to go, similar to the model often used for stroke centers? And for hospitals that take the plunge and offer hypothermia, should the therapy be the turf of specialists or generalists?
The answers to those questions will help determine not only how quickly hypothermia services are adopted, but the role of hospitalists in caring for patients who have been resuscitated and cooled.
Who should own it?
While relatively few American hospitals currently offer hypothermia, that appears to be changing. Guidelines have endorsed the therapy since 2003, and hypothermia has regularly received attention in popular media and at medical conferences. A number of major U.S. citiesóincluding New York, Miami and Bostonónow require ambulances to transport cardiac arrest patients only to hospitals with hypothermia capabilities.
Because the use of hypothermia is still new, itís largely viewed as up for grabs. In hospitals where hypothermia is already being performed, the service is largely carved up among emergency medicine, intensive care and neurology. But at several hospitals, hospitalists have taken charge and are running the cooling machines, caring for those who survive and communicating with the families of those who donít.
"Resuscitation has been one of those orphan fields in medicine for a long time," explains Dana P. Edelson, MD, assistant professor in the University of Chicago Medical Centerís section of hospital medicine and director of clinical research in the emergency resuscitation center. Because resuscitation overlaps so many clinical areasó including cardiology, critical care, anesthesia and emergency medicineóand because it isnít considered particularly profitable, nobody in the hospital really owns it, Dr. Edelson adds.
That makes it very similar to other quality assurance programs, like DVT prophylaxis and bed sore prevention, that are now routinely being claimed by hospitalists. "It would be great," says Dr. Edelson, "to see hospitalists play that kind of role in resuscitation as well."
Hospitalists taking the lead
At the University of Miamiís Jackson Memorial Hospital, hospitalists have taken a leading role in all phases of therapeutic hypothermia, in conjunction with critical care and emergency physicians and neurologists.
The hospitalists work with residents to respond to codes and resuscitate cardiac arrest patients on the floors. As part of those duties, hospitalists are charged with starting the hospitalís hypothermia protocol on eligible patients.
The hospitalists who staff some of the hospitalís open ICUs may follow these patients through the process. Once patients have been re-warmed, extubated and transported to a medical floor, hospitalists get involved again. That means that hospitalists have to be up to speed with very specific skills, explains Joshua D. Lenchus, DO, a hospitalist and assistant professor of medicine who is medical director of the medical consult service. Hospitalists need to be able to do "a good neurological exam to monitor patientsí neurological state," Dr. Lenchus points out. Hospitalists also need to understand complications due to the sedation or paralysis medications patients receive while being cooled to suppress shivering.
Now that the therapy is up and running, he adds, the results are "amazing." When caring for patients whose chances of recovering are "barely in the double digits to start with," Dr. Lenchus says, "you need every percentage point you can get. If therapeutic hypothermia gives you another 10%, thatís fantastic."
But that additional 10%, Dr. Lenchus admits, is often hard won. Thatís because hypothermia comes with "a lot of education and start-up issues."
For one, doctors are leery of any new therapy, particularly one geared to such sick patients. But when it comes to hypothermia therapy, says Dr. Lenchus, physicians also arenít sure which patients are covered by the protocol and which should be excluded.
Getting equipment to patients in a timely manner has also been a concern. Those are the kinds of barriers, Dr. Lenchus says, that prevent many eligible patients around the country from being cooled.
Start-up issues were likewise a problem at the University of Pittsburgh, explains Clifton Callaway, MD, associate professor in emergency medicine and one of the therapyís early adopters. As soon as the guidelines came out, he says, "We had the equipment and wrote an order set, and still our patients didnít reliably get on the pathway." Guidelines suggest starting the therapy within six hours of regaining a pulse.
One big obstacle, Dr. Callaway discovered, was the lack of a dedicated team in charge of cooling patients. While every doctor on a floor and in an ICU will experience arresting patients, he points out, most physicians will individually see only four or five a year.
Thatís why Dr. Callaway created a special consult service to visit all eligible cases. That service, staffed by ED physicians and critical care cardiologists, now sees 120 patients a year. These doctors, he says, are comfortable handling complications that arise during hypothermia, including bradycardia and bleeding.
High or low tech?
Another reason given by many for not offering the therapy is that they donít have the right equipment. However, Dr. Callaway says that while special equipment is nice, itís absolutely not necessary.
The University of Pittsburgh, he explains, made a "strategic decision" from the beginning to use only equipment that all hospitals have on hand. Ice comes from the ice machines, cooling blankets are borrowed from the operating rooms, and esophageal temperature probes come from the anesthesiologists.
"The intervention is no more complex than what nurses do everyday for fever suppression," says Dr. Callaway. "I felt that companies that make the catheters and the specialized cooling equipment were doing a disservice because they gave the impression that you needed a fancy machine to do this."
Others disagree. "Therapeutic hypothermia is way too labor intensive to not have the machines, frankly," explains James Rooks, MD, medical director of hospital medicine at St. John Medical Center in Tulsa, Okla. "The hassle factor involved in using cold saline and ice packs and regulating the temperature was too high. We tried that on a few patients and threw it out the window."
About two years ago, his hospital instituted a protocol that had physicians cooling in-hospital arrests only. The thinking was that the hospital would "work out the kinks" before tackling out-of-hospital cardiac arrest patients brought to the ED. Hospitalists who staff the ICU run the protocol.
A big part of ironing out those kinks was convincing several companies that make the machines to loan the hospital the equipment for several months. (For information on cooling methods, see "Internal vs. external cooling," below.)
New approach required
Whatever the technology used to cool patients, experts say the therapy requires a new approach to patient care, whether physicians are involved in cooling or providing follow-up care.
Even when hospitalists arenít the ones actually cooling patients, hospitalists "are likely to have to interface with the cold front that is passing through," says Patrick M. Kochanek, MD, professor of critical care medicine at the University of Pittsburgh. "The concept of rehabilitation was never felt to be very fruitful for patients who have had a global insult to their brain. But now with hypothermia, we are finding patients waking up a month after a cardiac arrest starting on some neurological rehabilitation therapies."
Chicagoís Dr. Edelson echoes that assessment. "Hypothermia slows everything down," she says, making it harder to tell early on who is going to wake up. "We may need to extend the observation period following successful resuscitation before determining futility and withdrawing care." That observation period may potentially be as long as five days, she explains, "or it might be longer. But it is becoming clear that patients treated with hypothermia are waking up later than we are used to."
During that time, there are complications to watch out for. Cooling exposes patients to greater risks of infection and bleeding, says Dr. Edelson, although mild hypothermia (32 degrees to 34 degrees for 12 to 24 hours) seems to result in fewer side effects.
And according to Dr. Lenchus, follow-up care includes watching for irregular heartbeats, blood clotting abnormalities, urinary or respiratory tract infections from poor immune response, and some metabolic abnormalities like poor potassium or sugar.
Altered recovery patterns
The management of patients recovering from cardiac arrest may not necessarily change because the patient was cooled, but recovery patterns may be altered.
"When the heart stops, everything gets harmed," says William David Freeman, MD, a neurohospitalist at Mayo Clinic in Jacksonville, Fla., who directs the neurosciences ICU and helped bring therapeutic hypothermia to the hospital. "That 12 to 24 hour period of cooling is just one part of the whole continuum of care."
As a result, hospitalists providing therapeutic hypothermia need to make sure they have appropriate neurologist back-up for neurologic prognosis in many cases. That can be a problem, given the shortage of neurologists seeing inpatients.
And hospitals without neurohospitalists on staff, Dr. Freeman explains, may have to turn to general hospitalists "to provide a baseline neurologic exam" before cooling starts. When a neurologist finally comes to the hospital, even if itís several days later, that baseline neurologic exam will help with prognostication.
"If you donít make the right neurologic prognosis for these patients," Dr. Freeman says, "end-of-life decisions can be unnecessarily prolonged with the family."
"The patient just doesnít get re-warmed and sent home," he says. "There are a lot of things that hospitalists have to keep an eye on." Because there are so many facets to the therapy and its follow-up, "this really is a great multidisciplinary activity where neurologists, ICU and ER docs, and hospitalists all work together."
Deborah Gesensway is a freelance health care writer who covers U.S. health care from Toronto.
What to look for when making a prognosis
IS THERE ANY WAY TO PREDICT how well patients will recover neurologically post-hypothermia? According to a neurohospitalist expert, physicians have a number of misperceptions when it comes to prognostication.
At a hospital medicine conference held last fall by the University of California, San Francisco (UCSF), S. Andrew Josephson, MD, director of the neurohospitalist program and assistant professor of neurology at UCSF, said that many clinicians believe that fixed and dilated pupils during a code predict a poor outcome. That, Dr. Josephson said, is wrong.
"One of the mistakes we make with prognostication is thinking that there are things that we can do very early on after the code that will allow us to say whether someone has a poor prognosis," he explained. "That is simply not the case."
Another mistake is using MRIs to try to determine damage levels or recovery potential. "MRIs are fraught with false negatives and false positives," said Dr. Josephson. "It is a worthless test for now, although research on this topic is continuing."
So what tests may hold some value when it comes to prognosis? Immediately before initiating hypothermia, Dr. Josephson said, physicians should perform a detailed neurologic exam to make sure the patient is in a persistent coma. After patients are re-warmed, there are some characteristics that do predict universally poor outcomes without false positives, which help cliniciansóand family membersódecide on how aggressive a course to take.
The key element is conducting a neurologic exam at specific time points that relies on "fairly minimal" exam skills.
"If at three days, the pupils donít react, that is universally a sign of poor outcome," Dr. Josephson said. "Itís the same if you pinch each of the limbs at three days and either there is no movement or simply extensor posturing."
He added that hypothermia has thrown a wrench into that timeline. If the important exam is at 72 hours, is that post-arrest or after the patient has been re-warmed? Dr. Josephson said that research is needed to answer that question. He also noted that it is important to keep reexamining the patient.
Another reliable marker for poor outcomes is myoclonic seizures, which are bilateral, rhythmic, synchronous twitches of the limbs, trunk or face. An EEG, Dr. Josephson said, can help you differentiate between myoclonic seizures and post-anoxic myoclonus.
Hypothermia: How does it work?
Dana P. Edelson, MD, assistant professor in the University of Chicago Medical Center's section of hospital medicine, is one hospitalist who's actually cooling patients with therapeutic hypothermia.
As director of clinical research in the hospitalís emergency resuscitation center, she has also studied the science of resuscitation. And while she says itís not clear exactly why hypothermia works, the therapy is effectiveóand efficient.
"Itís cheap and easy," Dr. Edelson explains. "There is no real downside to it, and for the most part, itís safe and worth doing."
Another major plus? Physicians really don't have any other options to improve neurologic outcomes in resuscitated patients.
One theory about how cooling works to retain brain function has to do with what is known about fever and its related inflammatory cascade. Lab studies have shown that cells donít die during the period when they are not getting blood flow, but die instead when the blood comes back.
"That may be what hypothermia does: attenuate that reaction," Dr. Edelson says. "Itís as if you are slowing down the return of the blood and all the inflammatory response that you get with that return."
Some of the newest work in the field, adds Patrick M. Kochanek, MD, professor of critical care medicine at the University of Pittsburgh and director of the Safar Center for Resuscitation Research there, has to do with rethinking hyperthermiaófeveróin the care of any patient with acute brain injury.
"The fact that hypothermia works has led people to think that maybe some benefits from hypothermia after a brain injury is actually preventing fever," he says. Dr. Kochanek was chair of an international consensus conference on therapeutic hypothermia convened last spring by the Society of Critical Care Medicine. A report from that conference will be released this spring.
It is very likely, Dr. Kochanek adds, that hospitalists interfacing with patients with acute brain injuryówhether from cardiac arrest, stroke, meningitis or traumaó"will be needing to pay more attention to strict temperature control."
The American Heart Association and the International Liaison Committee on Resuscitation in 2003 published recommendations that "unconscious adult patients with spontaneous circulation after out-of-hospital cardiac arrest" be cooled when the initial rhythm was ventricular fibrillation and that "such cooling may also be beneficial for other rhythms or in-hospital cardiac arrest."
Several studies have found that Americans have been slow to jump on the bandwagon. One published in the July 2006 issue of Critical Care Medicine, for instance, found that 74% of physicians surveyed in the U.S. had never used therapeutic hypothermia, lower than in other countries.