New Cooling Technology at UCNI to Help Protect Brain Following Cardiac Arrest

The Neurocritical Care Program at the University of Cincinnati Gardner Neuroscience Institute (UCNI) has implemented a new hypothermia protocol and technology in its effort to protect the brain in patients who have suffered a cardiac arrest. The aggressive, state-of-the-art protocol is designed to treat comatose patients from the damaging effects of oxygen deprivation by mildly cooling them following a cardiac arrest.

The centerpiece of the program is a new endovascular cooling device that enables gradual, controlled cooling of the body and a similarly controlled re-warming 18 to 24 hours later.

“Hypothermia after cardiac arrest is a neuroprotectant therapy that was shown to be effective in landmark studies in the early 2000s,” says William Knight, MD, a neuro-intensivist with UCNI and the Mayfield Clinic. “It has since become standard of care. People who experience a cardiac arrest are not getting appropriate blood and oxygen flow to the brain. They suffer a brain injury as a result, and universally these patients have done very, very poorly.”

Patients treated at University Hospital following cardiac arrest have undergone medically induced hypothermia since the mid-2000s. Building on that standard of care, the new protocol:

• expands hypothermia therapy to a larger group of patients • provides for immediate hypothermia treatment upon the patient’s arrival and resuscitation • integrates improved technologies, such as continuous seizure monitoring and controlled, machine-driven cooling.

Dr. Knight, Assistant Professor of Emergency Medicine and Neurosurgery, wrote the new protocol.

Patients treated with hypothermia are in a coma. “They are cooled immediately from a normal temperature of 37 degrees centigrade to 31 to 33 centigrade, and this state of mild hypothermia is maintained for 18 to 24 hours,” explains Dr. Knight. “The Neurocritical Care Program, including all faculty and fellows, now provide 24-7 coverage of hypothermia after cardiac arrest. So we are now cooling these individuals early and aggressively in accordance with current standards of care.”

Cooling traditionally has been accomplished with water-filled cooling blankets, fans and cold saline and by placing ice packs around the patient’s groin, armpits, neck and trunk, a process Dr. Knight describes as rudimentary. “It’s very easy to overshoot or undershoot your target temperature.”

The endovascular cooling device should eliminate the guesswork. The Thermogard XP™, manufactured by ZOLL Medical Corporation, circulates cold saline through narrow balloons contained within a long catheter that is inserted into the groin or neck. By cooling the blood in this way, the body temperature drops in a controlled manner, at a rate of .3 to .5 degrees centigrade per hour.

As patients are being cooled, they are also connected to portable EEG machines and monitored continuously for seizures, which may or may not be visible to the eye. If no seizures are detected, EEG monitoring is discontinued once the patient has been re-warmed.

Implementing the multidisciplinary protocol can involve more than 10 physicians from multiple disciplines, including emergency medicine, medical intensive care, cardiology, neurology (epileptology) and neurocritical care.  “Patients can be treated in the Cardiovascular Intensive Care Unit, the Cath Lab, the Neuroscience Intensive Care Unit, the Medical ICU or the Surgical ICU,” Dr. Knight says. “Our goal is not only to fix the patient’s cause of cardiac arrest but also to allow the patient to wake up and have a meaningful neurologic recovery afterwards.”

Meanwhile, a $5,000 grant from the Emergency Medicine Foundation will allow Dr. Knight and his colleagues in the Departments of Emergency Medicine and Neurosurgery to study, retrospectively, the incidence of seizures in people who have suffered a cardiac arrest, are in a coma, and have been treated with hypothermia.

“We know that 15 to 30 percent of all people in a coma have seizures,” Dr. Knight says. “We’re not exactly sure what that incidence is in patients who have undergone hypothermia after cardiac arrest. We’re going to look at our data and try to define the incidence.”

The data would be helpful, Dr. Knight says, because it could impact prognosis. A patient who is in a coma because of silent seizures might have a different likelihood of recovery, for example, than a patient who is in a coma as a result of catastrophic oxygen deprivation to the brain.

The grant will fund data collection and analysis.

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