"Ice Slurry" Used to Treat Cardiac Arrest

Originally Published MDDI January 2003

R&D DIGEST

Time is an essential factor in treating patients experiencing a cardiac arrest. Within 10 to 12 minutes of an arrest, lack of blood flow causes brain cells to begin dying rapidly. But research suggests that the timely application of cold to reduce the patient's body temperature may be a key to reducing morbidity and mortality resulting from cardiac arrest. A number of techniques and devices are currently being studied (see R&D Digest in the September 2001 MD&DI, p. 50).

A new approach developed by researchers at the U.S. Department of Energy's Argonne National Laboratory (Argonne, IL) and the University of Chicago's Emergency Resuscitation Research Center entails injecting patients with a high-fluidity ice particle mixture—essentially an ice slurry—to cool the blood and preserve cells. The researchers explain that during the procedure, the slurry would be injected into the lungs to cool the surrounding blood. Chest compression would be performed by medical personnel to circulate the cooled blood, allowing it to reach the brain and preserve cells there.

The researchers include Roger Poeppel, director of the Argonne Energy Technology Division, and Ken Kasza, a senior mechanical engineer who leads the research at Argonne. In 1999, they began working with Lance Becker and Terry Vanden Hoek from the University of Chicago Hospitals to develop the Emergency Resuscitation Research Center where health problems such as cardiac arrest could be studied.

When cells are cooled, their metabolism and chemical processes slow significantly. The researchers note, for example, that a skater who falls into an icy pond can be resuscitated even after being submerged for a long period of time. Because external cooling works slowly, however, the researchers proposed that the ice slurry be injected directly into the body to induce internal cooling at a more rapid rate. They suggested that the method could quickly and effectively cool critical organs using just a small amount of coolant. The slurry melts slowly in the body, and is removed later with a suction device on the end of an endotracheal tube.

Data from the university team's initial studies have shown that the method cools the brain cells by 2° to 5°C, and can maintain the reduced temperature for about an hour. This would give medical personnel and doctors more time to attempt restoration of normal blood flow and brain activity. The group believes that this extra time could reduce the incidence of brain damage to little or none.

Kasza and Becker explain that the ice slurry procedure will still be secondary to defibrillation. Treatment would begin immediately with defibrillation. If a proper response were not obtained, however, the cooling procedure would then be used. The researchers believe the method could also be used to treat stroke, but say a number of issues will require additional research. Studies are needed to determine optimal cooling levels and identify correct timing and protocols. Toxicity levels also must be assessed, and it must be determined how much of the brain is conserved by the method.

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