Cold-hearted treatment

A specially-engineered ice slurry could be used to cool the brain and major organs, delaying cell death and giving doctors and paramedics more time to revive heart attack and accident victims.

The technique, developed at the Argonne National Laboratory and the University of Chicago, uses a highly fluid mixture of small ice particles suspended in a saline solution. This is injected into the patient to rapidly cool the blood of targeted organs.

When a person suffers a cardiac arrest, brain cells start dying rapidly from lack of oxygen after 10–12 minutes. But the metabolism and chemical processes of cooled cells slows dramatically; this is why people who have been rescued after falling into icy water can often be revived after being submerged for many minutes.

In future doctors would use a defibrillator to try and restart the heart, but would begin rapid cooldown if this method failed.

Using ice slurry, the brain can be cooled by two to five degrees C in a few minutes. Once the ice is delivered, the brain stays cool for around an hour, giving doctors time to restore normal blood flow and reduce brain damage.

The slurry could be used during surgery to give doctors more time to complete procedures where blood flow to an organ must be stopped, such as during removal of tumours. This would allow open procedures on areas such as the kidneys to be replaced by keyhole surgery, reducing scarring. Internal cooling could also be used to treat heat-stroke, and could help preserve donated organs for longer during transit.

To ensure that the ice doesn’t create a blockage during injection, the particles have rounded edges and flow characteristics that allow them to be pumped smoothly through small tubes. The team is currently patenting the machinery used to make the ice, as well as the equipment to deliver it.

An ice slurry, delivered through an endotracheal tube, would fill the lungs – cooling the lungs and the heart. The area surrounding each carotid artery also could be filled with the slurry through a hypodermic syringe.

Slurry can be delivered to the lungs or organs such as the stomach that are used as heat exchangers by the body to cool the surrounding blood. In the case of a heart attack, medics would perform chest compressions to circulate the cooled blood to the brain. As the slurry melts, it acts like a drip bag saline solution.

 ‘Before teaming up with doctors from the University of Chicago Medical School we had been working on ice slurry development for large distribution systems for industrial premises,’ said senior mechanical engineer Ken Kasza, who led the research at Argonne.

He added that the US Defence Department has expressed interest in using the method on soldiers suffering from shock after massive blood loss on the battlefield. Julia Pierce