Cognitive loss and personality change are often the direct result of surgery when the heart has to be stopped. It is the result of small bubbles of air being released into the blood stream by the heart-lung machine that is keeping the recipient alive.

The machine also ruptures red blood cells releasing hemoglobin into bodily organs, where it's toxic. Combine this with plastic tubing triggering white blood cell immuniological alerts on a mamoth scale and you can see why this sort of surgery is limited to extreme cases.

The purpose of the heart lung machine is, of course, to reduce damage to the body and particularly the brain from oxygen deprivation during periods when the heart is incapable of supplying the oxygen. The reciprical approach to the problem is to reduce the demand of oxygen by the body and the consequent damage from deprivation.

This is achieved by drastically reducing the temperature of the areas of the body that are subject to oxygen deprivation, called therapeutic hypothermia. There are problems with this approach of course. The most obvious being the the affect that it has on the blood. Dropping the temperature below 90 degrees causes the blood to thicken and protiens to loose their shape, which is bad. It leads to catastrophic circulatory dysfunction.

A company called Biotime has come up with a blindingly obvious solution to the problem, human blood anti-freeze. The product is called Hextend and has been approved by the FDA. Hextend allows the blood temperature to be reduced to 35 degrees, at this temperature the brain takes hours to suffer the same damage that would only take minutes to occur at normal body temperature.

Interestingly, the compound was developed to assist in the Cryogenics industry but is now finding huge success in the mainstream surgical community.

Read more in Wired.