Investigating Methods to Cool the Brain After a Heart Attack
Doctors from different institutions have found that cooling the body after a heart attack can limit damage to the brain and develop new techniques to reduce the temperature of that body without affecting the rest of the body, reports the magazine New Scientist. “
The researchers suspect that the fact the brain cool 4 degrees Celsius (at a temperature of 33 degrees) reduces the metabolism of brain cells and limits their appetite for oxygen at crucial moments in which there are problems with blood flow.
In the past, doctors induced therapeutic hypothermia using ice packs or cooling blankets the entire body or in the veins by injecting cold saline solution, but the whole body cooling may increase the risk of infection and pneumonia.
Bridget Harris, a medical student at the University of Edinburgh, has invented a kind of old coolant that can induce a mild hyperthermia.
The ingenuity, developed with the help of medical technology company KCI, San Antonio (Texas, USA), uses the dense network of blood vessels in the scalp that carry blood to the brain.
It consists of two layers of nylon to fit the head, one over the other, and those closest to the skin has small holes.
When cold air is blown between the layers, the holes allow air to penetrate the skin at regular intervals, which cools the blood vessels.
In tests conducted with volunteers, this kind of hood brain cooled by one degree Celsius in one hour, more or less what has been achieved with traditional methods of cooling the entire body.
In order to produce a faster change in brain temperature, other researchers are developing different techniques to cool the blood before it reaches the brain.
For example, in the nose: the nasal cavity is filled with blood vessels to warm the air entering through these holes, says Allan Rozenberg, BeneChill Company (San Diego, California).
The arteries that carry blood to the brain pass near the capillary network, so if it cools the nasal cavity is reduced while the temperature of the blood supply to that organ.
BeneChill has developed a system called RhinoChill, that sprays droplets of perfluorocarbon in the depths of nasal cavity through two tubes inserted in the nostrils.
Perfluorocarbon was chosen because it evaporates quickly, which cools the walls of the nasal cavity, and the arrival of a steady stream of oxygen further accelerates evaporation.
Studies conducted in animals indicate that this mechanism can cool the brain to 2.4 degrees Celsius in one hour.
According to Rozenberg, currently underway two clinical trials with people who have suffered a heart attack or stroke, but the healthy volunteers were tested in the prototypes that used a saline cooled responded positively.
Another possibility is to cool the blood from the lungs, since the carotid arteries of the heart goes directly to the head, and that's something to try now a team from the Argonne National Laboratory of Illinois (USA).
The scientists inserted a small frozen mass by a tube inserted in the trachea: the ice can cool the brain at 4 degrees Celsius-ceiling beyond which damage may occur, in less than fifteen minutes.
Once the desired temperature has been achieved in the brain, the ice is reabsorbed through the same tube in a process similar to that used to draw water from the lungs of someone who has been on the verge of drowning.
The same team are now investigating whether ice can be applied to the kidneys and the heart during delicate intervention to prevent organ damage when blood flow is stopped for the operation
