“For decades, the medical community has championed 100 percent oxygen as the gold standard for resuscitation. But no one has reported what happens inside our brains when we inhale pure oxygen,” explained Ronald Harper, distinguished professor of neurobiology at the David Geffen School of Medicine at University of California, Los Angeles (UCLA).
Harper’s team used functional magnetic resonance imaging (fMRI) to capture detailed pictures of what occurs inside the human brain. The researchers scanned the brains of 14 healthy children, ages 8 – 15, as they inhaled 100 percent oxygen through a mouthpiece. After waiting eight minutes for the youngsters’ breathing to return to normal, the team added 5 percent carbon dioxide to the gas mixture and repeated the scan.
A comparison of the two scans revealed dramatic differences. “When the children inhaled pure oxygen, their breathing quickened, resulting in the rapid exhalation of carbon dioxide from their bodies,” said coauthor Paul Macey, associate researcher in neurobiology. “The drop in carbon dioxide narrowed their blood vessels, preventing oxygen from reaching tissue in the brain and heart.”
That’s when something surprising happened on the MRI scan. Three brain structures suddenly lit up: the hippocampus, the cingulate cortex and the insula. All this activity awakened the hypothalamus, which regulates heart rate and hormonal outflow. Activation of the hypothalamus triggered a cascade of harmful reactions and released chemicals that can injure the brain and heart.
When the children inhaled the carbon dioxide-oxygen mix, the hypothalamus’ hyperactivity vanished from the MRI scan. “Adding carbon dioxide to the oxygen relaxed the blood vessels, allowed oxygen to reach the heart and brain, calmed the hypothalamus and slowed the release of dangerous chemicals,” said Macey.
MEDICA.de; Source: University of California, Los Angeles