Ohio State University LogoThis news may concern a wide range of people who suffer from heart problems or who are at a risk of stroke. Apparently study experts have contradicted the results of previous clinical trials by demonstrating that giving supplemental oxygen to animals during a stroke may lessen injury to brain tissue near the clot. It is said that the timing of the delivery of 100 percent oxygen, either by mask or in a hyperbaric chamber, could be vital to attain the gain.

Preceding clinical trials in humans have proposed that administering oxygen under pressure could damage stroke patients. But the studies apparently did not take into account the position of blood flow in the brain at the time the oxygen was transported.

The kinds of stroke under study are ischemic, meaning a clot is obstructing blood flow in the brain, rather than hemorrhagic, strokes that take place when blood vessels burst in the brain.

“The use of supplemental oxygen after blood flow is restored in the brain appears to actually cause harm by unleashing free radicals. The resulting tissue damage was worse than stroke-affected tissue that received no treatment at all,” commented, Savita Khanna, assistant professor of surgery at Ohio State University and principal investigator of the study.

The new Ohio State study illustrated that the use of pure oxygen that was delivered by mask during stroke appeared to be effectual, making for simpler clinical application of such a therapy when the time for that is correct.

Nevertheless, technology doesn’t yet let rapid and incessant real-time quantity of blood flow in the brain in a hospital. This means clinicians treating stroke patients apparently cannot risk administering hyperbaric oxygen that could do more damage than benefit if it is not timed correctly.

Cameron Rink, assistant professor of surgery at Ohio State and a co-investigator on the study, mentioned, “Hyperbaric oxygen during stroke shows the promise of being an effective tool, but there are things that need to occur before this can be applied in a clinical setting. We need to find better ways to monitor blood flow in humans in real time.”

The standard time between the beginning of a stroke and a patient’s arrival at a hospital is about four hours, which contributes to the treatment challenge, as per the experts.

Khanna, Rink and colleagues examined the impact of supplemental oxygen therapy on around five groups of rats in which the experts apparently provoked a 90-minute ischemic stroke and then reinstated blood flow in the animals’ brains. Two groups of animals were apparently given either normal oxygen or pressurized oxygen while blood flow was obstructed in the brain. Two other sets of rats were given normal or pressurized oxygen after blood flow was reinstated. A control group were not given any supplemental oxygen but had to make do with only the breathing room air.

After two days, the experts observed the rats’ brains by means of potent 4.7-Tesla magnetic resonance imaging to compute the extent of damaged tissue. The images displayed the size of the infarct, or the region of tissue which is vulnerable to stroke damage as an outcome of poor oxygenation.

The images showed that the animals that were given supplemental oxygen treatment while blood flow was obstructed had a considerably lesser quantity of tissue damage as opposed to the rats that were given oxygen after blood flow was reinstated.

By further probing images of the rats’ brains, the experts found out that the supplemental oxygen during the active phase of a stroke particularly decreased the death of neurons and averted the damage that free radicals could cause to lipids that assist in guarding those brain cells. In contrast, more dead neurons and oxidative stress were discovered in the brains of rats receiving oxygen only after blood flow was reinstated.

Rink remarked, “Ultimately, the supplemental oxygen after blood flow is restored is more than the tissue can handle, and is more than it needs. Why add oxygen on top of tissue that’s already oxygenated? Supplemental oxygen during the blockage, on the other hand, is highly protective.”

The experts are using other technologies to find out how the loss of oxygen impacts the roles of genes in the brain. Of the approximately 30,000 genes examined to date, at least 6,000 are believed to be either inactivated or extremely activated when a stroke decreases the oxygen in the brain. Their upcoming work will discover the consequences of those altered gene roles.

The study was presented at the Society for Neuroscience annual meeting in Chicago.