Hyperbaric hyperoxia (also know as HBO) treatment has received acclaim for being highly effective in healing traumatic brain injury and stroke patients. Other serious conditions like decompression sickness and carbon monoxide poisoning can also be cured with HBO treatment. HBO exposure regulates blood flow, vasoreactivity and aerobic metabolism in the brain. However, the mechanisms of the treatment have been a subject of recent debates. As a result, investigations have been recently carried out to check the effect of HBO exposure on the distribution of regional cerebral blood flow (rCBF).
Seven healthy subjects were chosen for the test to investigate their rCBF responses. They were exposed to either HBO with a pressure of 250/250 kPa or normobaric normoxia with a pressure of 101/21 kPa. After spending 40 to 45 minutes under the pressure, the subjects were introduced to a perfusion tracer. They also experienced Single-Photon Emission Computed Tomography (SPECT). Statistical Parametric Mapping was used to take note of the changes caused to the rCBF distribution.
As the results of subjects exposed to HBO came out, it was seen that the angular gyrus, middle temporal gyrus, superior frontal gyrus, posterior and visual cingulate cortices, premotor and sensory-motor have an increased level of rCBF distribution.
As the results of subjects exposed to normobaric normoxia came out, it was seen that the anterior cingulated cortex, bilateral hippocampi, right insula and subcortical structures have an increased level of 99m Tc-HMPAO distribution.
Two things were clear from the tests. Firstly, HBO accelerates the distribution of rCBF in the visual cortices and sensory motor. Secondly, a greater perfusion-tracer distribution in default mode network and the dorsal attention system were found for the first time. According to these finds, it becomes clear how HBO treatment helps in improving the externally directed cognition state.