When a patient is admitted to the hospital for a traumatic brain injury, medical staff members monitor intracranial pressure (pressure which builds up in the brain from trauma infarction, swelling or bleeding into the brain) and blood flow to the brain.
Too much pressure or too little blood flow may be a sign that additional treatment is needed or that the patient is in danger. Swelling can prevent normal oxygenation by restricting blood flow. As a result, the volume of well-oxygenated blood is decreased.
Now researchers at the University of Pennsylvania Medical Center have published new findings related to brain oxygenation that call into question old treatment assumptions.
“Cerebral hypoxia” is the medical term for reduced oxygen supply to the brain. The longer a person’s brain is without adequate oxygen, the more cell death occurs, ultimately leading to the death of the injured person.
The study followed 103 patients with traumatic brain injury who were monitored for all three factors. The researchers then looked at the relationships between each of the measurements and the health outcome of the patient. A poor outcome was severe disability, vegetative state or death.
High intracranial pressure had previously been regarded as the most significant predictor of a poor outcome, but the study found that 81 percent of patients with high pressure but no hypoxia had good outcomes. Only 46 percent of patients with both high intracranial pressure and hypoxia had good outcomes.
Blood flow to the brain (cerebral perfusion pressure) was not an adequate indicator of oxygen getting to the brain. Some patients had good oxygen levels, but reduced blood flow. And currently recommended levels of blood flow were not always sufficient to avoid hypoxia and injury.
The greater the drop in oxygenation and the longer the patient went without sufficient oxygen, the worse the outcome. The researchers found that patients with a poor outcome experienced an average of eight (8) hours of reduced oxygen levels, while those with good outcomes experienced just under two (2) hours of hypoxia. (For each hour a patient suffers reduced oxygen levels, the risk of severe damage or death increases by 11 percent.)
The research supports a recent change in the medical guidelines for treating brain-injured patients with TBI. Medical staff should now monitor patients with severe head injury for brain oxygenation during the intensive care period.