Newly published research from the Department of Geriatrics and Gerontology at the Rowan University School of Osteopathic Medicine in Stratford, NJ, explains why up to half of older adults who undergo general anesthesia develop postoperative delirium, which is the sudden onset of confusion, aggression, or agitated behavior that could progress to dementia. The findings indicate that older patients who are undergoing surgery might benefit from a less-potent, slower-acting anesthetic.
Working with animal models, the research team tested two inhaled anesthetics: sevoflurane and isoflurane. Sevoflurane is one of the commonly used inhaled anesthetics for inducing general anesthesia because it acts more quickly and has a shorter recovery time. However, the researchers found that sevoflurane caused increased disruption of the blood-brain barrier, the cellular structure that regulates the entry and removal of various blood components in the brain. Isoflurane, however, failed to demonstrate similar levels of blood-brain barrier breach.
“Our research has shown that when the blood-brain barrier breaks down, various plasma components, such as immunoglobulin, gain access into the brain and selectively bind to pyramidal neurons,” said lead author Nimish K. Acharya, PhD, at the Biomarker Discovery Center, New Jersey Institute for Successful Aging, Rowan University School of Osteopathic Medicine, and Department of Geriatrics and Gerontology, both at the Rowan University School of Osteopathic Medicine. “This may disrupt normal neuronal activity and could cause the onset the symptoms that define postoperative delirium.”
The selective binding of those autoantibodies to the pyramidal neurons that dominate the cerebral cortex occurred in animals treated with both inhaled anesthetics. However, older animals treated with sevoflurane showed a “dramatic and significant increase in the density and extent of vascular leak” caused by a disruption in the blood-brain barrier. By contrast, older animals exposed to isoflurane failed to show any significant age-related differences in the density or extent of vascular leaks.
The study’s corresponding author, Robert Nagele, PhD, director of the Biomarker Discovery Center and a professor of medicine, both at the Rowan University School of Osteopathic Medicine, said, “Extrapolating this data to humans suggests that older patients who will be exposed to inhaled anesthetics during surgery would benefit from a less potent anesthetic that would presumably pose less risk of blood-brain barrier compromise and minimize the risk of subsequent postoperative delirium.” The authors of the study suggest that more research is needed to identify other anesthetics for use in surgery that would be less disruptive to the blood-brain barrier and less likely to lead to postoperative complications such as delirium, cognitive decline, and dementia. This study, which appears online in Brain Research, was supported by funding from the Osteopathic Heritage Foundation.
To access the study, go to http://bit.ly/1KQISRH.
