Multimodal non-invasive neurological monitoring reduces postoperative delirium in older cardiac patients

Patients undergoing cardiac surgery are at an increased risk of developing delirium and other changes in cognitive function in the days following surgery. However, new research presented at the ANESTHESIOLOGY^® 2015 annual meeting, found using monitors to track depth of anesthesia and oxygenation levels in older patients' brains during cardiac surgery significantly reduced their incidence of postoperative delirium and associated cognitive decline.

"Delirium occurs in up to half of all patients after cardiac surgery, with older patients being particularly susceptible, and has significant implications on long-term cognitive health and mortality," said Gudrun Kunst, M.D., Ph.D., clinical lead in cardiac anesthesia at King's College Hospital, London. "Our research found using current technologies to track and measure the level of sedation and cerebral oxygenation provided to patients allowed for improved early postoperative neurological outcomes."

Delirium is a serious, acute disturbance in mental abilities characterized by confused thinking and reduced awareness of the surrounding environment. Research has shown postoperative delirium may result in longer hospital stays, higher six-month and one-year mortality rates and increased costs. Recently, delirium after heart surgery also has been associated with the onset of cognitive decline - having issues with memory, learning new things, concentrating or making decisions that affect everyday life.

In the proof-of-concept study, researchers examined 81 patients, aged 65 or older, who had coronary artery bypass graft surgery. All patients had a baseline score of 25 or greater (out of 30) on the Mini Mental State Examination (MMSE), which assessed cognitive levels, prior to surgery. The BiSpectral Index (BIS) - a non-invasive technology used to monitor depth of anesthesia and accurate anesthetic administration - and cerebral (brain) oxygenation monitor, were used in an intervention group (physician anesthesiologists used monitors) and control group (monitors were blinded to physicians). BIS and oxygenation levels were recorded continually before, during and after surgery. Delirium and cognitive decline were assessed at three days, six weeks and one year following surgery.

Researchers found postoperative delirium was significantly more prevalent in the control group (22.5 percent vs. 2.7 percent) and was associated with a significant reduction in postoperative MMSE scores at three days and one year after surgery.

"Multimodal non-invasive neurological monitoring - which helps to measure and maintain the appropriate amount of anesthetic needed for patients - has the potential to improve patient outcomes," said Dr. Kunst. "Postoperative delirium and cognitive decline often experienced by older cardiac surgery patients is a serious, growing health issue and in the future multicenter randomized controlled trials will be necessary to confirm whether multimodal neurological monitoring improves neurological outcomes.