Postoperative Delirium: Brain Vulnerability and Recovery

Postoperative Delirium: Brain Vulnerability and Recovery

In this study, we propose to use EEG and a brain imaging technique known as diffuse optical tomography (DOT) to study when people are in delirium and when they recovery. We plan to also compare brain function of patients who recovered from delirium to patients who did not have delirium using DOT and fMRI. We will also continually monitor the participant's EMR to help coordinate timing of study procedures, as well as to collect information pertaining to their surgery, recovery progress, and indicators of mental status including delirium.

Postoperative delirium - a mental state of confusion, inattention, and impaired thought - is a potentially life-threatening condition. As many as half of patients that have heart and non heart-related surgery will experience postoperative delirium. Patients diagnosed with postoperative delirium have poorer outcomes and longer hospitalizations. Unfortunately, it is an under-diagnosed condition with a variable delay in when it appears. Additionally, there are no objective tools or tests that can be before or after surgery to anticipate and identify those patients who are at risk. Electroencephalography [EEG] and functional magnetic resonance imaging [fMRI] have helped us understand the changes in the brain during delirium. These suggest that a weakening in correlated activity within a group of brain regions, known as the default mode network (DMN), may be related to delirium.

Common inclusion criteria:

1. Age ≥ 60
2. Surgery requiring cardiopulmonary bypass (CPB) for coronary artery bypass grafting, septal myectomy and/or heart valve repair/replacement
3. English speaking.

Common exclusion criteria:

1. Implanted pacemaker
2. Automatic internal cardiac defibrillator or other implant for which non-contrast magnetic resonance imaging (MRI) is contraindicated
3. Concomitant aortic or cerebrovascular procedure
4. Inability to lay flat or still for MRI
5. Legal blindness or severe deafness
6. Seizure history
7. Known focal brain lesion larger than 3 cm.

Delirium Case Arm:

1. Delirious as diagnosed by the Confusion Assessment Method (CAM)/ Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) at some point during postoperative day 1-5.

Postoperative Control Arm:

1. Not delirious as diagnosed by the CAM/CAM-ICU on postoperative day 1-5.