Clinical Investigation of an Eye-Tracking Device as a Predictor of Delirium in the Recovery Room After Surgery With General Anesthesia

How the brain restores baseline consciousness at the end of a perioperative anesthetic is not known. However, it is becoming increasingly evident that arousal after sleep, coma, or anesthesia is an active process, not a passive process relying on simple clearance of anesthetic drugs. Insight into the specific sequence of brain circuit activation and inactivation during the end of an anesthetic may not only lead to an understanding of anesthetic emergence but provide important information for the potential long-term consequences of anesthetic drugs (anesthetic neurotoxicity, and the role of anesthetic drugs in delirium and dementia). The possibility of anesthesia causing harm to the brains of our patients is a controversy that has received a lot of attention from anesthesiologists, surgeons, and patients alike. The investigators' approach is to determine if techniques based on eye movements and/or pupillometry can predict and guide the post anesthesia management of delirium.

The conventional pupillary exam involves assessment of pupil size, shape, symmetry, and reactivity to light. Mechanistically, the pupillary light reflex involves the retina, cranial nerve II and III, pretectal nucleus in the midbrain, Edinger-Westphal nuclei, and the ciliary ganglion. With the use of an automated pupillometer, the pupillary response to light can also be quantified with measures of maximal diameter, latency, constriction velocity, minimal diameter, and dilation velocity. Beyond the reliability and accuracy that the device affords, pupillometry may have other utilities, potentially predicting postoperative delirium, episodes of intracranial hypertension, and even supratentorial herniation.

On the other hand, smooth pursuit involves conjugate eye movements that are required to maintain an object in motion on the fovea. The mechanism is quite complex, involving the lateral geniculate nucleus, primary visual cortex, middle temporal visual cortex, frontal pursuit area, superior colliculus, several pontine nuclei, the cerebellum, and nuclei of cranial nerves III, IV, and VI. It should not be surprising that cortical atrophy that occurs with normal aging or a dementing process may alter eye movements. The utility and relationship of pupillometry and Neurotrack™, alone and in combination with intraoperative electroencephalogram (EEG), is of immense interest. Prediction of post-operative delirium and cognitive decline with simple non-invasive means would be a significant clinical advancement.