Pupillometry for the Prediction of Neurologic Outcomes in Severe Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of morbidity and mortality in the US. The CDC states that 1.7 million people sustain a traumatic brain injury each year, with death occurring in 52,000 of these injured patients. It is also estimated that 275,000 yearly require hospitalization. The costs of TBI can be devastating to our society, with the 2010 economic cost estimated to be approximately $76.5 billion. 90% of this cost involves fatal or hospitalized brain injured patients. Furthermore, survivors of traumatic brain injury have high rates of institutionalization, readmission, and disability. The prediction of prognosis in severe TBI is a difficult problem for physicians. Prognosis evaluation in the acute phase of care varies widely among physicians caring for these patients\[3\]. With prognosis often in doubt, physicians have difficulty leading families and patients toward the most appropriate treatment which often leads to expensive testing and patient management. The Brain Trauma Foundation has recommended several early indicators of prognosis in severe TBI, including age, hypotension, CT scan features, Glasgow Outcome Scale score, and pupillary diameter with light reflexes. Pupillary diameter and light reflexes have been extensively studied, however accurate measurements of these prognostic factors have not been performed due to a lack of standardized measuring procedure. A new device has been validated to measure both pupil size and reactivity using infrared pupillometry. This device has also been studied to create the Neurological Pupil Index (NPi) as a measure of pupillary reactivity. The NPi has been shown to correlate with intracranial pressure readings, however there are no studies correlating the pupillometer findings with outcome measures in TBI. This study will prospectively evaluate the pupillometer readings of pupillary size and reactivity (NPi) to test the hypothesis that the NPi is a realiable predictor of 30-day outcomes in patients with s