NeurOptics’ NPi-200 pupillometer
A new study has found that NeurOptics’ NPi-200 pupillometer, which provides an automated assessment of the pupillary light reflex, may give an early warning of delayed cerebral ischemia, enabling preemptive care. The study was published in the Journal of Neurosurgery.
The study analyzed 56 patients diagnosed with aneurysmal subarachnoid hemorrhage and admitted to the neuro-intensive care unit of the University of Texas Southwestern Medical Center between 2015 and 2017. Patients were monitored using transcranial Doppler and the infrared NPi-200 pupillometer, which calculates a neurological pupil index (NPi). NPi values range from 0 to 5, with 3 or greater considered normal. Most patients had multiple daily NPi readings, and the lowest value was recorded.
The 635 paired observations of daily Doppler and NPi data showed a significant and strong association between the development of delayed cerebral ischemia and an abnormal decrease in NPi readings, investigators found. Twelve patients experienced delayed cerebral ischemia, with seven showing a decrease in their NPi to an abnormal range. This change occurred more than eight hours prior to the clinical decline 71.4% of the time, the study found. The NPi normalized in all patients after treatment.
The aftermath of aneurysmal subarachnoid hemorrhage remains devastating despite modern advances in neurocritical care. Patients who do not succumb to the initial aneurysmal rupture are at risk for cerebral vasospasm, which occurs in about 70% of patients, according to previously published studies. Approximately 25% to 40% of these patients develop delayed cerebral ischemia, with neurological deficits and possible cognitive decline. Transcranial Doppler has been shown to be predictive of delayed cerebral ischemia, but with poor positive predictive value, one study found.
Automated assessment of the pupillary light reflex has emerged as an objective means of assessing pupillary reactivity across a broad spectrum of neurological disease, including stroke, traumatic brain injury and edema, tumoral herniation syndromes, and sports or war injuries. Pupillometers use infrared technology to assess an array of objective pupillary variables including size, constriction velocity, latency, and dilation velocity, which are normalized and standardized to compute the neurological pupil index. The NeurOptics NPi-200 pupillometer was designed to eliminate the variability and subjectivity inherent in manual pupillary evaluation to provide more accurate, reliable, and objective pupil size and reactivity measurement, according to the Laguna Hills, Calif.-based company.
“Detecting and responding to neurological changes as early as possible is critical for patients,” said neurologist H. Hunt Batjer, M.D., of UT Southwestern Medical Center, said in a prepared statement. “These results showed that pupillometer changes may occur hours prior to the clinical neurological decline, and the NPi-200 has the potential to provide enough warning to initiate therapeutic measures before the development of irreversible neurological damage. Pupillometry may be a key piece to the larger picture when used as a complement to a good clinical, radiological, and sonographic examination.”
