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. 2011:2:82.
doi: 10.4103/2152-7806.82248. Epub 2011 Jun 21.

Pupillary reactivity as an early indicator of increased intracranial pressure: The introduction of the Neurological Pupil index

Jeff W Chen  1 , Zoe J Gombart, Shana Rogers, Stuart K Gardiner, Sandy Cecil, Ross M Bullock
Affiliations

Pupillary reactivity as an early indicator of increased intracranial pressure: The introduction of the Neurological Pupil index

Jeff W Chen et al. Surg Neurol Int. 2011.

Abstract

Background: This paper introduces the 7/5/2011al Pupil index (NPi), a sensitive measure of pupil reactivity and an early indicator of increasing intracranial pressure (ICP). This may occur in patients with severe traumatic brain injury (TBI), aneurysmal subarachnoid hemorrhage, or intracerebral hemorrhage (ICH).

Methods: 134 patients (mean age 46 years, range 18-87 years, 54 women and 80 men) in the intensive care units at eight different clinical sites were enrolled in the study. Pupillary examination was performed using a portable hand-held pupillometer.

Results: Patients with abnormal pupillary light reactivity had an average peak ICP of 30.5 mmHg versus 19.6 mmHg for the normal pupil reactivity population (P = 0.0014). Patients with "nonreactive pupils" had the highest peaks of ICP (mean = 33.8 mmHg, P = 0.0046). In the group of patients with abnormal pupillary reactivity, we found that the first evidence of pupil abnormality occurred, on average, 15.9 hours prior to the time of the peak of ICP.

Conclusions: Automated pupillary assessment was used in patients with possible increased ICP. Using NPi, we were able to identify a trend of inverse relationship between decreasing pupil reactivity and increasing ICP. Quantitative measurement and classification of pupillary reactivity using NPi may be a useful tool in the early management of patients with causes of increased ICP.

Keywords: Intracranial pressure; Neurological Pupil index; pupillometer; traumatic brain injury.

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Figures

Figure 1
Figure 1
The portable pupillometer held up to a patient's eye during a measurement
Figure 2
Figure 2
Peak of ICP was defined for each single patient as the maximum event of sustained ICP. The distribution of peak of ICP varied depending on the pupil NPi reactivity score. Those patients with normal pupil reactivity NPi (3–5, Group 1) had the lowest ICP. Those with one or more occurrences of abnormal NPi (<3, Group 2) had a significantly larger distribution of sustained ICP. Group 3, with the highest sustained ICPs, includes those patients who developed or had occurrences of a nonreactive pupil. Red error bars indicate 95% Confidence Interval (CI)
Figure 3
Figure 3
Temporal progression of pupil reactivity and ICP in two patients; ICP in the top panels, pupil reactivity (NPi) in the lower panels, red for the right pupil and blue for the left pupil (see text for clinical information). Normal range of pupil reactivity is for NPi values between 3 and 5. The threshold between normal and abnormal pupil reactivity is indicated with a solid back horizontal line in the lower panels
See this image and copyright information in PMC

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