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Can Quantitative Pupillometry be used to Screen for Elevated Intracranial Pressure? A Retrospective Cohort Study
Jakob Pansell1,2, Robert Hack3, Peter Rudberg3,4
1Department of Clinical Neuroscience, Karolinska Institutet, Central Intensive Care Unit E5:67, Karolinska University Hospital, Stockholm, 17176, Sweden. jakob.pansell@regionstockholm.se.
Quantitative pupillometry using the Neurological Pupil index (NPi) can help screen for elevated intracranial pressure (ICP) in brain injury patients. This noninvasive tool aids clinical decisions by reliably ruling out high ICP, reducing the need for invasive monitoring.
Area of Science:
- Neuroscience
- Critical Care Medicine
- Medical Devices
Background:
- Elevated intracranial pressure (ICP) is a critical complication following brain injury.
- Current ICP monitoring is invasive, posing risks and limiting its use in all at-risk patients.
- Noninvasive screening tools are needed to identify patients with elevated ICP.
Purpose of the Study:
- To evaluate quantitative pupillometry, specifically the Neurological Pupil index (NPi), as a noninvasive screening tool for elevated ICP.
- To determine the association between NPi measurements and invasively monitored ICP.
- To assess the utility of NPi in identifying patients who may benefit from invasive ICP monitoring.
Main Methods:
- A retrospective observational study involving 65 patients with invasive ICP monitoring.
- Quantitative pupillometry was performed using the Neuroptics NPi-200 pupillometer.
- Nonparametric receiver operator curve analysis and logistic regression were used to analyze the association between NPi and elevated ICP (≥20 mm Hg).
Main Results:
- The study analyzed 2,705 ICP measurements.
- Quantitative pupillometry (NPi) demonstrated an area under the receiver operator curve of 0.72 for detecting elevated ICP.
- An optimal mean NPi cutoff value of ≥3.9 was identified to rule out elevated ICP, with decreasing probability of elevated ICP as NPi increased (OR 0.55).
Conclusions:
- Screening with NPi can reliably rule out elevated ICP, informing clinical decisions regarding invasive monitoring.
- NPi provides a quantitative measure that aids in estimating the probability of elevated ICP.
- The ease of use and excellent interrater reliability of NPi suggest its potential as a valuable noninvasive screening tool for elevated ICP, warranting further investigation.
Related Concept Videos
Increased Intracranial Pressure l: Introduction
Increased Intracranial Pressure ll: Pathophysiology

