What is the clinical evidence from this study?

Study design: Cohort. Population: acute brain injury (n=57). Intervention: Neurological Pupil Index assessment. Primary outcome: Association between the number of NPi-d and pNPi-d with outcomes at ICU discharge (RR 3.58, 95% CI [1.49-8.60], p=0.004).

What question did this study set out to answer?

The study aims to evaluate the prognostic value of NPi differentials in ICU patients with acute brain injury.

January 10, 2026Journal of Anesthesia Analgesia and Critical Care0 citationsOpen Access

Persistence of NPi differential predicts outcome at intensive care unit discharge: a single-center retrospective analysis

Q: What does this research mean for the field?

The number of Neurological Pupil index differentials is significantly associated with increased risk of poor neurological outcomes and death during ICU stay. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

SZSimone Maria ZerbiOspedale Sant'Anna SMStella Martina MartoranaOspedale Sant'Anna SRSamanta RanaOspedale Sant'Anna

Key Result

The number of NPi differentials is significantly associated with increased risk of poor neurological outcomes and death during ICU stay.

Key Points

The study aims to evaluate the prognostic value of NPi differentials in ICU patients with acute brain injury.
Retrospective analysis of 57 patients with acute brain injuries
Utilized serial quantitative pupillometry to measure NPi
Defined NPi-d as a difference of ≥ 0.7 between pupils
Measured persistence of the differential over time
NPi-d events and pNPi-d were significantly linked to poor neurological outcomes and increased mortality
Increased number of NPi-d raised the risk of poor outcomes by over three times
Higher pNPi-d values correlated with elevated odds of poor outcomes, death, and longer ICU stays

Study Design

Type

Cohort (n=57)

Multicenter

Structured PICO

Does the frequency and persistence of Neurological Pupil index (NPi) differentials predict poor neurological outcomes and mortality at ICU discharge in patients with acute brain injury?

Population

57 adults (aged ≥18 years) with acute brain injury (traumatic brain injury, spontaneous subarachnoid hemorrhage, or intraparenchymal hemorrhage) and spontaneous coma (GCS ≤8) or rapid neurological deterioration requiring intubation. Mean age 62.9 ± 16.8 years, 58% male. Single-center (Italy).

Intervention

Serial quantitative pupillometry monitoring to assess the frequency of Neurological Pupil index differentials (NPi-d ≥ 0.7) and persistence of the differential (pNPi-d) over time.

Comparator

Patients with no or lower frequency/persistence of NPi differentials (observational comparison).

Outcome

Neurological outcomes at ICU discharge, categorized as Good outcome (GCS 15–14), Poor outcome (GCS 3–13), or Death.hard clinical

Dynamic pupillometry measures, specifically the frequency and persistence of NPi asymmetries, provide valuable early prognostic information for predicting poor outcomes and mortality in critically ill patients with acute brain injury.

Main Result

Effect estimate: RR 3.58 (95% CI [1.49-8.60])

Absolute Event Rate: 24% vs 10%

p-value: p=0.004

Limitations

Small sample size
Retrospective design
Potential measurement variability

Abstract

This retrospective study explores the prognostic significance of the frequency and persistence of Neurological Pupil index (NPi) differentials (NPi-d) in patients with acute brain injury admitted to the intensive care unit. A total of 57 patients with traumatic brain injury, subarachnoid hemorrhage, or intracerebral hemorrhage were included, all of whom underwent serial quantitative pupillometry. An NPi-d was defined as a difference of ≥ 0.7 between the NPi of the two pupils, while the persistence of the differential (pNPi-d) captured sustained asymmetry over time, regardless of whether the threshold was reached. The analysis revealed that both the number of NPi-d events and the pNPi-d were significantly associated with unfavorable neurological outcomes and mortality at intensive care unit (ICU) discharge. Multinomial logistic regression showed that an increased number of NPi-d was associated with a more than threefold increased risk of poor outcome and death. Similarly, higher pNPi-d values correlated with greater odds of poor outcome, death, elevated need for therapeutic interventions to manage intracranial hypertension, decompressive craniectomy, and longer ICU stay. These findings suggest that, beyond static NPi thresholds, dynamic measures such as the frequency and persistence of NPi asymmetries provide valuable prognostic information. Incorporating these pupillometry-based metrics into routine neuromonitoring could enhance early risk stratification and guide treatment strategies in critically ill neurological patients.

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