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Observational Study
. 2025 Feb 1;82(2):176-184.
doi: 10.1001/jamaneurol.2024.4189.

Neurological Pupil Index and Intracranial Hypertension in Patients With Acute Brain Injury: A Secondary Analysis of the ORANGE Study

Matteo Petrosino  1   2 , Elisa Gouvêa Bogossian  3 , Paola Rebora  1   2   4 , Stefania Galimberti  1   2   4 , Randall Chesnut  5   6 , Pierre Bouzat  7 , Mauro Oddo  8   9 , Fabio Silvio Taccone  3 , Giuseppe Citerio  2   10 ; ORANGE Participants and Investigators
Affiliations
Observational Study

Neurological Pupil Index and Intracranial Hypertension in Patients With Acute Brain Injury: A Secondary Analysis of the ORANGE Study

Matteo Petrosino et al. JAMA Neurol. .

Abstract

Importance: Invasive intracranial pressure (ICP) is the standard of care in patients with acute brain injury (ABI) with impaired consciousness. The Neurological Pupil Index (NPi) obtained by automated pupillometry is promising for noninvasively estimating ICP.

Objectives: To evaluate the association between repeated NPi and invasive ICP values.

Design, setting, and participants: This study is a secondary analysis of the Outcome Prognostication of Acute Brain Injury With the Neurological Pupil Index (ORANGE), a multicenter, prospective, observational study of patients with ABI performed from October 1, 2020, to May 31, 2022, with follow-up at 6 months after ABI. The ORANGE study was performed at neurologic intensive care units of tertiary hospitals in Europe and North America. In ORANGE, 514 adult patients receiving mechanical ventilatory support were admitted to the intensive care unit after ABI.

Exposure: Invasive ICP monitoring and automated pupillometry assessment every 4 hours during the first 7 days, considered as a standard of care.

Main outcomes and measures: Association between ICP and NPi values over time, using bayesian joint models, with linear and logistic mixed-effects longitudinal submodels.

Results: The study included 318 adult patients (median [IQR] age, 58 [43-69] years; 187 [58.8%] male) who required intensive care unit admission, intubation, and mechanical ventilatory support due to acute traumatic brain injury (n = 133 [41.8%]), intracerebral hemorrhage (n = 104 [32.7%]), or aneurysmal subarachnoid hemorrhage (n = 81 [25.5%]) and had automatic infrared pupillometry used as part of the standard evaluation practice and ICP monitoring. A total of 8692 ICP measurements were collected, with a median (IQR) of 31 (18-37) evaluations per patient. The median (IQR) NPi and ICP for the study population were 4.1 (3.5-4.5) and 10 (5-14) mm Hg, respectively. In a linear mixed model, the mean change in the NPi value, as a continuous variable, was -0.003 (95% credible interval [CrI], -0.006 to 0.000) for each 1-mm Hg ICP increase. No significant association between ICP and abnormal NPi (<3; odds ratio, 1.01; 95% CrI, 0.99-1.03) or absent NPi (0; odds ratio, 1.03; 95% CrI, 0.99-1.06) was observed.

Conclusions and relevance: Although an abnormal NPi could indicate brainstem dysfunction, in this large and heterogeneous population of patients, NPi values were not significantly associated overall with ICP values. Repeated NPi measurements may not be a sufficient replacement for invasive monitoring.

Trial registration: ClinicalTrials.gov Identifier: NCT04490005.

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Conflict of interest statement

Conflict of Interest Disclosures: Profs Oddo, Taccone, and Citerio reported receiving personal fees from NeurOptics outside the submitted work. Prof Taccone also reported receiving personal fees from Eurosets and Nihon Khoden outside the submitted work. Prof Citerio also reported receiving grants and personal fees from Integra outside the submitted work. No other disclosures were reported.

References

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