Association Between Pain, Agitation, and Intracranial Pressure with Cerebral Near-Infrared Spectroscopy in Critically Ill Children: A Prospective Pilot Study.

Background/

Objectives

Invasive intracranial pressure (ICP) monitoring is standard in pediatric neurocritical care, but the potential of non-invasive near-infrared spectroscopy (NIRS) and the bedside drivers of ICP remain under-explored. We evaluated the association between cerebral NIRS (rSO2), pain and agitation, systemic hemodynamics, inflammatory markers, and invasive ICP in critically ill children.

Methods

In this prospective pilot study, children undergoing external ventricular-drain-based ICP monitoring were followed with repeated measurements. Linear Mixed Models (LMM) with a random patient intercept were used to assess the NIRS-ICP association, adjusting for hemodynamic (mean arterial pressure (MAP), heart rate) and clinical variables. The Mann-Whitney U test compared parameters across a 20 mmHg ICP threshold, and the Kruskal-Wallis test compared ICP burden across etiology and outcome subgroups. Inflammatory markers (CRP, WBC, procalcitonin) were evaluated separately.

Results

A total of 596 measurements from 21 patients were analyzed. Cerebral NIRS was the strongest independent predictor of ICP, showing a significant inverse association (estimate -0.609, p < 0.001). Agitation was independently associated with higher ICP (estimate 0.856, p < 0.001), and this effect was significantly modified by the patient's behavioral state, being attenuated during sleep and calm wakefulness compared with agitated wakefulness (sleep × agitation interaction, p = 0.002). MAP retained an independent positive association with ICP (estimate 0.044, p = 0.019), whereas pain score did not. After adjustment for etiology and sex, these associations remained unchanged; etiology was itself an independent predictor of ICP (p = 0.001), whereas sex was not. Serum CRP independently predicted ICP (t = 2.382, p = 0.018), whereas WBC and procalcitonin did not. ICP burden differed by etiology, with intracranial masses and leukemia showing the highest loads (p < 0.001), but not across clinical-outcome groups (p = 0.192).

Conclusions

Cerebral NIRS-derived rSO2 was an independent inverse correlate of invasive ICP, and agitation was independently associated with ICP in a state-dependent manner, with its effect attenuated during sleep and calm wakefulness. CRP and etiology further shaped ICP burden. These findings support integrating non-invasive cerebral oximetry into multimodal pediatric neuromonitoring and highlight the value of managing distress to mitigate intracranial hypertension.