Quantitative pupillometry for the monitoring of intracranial hypertension in patients with severe traumatic brain injury

Abstract

Background: Elevated intracranial pressure (ICP) is frequent after traumatic brain injury (TBI) and may cause abnormal pupillary reactivity, which in turn is associated with a worse prognosis. Using automated infrared pupillometry, we examined the relationship between the Neurological Pupil index (NPi) and invasive ICP in patients with severe TBI. Methods: This was an observational cohort of consecutive subjects with severe TBI (Glasgow Coma Scale [GCS] < 9 with abnormal lesions on head CT) who underwent parenchymal ICP monitoring and repeated NPi assessment with the NPi-200® pupillometer. We examined NPi trends over time (four consecutive measurements over intervals of 6 h) prior to sustained elevated ICP > 20 mmHg. We further analyzed the relationship of cumulative abnormal NPi burden (%NPi values < 3 during total ICP monitoring time) with intracranial hypertension (ICHT)-categorized as refractory (ICHT-r; requiring surgical decompression) vs. non-refractory (ICHT-nr; responsive to medical therapy)-and with the 6-month Glasgow Outcome Score (GOS). Results: A total of 54 patients were studied (mean age 54 ± 21 years, 74% with focal injuries on CT), of whom 32 (59%) had ICHT. Among subjects with ICHT, episodes of sustained elevated ICP (n = 43, 172 matched ICP-NPi samples; baseline ICP [T − 6 h ] 14 ± 5 mmHg vs. ICPmax [T 0 h ] 30 ± 9 mmHg) were associated with a concomitant decrease of the NPi (baseline 4.2 ± 0.5 vs. 2.8 ± 1.6, p < 0.0001 ANOVA for repeated measures). Abnormal NPi values were more frequent in patients with ICHT-r (n = 17; 38 [3-96]% of monitored time vs. 1 [0-9]% in patients with ICHT-nr [n = 15] and 0.5 [0-10]% in those without ICHT [n = 22]; p = 0.007) and were associated with an unfavorable 6-month outcome (15 [1-80]% in GOS 1-3 vs. 0 [0-7]% in GOS 4-5 patients; p = 0.002). Conclusions: In a selected cohort of severe TBI patients with abnormal head CT lesions and predominantly focal cerebral injury, elevated ICP episodes correlated with a concomitant decrease of NPi. Sustained abnormal NPi was in turn associated with a more complicated ICP course and worse outcome.

Neuromonitoring of delirium with quantitative pupillometry in sedated mechanically ventilated critically ill patients

“…1. In the subset of patients in whom pupillometry measurements were performed at days 6 and 7 (n = 30), q-PLR remained significantly lower in patients with delirium (median 22 [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] vs. 30 [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] in non-delirious patients at day 6, and 27 [25][26][27][28][29][30][31] vs. 35 [27][28][29][30][31][32][33][34][35][36][37][38] at day 7; both p < 0.05).…”

“…Neuroimaging was not systematically performed, but we excluded all patients admitted for a primary acute brain injury or with a previous known neurological disease thereby limiting as much as possible intrinsic brain factors that may potentially alter pupillometry assessment [42,43]. Furthermore, pupillometry measurements were performed by an experienced research ICU physician or nurse, thereby guaranteeing data reliability and quality, and the pupillometry data were blinded to clinicians involved in patient care.…”

Essential Noninvasive Multimodality Neuromonitoring for the Critically Ill Patient

“…Jahns et al assessed 54 patients with severe TBI with abnormal lesions on head computed tomography (CT) imaging who underwent parenchymal ICP monitoring and repeated NPi assessment through four consecutive measurements over intervals of 6 h prior to sustained elevated ICP >20 mmHg and found that episodes of elevated ICP correlated with a concomitant decrease in NPi. Sustained abnormal NPi was in turn associated with a more complicated ICP course and worse outcome [14].…”

Quantitative Pupillometry in the Intensive Care Unit

“…Additionally, the rate of abnormal NPi was higher in patients who went on to have a poor outcome versus good outcome (15% vs 0%, P ¼ .002) as defined by Glasgow Outcome Scale after 6 months. 58 In addition to detecting increased ICP, changes in pupillometry have been shown to precede TTH. A small study of 3 patients with a total of 12 independent TTH events evaluated with pupillometry found that the NPi was zero in 58% of cases of TTH and abnormal in the remaining cases.…”