Automated Pupillometry as an Assessment Tool for Intracranial Hemodynamics in Septic Patients

Abstract

Impaired cerebral autoregulation (CA) may increase the risk of brain hypoperfusion in septic patients. Sepsis dysregulates the autonomic nervous system (ANS), potentially affecting CA. ANS function can be assessed through the pupillary light reflex (PLR). The aim of this prospective, observational study was to investigate the association between CA and PLR in adult septic patients. Transcranial Doppler was used to assess CA and calculate estimated cerebral perfusion pressure (eCPP) and intracranial pressure (eICP). An automated pupillometer (AP) was used to record Neurological Pupil Index (NPi), constriction (CV) and dilation (DV) velocities. The primary outcome was the relationship between AP-derived variables with CA; the secondary outcome was the association between AP-derived variables with eCPP and/or eICP. Among 40 included patients, 21 (53%) had impaired CA, 22 (55%) had low eCPP (<60 mmHg) and 15 (38%) had high eICP (>16 mmHg). DV was lower in patients with impaired CA compared to others; DV predicted impaired CA with area under the curve, AUROC= 0.78 [95% Confidence Interval, CI 0.63–0.94]; DV < 2.2 mm/s had sensitivity 85% and specificity 69% for impaired CA. Patients with low eCPP or high eICP had lower NPi values than others. NPi was correlated with eCPP (r = 0.77, p < 0.01) and eICP (r = −0.87, p < 0.01). Automated pupillometry may play a role to assess brain hemodynamics in septic patients.

Evaluating the utility of quantitative pupillometry in a neuro-critical care setting for the monitoring of intracranial pressure: A prospective cohort study

“…23 In a cohort of septic patients with impaired cerebral autoregulation, abnormal NPI was also identi ed in patients with impaired autoregulation and those with raised estimated ICP. 24 However, to the best of our knowledge, our study is the rst to try to identify which of the many QP variables offered would be most sensitive to overall ICP trends.…”

Neuromonitoring of Pediatric and Adult Extracorporeal Membrane Oxygenation Patients: The Importance of Continuous Bedside Tools in Driving Neuroprotective Clinical Care

“…43 Another prospective observational study using an automated pupillometer to detect dilation velocity (DV) established a correlation between DV and cerebral autoregulation (CA) in septic patients. 44 Although pupillometry is a promising neuromonitoring technique, it is intermittent with an hourly frequency and is affected by numerous pathologies: the complexity and extensive pathway of the pupillary reflex make interpretation challenging in isolation. Therefore, this monitoring technique may best be used in conjunction with other neuromonitoring methods to detect impending brain injury and impaired CA.…”

Application of Pupillometry in Neurocritical Patients

“…The NPi takes into account various variables, such as latency, CV, mean CV, baseline pupil size, percentage of change, and DV. A lower NPi score (less than 3) has been associated with increased intracranial pressure [43,44] as well as poorer outcomes in critically ill patients [45][46][47][48][49]. Thus, the NPi provides an objective and automated assessment of pupil parameters, thereby overcoming the subjectivity and technician-dependence associated with traditional methods of pupil assessment.…”

“…Pupillometry has emerged as a crucial tool in neurocritical care, enabling clinicians to detect elevated intracranial pressure and impending neurological deterioration at an early stage [44,46,[53][54][55][56][57]. Pupil evaluation using a penlight for reactivity and a pupil gauge for size is often performed, but the results are often heterogenous and inconsistent, with variations in the intensity and duration of ambient light, as well as with different examiners.…”