Quantitative Pupillometry for Intracranial Pressure (ICP) Monitoring in Traumatic Brain Injury: A Scoping Review.

The neurological examination has remained key for the detection of worsening in neurocritical care patients, particularly after traumatic brain injury (TBI). New-onset, unreactive anisocoria frequently occurs in such situations, triggering aggressive diagnostic and therapeutic measures to address life-threatening elevations in intracranial pressure (ICP). As such, the field needs objective, unbiased, portable, and reliable methods for quickly assessing such pupillary changes. In this area, quantitative pupillometry (QP) proves promising, leveraging the analysis of different pupillary variables to indirectly estimate ICP. Thus, this scoping review seeks to describe the existing evidence for the use of QP in estimating ICP in adult patients with TBI as compared with invasive methods, which are considered the standard practice. This review was conducted in accordance with the Joanna Briggs Institute methodology for scoping reviews, with a main search of PubMed and EMBASE. The search was limited to studies of adult patients with TBI published in any language between 2012 and 2022. Eight studies were included for analysis, with the vast majority being prospective studies conducted in high-income countries. Among QP variables, serial rather than isolated measurements of neurologic pupillary index, constriction velocity, and maximal constriction velocity demonstrated the best correlation with invasive ICP measurement values, particularly in predicting refractory intracranial hypertension. Neurologic pupillary index and ICP also showed an inverse relationship when trends were simultaneously compared. As such, QP, when used repetitively, seems to be a promising tool for noninvasive ICP monitoring in patients with TBI, especially when used in conjunction with other clinical and neuromonitoring data.

Associations of an eye-tracking task and pupillary metrics with age and ASA physical status score in a preoperative cohort.

Advanced age, American Society of Anesthesiologists physical status (ASA) classification and the presence of cognitive impairment are associated with an elevated risk of postoperative morbidity and mortality. The visual paired comparison (VPC) task, which relies on recognition of novel images, examines declarative memory. VPC scores have demonstrated the ability to detect mild cognitive impairment and track progression of neurodegenerative disease. Quantitative pupillometry may have similar value. We evaluate for associations between these variables of interest and the feasibility of performing these tests in the preoperative clinic. Prospective data from 199 patients seen in the preoperative clinic at a tertiary academic center were analyzed. A 5 min VPC task (Neurotrack Technologies, Inc, Redwood City, CA) was administered during their scheduled preoperative clinic visit. Pupillary light reflexes were measured at the same visit (PLR-3000™, Neuroptics Corp, Irvine, California).Thirty-four percent of patients were categorized as ASA 2 and 58% as ASA 3. Median age was 57 (IQR: 44-69). Associations were demonstrated between age and ASA physical status (Mann-Whitney U Test, p < 0.0001), maximum pupil size (Spearman Rank Correlation, r = - 0.40, p < 0.0001), and maximum constriction velocity (Spearman Rank Correlation, r = - 0.39, p < 0.0001). Our data also revealed an association between VPC score and age (Spearman Rank Correlation, p = 0.0016, r = - 0.21) but not ASA score (Kruskal-Wallis Test, p = 0.14). When compared to a nonsurgical cohort with no history of memory impairment, our population scored worse on the VPC task (Mann-Whitney U Test, p = 0.0002). A preoperative 5 min VPC task and pupillometry are feasible tests in the preoperative setting and may provide a valuable window into an individual's cognition prior to elective surgery.

Pupil assessment with a new handheld pupillometer in healthy subjects.

OBJECTIVE: To assess the pupil response with a new handheld pupillometer in healthy subjects. METHODS: Sixty-four eyes of 32 healthy subjects (mean age 21.2 years) were tested. After dark adaptation for 10 min, pupil responses to 1 s red and blue light stimuli at 100 cd/m2 were measured in the order from right to left eyes with a 1 min interval. The initial pupil size (D1, mm), minimum pupil size (D2, mm), and constriction rate (CR, %) were obtained. Intra-examiner reproducibility was examined using the coefficient of variation (CV, %) and the Bland-Altman plot. Inter-examiner consistency was examined using the interclass correlation coefficient (ICC) and the agreements with a conventional device, by Pearson's correlation coefficient (r). RESULTS: The CV of all parameters have high reproducibility in the red (11.0-20.7%) and blue (5.5-12.1%) light stimuli. Bland-Altman plot analysis showed no bias with both light stimuli. "Almost perfect" and "substantial" correlations between the examiners were obtained in the red (ICC = 0.78-0.94) and blue (ICC = 0.71-0.89) light stimuli. "Excellent" and "good" correlations between the devices were obtained, except for the CR parameter in the red (D1: r = 0.90; p < 0.001, D2: 0.72; p < 0.001, and CR: 0.08; p = 0.631, respectively) and blue (D1: r = 0.87; p < 0.001, D2: 0.70; p < 0.001, and CR: 0.19; p = 0.274, respectively) light stimuli. CONCLUSION: The novel pupillometer is useful for assessing pupil response. However, because of their different constructions, the CR values cannot be compared directly between the devices.

Pupil response to painful stimuli during inhalation anaesthesia without opioids in children.

BACKGROUND: Pupil dilation reflex measured by a pupillometer is known to be a useful parameter for assessing the response to perioperative noxious stimuli. In children, pupillometer can reflect changes after painful stimuli during anaesthesia or guide anaesthesia to reduce opioid consumption. However, to date, there are no data regarding pupil response during inhalation anaesthesia with analgesia by intravenous acetaminophen in children. METHODS: We planned a prospective, single-armed study of children aged between 3 and 12 years who underwent surgery under general anaesthesia. Anaesthesia was maintained by 1 minimum alveolar concentration (MAC) of sevoflurane, and 15 mg/kg of acetaminophen was administered. Patients' left eye was examined using a pupillometer after induction, before and after skin incision and train-of-four stimulus. Pupil diameter and other pupillometric parameters were recorded. Increase in heart rate by 15% was regarded as insufficient analgesia to skin incision and indicative powers of pupillometric parameters for insufficient analgesia were examined by receiver-operating characteristics. RESULTS: A total of 33 patients were included. Enlarged pupil, large increase in pupil diameter and low neurological pupil index (NPi) after skin incision were good indicators of insufficient analgesia for skin incision. Children with insufficient analgesia showed abnormal NPi value. However, increase in pupil diameter and decrease in NPi were observed even in patients without increase in the heart rate after the skin incision. CONCLUSIONS: We suggest dilation of the pupil and decrease in NPi can indicate response to noxious stimuli in children. Regardless of sufficiency of analgesia, pupil dilation and decrease in NPi were observed after skin incision in children under general anaesthesia with 1 MAC of sevoflurane and intravenous acetaminophen.

Repeatability and clinical use of pupillary light reflex measurement using RAPDx® pupillometer.

OBJECTIVE: To evaluate the repeatability of pupillary light reflex metrics measured by the RAPDx® dynamic pupillometer in healthy subjects and clinical application in patients with unilateral optic neuritis (ON). METHODS: Sixty eyes of 30 healthy volunteers were measured three times consecutively by the same technician. The amplitude of constriction (AC), the latency of constriction (LOC), the velocity of peak constriction (VC) of light-evoked pupillary constriction, RAPD score for amplitude and latency were measured using RAPDx® dynamic pupillometer. The repeatability of above metrics was assessed by the intraclass correlation coefficient (ICC) and coefficient of variation (Cov). Furthermore, pupillary light reflex measurements were performed in 48 eyes of 24 patients diagnosed with unilateral optic neuritis (ON). Interocular symmetry was evaluated both in the healthy subjects and the ON-involved patients. RESULTS: High repeatability of AC, LOC, and VC in healthy subjects was displayed, presenting with the ICC value over 0.80 and the Cov less than 8.00%. But the RAPD score for amplitude (ICC: 0.67) and RAPD score for latency (ICC: 0.65) showed only moderate repeatability. Furthermore, a slight declining trend was found in amplitude and peak velocity when continuous and multiple measurements in the healthy subjects. Good symmetry of the AC, LOC, and VC of pupillary light constriction between the two eyes was displayed in the healthy subjects (P > 0.05). By contrast, there was a distinct decrease of AC and VC (P < 0.01), and a mild increase of LOC (P < 0.01) in the ON-involved eye in direct pupillary light reflex. CONCLUSIONS: Pupillary light reflex measured by the RAPDx® pupillometer achieved overall good repeatability and interocular symmetry in healthy subjects. The device also presented decent preliminary results in patients with unilateral ON, suggesting its potential value to be developed as a tool in optic nerve diseases.

Pupillometry in perioperative medicine: a narrative review.

PURPOSE: Pupillometry is a technique for objective quantification of nociception that takes into account the central processing of noxious stimuli and its sympathetic response. This narrative review provides an overview of the physiology of the pupil, the principles of pupillometry, and its potential application in the perioperative environment, especially in nociception monitoring and quantifying responses to opioids. SOURCE: Relevant articles, including reports of original investigation, review articles, and meta-analyses were identified from searches of PubMed and Google Scholar databases. Articles that described pupillary physiology and pupillometry, along with original research reports of the application of pupillometry in perioperative and critical care environment were used to synthesize a narrative review. PRINCIPAL FINDINGS: Pupillometry is emerging as an objective measure of nociception, especially in patients under general anesthesia, children, non-verbal patients, and critically ill patients who cannot effectively communicate ongoing pain. Portable automated pupillometers have made accurate quantification of pupillary reflexes, including light reflex and dilatation reflex, possible. This technique has been successfully studied in the perioperative setting for a number of applications, including quantification of nociception, response to analgesia, and assessing efficacy of regional blocks. Pupillary oscillations have shown promise in assessing central opioid effects. Pupillometers can also accurately quantify light reflexes during the neurologic evaluation of critically ill patients. CONCLUSIONS: Pupillometry is an easy to use non-invasive bedside technique to quantify nociception and monitor opioid effects. It has the potential to personalize pain management in perioperative and intensive care unit environments. Additional studies are needed to further understand the utility of pupillometry in this context.

RéSUMé: OBJECTIF: La pupillométrie est une technique de quantification objective de la nociception qui tient compte de l'intégration centrale des stimuli douloureux et de la réponse sympathique de la pupille. Cette revue narrative donne un aperçu de la physiologie de la pupille, des principes de la pupillométrie et de son application potentielle dans le contexte périopératoire, en particulier dans le monitorage de la nociception et la quantification des réponses aux opioïdes. SOURCE: Les articles pertinents, comprenant les comptes rendus de recherche originale, les articles de synthèse et les méta-analyses, ont été identifiés à partir de recherches dans les bases de données PubMed et Google Scholar. Les articles décrivant la physiologie de la pupille et la pupillométrie, ainsi que des comptes rendus de recherche originale portant sur l'application de la pupillométrie dans le contexte périopératoire et des soins intensifs, ont été utilisés pour synthétiser un compte rendu narratif. CONSTATATIONS PRINCIPALES: La pupillométrie est une modalité émergente en tant que mesure objective de la nociception, en particulier chez les patients sous anesthésie générale, les patients pédiatriques, les patients qui ne parlent pas et les patients en état critique qui ne peuvent pas communiquer de façon efficace leur douleur. Les pupillomètres automatisés portatifs ont rendu possible la quantification précise des réflexes pupillaires, y compris du réflexe photomoteur et du réflexe de dilatation. Cette technique a été étudiée avec succès dans le cadre périopératoire pour plusieurs applications, y compris la quantification de la nociception, la réponse à l'analgésie et l'évaluation de l'efficacité des blocs régionaux. Les oscillations pupillaires se sont montrées prometteuses pour l'évaluation des effets centraux des opioïdes. Les pupillomètres peuvent également quantifier avec précision les réflexes photomoteurs lors de l'évaluation neurologique des patients en état critique. CONCLUSION: La pupillométrie est une technique au chevet non invasive facile à utiliser pour quantifier la nociception et surveiller les effets des opioïdes. Cette technique pourrait permettre de personnaliser la prise en charge de la douleur dans les environnements périopératoires et de soins intensifs. D'autres études sont nécessaires pour mieux comprendre l'utilité de la pupillométrie dans ce contexte.

Dilation velocity is associated with Glasgow Coma Scale scores in patients with brain injury.

Background: Pupillary light reflex (PLR) is informative about patients with neurological injury. Automated pupillometry provides discrete variables such as dilation velocity (DV). The objective of this study is to determine association between DV and Glasgow Coma Score (GCS), for patients with acquired brain injury.Methods: There were 2,208 patients with acquired brain injury, pupillometer readings, and daily GCS values available in our registry. GCS was trichotomized as severe (GCS ≤ 8), moderate (GCS = 9-12), or mild injury (GCS = 13-15). Generalized Linear Mixed Model regression was used to identify correlation between DV and GCS.Results: Patient mean age was 58.9 years, and 49.11% were female. There were 42,229 observations of GCS and DV. Mean admission GCS was 11.7. In the left eye, there was a statistically significant negative association for mean DV in patients with mild (DV = 0.85 mm/s), moderate (DV = 0.71 mm/s), and severe (DV = 0.48 mm/s) injury (p < .0001). Similar results were noted in the right eye with mild (DV = 0.87 mm/s), moderate (DV = 0.72 mm/s), and severe (DV = 0.50 mm/s) injury (p < .0001).Conclusion: Higher GCS is associated with faster DV. PLR may provide a biomarker of injury when a neurological exam is limited.Trial Registration: NCT02804438 (June 17, 2016).ABBREVIATIONS: GCS: Glasgow Coma Scale; PLR: Pupillary Light Reflex; DV: Dilation velocity; ICP: Intracranial pressure; NPi: Neurological pupil index; mRS: Modified Rankin Score; PCT: Percent change in size (pre and post constriction); Lat: Latency; CV: Constriction velocity; GLMM: Generalized Linear Mixed Model.

Feasibility study of a smartphone pupillometer and evaluation of its accuracy.

Measurement of pupillary characteristics, such as pupillary unrest in ambient light, and reflex dilation have been shown to be useful in a variety of clinical situations. Dedicated pupillometers typically capture images in the near-infrared to allow imaging in both light and darkness. However, because a subset of pupillary measurements can be acquired with levels of visible light suitable for conventional cameras, it is theoretically possible to capture data using general purpose cameras and computing devices such as those found on smartphones. Here we describe the development of a smartphone-based pupillometer and compare its performance with a commercial pupillometer. Smartphone pupillometry software was developed and then compared with a commercial pupillometer by performing simultaneous scans in both eyes, using the smartphone pupillometer and a commercial pupillometer. The raw scans were compared, as well as a selected pupillary index: pupillary unrest in ambient light. In 77% of the scans the software was able to successfully identify the pupil and iris. The raw data as well as calculated values of pupillary unrest in ambient light were in clinically acceptable levels of agreement; Bland-Altman analysis of raw pupil measurements yielded a 95% confidence interval of 0.26 mm. In certain situations a smartphone pupillometer may be an appropriate alternative to a commercial pupillometer.

Multimodal non-invasive assessment of intracranial hypertension: an observational study.

BACKGROUND: Although placement of an intra-cerebral catheter remains the gold standard method for measuring intracranial pressure (ICP), several non-invasive techniques can provide useful estimates. The aim of this study was to compare the accuracy of four non-invasive methods to assess intracranial hypertension. METHODS: We reviewed prospectively collected data on adult intensive care unit (ICU) patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), or intracerebral hemorrhage (ICH) in whom invasive ICP monitoring had been initiated and estimates had been simultaneously collected from the following non-invasive indices: optic nerve sheath diameter (ONSD), pulsatility index (PI), estimated ICP (eICP) using transcranial Doppler, and the neurological pupil index (NPI) measured using automated pupillometry. Intracranial hypertension was defined as an invasively measured ICP > 20 mmHg. RESULTS: We studied 100 patients (TBI = 30; SAH = 47; ICH = 23) with a median age of 52 years. The median invasively measured ICP was 17 [12-25] mmHg and intracranial hypertension was present in 37 patients. Median values from the non-invasive techniques were ONSD 5.2 [4.8-5.8] mm, PI 1.1 [0.9-1.4], eICP 21 [14-29] mmHg, and NPI 4.2 [3.8-4.6]. There was a significant correlation between all the non-invasive techniques and invasive ICP (ONSD, r = 0.54; PI, r = 0.50; eICP, r = 0.61; NPI, r = - 0.41-p < 0.001 for all). The area under the curve (AUC) to estimate intracranial hypertension was 0.78 [CIs = 0.68-0.88] for ONSD, 0.85 [95% CIs 0.77-0.93] for PI, 0.86 [95% CIs 0.77-0.93] for eICP, and 0.71 [95% CIs 0.60-0.82] for NPI. When the various techniques were combined, the highest AUC (0.91 [0.84-0.97]) was obtained with the combination of ONSD with eICP. CONCLUSIONS: Non-invasive techniques are correlated with ICP and have an acceptable accuracy to estimate intracranial hypertension. The multimodal combination of ONSD and eICP may increase the accuracy to estimate the occurrence of intracranial hypertension.

A comparison of manual pupil examination versus an automated pupillometer in a specialised neurosciences intensive care unit.

BACKGROUND: The assessment of pupil size and reaction to light is a fundamental part of the neurological assessment; however, manual examination is prone to inaccuracies. The use of an automated infrared pupillometer is one strategy to limit error in pupil examination. OBJECTIVE: The main objective was to assess agreement between manual examination and examination using an automated infrared pupillometer in relation to pupil reaction and size in a specialised neurosciences intensive care unit. METHODS: We conducted a single-centre prospective observational study in a specialised tertiary neurosciences intensive care unit. Participants' pupils were examined hourly for 24 h by both manual examination using a pen torch and examination using an automated infrared pupillometer. RESULTS: Twenty-two participants were enrolled. A total of 935 paired pupil observations were obtained for both pupil reaction and size. There was no statistically significant disagreement in assessing pupil reaction (McNemar's test p = 0.106). Percentage agreement was 96.68% for pupil reaction, with Kappa coefficient, 0.841 (95% confidence interval: 0.7864-0.8956). For all participants, the mean difference in pupil size was 0.154 mm, with limits of agreement of -1.294 mm to +1.603 mm. CONCLUSION: There was no significant disagreement between manual and automated pupillometer observations for pupil reaction. The mean difference in measurement of pupil size was small.

Automated Pupillometry in Neurocritical Care: Research and Practice.

PURPOSE OF REVIEW: The purpose of this review is to examine the impact of pupillometer assessment on care and research of patients with neurological injury. RECENT FINDINGS: Recent studies demonstrate that automated pupillometry outperforms manual penlight pupil examination in neurocritical care populations. Further research has identified specific changes in the pupillary light reflex associated with pathologic conditions, and pupillometry has been used to successfully identify early changes in neurologic function, intracranial pressure, treatment response to osmotherapy, and prognosis after cardiac arrest. Automated pupillometry is being increasingly adopted as a routine part of the neurologic examination, supported by a growing body of literature demonstrating its reliability, accuracy, and ease of use. Automated pupillometry allows rapid, non-invasive, reliable, and quantifiable assessment of pupillary function which may allow rapid diagnosis of intracranial pathology that affects clinical decision making.

Prediction of pupil size under binocular open-view settings using the new CASIA2 device.

PURPOSE: Pupillometry should be performed under conditions as close to natural viewing as possible. The present study aimed to determine whether pupil size in binocular open-view settings can be predicted based on pupil size measured using the CASIA2 device. METHODS: The present study included 61 participants (25 men and 36 women; mean age, 49 ± 15 years; age range, 22-69 years) with no history of ophthalmic disease other than refractive errors and cataract. We measured pupil size using the new CASIA2 device and a binocular open-view digital pupillometer (FP-10000II, TMI Co., Ltd., Saitama). Intra-class and inter-class reliabilities were evaluated by measuring pupil times three times with each device (two independent examiners) in 21 of the 61 participants. Reproducibility was analyzed using intra-class and inter-class correlation coefficients (ICCs). Regression formulae for calculating FP10000II pupil size based on CASIA2 pupil size were developed via simple linear regression analyses. RESULTS: Both devices exhibited high ICC values (> 0.80). The regression formulae for calculating the FP10000II pupil size for the distant and near views based on CASIA2 pupil size were y = 0.5702x + 0.4611 (determination coefficient, 0.67) and y = 0.502x + 0.445 (determination coefficient, 0.64), respectively. CONCLUSIONS: Pupil size under binocular open-view settings can be predicted based on simultaneous measurement of pupil size during evaluation of the anterior segment using the CASIA2 device. The calculated pupil size may represent a useful index for determining the most appropriate treatment strategy in candidates for cataract and refractive surgery.

Saved by the Pupillometer! - A role for pupillometry in the acute assessment of patients with traumatic brain injuries?

There is good evidence that pupil reactivity is useful for prognostication in acute head injuries. Despite this, most pupil assessments are subjective and are performed by physicians who may not be experts. They can therefore be unreliable. We present a case of a patient with seemingly irreversible demise from an acute traumatic subdural haematoma. This was determined by assessment of his pupils, which were non-reactive to light at the time of arrival to the neurosurgical theatre. He was transferred to the neurointensive care for brainstem death testing, where assessment by objective pupillometry determined that his pupils were in fact reactive. He made a good recovery following subsequent surgery to evacuate his subdural haematoma. We propose the widespread adoption of objective pupillometers in the assessment of acute head-injured patients and offer our case as an example of how an objective and accurate assessment can make a difference to patients' outcome.

The use and uptake of pupillometers in the Intensive Care Unit.

BACKGROUND: Traumatic brain injury (TBI) is a significant public health issue. Assessing pupil reactivity is a crucial aspect of its management and the pupillometer has been shown to be a more objective tool compared to the standard penlight. Its use, however, is not widespread. OBJECTIVE: To investigate the paucity in uptake, we examined the frequency of use of pupillometers (NeurOptics®NPi-100™) amongst Intensive Care Unit (ICU) doctors and nurses, evaluated its user-friendliness and explored barriers to its use. DESIGN: An online cross-sectional survey. METHODS: Surveys were distributed five months after the introduction of pupillometers (in May 2015) to ICU doctors and nurses working in a quaternary referral centre providing state services for trauma. The survey included sections on: questions on demographics and experience, methods of conventional pupillary assessment in patients with TBI, experience of using the pupillometer, and questions on barriers to its use. Responses were collated as discrete variables and summarised using counts and proportions. Comparisons among proportions were undertaken using the chi-squared test and reported with 95% confidence intervals. RESULTS: A total of 79 responses were recorded, predominantly 94.9% (n=75) from nursing staff. A total of 50 (63.3%) responders were using the pupillometers, with a mean frequency-of-use rating of 4.67 out of 10 and a mean user-friendliness rating of 6.28 out of 10. There was no association between frequency of use and user-friendliness (p=0.36). The main identified barriers to its use included a lack of education with regards to its use, a perceived lack of clinical significance, a lack of standardisation of documenting findings, and difficulties with access to disposable patient shields (Smartguards). CONCLUSIONS: There was good adoption of the technology in the early phases of ICU implementation with user-friendliness rated favourably. In this paper we identify barriers to use and discuss possible solutions to increase clinical utility.

Relative Afferent Pupillary Defects in Homonymous Visual Field Defects Caused by Stroke of the Occipital Lobe Using Pupillometer.

Relative afferent pupillary defects (RAPD) may be detected in patients with occipital lobe lesions. However, no previous report has used an objective technique to record the abnormal pupillary light reflex in such cases. Therefore, we measured the pupillary light reflex objectively in 15 patients with homonymous visual field defects (HVFD) due to occipital stroke using a new pupillometer. This study detected significantly smaller and slower pupillary light reflexes in the contralateral eyes than in the other eyes, which is equivalent to the presence of RAPD in patients with HVFDs caused by retrogeniculate lesions using an objective technique. Our results confirmed those of the previous reports using the swinging flashlight test more objectively.

The effects of anesthetic agents on pupillary function during general anesthesia using the automated infrared quantitative pupillometer.

Pupil reactivity can be used to evaluate central nervous system function and can be measured using a quantitative pupillometer. However, whether anesthetic agents affect the accuracy of the technique remains unclear. We examined the effects of anesthetic agents on pupillary reactivity. Thirty-five patients scheduled for breast or thyroid surgery were enrolled in the study. Patients were divided into four groups based on the technique used to maintain anesthesia: a sevoflurane-remifentanil (SEV/REM) group, a sevoflurane (SEV) group, a desflurane-remifentanil (DES/REM) group, and a propofol-remifentanil (PRO/REM) group. We measured maximum resting pupil size (MAX), reduction pupil size ratio (%CH), latency duration (LAT) and neurological pupil index (NPi). A marked reduction in MAX and %CH compared with baseline was observed in all groups, but LAT was unchanged during surgery. NPi reduced within the first hour of surgery in the SEV/REM, SEV, and DES/REM groups, but was not significantly different in the PRO/REM group. Compared with the PRO/REM group, mean %CH and NPi in patients anesthetized with SEV/REM, SEV or DES/REM were markedly lower at 1 h after surgery had commenced. There was no correlation between NPi and bispectral index. Fentanyl given alone decreased pupil size and %CH in light reflex, but did not change the NPi. NPi was decreased by inhalational anesthesia not but intravenous anesthesia. The difference in pupil reactivity between inhalational anesthetic and propofol may indicate differences in the alteration of midbrain reflexs in patients under inhalational or intravenous anesthesia.

Digital Pupillometry in Normal Subjects.

The aim of this study was to evaluate the pupil size of normal subjects at different illumination levels with a novel pupillometer. The pupil size of healthy study participants was measured with an infrared-video PupilX pupillometer (MEye Tech GmbH, Alsdorf, Germany) at five different illumination levels (0, 0.5, 4, 32, and 250 lux). Measurements were performed by the same investigator. Ninety images were executed during a measurement period of 3 seconds. The absolute linear camera resolution was approximately 20 pixels per mm. This cross-sectional study analysed 490 eyes of 245 subjects (mean age: 51.9 ± 18.3 years, range: 6-87 years). On average, pupil diameter decreased with increasing light intensities for both eyes, with a mean pupil diameter of 5.39 ± 1.04 mm at 0 lux, 5.20 ± 1.00 mm at 0.5 lux, 4.70 ± 0.97 mm at 4 lux, 3.74 ± 0.78 mm at 32 lux, and 2.84 ± 0.50 mm at 250 lux illumination. Furthermore, it was found that anisocoria increased by 0.03 mm per life decade for all illumination levels (R2 = 0.43). Anisocoria was higher under scotopic and mesopic conditions. This study provides additional information to the current knowledge concerning age- and light-related pupil size and anisocoria as a baseline for future patient studies.

Reliability of standard pupillometry practice in neurocritical care: an observational, double-blinded study.

BACKGROUND: In critical care units, pupil examination is an important clinical parameter for patient monitoring. Current practice is to use a penlight to observe the pupillary light reflex. The result seems to be a subjective measurement, with low precision and reproducibility. Several quantitative pupillometer devices are now available, although their use is primarily restricted to the research setting. To assess whether adoption of these technologies would benefit the clinic, we compared automated quantitative pupillometry with the standard clinical pupillary examination currently used for brain-injured patients. METHODS: In order to determine inter-observer agreement of the device, we performed repetitive measurements in 200 healthy volunteers ranging in age from 21 to 58 years, providing a total of 400 paired (alternative right eye, left eye) measurements under a wide variety of ambient light condition with NeuroLight Algiscan pupillometer. During another period, we conducted a prospective, observational, double-blinded study in two neurocritical care units. Patients admitted to these units after an acute brain injury were included. Initially, nursing staff measured pupil size, anisocoria and pupillary light reflex. A blinded physician subsequently performed measurement using an automated pupillometer. RESULTS: In 200 healthy volunteers, intra-class correlation coefficient for maximum resting pupil size was 0.95 (IC: 0.93-0.97) and for minimum pupil size after light stimulation 0.87 (0.83-0.89). We found only 3-pupil asymmetry (≥ 1 mm) in these volunteers (1.5% of the population) with a clear pupil asymmetry during clinical inspection. The mean pupil light reactivity was 40 ± 7%. In 59 patients, 406 pupillary measurements were prospectively performed. Concordance between measurements for pupil size collected using the pupillometer, versus subjective assessment, was poor (Spearmen's rho = 0.75, IC: 0.70-0.79; P < 0.001). Nursing staff failed to diagnose half of the cases (15/30) of anisocoria detected using the pupillometer device. A global rate of discordance of 18% (72/406) was found between the two techniques when assessing the pupillary light reflex. For measurements with small pupils (diameters <2 mm) the error rate was 39% (24/61). CONCLUSION: Standard practice in pupillary monitoring yields inaccurate data. Automated quantitative pupillometry is a more reliable method with which to collect pupillary measurements at the bedside.

Interdevice Agreement between a Smartphone and a Commercial Pupillometer.

Background: The reliability of dynamic pupillometry parameters varies from one pupillometer to another, making it difficult to standardize the values for any particular device. Hence, further studies are required to evaluate the agreement of various pupillometer devices and explore their utility in routine clinical settings. Aim: This study sought to evaluate the agreement between smartphone and commercial pupillometer measurements in routine clinical settings. Methods: The study included pupillary measurements obtained by a single investigator from 100 healthy participants (200 eyes) with each pupillometer. Pupillary measurements taken by a smartphone pupillometry application (reflex pupillary light reflex analyzer by Brightlamp [Indianapolis, IN, USA]) were compared with a commercial pupillometer (neurological pupil index-200, NeurOptics Inc., Irvine, USA). Results: The comparison of descriptive statistics revealed a statistically significant difference between the smartphone and commercial pupillometers for various parameters, including maximum diameter, minimum diameter, constriction velocity (CV), maximum CV, and dilatation velocity (P < 0.05), except for latency (P = 0.36). The intraclass correlation coefficient revealed poor agreement between the two devices (<0.50). Conclusion: The measurements by smartphone pupillometry application were found to be unreliable, indicating that they may not be an ideal substitute for commercial pupillometers in their present form in the Indian population. Further studies with larger sample size as well as improvements in the processing and interpretation of the measurements by the software, are needed to determine its utility in routine clinical settings.