A practical approach to neurologic evaluation in the intensive care unit

Touchless short-wave infrared imaging for dynamic rapid pupillometry and gaze estimation in closed eyes

BACKGROUND

Assessments of gaze direction (eye movements), pupil size, and the pupillary light reflex (PLR) are critical for neurological examination and neuroscience research and constitute a powerful tool in diverse clinical settings ranging from critical care through endocrinology and drug addiction to cardiology and psychiatry. However, current bedside pupillometry is typically intermittent, qualitative, manual, and limited to open-eye cases, restricting its use in sleep medicine, anesthesia, and intensive care.

METHODS

We combined short-wave infrared (SWIR, ~0.9-1.7μm) imaging with image processing algorithms to perform rapid (~30 ms) pupillometry and eye tracking behind closed eyelids. Forty-three healthy volunteers participated in two experiments with PLR evoked by visible light stimuli or directing eye movements towards screen targets. Imaging was performed simultaneously on one eye closed, and the other open eye serving as ground truth. Data analysis was performed with a custom approach quantifying changes in brightness around the pupil area or with a deep learning U-NET-based procedure.

RESULTS

Here we show that analysis of SWIR imaging data can successfully measure stimulus-evoked PLR in closed-eye conditions, revealing PLR events in single trials and significant PLRs in nearly all individual subjects, as well as estimating gaze direction. The neural net-based analysis could successfully use closed-eye SWIR data to recreate estimates of open-eye images and assess pupil size.

CONCLUSIONS

Continuous touchless monitoring of rapid dynamics in pupil size and gaze direction through closed eyes paves the way for developing devices with wide-ranging applications, fulfilling long-standing goals in clinical and research fields.

Application of Pupillometry in Neurocritical Patients

Pupillary light reflex (PLR) assessment is a crucial examination for evaluating brainstem function, particularly in patients with acute brain injury and neurosurgical conditions. The PLR is controlled by neural pathways modulated by both the sympathetic and parasympathetic nervous systems. Altered PLR is a strong predictor of adverse outcomes after traumatic and ischemic brain injuries. However, the assessment of PLR needs to take many factors into account since it can be modulated by various medications, alcohol consumption, and neurodegenerative diseases. The development of devices capable of measuring pupil size and assessing PLR quantitatively has revolutionized the non-invasive neurological examination. Automated pupillometry, which is more accurate and precise, is widely used in diverse clinical situations. This review presents our current understanding of the anatomical and physiological basis of the PLR and the application of automated pupillometry in managing neurocritical patients. We also discuss new technologies that are being developed, such as smartphone-based pupillometry devices, which are particularly beneficial in low-resource settings.

Prevalence and independent predictors of in-hospital stroke among patients who developed acute alteration of consciousness in the medical intensive care unit: A retrospective case-control study

Background

In-hospital stroke is a serious event, associated with poor outcomes and high mortality. However, identifying signs of stroke may be more difficult in critically ill patients.

Objectives

This study investigated the prevalence and independent predictors of in-hospital stroke among patients with acute alteration of consciousness in the medical intensive care unit (MICU) who underwent subsequent brain computed tomography (CT).

Methods

This retrospective study enrolled eligible patients during the period 2007 - 2017. The alterations researched were radiologically confirmed acute ischaemic stroke (AIS) and intracerebral haemorrhage (ICH).

Results

Of 4 360 patients, 113 underwent brain CT. Among these, 31% had AIS, while 15% had ICH. They had higher diastolic blood pressures and arterial pH than non-stroke patients. ICH patients had higher mean (standard deviation (SD) systolic blood pressures (152 (48) v. 129 (25) mmHg; p=0.01), lower mean (SD) Glasgow Coma Scale scores (4 (3) v. 7 (4); p=0.004), and more pupillary abnormalities (75% v. 9%; p<0.001) than AIS patients. AIS patients were older (65 (18) v. 57 (18) years; p=0.03), had more hypertension (60% v. 39%; p=0.04), and more commonly presented with the Babinski sign (26% v. 9%; p=0.04). Multivariate analysis found that pupillary abnormalities independently predicted ICH (adjusted odds ratio (aOR) 26.9; 95% CI 3.7 - 196.3; p=0.001). The Babinski sign (aOR 5.1; 95% CI 1.1 - 23.5; p=0.04) and alkalaemia (arterial pH >7.4; aOR 3.6; 95% CI 1.0 - 12.3; p=0.05) independently predicted AIS.

Conclusion

Forty-six percent of the cohort had ICH or AIS. Both conditions had high mortality. The presence of pupillary abnormalities predicts ICH, whereas the Babinski sign and alkalaemia predict AIS.

Contributions of the study

The present study reports that almost half (46%) of critically ill patients with alterations of consciousness had an acute stroke. Of these, two-thirds had an acute ischaemic stroke (AIS), and one-third had an intracranial haemorrhage (ICH). Multivariate analysis revealed that a pupillary abnormality was a predictor for ICH and the Babinski sign was identified as a predictor of AIS.

BIS monitoring versus clinical assessment for sedation in mechanically ventilated adults in the intensive care unit and its impact on clinical outcomes and resource utilization

BACKGROUND

Patients admitted to intensive care and on mechanical ventilation, are administered sedative and analgesic drugs to improve both their comfort and interaction with the ventilator. Optimizing sedation practice may reduce mortality, improve patient comfort and reduce cost. Current practice is to use scales or scores to assess depth of sedation based on clinical criteria such as consciousness, understanding and response to commands. However these are perceived as subjective assessment tools. Bispectral index (BIS) monitors, which are based on the processing of electroencephalographic signals, may overcome the restraints of the sedation scales and provide a more reliable and consistent guidance for the titration of sedation depth.The benefits of BIS monitoring of patients under general anaesthesia for surgical procedures have already been confirmed by another Cochrane review. By undertaking a well-conducted systematic review our aim was to find out if BIS monitoring improves outcomes in mechanically ventilated adult intensive care unit (ICU) patients.

OBJECTIVES

To assess the effects of BIS monitoring compared with clinical sedation assessment on ICU length of stay (LOS), duration of mechanical ventilation, any cause mortality, risk of ventilator-associated pneumonia (VAP), risk of adverse events (e.g. self-extubation, unplanned disconnection of indwelling catheters), hospital LOS, amount of sedative agents used, cost, longer-term functional outcomes and quality of life as reported by authors for mechanically ventilated adults in the ICU.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, ProQuest, OpenGrey and SciSearch up to May 2017 and checked references citation searching and contacted study authors to identify additional studies. We searched trial registries, which included clinicaltrials.gov and controlled-trials.com.

SELECTION CRITERIA

We included all randomized controlled trials comparing BIS versus clinical assessment (CA) for the management of sedation in mechanically ventilated critically ill adults.

DATA COLLECTION AND ANALYSIS

We used Cochrane's standard methodological procedures. We undertook analysis using Revman 5.3 software.

MAIN RESULTS

We identified 4245 possible studies from the initial search. Of those studies, four studies (256 participants) met the inclusion criteria. One more study is awaiting classification. Studies were, conducted in single-centre surgical and mixed medical-surgical ICUs. BIS monitor was used to assess the level of sedation in the intervention arm in all the studies. In the control arm, the sedation assessment tools for CA included the Sedation-Agitation Scale (SAS), Ramsay Sedation Scale (RSS) or subjective CA utilizing traditional clinical signs (heart rate, blood pressure, conscious level and pupillary size). Only one study was classified as low risk of bias, the other three studies were classified as high risk.There was no evidence of a difference in one study (N = 50) that measured ICU LOS (Median (Interquartile Range IQR) 8 (4 to 14) in the CA group; 12 (6 to 18) in the BIS group; low-quality evidence).There was little or no effect on the duration of mechanical ventilation (MD -0.02 days (95% CI -0.13 to 0.09; 2 studies; N = 155; I² = 0%; low-quality evidence)). Adverse events were reported in one study (N = 105) and the effects on restlessness after suction, endotracheal tube resistance, pain tolerance during sedation or delirium after extubation were uncertain due to very low-quality evidence. Clinically relevant adverse events such as self-extubation were not reported in any study. Three studies reported the amount of sedative agents used. We could not measure combined difference in the amount of sedative agents used because of different sedation protocols and sedative agents used in the studies. GRADE quality of evidence was very low. No study reported other secondary outcomes of interest for the review.

AUTHORS' CONCLUSIONS

We found insufficient evidence about the effects of BIS monitoring for sedation in critically ill mechanically ventilated adults on clinical outcomes or resource utilization. The findings are uncertain due to the low- and very low-quality evidence derived from a limited number of studies.

Pupillary abnormalities in non-selected critically ill patients: an observational study

BACKGROUND

Repeated pupillary examination is a key element of neurologic surveillance in intensive care units (ICU). However, in non-selected critically ill patients, the clinical interest of monitoring pupillary diameter and light reflex is poorly documented. We aimed to determine the prevalence and the etiologies of pupillary abnormalities (PAs) in this ICU patient population.

METHODS

We performed a prospective, observational study in a medical university affiliated ICU over a 6-month period. All patients with at least one pupillary examination were included. PA was defined as areflexia and/or anisocoria present at the time of ICU admission or occurring during the ICU stay.

RESULTS

During the study period, we included 297 patients who had 6±9 pupillary examinations per day (totaling 11,360 pupillary assessments). The majority of patients (n=161, 54%) were admitted to the ICU for acute respiratory or cardiovascular failure. A total of 128 PAs were recorded in 109 patients: 78 areflexia alone (61%), 33 anisocoria alone (26%) and 17 (13%) with associated anisocoria and areflexia. The main causes of PAs were related to acute brain ischemia (n=41, 32%) and sedation/analgesia (n=50, 39%). Among the PAs, 59 (46%) were present upon ICU admission. The etiologies of the PAs at admission did not differ from those occurring during ICU stay (P=NS). Interestingly, 9 (7%) PAs were attributed to ipratropium nebulization in patients with chronic obstructive pulmonary disease exacerbation.

CONCLUSIONS

The high prevalence of PAs, frequently associated with both brain organic lesions and drug side effects, highlights the clinical interest of pupillary surveillance in non-selected critically ill patients.

The Use of Automated Pupillometry in Critical Care

The neurologic examination (neuroexamination) is one of the most powerful tools available to nurses and physicians caring for patients with neurologic or neurosurgical illness. Assessing cranial nerve function is one of the most vital components of the neuroexamination. The pupillary light reflex helps to evaluate the status of the second and third cranial nerves and is one of the most well-known elements of the cranial nerve examination. Automated pupillometers have been developed that provide objective measures of size of the pupil and the responsiveness of the pupil to light (neuropupillary index).

Advances in cerebral monitoring for the patient with traumatic brain injury

A brief overview of the most common invasive and noninvasive monitoring tools collectively referred to using the term "multimodal monitoring" is provided. Caring for the critically ill patient with traumatic brain injury requires careful monitoring to prevent or reduce secondary brain injury. Concurrent to the growth of the subspecialty of neurocritical care, there has been a concerted effort to discover novel mechanisms to monitor the physiology of brain injury. The past 2 decades have witnessed an exponential growth in neurologic monitoring in terms of intracranial pressure, blood flow, metabolism, oxygenation, advanced neuroimaging, and electrophysiology.