Eye tracking technology: a fresh approach in delirium assessment?

Continuous Non-Invasive Eye Tracking In Intensive Care

Delirium, an acute confusional state, is a common occurrence in Intensive Care Units (ICUs). Patients who develop delirium have globally worse outcomes than those who do not and thus the diagnosis of delirium is of importance. Current diagnostic methods have several limitations leading to the suggestion of eye-tracking for its diagnosis through in-attention. To ascertain the requirements for an eye-tracking system in an adult ICU, measurements were carried out at Chelsea & Westminster Hospital NHS Foundation Trust. Clinical criteria guided empirical requirements of invasiveness and calibration methods while accuracy and precision were measured. A non-invasive system was then developed utilising a patient-facing RGB camera and a scene-facing RGBD camera. The system's performance was measured in a replicated laboratory environment with healthy volunteers revealing an accuracy and precision that outperforms what is required while simultaneously being non-invasive and calibration-free The system was then deployed as part of CONfuSED, a clinical feasibility study where we report aggregated data from 5 patients as well as the acceptability of the system to bedside nursing staff. To the best of our knowledge, the system is the first eye-tracking systems to be deployed in an ICU for delirium monitoring.

Delirium clinical motor subtypes: a narrative review of the literature and insights from neurobiology

INTRODUCTION

Clinical motor subtypes have been long recognised in delirium and, despite a growing body of research, a lack of clarity exists regarding the importance of these motor subtypes. The aims of this review are to (1) examine how the concept of motor subtypes has evolved, (2) explore their relationship to the clinical context, (3) discuss the relationship between the phenomenology of delirium and motor activity, (4) discuss the application of neurobiology to the theory of delirium motor subtypes, and (5) identify methodological issues and provide solutions for further studies.

METHODS

The following databases were searched: PubMed, PsychInfo, EBSCO, Medline, BioMed central and Science Direct. Inclusion criteria specified peer-reviewed research assessing delirium motor subtypes published between 1990 and 2016.

RESULTS

Sixty-one studies met the inclusion criteria. The majority of studies (n = 50) were found to use validated psychometric tools, while the remainder (n = 11) used clinical criteria. The majority of studies (n = 45) were conducted in the medical setting, while the remainder were in the ICU/post-operative setting (n = 17).

CONCLUSION

Although host sensitivities (e.g. frailty) and exogenous factors (e.g. medication exposure) may determine the type of motor disturbance, it remains unclear to what extent motor subtypes are influenced by other features of delirium. The use of more specialised tools (e.g. delirium motor subtyping scale), may enable researchers to develop an approach to delirium that has a greater nosological consistency. Future studies investigating delirium motor subtypes may benefit from enhanced theoretical considerations of the dysfunctional neural substrate of the delirious state.

The Letter and Shape Drawing (LSD) test: An efficient and systematised approach to testing of visuospatial function

The automation and systemisation of the next generation of cognitive assessment approaches have the potential to change how clinicians assess and interact with patients. This may be especially pertinent in the case of delirium, as current methods often rely on the subjective opinion of clinicians and specialists, with potential for the condition to be overlooked or misdiagnosed. Currently, one of the most commonly used tests, is the clock-drawing test, which has relatively wide appeal as a cognitive screening instrument due to its clinical utility and psychometric properties. However, there are a number of inconsistencies associated with its use and interpretation. In this paper, we describe a new assessment methodology that we have developed, facilitated by the advances in tablet technology. In trials, our "Letter and Shape Drawing (LSD)" tool, involving both an automated scoring capability and a simpler user interaction, has demonstrated correlation with other conventional cognitive test methods although some optimisation requirements remain.

The role of predictive coding in the pathogenesis of delirium

Delirium and dementia represent an emerging global crisis in healthcare. Attempts have been made to identify the pathognomonic feature that would make delirium stand out from dementia but unfortunately the global neural dysfunction of both disorders has made the establishment of a direct measurement difficult. Modern conceptualisations of delirium have been influenced by the assessment tools used to assess, detect, and analyse its complex and transient nature. Recent publication of the DSM-V criteria for delirium has marginally altered the previous DSM-IV criteria with a focus upon inattention with vague terms such as consciousness downplayed. Such an alteration has been found to be restrictive and thus impact upon delirium case identification. Although these findings are approximating the empirical state of delirium as measured by validated instruments, a more refined neuroscientifically informed phenomenological framework is required in order to enhance the theoretical understanding of delirium assessment and resolve these challenges. One such application is the predictive coding (PC) model, also known as the hierarchical Bayesian inference model, to interpreting delirium pathophysiology. Therefore, the aims of this paper are to 1) propose the hypothesis that delirium pathophysiology can be explained in terms of the PC model, 2) support this hypothesis by applying this model to current methods of assessing delirium phenomenology, particularly attention, and 3) outline a future programme of research to test many of the parameters of this application.

Assessment of Performance Validity Using Embedded Saccadic and Manual Indices on a Continuous Performance Test

OBJECTIVE

In addition to manual (i.e., "button press") metrics, oculomotor metrics demonstrate considerable promise as tools for detecting invalid responding in neurocognitive assessment. This study was conducted to evaluate saccadic and manual metrics from a computerized continuous performance test as embedded indices of performance validity.

METHOD

Receiver operating characteristic analyses, logistic regressions, and ANOVAs were performed to evaluate saccadic and manual metrics in classification of healthy adults instructed to feign deficits ("Fake Bad" group; n = 24), healthy adults instructed to perform their best ("Best Effort" group; n = 26), and adults with a history of mild traumatic brain injury (TBI) who passed a series of validity indices ("mTBI-Pass" group; n = 19).

RESULTS

Several saccadic and manual metrics achieved outstanding classification accuracy between Fake Bad versus Best Effort and mTBI-Pass groups, including variability (consistency) of saccadic and manual response time (RT), saccadic commission errors, and manual omission errors. Very large effect sizes were obtained between Fake Bad and Best Effort groups (Cohen's d range: 1.89-2.90; r range: .75-.78) as well as between Fake Bad and mTBI-Pass groups (Cohen's d range: 1.32-2.21; r range: .69-.71). The Fake Bad group consistently had higher saccadic and manual RT variability, more saccadic commission errors, and more manual omission errors than the Best Effort and mTBI-Pass groups.

CONCLUSIONS

These findings are the first to demonstrate that eye movements can be used to detect invalid responding in neurocognitive assessment. These results also provide compelling evidence that concurrently measured saccadic and manual metrics can detect invalid responding with high levels of sensitivity and specificity.

Attention! A good bedside test for delirium?

BACKGROUND

Routine delirium screening could improve delirium detection, but it remains unclear as to which screening tool is most suitable. We tested the diagnostic accuracy of the following screening methods (either individually or in combination) in the detection of delirium: MOTYB (months of the year backwards); SSF (Spatial Span Forwards); evidence of subjective or objective 'confusion'.

METHODS

We performed a cross-sectional study of general hospital adult inpatients in a large tertiary referral hospital. Screening tests were performed by junior medical trainees. Subsequently, two independent formal delirium assessments were performed: first, the Confusion Assessment Method (CAM) followed by the Delirium Rating Scale-Revised 98 (DRS-R98). DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, fourth edition) criteria were used to assign delirium diagnosis. Sensitivity and specificity ratios with 95% CIs were calculated for each screening method.

RESULTS

265 patients were included. The most precise screening method overall was achieved by simultaneously performing MOTYB and assessing for subjective/objective confusion (sensitivity 93.8%, 95% CI 82.8 to 98.6; specificity 84.7%, 95% CI 79.2 to 89.2). In older patients, MOTYB alone was most accurate, whereas in younger patients, a simultaneous combination of SSF (cut-off 4) with either MOTYB or assessment of subjective/objective confusion was best. In every case, addition of the CAM as a second-line screening step to improve specificity resulted in considerable loss in sensitivity.

CONCLUSIONS

Our results suggest that simple attention tests may be useful in delirium screening. MOTYB used alone was the most accurate screening test in older people.

Practical assessment of delirium in palliative care

CONTEXT

Delirium is a common, distressing neuropsychiatric complication for patients in palliative care settings, where the need to minimize burden yet accurately assess delirium is hugely challenging.

OBJECTIVES

This review focused on the optimal clinical and research application of delirium assessment tools and methods in palliative care settings.

METHODS

In addition to multidisciplinary input from delirium researchers and other relevant stakeholders at an international meeting, we searched PubMed (1990-2012) and relevant reference lists to identify delirium assessment tools used either exclusively or partly in the context of palliative care.

RESULTS

Of the 26 delirium scales identified, we selected six for in-depth review: three screening tools, two severity measures, and one research tool for neuropsychological assessment of delirium. These tools differed regarding intended use, ease of use, training requirements, psychometric properties, and validation in or suitability for palliative care populations. The Nursing Delirium Screening Scale, Single Question in Delirium, or Confusion Assessment Method, ideally with a brief attention test, can effectively screen for delirium. Favoring inclusivity, use of Diagnostic and Statistical Manual of Mental Disorders-IV criteria gives the best results for delirium diagnosis. The Revised Delirium Rating Scale and the Memorial Delirium Assessment Scale are the best available options for monitoring severity, and the Cognitive Test for Delirium provides detailed neuropsychological assessment for research purposes.

CONCLUSION

Given the unique characteristics of patients in palliative care settings, further contextually sensitive studies of delirium assessment are required in this population.

Delirium diagnostic and classification challenges in palliative care: subsyndromal delirium, comorbid delirium-dementia, and psychomotor subtypes

CONTEXT

Delirium often presents difficult diagnostic and classification challenges in palliative care settings.

OBJECTIVES

To review three major areas that create diagnostic and classification challenges in relation to delirium in palliative care: subsyndromal delirium (SSD), delirium in the context of comorbid dementia, and classification of psychomotor subtypes, and to identify knowledge gaps and research priorities in relation to these three areas of focus.

METHODS

We combined multidisciplinary input from delirium researchers and knowledge users at an international delirium study planning meeting and relevant PubMed literature searches as the knowledge synthesis strategy in this review.

RESULTS

We identified six (SSD), 33 (dementia), and 44 (psychomotor subtypes) articles of relevance in relation to the focus of our review. Recent literature data highlight the frequency and impact of SSD, the relevance of comorbid dementia, and the propensity for a hypoactive presentation of delirium in the palliative population. The differential diagnoses to consider are wide and include pain, fatigue, mood disturbance, psychoactive medication effects, and other causes for altered consciousness.

CONCLUSION

Challenges in the diagnosis and classification of delirium in people with advanced disease are compounded by the generalized disturbance of central nervous system function that occurs in the seriously ill, often with comorbid illness, including dementia. Further research is needed to delineate the pathophysiological and clinical associations of these presentations and thus inform therapeutic strategies. The expanding aged population and growing focus on dementia care in palliative care highlight the need to conduct this research.

Tools to detect delirium superimposed on dementia: a systematic review

OBJECTIVES

To identify valid tools to diagnose delirium superimposed on dementia.

DESIGN

Systematic review of studies of delirium tools that explicitly included individuals with dementia.

SETTING

Hospital.

PARTICIPANTS

Studies were included if delirium assessment tools were validated against standard criteria, and the presence of dementia was assessed according to standard criteria that used validated instruments.

MEASUREMENTS

PubMed, Embase, and Web of Science databases were searched for articles in English published between January 1960 and January 2012.

RESULTS

Nine studies fulfilled the selection criteria. Of 1,569 participants, 401 had dementia, and 50 had delirium superimposed on dementia. Six delirium tools were evaluated. One study using the Confusion Assessment Method (CAM) with 85% of participants with dementia had high specificity (96-100%) and moderate sensitivity (77%). Two intensive care unit studies that used the CAM for the Intensive Care Unit (CAM-ICU) reported 100% sensitivity and specificity for delirium in 23 individuals with dementia. One study using electroencephalography reported sensitivity of 67% and specificity of 91% in a population with a 100% prevalence of dementia. No studies examined potential effects of dementia severity or subtype on diagnostic accuracy.

CONCLUSIONS

The evidence base on tools for detection of delirium superimposed on dementia is limited, although some existing tools show promise. Further studies of existing or refined tools with larger samples and more-detailed characterization of dementia are required to address the identification of delirium superimposed on dementia.

Differences in examination characteristics of pigmented skin lesions: results of an eye tracking study

OBJECTIVE

To use computer-based eye tracking technology to record and evaluate examination characteristics of the diagnosis of pigmented skin lesions.

METHODOLOGY

16 study participants with varying levels of diagnostic expertise (little, intermediate, superior) were recorded while diagnosing a series of 28 digital images of pigmented skin lesions, obtained by non-invasive digital dermatoscopy, on a computer screen. Eye tracking hardware recorded the gaze track and fixations of the physicians while they examined the lesion images. Analysis of variance was used to test for differences in examination characteristics between physicians grouped according to expertise.

RESULTS

There were no significant differences between physicians with little and intermediate levels of expertise in terms of average time until diagnosis (6.61 vs. 6.19s), gaze track length (6.65 vs. 6.15 kilopixels), number of fixations (23.1 vs. 19.1), and time in fixations (4.91 vs. 4.17s). The experts were significantly different with 3.17s time until diagnosis, 4.53 kilopixels gaze track length, 9.9 fixations, and 1.74s in fixations, respectively. Differentiation between benign and malignant lesions had no effect on examination measurements.

CONCLUSION

The results show that experience level has a significant impact on the way in which lesion images are examined. This finding can be used to construct decision support systems that employ important diagnostic features identified by experts, and to optimize teaching for less experienced physicians.