Detecting Delirium Using a Physiologic Monitor

Nonpharmacological Cognitive Impairment Prevention Interventions in Older Adults Undergoing Cardiac Surgery: A Systematic Review

BACKGROUND

More than 1 million individuals undergo cardiothoracic surgery for coronary artery bypass graft or valve repair/replacement annually in the United States. There is an increased risk of developing serious cognitive impairment post cardiothoracic surgery. Pharmacological interventions and surgical techniques were associated with improvements in cognitive function in previous systematic reviews. However, a gap in the literature exists regarding how nonpharmacological interventions can mitigate cognitive impairment in adults undergoing cardiac surgery.

OBJECTIVE

The aim of this study was to explore the effectiveness of nonpharmacological interventions to reduce the detrimental effects of cardiac surgery on cognitive function in patients after cardiothoracic surgery.

METHODS

CINAHL, MEDLINE, PubMed, EMBASE, PsycINFO, and Web of Science databases were searched following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines from January 2011 to February 2022.

RESULTS

Nineteen studies were included in this review. Researchers defined cognitive impairment differently across studies. Various interventions were used to reduce cognitive impairment post cardiothoracic surgery, with the most common being remote ischemic limb conditioning. The interventions used to reduce cognitive impairment were heterogeneous in outcomes, measurements, and time of assessment, but only 2 interventions were associated with a reduction in cognitive impairment.

CONCLUSIONS

This review is a unique synthesis of the quality of interventions that address broader components of cognition. Researchers used various interventions to reduce cognitive impairment; the outcomes, instruments, and time interval for measurements were heterogeneous. Researchers should conduct future studies at multiple time intervals, using a comprehensive measure of cognitive impairment to better understand the impact of cognitive impairment interventions postoperatively.

Sleep Fragmentation, Electroencephalographic Slowing, and Circadian Disarray in a Mouse Model for Intensive Care Unit Delirium

BACKGROUND

We aimed to further validate our previously published animal model for delirium by testing the hypothesis that in aged mice, Anesthesia, Surgery and simulated ICU conditions (ASI) induce sleep fragmentation, electroencephalographic (EEG) slowing, and circadian disarray consistent with intensive care unit (ICU) patients with delirium.

METHODS

A total of 41 mice were used. Mice were implanted with EEG electrodes and randomized to ASI or control groups. ASI mice received laparotomy, anesthesia, and simulated ICU conditions. Controls did not receive ASI. Sleep was recorded at the end of ICU conditions, and hippocampal tissue was collected on EEG recording. Arousals, EEG dynamics, and circadian gene expression were compared with t tests. Two-way repeated measures analysis of variance (RM ANOVA) was used to assess sleep according to light.

RESULTS

ASI mice experienced frequent arousals (36.6 ± 3.2 vs 26.5 ± 3.4; P = .044; 95% confidence interval [CI], 0.29-19.79; difference in mean ± SEM, 10.04 ± 4.62) and EEG slowing (frontal theta ratio, 0.223 ± 0.010 vs 0.272 ± 0.019; P = .026; 95% CI, -0.091 to -0.007; difference in mean ± SEM, -0.05 ± 0.02) relative to controls. In ASI mice with low theta ratio, EEG slowing was associated with a higher percentage of quiet wakefulness (38.2 ± 3.6 vs 13.4 ± 3.8; P = .0002; 95% CI, -35.87 to -13.84; difference in mean ± SEM, -24.86 ± 5.19). ASI mice slept longer during the dark phases of the circadian cycle (nonrapid eye movement [NREM], dark phase 1 [D1]: 138.9 ± 8.1 minutes vs 79.6 ± 9.6 minutes, P = .0003, 95% CI, -95.87 to -22.69, predicted mean difference ± SE: -59.28 ± 13.89; NREM, dark phase 2 (D2): 159.3 ± 7.3 minutes vs 112.6 ± 15.5 minutes, P = .006, 95% CI, -83.25 to -10.07, mean difference ± SE, -46.66 ± 13.89; rapid eye movement (REM), D1: 20.5 ± 2.1 minutes vs 5.8 ± 0.8 minutes, P = .001, 95% CI, -24.60 to -4.71, mean difference ± SE, -14. 65 ± 3.77; REM, D2: 21.0 ± 2.2 minutes vs 10.3 ± 1.4 minutes, P = .029, 95% CI, -20.64 to -0.76, mean difference ± SE, -10.70 ± 3.77). The expression of essential circadian genes was also lower in ASI mice (basic helix-loop-helix ARNT like [BMAL1] : -1.3 fold change; circadian locomotor output cycles protein kaput [CLOCK] : -1.2).

CONCLUSIONS

ASI mice experienced EEG and circadian changes mimicking those of delirious ICU patients. These findings support further exploration of this mouse approach to characterize the neurobiology of delirium.

Relationship between angiotensin-converting enzyme inhibitors and angiotensin receptor blockers prescribing and delirium in the ICU-A secondary analysis

BACKGROUND

Studies suggest Angiotensin-Converting Enzyme inhibitors (ACEI) and Angiotensin Receptor Blockers (ARB) may slow the decline of memory function in individuals with mild to moderate Alzheimer's disease by regulating migroglial activation and oxidative stress within the brain's reticular activating system. Therefore, we evaluated the relationship between delirium prevalence and being prescribed ACEI and ARB in participants admitted to the intensive care units (ICU).

METHODS

A secondary analysis of data from two parallel pragmatic randomized controlled trials was performed. ACEI and ARB exposure was defined as being prescribed an ACEI or an ARB within six months prior to the ICU admission. The primary endpoint was the first positive delirium assessment based on Confusion Assessment Method for the ICU (CAM-ICU) for up to thirty days.

RESULTS

A total of 4791 patients admitted to the medical, surgical, and progressive ICU and screened for eligibility for the parent studies between February 2009 and January 2015 from two level 1 trauma and one safety net hospital in a large urban academic health system were included. Delirium rates in the ICU were not significantly different among participants with no exposure to ACEI/ARB (12.6%), or exposure to ACEI (14.4%), ARB (11.8%), or ACEI and ARB in combination (15.4%) in six months prior to the ICU admission. Exposure to ACEI (OR = 0.97[0.77, 1.22]), ARB (OR = 0.70 [0.47, 1.05]), or both (OR = 0.97 [0.33, 2.89]) in six months prior to ICU admission was not significantly associated with odds of delirium during the ICU admission after adjusting for age, gender, race, co-morbidities, and insurance status.

CONCLUSIONS

While the impact of ACEI and ARB exposure prior to the ICU admission was not associated with the prevalence of delirium in this study, further research is needed to fully understand the impact of antihypertensive medications on delirium.

Altered EEG, disrupted hippocampal long-term potentiation and neurobehavioral deficits implicate a delirium-like state in a mouse model of sepsis

Sepsis and systemic inflammation are often accompanied by severe encephalopathy, sleep disruption and delirium that strongly correlate with poor clinical outcomes including long-term cognitive deficits. The cardinal manifestations of delirium are fluctuating altered mental status and inattention, identified in critically ill patients by interactive bedside assessment. The lack of analogous assessments in mouse models or clear biomarkers is a challenge to preclinical studies of delirium. In this study, we utilized concurrent measures of telemetric EEG recordings and neurobehavioral tasks in mice to characterize inattention and persistent cognitive deficits following polymicrobial sepsis. During the 24-hour critical illness period for the mice, slow-wave EEG dominance, sleep disruption, and hypersensitivity to auditory stimuli in neurobehavioral tasks resembled clinical observations in delirious patients in which alterations in similar outcome measurements, although measured differently in mice and humans, are reported. Mice were tested for nest building ability 7 days after sepsis induction, when sickness behaviors and spontaneous activity had returned to baseline. Animals that showed persistent deficits determined by poor nest building at 7 days also exhibited molecular changes in hippocampal long-term potentiation compared to mice that returned to baseline cognitive performance. Together, these behavioral and electrophysiological biomarkers offer a robust mouse model with which to further probe molecular pathways underlying brain and behavioral changes during and after acute illness such as sepsis.

Original Research: Practice Variations in Documenting Neurologic Examinations in Non-Neuroscience ICUs

BACKGROUND

In critical care units, the neurologic examination (neuro exam) is used to detect changes in neurologic function. Serial neuro exams are a hallmark of monitoring in neuroscience ICUs. But less is known about neuro exams that are performed in non-neuroscience ICUs. This knowledge gap likely contributes to the insufficient guidance on what constitutes an adequate neuro exam for patients admitted to a non-neuroscience ICU.

PURPOSE

The study purpose was to explore existing practices for documenting neuro exams in ICUs that don't routinely admit patients with a primary neurologic injury.

METHODS

A single-center, prospective, observational study examined documented neuro exams performed in medical, surgical, and cardiovascular ICUs. A comprehensive neuro exam assesses seven domains that can be divided into 20 components. In this study, each component was scored as present (documentation was found) or absent (documentation was not found); a domain was scored as present if one or more of its components had been documented.

RESULTS

There were 1,482 assessments documented on 120 patients over a one-week period. A majority of patients were male (56%), White (71%), non-Hispanic (77%), and over 60 years of age (50%). Overall, assessments of the domains of consciousness, injury severity, and cranial nerve function were documented 80% of the time or more. Assessments of the domains of pain, motor function, and sensory function were documented less than 60% of the time, and that of speech less than 5% of the time. Statistically significant differences in documentation were found between the medical, surgical, and cardiovascular ICUs for the domains of speech, cranial nerve function, and pain. There were no significant differences in documentation frequency between day and night shift nurses. Documentation practices were significantly different for RNs versus providers.

CONCLUSIONS

Our findings show that the frequency and specific components of neuro exam documentation vary significantly across nurses, providers, and ICUs. These findings are relevant for nurses and providers and may help to improve guidance for neurologic assessment of patients in non-neurologic ICUs. Further studies exploring variance in documentation practices and their implications for courses of treatment and patient outcomes are warranted.

Delirium detection using GAMMA wave and machine learning: A pilot study

Delirium occurs in as many as 80% of critically ill older adults and is associated with increased long-term cognitive impairment, institutionalization, and mortality. Less than half of delirium cases are identified using currently available subjective assessment tools. Electroencephalogram (EEG) has been identified as a reliable objective measure but has not been feasible. This study was a prospective pilot proof-of-concept study, to examine the use of machine learning methods evaluating the use of gamma band to predict delirium from EEG data derived from a limited lead rapid response handheld device. Data from 13 critically ill participants aged 50 or older requiring mechanical ventilation for more than 12 h were enrolled. Across the three models, accuracy of predicting delirium was 70 or greater. Stepwise discriminant analysis provided the best overall method. While additional research is needed to determine the best cut points and efficacy, use of a handheld limited lead rapid response EEG device capable of monitoring all five cerebral lobes of the brain for predicting delirium hold promise.

Using Electroencephalogram Biosignal Changes for Delirium Detection in Intensive Care Units

ABSTRACT

BACKGROUND: Biosignal data acquired during quantitative electroencephalography (QEEG) research may ultimately be used to develop algorithms for more accurate detection of delirium. This study investigates the biosignal changes during delirium states by using the QEEG data of patients in a medical intensive care unit. METHODS: This observational study was conducted between September 2018 and December 2019 at a tertiary hospital in South Korea. Delirium was measured using the Korean version of Confusion Assessment Method for the Intensive Care Unit in intensive care unit patients. Quantitative EEG measurements were recorded for 20 minutes in a natural state without external treatment or stimuli, and QEEG data measured in the centroparietal and parietal regions with eyes open were selected for analysis. Power spectrum analysis with a 5-minute epoch was conducted on the selected 65 cases. RESULTS: QEEG changes in the presence of delirium indicated that alpha, beta, gamma, and spectral edge frequency 50% waves showed significantly lower absolute power spectra than the corresponding findings in the absence of delirium. Brain-mapping results showed that these brain waves were inactivated in delirious states. CONCLUSION: QEEG assessments can potentially detect the changes in the centroparietal and parietal regions of delirium patients. QEEG changes, including lower power spectra of alpha, beta, and gamma waves, and spectral edge frequency 50%, can be successfully used to distinguish delirium from the absence of delirium.

Rapid Handheld Continuous Electroencephalogram (EEG) Has the Potential to Detect Delirium in Older Adults

BACKGROUND

Delirium-related biochemical derangements lead to electrical changes that can be detected in electroencephalographic (EEG) patterns followed by behavioral signs and symptoms. Studies using limited lead EEG show a large difference between patients with and without delirium while discriminating delirium from other causes. Handheld rapid EEG devices may be capable of detecting delirium before symptom onset, thus providing an objective physiological method to detect delirium when it is most amenable to interventions.

OBJECTIVE

The aim of this study was to explore the potential for rapid EEG to detect waveform pattern changes consistent with delirium status.

METHODS

This prospective exploratory pilot study used a correlational design and mixed models to explore the relationships between handheld portable EEG data and delirium status.

RESULTS

While being under powered minimized opportunities to detect statistical differences in EEG-derived ratios using spectral density analysis, sleep-to-wake ratios tended to be higher in patients with delirium.

CONCLUSIONS

Limited lead EEG may be useful in predicting adverse outcomes and risk for delirium in older critically ill patients. Although this population is at the highest risk for mortality, delirium is not easily identified by current clinical assessments. Therefore, further investigation of limited lead EEG for delirium detection is warranted.

Understanding Disorders of Consciousness: Opportunities for Critical Care Nurses

BACKGROUND

Disorders of consciousness are powerful predictors of outcomes including mortality among critically ill patients. Encephalopathy, delirium, and coma are disorders of consciousness frequently encountered by critical care nurses but often classified incorrectly.

OBJECTIVE

To provide a greater understanding of disorders of consciousness and to provide standardized assessments and nursing interventions for these disorders.

METHODS

A literature search was conducted by using the terms consciousness, mental status, awareness, arousal, wakefulness, assessment, disorders of consciousness, delirium, encephalopathy, coma, vegetative state, and minimal consciousness. Articles were published in the past 10 years in CINAHL and PubMed. Articles were excluded if they were not in English or directly related to caring for patients with a disorder of consciousness. The remaining 142 articles were evaluated for inclusion; 81 articles received full review.

RESULTS

A disorder of consciousness signifies that the threshold for compensation has been surpassed with potentially irreversible damage. Altered thalamocortical interactions and reduced cortical activity impair communication networks across the various parts of the brain, causing a disturbance in consciousness.

DISCUSSION

The cue-response theory is a model that describes the process and impact of nursing care on recovery from acute brain injury. Appropriate standardized assessments and interventions must be used to manage altered levels of consciousness in critically ill patients.

CONCLUSIONS

Paying close attention to neurological changes and monitoring them with standardized assessments are critical to implementing early measures to prevent complications.

Q-15 Minutes Vital Sign Documentation Is a Poor Surrogate for Assessing Quality of Care After Acute Ischemic Stroke

OBJECTIVE

Documenting vital signs and National Institutes of Health Stroke Scale (NIHSS) once every 15 minutes after intravenous thrombolytic therapy for acute ischemic stroke is often used as a metric to assess the quality of care. This study explores the association between "once every 15 minutes" documentation and stroke outcomes.

METHODS

This is a retrospective study of the first 2 hours of vital signs and NIHSS documentation after thrombolytic stroke therapy. Sociodemographic and clinical data, including NIHSS, temperature, heart rate, systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, and respiratory rate, were abstracted from the medical record. Missing documentation was examined for association with modified Rankin Scale (mRS) scores and neurologic changes.

RESULT

Among 84 patients with a mean age of 68.8 years, there were 2276 documented assessments from an expected 3780. There were 104 clinically significant changes in 1 or more index variables. The most commonly missed documentation occurred during interventional radiology. After controlling for admission NIHSS, there was no significant relationship between the completeness of documentation and discharge mRS score (r2 = 0.047, P = .0561), nor between vital sign documentation and discharge mRS (r2 = 0.003, P = .6338).

CONCLUSION

Frequency of documentation does not reflect the quality of care during the early phase of acute stroke treatment.

Sepsis Associated Delirium

Sepsis is a potentially life-threatening condition caused by a systemic dysregulated host response to infection. The brain is particularly susceptible to the effects of sepsis with clinical manifestations ranging from mild confusion to a deep comatose state. Sepsis-associated delirium (SAD) is a cerebral manifestation commonly occurring in patients with sepsis and is thought to occur due to a combination of neuroinflammation and disturbances in cerebral perfusion, the blood brain barrier (BBB) and neurotransmission. The neurological impairment associated with SAD can persist for months or even longer, after the initial septic episode has subsided which may impair the rehabilitation potential of sepsis survivors. Early identification and treatment of the underlying sepsis is key in the management of SAD as once present it can be difficult to control. Through the regular use of validated screening tools for delirium, cases of SAD can be identified early; this allows potentially aggravating factors to be addressed promptly. The usefulness of biomarkers, neuroimaging and electroencephalopathy (EEG) in the diagnosis of SAD remains controversial. The Society of Critical Care Medicine (SCCM) guidelines advise against the use of medications to treat delirium unless distressing symptoms are present or it is hindering the patient’s ability to wean from organ support.