Update on Perioperative Delirium.

A strong association between frailty and in-hospital delirium in nonsurgical patients has been shown. Physical and cognitive frailties have been associated with decline and dysfunction in the frontal cognitive domains. Risk factors for frailty are similar to risk factors for postoperative delirium (POD). Frailty can be screened and diagnosed by various tools and instruments. Different anesthetic techniques have been studied to decrease the incidence of POD. However, no anesthetic technique has been conclusively proven to decrease the risk of POD. Patients with dementia develop delirium more often, and delirium is associated with accelerated cognitive decline.

Pro-Con Debate: Judicious Benzodiazepine Administration for Preoperative Anxiolysis in Older Patients.

In this Pro-Con commentary article, we discuss the risks and benefits of administering preoperative benzodiazepines to older patients to decrease preoperative anxiety. The Pro side first focuses on the critical importance of treating preoperative anxiety and that benzodiazepines are the best tool to achieve that goal. The competing argument presented by the Con side is that myriad options exist to treat preoperative anxiety without simultaneously increasing the risk for devastating complications such as postoperative delirium. Both sides call for more high-quality investigations to determine the most effective strategies for decreasing preoperative anxiety in older adults while improving outcomes and reducing morbidity.

The Effect of Self-Reported Visual Impairment and Sleep on Cognitive Decline: Results of the Hispanic Community Health Study/Study of Latinos.

BACKGROUND: Visual impairment could worsen sleep/wake disorders and cognitive decline. OBJECTIVE: To examine interrelations among self-reported visual impairment, sleep, and cognitive decline in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) Miami-site. METHOD: HCHS/SOL Miami-site participants ages 45-74 years (n = 665) at Visit-1, who returned for cognitive test 7-years later (SOL-INCA). Participants completed the National Eye Institute Visual Functioning Questionnaire (NEI-VFQ), validated sleep questionnaires and test for obstructive sleep apnea (OSA) at Visit-1. We obtained verbal episodic learning and memory, verbal fluency, processing speed, and executive functioning at Visit-1 and at SOL-INCA. Processing speed/executive functioning were added to SOL-INCA. We examined global cognition and change using a regression-based reliable change index, adjusting for the time lapse between Visit-1 and SOL-INCA. We used regression models to test whether 1) persons with OSA, self-reported sleep duration, insomnia, and sleepiness have an increased risk for visual impairment, 2a) visual impairment is associated with worse cognitive function and/or decline, and 2b) sleep disorders attenuate these associations. RESULT: Sleepiness (ß= 0.04; p < 0.01) and insomnia (ß= 0.04; p < 0.001) were cross-sectionally associated with visual impairment, adjusting for sociodemographic characteristics, behavioral factors, acculturation, and health conditions. Visual impairment was associated with lower global cognitive function at Visit-1 (ß= -0.16; p < 0.001) and on average 7-years later (ß= -0.18; p < 0.001). Visual impairment was also associated with a change in verbal fluency (ß= -0.17; p < 0.01). OSA, self-reported sleep duration, insomnia, and sleepiness did not attenuate any of the associations. CONCLUSION: Self-reported visual impairment was independently associated with worse cognitive function and decline.

Comparison of optical measurements of critical closing pressure acquired before and during induced ventricular arrhythmia in adults.

Significance: The critical closing pressure (CrCP) of cerebral circulation, as measured by diffuse correlation spectroscopy (DCS), is a promising biomarker of intracranial hypertension. However, CrCP techniques using DCS have not been assessed in gold standard experiments. Aim: CrCP is typically calculated by examining the variation of cerebral blood flow (CBF) during the cardiac cycle (with normal sinus rhythm). We compare this typical CrCP measurement with a gold standard obtained during the drops in arterial blood pressure (ABP) caused by rapid ventricular pacing (RVP) in patients undergoing invasive electrophysiologic procedures. Approach: Adults receiving electrophysiology procedures with planned ablation were enrolled for DCS CBF monitoring. CrCP was calculated from CBF and ABP data by three methods: (1) linear extrapolation of data during RVP ( CrCP RVP ; the gold standard); (2) linear extrapolation of data during regular heartbeats ( CrCP Linear ); and (3) fundamental harmonic Fourier filtering of data during regular heartbeats ( CrCP Fourier ). Results: CBF monitoring was performed prior to and during 55 episodes of RVP in five adults. CrCP RVP and CrCP Fourier demonstrated agreement ( R = 0.66 , slope = 1.05 (95%CI, 0.72 to 1.38). Agreement between CrCP RVP and CrCP Linear was worse; CrCP Linear was 8.2 ± 5.9 mmHg higher than CrCP RVP (mean ± SD; p < 0.001 ). Conclusions: Our results suggest that DCS-measured CrCP can be accurately acquired during normal sinus rhythm.

Hierarchical Cluster Analysis Identifies Distinct Physiological States After Acute Brain Injury.

BACKGROUND: Analysis of intracranial multimodality monitoring data is challenging, and quantitative methods may help identify unique physiological signatures that inform therapeutic strategies and outcome prediction. The aim of this study was to test the hypothesis that data-driven approaches can identify distinct physiological states from intracranial multimodality monitoring data. METHODS: This was a single-center retrospective observational study of patients with either severe traumatic brain injury or high-grade subarachnoid hemorrhage who underwent invasive multimodality neuromonitoring. We used hierarchical cluster analysis to group hourly values for heart rate, mean arterial pressure, intracranial pressure, brain tissue oxygen, and cerebral microdialysis across all included patients into distinct groups. Average values for measured physiological variables were compared across the identified clusters, and physiological profiles from identified clusters were mapped onto physiological states known to occur after acute brain injury. The distribution of clusters was compared between patients with favorable outcome (discharged to home or acute rehab) and unfavorable outcome (in-hospital death or discharged to chronic nursing facility). RESULTS: A total of 1704 observations from 20 patients were included. Even though the difference in mean values for measured variables between patients with favorable and unfavorable outcome were small, we identified four distinct clusters within our data: (1) events with low brain tissue oxygen and high lactate-to-pyruvate ratio-values (consistent with cerebral ischemia), (2) events with higher intracranial pressure values without evidence for ischemia (3) events which appeared to be physiologically "normal," and (4) events with high cerebral lactate without brain hypoxia (consistent with cerebral hyperglycolysis). Patients with a favorable outcome had a greater proportion of cluster 3 (normal) events, whereas patients with an unfavorable outcome had a greater proportion of cluster 1 (ischemia) and cluster 4 (hyperglycolysis) events (p < 0.0001, Fisher-Freeman-Halton test). CONCLUSIONS: A data-driven approach can identify distinct groupings from invasive multimodality neuromonitoring data that may have implications for therapeutic strategies and outcome predictions. These groupings could be used as classifiers to train machine learning models that can aid in the treatment of patients with acute brain injury. Further work is needed to replicate the findings of this exploratory study in larger data sets.

Frailty Is Associated With Postoperative Delirium But Not With Postoperative Cognitive Decline in Older Noncardiac Surgery Patients.

BACKGROUND: Postoperative cognitive dysfunction (POCD) and delirium are the most common perioperative cognitive complications in older adults undergoing surgery. A recent study of cardiac surgery patients suggests that physical frailty is a risk factor for both complications. We sought to examine the relationship between preoperative frailty and postoperative delirium and preoperative frailty and POCD after major noncardiac surgery. METHODS: We performed a prospective cohort study of patients >65 years old having major elective noncardiac surgery with general anesthesia. Exclusion criteria were preexisting dementia, inability to consent, cardiac, intracranial, or emergency surgery. Preoperative frailty was determined using the FRAIL scale, a simple questionnaire that categorizes patients as robust, prefrail, or frail. Delirium was assessed with the Confusion Assessment Method for the intensive care unit (CAM-ICU) twice daily, starting in the recovery room until hospital discharge. All patients were assessed with neuropsychological tests (California Verbal Learning Test II, Trail Making Test, subtests from the Wechsler Adult Intelligence Scale, Logical Memory Story A, Immediate and Delayed Recall, Animal and Vegetable verbal fluency, Boston Naming Test, and the Mini-Mental Status Examination) before surgery and at 3 months afterward. RESULTS: A total of 178 patients met inclusion criteria; 167 underwent major surgery and 150 were available for follow-up 3 months after surgery. The median age was 70 years old. Thirty-one patients (18.6%) tested as frail, and 72 (43.1%) prefrail before surgery. After adjustment for baseline cognitive score, age, education, surgery duration, American Society of Anesthesiologists (ASA) physical status, type of surgery, and sex, patients who tested frail or prefrail had an estimated 2.7 times the odds of delirium (97.5% confidence interval, 1.0-7.3) when compared to patients who were robust. There was no significant difference between the proportion of POCD between patients who tested as frail, prefrail, or robust. CONCLUSIONS: After adjustment for baseline cognition, testing as frail or prefrail with the FRAIL scale is associated with increased odds of postoperative delirium, but not POCD after noncardiac surgery.

Defining a Taxonomy of Intracranial Hypertension: Is ICP More Than Just a Number?

Intracranial pressure (ICP) monitoring and control is a cornerstone of neuroanesthesia and neurocritical care. However, because elevated ICP can be due to multiple pathophysiological processes, its interpretation is not straightforward. We propose a formal taxonomy of intracranial hypertension, which defines ICP elevations into 3 major pathophysiological subsets: increased cerebral blood volume, masses and edema, and hydrocephalus. (1) Increased cerebral blood volume increases ICP and arises secondary to arterial or venous hypervolemia. Arterial hypervolemia is produced by autoregulated or dysregulated vasodilation, both of which are importantly and disparately affected by systemic blood pressure. Dysregulated vasodilation tends to be worsened by arterial hypertension. In contrast, autoregulated vasodilation contributes to intracranial hypertension during decreases in cerebral perfusion pressure that occur within the normal range of cerebral autoregulation. Venous hypervolemia is produced by Starling resistor outflow obstruction, venous occlusion, and very high extracranial venous pressure. Starling resistor outflow obstruction tends to arise when cerebrospinal fluid pressure causes venous compression to thus increase tissue pressure and worsen tissue edema (and ICP elevation), producing a positive feedback ICP cycle. (2) Masses and edema are conditions that increase brain tissue volume and ICP, causing both vascular compression and decrease in cerebral perfusion pressure leading to oligemia. Brain edema is either vasogenic or cytotoxic, each with disparate causes and often linked to cerebral blood flow or blood volume abnormalities. Masses may arise from hematoma or neoplasia. (3) Hydrocephalus can also increase ICP, and is either communicating or noncommunicating. Further research is warranted to ascertain whether ICP therapy should be tailored to these physiological subsets of intracranial hypertension.

State of the clinical science of perioperative brain health: report from the American Society of Anesthesiologists Brain Health Initiative Summit 2018.

Cognitive recovery after anaesthesia and surgery is a concern for older adults, their families, and caregivers. Reports of patients who were 'never the same' prompted a scientific inquiry into the nature of what patients have experienced. In June 2018, the ASA Brain Health Initiative held a summit to discuss the state of the science on perioperative cognition, and to create an implementation plan for patients and providers leveraging the current evidence. This group included representatives from the AARP (formerly the American Association of Retired Persons), American College of Surgeons, American Heart Association, and Alzheimer's Association Perioperative Cognition and Delirium Professional Interest Area. This paper summarises the state of the relevant clinical science, including risk factors, identification and diagnosis, prognosis, disparities, outcomes, and treatment of perioperative neurocognitive disorders. Finally, we discuss gaps in current knowledge with suggestions for future directions and opportunities for clinical and translational projects.

Continuous non-invasive optical monitoring of cerebral blood flow and oxidative metabolism after acute brain injury.

Rapid detection of ischemic conditions at the bedside can improve treatment of acute brain injury. In this observational study of 11 critically ill brain-injured adults, we employed a monitoring approach that interleaves time-resolved near-infrared spectroscopy (TR-NIRS) measurements of cerebral oxygen saturation and oxygen extraction fraction (OEF) with diffuse correlation spectroscopy (DCS) measurement of cerebral blood flow (CBF). Using this approach, we demonstrate the clinical promise of non-invasive, continuous optical monitoring of changes in CBF and cerebral metabolic rate of oxygen (CMRO2). In addition, the optical CBF and CMRO2 measures were compared to invasive brain tissue oxygen tension (PbtO2), thermal diffusion flowmetry CBF, and cerebral microdialysis measures obtained concurrently. The optical CBF and CMRO2 information successfully distinguished between ischemic, hypermetabolic, and hyperemic conditions that arose spontaneously during patient care. Moreover, CBF monitoring during pressor-induced changes of mean arterial blood pressure enabled assessment of cerebral autoregulation. In total, the findings suggest that this hybrid non-invasive neurometabolic optical monitor (NNOM) can facilitate clinical detection of adverse physiological changes in brain injured patients that are otherwise difficult to measure with conventional bedside monitoring techniques.

Does the melatonin receptor 1B gene polymorphism have a role in postoperative delirium?

INTRODUCTION: Patients undergoing cardiac surgery are at high risk for postoperative delirium, which is associated with longer hospital and intensive care lengths of stays, increased morbidity and mortality. Because sleep disturbances are common in delirium, melatonin has been an area of interest in the treatment of delirium. The rs10830963 single nucleotide polymorphism of the melatonin receptor 1B gene can cause pathological dysfunction of this receptor and is associated with delayed morning offset of melatonin. We hypothesized patients undergoing aortic cardiac surgery who have the risk genotype of a melatonin receptor 1B polymorphism would have a higher incidence of postoperative delirium. METHODS: Ninety-eight patients undergoing aortic root or valve surgery underwent analysis for melatonin receptor 1B single nucleotide polymorphism, rs10830963. Using a validated method, CHART-DEL, all charts were retrospectively reviewed and scored for the presence of delirium while blinded to the results of the melatonin receptor 1B gene polymorphism. RESULTS: Genotyping for melatonin receptor 1B polymorphism was acceptable in 76 subjects of European descent of which 18 (23.7%) had delirium. Four of seven subjects with the risk genotype had delirium versus only 20.3% of subjects without the risk genotype. This carried an odds ratio of 5.2 (1.0, 26.1), p = 0.050. CONCLUSION: This observation suggests a role of the risk genotype of a melatonin receptor 1B polymorphism in the development of postoperative delirium. These hypotheses generating results warrant further prospective studies in a larger cohort group with delirium, circadian rhythm and melatonin assessments.