Neurologic Complications of Systemic Critical Illness

Propofol shows less negative effects on cognitive performances than dexmedetomidine in elderly intensive care unit patients

BACKGROUND

Due to the improved clinical management of aging population and the consequently declined mortality among patients with critical illnesses, the number of survivors from intensive care units (ICUs) keeps rising. Studies to examine the association of cognitive impairment analgesic and sedation strategies would be beneficial to improve the quality of life of ICU survivors.

METHODS

A prospective clinical trial was designed to compare the effects of two drugs, propofol, and dexmedetomidine, on short-term cognitive impairment after sedation in elderly ICU survivors by evaluating the extent of independence limited by the dementia-related activities of daily livings (ADLs). The plasma concentrations of brain injury biomarkers including S100β and neuron-specific enolase (NSE) were determined using an enzyme immunoassay. There were 136 patients allocated into both the dexmedetomidine group and the propofol group, respectively, with matched demographic characteristics.

RESULTS

The dementia scale of the patients in the dexmedetomidine group was significantly higher than the propofol group at weeks 1-4. Moreover, the changes in S100β and NSE concentrations in the dexmedetomidine group were significantly more pronounced than the propofol group. ICU patients who received dexmedetomidine intervention showed higher cognitive impairment than patients who received propofol, and this protective effect of propofol was not associated with the levels of brain injury markers S100β and NSE.

CONCLUSION

Our study compared the effects of commonly used medications on short-term cognitive impairment in elderly ICU patients, which would aid the selection of sedation plan for the benefit of ICU patients.

Diagnosing acute brain dysfunction due to sepsis

Developments in the management of critically ill patients suffering organ dysfunctions have demonstrated that brain is the prominent organ to be effected during critical illness. Acute brain dysfunction due to pathologic neuroinflammatory processes associated with sepsis is commonly seen and related to morbidity and mortality in the ICU treatment. Studies reported that survivors of sepsis may suffer long-term cognitive dysfunction that affects quality of life. However, there are no specific approaches to diagnose acute brain dysfunction in the early phase to target protective measures. In recent years, imaging methods and biomarkers are the most important issues of studies. This review will address the current diagnostic approaches to acute brain dysfunction related to sepsis.

Neurologic Complications in the Intensive Care Unit

Complications involving the central and peripheral nervous system are frequently encountered in critically ill patients. All components of the neuraxis can be involved including the brain, spinal cord, peripheral nerves, neuromuscular junction, and muscles. Neurologic complications adversely impact outcome and length of stay. These complications can be related to underlying critical illness, pre-existing comorbid conditions, and commonly used and life-saving procedures and medications. Familiarity with the myriad neurologic complications that occur in the intensive care unit can facilitate their timely recognition and treatment. Additionally, awareness of treatment-related neurologic complications may inform decision-making, mitigate risk, and improve outcomes.

[Formula: see text]evidence of neuropsychological dysfunction in Stevens-Johnson Syndrome and toxic epidermal necrolysis: case report

Stevens-Johnson Syndrome (SJS) and toxic epidermal necrolysis (TEN) is a potentially life-threatening critical illness affecting multiple organ systems including the peripheral and central nervous system. This case report involves a young man who was diagnosed with SJS/TEN at age 16 and underwent neuropsychological assessment at age 21. Results indicate a diffuse pattern of cerebral compromise and represent a decline from premorbid level of functioning. The etiology of the cognitive impairment in this patient is likely multifactorial with possible pathophysiologic mechanisms including hypoxemia, metabolic acid-base perturbations, hyperglycemia, and delirium, as well as sepsis and inflammation.

Systemic inflammation is associated with a reduction in Synaptopodin expression in the mouse hippocampus

Systemic inflammation is known to affect memory function through the activation of immune cells and the release of inflammatory cytokines. However, the neuronal targets by which inflammatory signaling pathways affect synaptic plasticity remain not well understood. Here, we addressed the question of whether systemic lipopolysaccharide (LPS)-induced inflammation influences the expression of Synaptopodin (SP). SP is an actin-binding protein, which is considered to control the ability of neurons to express synaptic plasticity by regulating the actin-cytoskeleton and/or intracellular Ca(2+) stores. This makes SP an interesting target molecule in the context of inflammation-induced alterations in synaptic plasticity. Using quantitative PCR (qPCR)-analysis and immunohistochemistry we here demonstrate that intraperitoneal LPS-injection in two-month old male Balb/c mice leads to a reduction in hippocampal SP-levels (area CA1; 24h after injection). These changes are accompanied by a defect in the ability to induce long-term potentiation (LTP) of Schaffer collateral-CA1 synapses, similar to what is observed in SP-deficient mice. We therefore propose that systemic inflammation could exert its effects on neural plasticity, at least in part, through the down-regulation of SP in vivo.

Neurologic changes during critical illness: brain imaging findings and neurobehavioral outcomes

Encephalopathy and other neurologic morbidities are common in critical illness, sepsis, and prolonged mechanical ventilation. We assessed structural changes on brain imaging and neuropsychological outcomes in critically ill patients who developed neurological changes during their intensive care unit (ICU) stay. Patients who underwent brain imaging for neurological changes were included in the study. Medical, neuroradiological, and outcome data were obtained from patient medical records. Sixty-four patients underwent brain imaging for neurological changes. Forty-one (64%) patients had abnormalities on brain imaging. There were no differences for age, hospital length of stay, ICU length of stay, duration of mechanical ventilation or APACHE II scores for patients with normal compared to abnormal brain imaging. Cognitive impairments occurred in 48% of survivors and 6% developed psychiatric disorders. Our study demonstrates that abnormalities on brain imaging are common in critically ill patients. We also confirm previous findings that survivors of critical illness have cognitive impairments post-ICU discharge. This study further illustrates the adverse effects of critical illness on the brain and highlights the need for additional research in this emerging area.

Brain atrophy and cognitive impairment in survivors of acute respiratory distress syndrome

PRIMARY OBJECTIVES

Acute Respiratory Distress Syndrome (ARDS) is characterized by severe acute lung injury, hypoxemia and is associated with neurological and cognitive impairments. This study assessed quantitative brain and ventricular volumes in survivors of ARDS with brain computed tomography (CT) scans compared to normal controls. It also compared the medical and cognitive outcome data of patients with ARDS with and without CT scans.

RESEARCH DESIGN

Observational cohort study.

METHODS

Sixty-six consecutive acute respiratory distress patients, of which 15 patients with ARDS underwent brain CT and 51 patients had no brain imaging. Brain CT scans from 15 survivors of ARDS were compared to age- and sex-matched normal controls. Clinical radiological findings and ventricular volumes, brain volume and generalized brain atrophy.

RESULTS

The patients with ARDS and brain imaging had cognitive impairments, significant brain atrophy, ventricular enlargement and 53% had atrophy or lesions by radiological report.

CONCLUSIONS

Clinicians need to be aware that ARDS can cause significant long-term brain-related morbidity manifest by brain atrophy, lesions and neurocognitive impairments.

Continuous electroencephalography in the medical intensive care unit

OBJECTIVES

To examine predictors and the prognostic value of electrographic seizures (ESZs) and periodic epileptiform discharges (PEDs) in medical intensive care unit (MICU) patients without a primary acute neurologic condition.

DESIGN

Retrospective study.

SETTING

MICU in a university hospital.

PATIENTS

A total of 201 consecutive patients admitted to the MICU between July 2004 and January 2007 without known acute neurologic injury and who underwent continuous electroencephalography monitoring (cEEG) for investigation of possible seizures or changes in mental status.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Median time from intensive care unit (ICU) admission to cEEG was 1 day (interquartile range 1-4). The majority of patients (60%) had sepsis as the primary admission diagnosis and 48% were comatose at the time of cEEG. Ten percent (n = 21) of patients had ESZs, 17% (n = 34) had PEDs, 5% (n = 10) had both, and 22% (n = 45) had either ESZs or PEDs. Seizures during cEEG were purely electrographic (no detectable clinical correlate) in the majority (67%) of patients. Patients with sepsis had a higher rate of ESZs or PEDs than those without sepsis (32% vs. 9%, p < 0.001). On multivariable analysis, sepsis at ICU admission was the only significant predictor of ESZs or PEDs (odds ratio 4.6, 95% confidence interval 1.9-12.7, p = 0.002). After controlling for age, coma, and organ dysfunction, the presence of ESZs or PEDs was associated with death or severe disability at hospital discharge (89% with ESZs or PEDs, vs. 39% if not; odds ratio 19.1, 95% confidence interval 6.3-74.6, p < 0.001).

CONCLUSION

In this retrospective study of MICU patients monitored with cEEG, ESZs and PEDs were frequent, predominantly in patients with sepsis. Seizures were mainly nonconvulsive. Both seizures and periodic discharges were associated with poor outcome. Prospective studies are warranted to determine more precisely the frequency and clinical impact of nonconvulsive seizures and periodic discharges, particularly in septic patients.

The role of future longitudinal studies in ICU survivors: understanding determinants and pathophysiology of brain dysfunction

PURPOSE OF REVIEW

Recent investigations demonstrate that most critical care survivors face significant brain-related morbidity including neurocognitive deficits. While current data on neurocognitive outcomes after critical illness are intriguing, gaps in the literature far exceed what we have learned to date. In this paper, we examine important areas of investigation heretofore unaddressed and propose directions for clinically oriented outcomes research.

RECENT FINDINGS

Neurocognitive impairments after critical illness, which affect multiple cognitive domains, may improve during the first 12 months after ICU discharge but may persist in many patients for years. These impairments appear to be independent of traditional measures of severity of critical illness or age, and risk factors for and mechanisms of injury are currently being defined.

SUMMARY

Over the last decade, ICU-related cognitive impairment has been identified as a significant public health problem and has become the focus of intense investigation by researchers around the world. While substantial work has been done to date, vitally important questions remain. Future research should evaluate the mechanisms of and risk factors for brain injury, the natural history of neurocognitive dysfunction, structural and functional brain-imaging studies, and therapeutic modalities designed to prevent or decrease neuropsychological disability.

Quality of life, emotional abnormalities, and cognitive dysfunction in survivors of acute lung injury/acute respiratory distress syndrome

This article provides a brief discussion of the recent literature linking quality-of-life impairment to physical dysfunction after acute lung injury/acute respiratory distress syndrome. Its main focus is a review of the current knowledge concerning cognitive and emotional outcomes after lung injury and their impact on long-term quality of life.

Long-term neurocognitive function after critical illness

BACKGROUND

Until relatively recently, critical care practitioners have focused on the survival of their patients and not on long-term outcomes. The incidence of chronic neurocognitive dysfunction has been underestimated and underreported, and only recently has it been studied in critically ill patients. However, neurocognitive outcomes have been the subject of extensive investigation in other medical populations for many years.

METHODS

Review of the current literature regarding long-term neurocognitive outcomes following critical illness.

RESULTS

Data from studies to date indicate that critical illness can lead to significant neurocognitive impairments. The neurocognitive impairments persist for months and years, and may have important consequences for quality of life, the ability to return to work, overall functional ability, and substantial economic costs. The mechanisms of the neurocognitive impairments are not fully understood but likely include delirium, hypoxia, glucose dysregulation, metabolic derangements, inflammation, and the effects of sedatives and narcotics among other factors. The contributions of these factors may be particularly significant in patients with preexisting vulnerabilities for the development of cognitive impairments such as mild cognitive impairment, dementia, prior traumatic brain injury, or other comorbid disorders associated with neurocognitive impairments.

CONCLUSIONS

Current research indicates that neurocognitive sequelae following critical illness are common, may be permanent, and are associated with impairments in daily function, decreased quality of life, and an inability to return to work. Research needs to be done to better understand the prevalence, nature, risk factors, and nuances of the neurocognitive impairments observed in ICU survivors.

Chronic neurocognitive effects of critical illness

PURPOSE OF REVIEW

Until relatively recently critical care practitioners have focused on survival of their patients and not long-term outcomes. An increasing body of research has examined patient outcomes beyond discharge from the intensive care unit and hospital. One area of focus is neurobehavioral outcomes including neurocognitive sequelae and neuropsychiatric disorders such as depression and anxiety. Cognitive functions are brain-based or mental activities that involve acquiring, storing, retrieving, and using information and include domains such as memory, attention, executive function, mental processing speed, spatial abilities, and general intelligence. It is known from other medical specialties that impaired cognitive function can have a broad, substantial, and long-lasting impact on a patient's life. This paper examines the current evidence for neurocognitive impairments in survivors of critical illness.

RECENT FINDINGS

Recent studies support the hypothesis that critical illness can lead to significant impairments in neurocognitive function. Current work indicates that the neurocognitive impairments can last for months or years after a patient arrives home and may have important consequences for quality of individual and family life and for ability to return to work as well as substantial economic costs. The mechanisms of neurocognitive impairments are not fully understood, but in acute respiratory distress syndrome hypoxemic burden appears important.

SUMMARY

Among the potential consequences of critical illness are now included neurocognitive impairments. Future research should include the search for strategies for the early identification of neurocognitive impairments, mechanisms of brain injury, and therapeutic modalities designed to prevent or decrease neurocognitive morbidity.

Acute quadriplegia complicating critical illness polyneuropathy in a patient with infective endocarditis: a case report

A 75-year-old woman with infective endocarditis developed critical illness polyneuropathy (CIP) with quadriplegia after cardiac surgery. The quadriplegia resolved gradually after aggressive treatment of the underlying infection and with rehabilitation. However, a MEDLINE search of the English-language literature failed to yield results matching quadriplegia and infective endocarditis. CIP is a complication of septic syndrome and sepsis. This complication has been largely unrecognized in intensive care units owing to difficulties in performing a clinical examination or electrophysiologic studies. Difficulty in weaning from the ventilator is an important early manifestation of CIP. Electroneuromyography (ENMG) should be routinely performed to establish the diagnosis. We suggest that any septic patients with unexplained muscle weakness, paralysis, or difficulty in weaning from the ventilator should be evaluated for CIP.

Hemodynamic disturbances in premature infants born after chorioamnionitis: association with cord blood cytokine concentrations

Chorioamnionitis and elevated cord blood inflammatory cytokine concentrations are associated with detectable disturbances of systemic and cerebral hemodynamics in premature newborns. Fifty-five infants (25-31 wk gestation) were enrolled. Chorioamnionitis was defined by placental histology. IL-6, IL-1beta, and tumor necrosis factor-alpha were quantified by ELISA. Blood pressure, heart rate, cardiac output, stroke volume, fractional shortening, and middle cerebral artery blood flow velocities were measured at 3 +/- 1 h after birth. Chorioamnionitis was evident in 22 placentas and was associated with increased IL-6 (p < 0.001), IL-1beta (p = 0.035), and heart rate (p = 0.027); and with decreased mean and diastolic blood pressure (p = 0.026 and p = 0.019, respectively). IL-6 concentration correlated inversely with systolic, mean, and diastolic blood pressures. Right ventricular cardiac output was elevated (p = 0.028) in infants with fetal vessel inflammation. Maternal temperature >or=38.0 degrees C and newborn immature-to-total white blood cell ratio >or=0.4 were associated with significant decreases in left ventricular fractional shortening (p = 0.001 and p = 0.005, respectively). Neither chorioamnionitis nor elevated cytokine concentrations were associated with changes in middle cerebral artery Doppler blood flow velocities. Chorioamnionitis and elevated cord blood IL-6 concentrations are associated with decreased blood pressure in premature newborns. Inflammation of the fetal vessels and nonspecific indicators of infection are associated with disturbances in cardiac function. Infants with chorioamnionitis and elevated cytokine concentrations do not manifest changes in cerebral Doppler indices within the first few postnatal hours. We speculate that cytokine-associated systemic hemodynamic disturbances in premature infants born after chorioamnionitis predispose such infants to perinatal brain injury.

Abnormal sleep/wake cycles and the effect of environmental noise on sleep disruption in the intensive care unit

Little is known about sleep/wake abnormalities in intensive care and less is known about the mechanisms responsible for these abnormalities. We studied 22 (20 mechanically ventilated) medical intensive care unit (ICU) patients with continuous polysomnography (PSG) and environmental noise measurements for 24-48 h to characterize sleep-wake patterns and objectively determine the effect of environmental noise on sleep disruption. All 22 patients demonstrated sleep-wake cycle abnormalities. There were large variations in total sleep time (TST) with the mean total sleep time per 24-h study period of 8.8 +/- 5.0 h. Sleep-wake cycles were fragmented and nonconsolidated with a mean of 57 +/- 18% and 43 +/- 18% of the TST occurring during the day and night, respectively. Environmental noise was responsible for 11.5 and 17% of the overall arousals and awakenings from sleep, respectively. The mean noise arousal index was 1.9 +/- 2.1 arousals/h sleep.

CONCLUSIONS

(1) ICU patients are qualitatively, but not necessarily quantitatively, sleep deprived; and (2) although environmental noise is in part responsible for sleep-wake abnormalities, it is not responsible for the majority of the sleep fragmentation and may therefore not be as disruptive to sleep as the previous literature suggests.

Metabolic encephalopathy in critically ill patients suffering from septic or nonseptic multiple organ failure

OBJECTIVE

Evaluation of changes in the peak latencies of sensory evoked potentials in different patient groups, to evaluate differences in metabolic encephalopathy of critically ill patients with multiple organ failure as a result of septic or nonseptic conditions.

DESIGN

Prospective cohort study.

SETTING

Intensive care units of the university hospital, Vienna.

PATIENTS

Patients (n = 103) treated on an intensive care unit because of multiple organ failure with additional metabolic encephalopathy. Multiple organ failure was induced by sepsis (group A; n = 56), surgery (group B; n = 29), or both (group C; n = 18).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Metabolic encephalopathy was determined by measuring median nerve-stimulated short-latency and long-latency sensory evoked potentials. No differences in the peak latencies of the sensory evoked potentials were detected among the groups. Septic patients had a N70 peak latency of 131+/-21 msecs, nonseptic postsurgical patients of 132+/-17 msecs, and septic postsurgical patients of 134+/-17 msecs. The cervicomedullary N13 to cortical N20 conduction times were 6.4+/-1 msec, 6.4+/-1.4 msecs, and 6.8+/-1.2 msecs, respectively. All measured peak latencies were significantly prolonged compared with peak latencies of healthy controls. The severity of illness assessed by the Acute Physiology and Chronic Health Evaluation III score was not different between the three groups. An increase of the delay of N70 peak latencies was significantly correlated with the severity of illness (r2 = .15; p < .00005).

CONCLUSION

There was no difference in sensory evoked potential measurements detectable among septic patients with multiple organ failure, nonseptic postsurgical patients with multiple organ failure, and septic postsurgical patients with multiple organ failure. The N70 peak latency was significantly correlated with the severity of illness but not with the presence or absence of sepsis. In postsurgical patients with multiple organ failure and superimposed sepsis, the N70 peak latencies were not further prolonged compared with postsurgical patients without sepsis.