Is dopamine administration possibly a risk factor for delirium?

Pathogenesis of sepsis-associated encephalopathy: more than blood-brain barrier dysfunction

Sepsis-associated encephalopathy is a common neurological complication of sepsis and is responsible for higher mortality and poorer long-term outcomes in septic patients. Sepsis-associated encephalopathy symptoms can range from mild delirium to deep coma, which occurs in up to 70% of patients in intensive care units. The pathological changes in the brain associated with sepsis include cerebral ischaemia, cerebral haemorrhage, abscess and progressive multifocal necrotic leukoencephalopathy. Several mechanisms are involved in the pathogenesis of sepsis-associated encephalopathy, such as blood-brain barrier dysfunction, cerebral blood flow impairment, glial cell activation, leukocyte transmigration, and neurotransmitter disturbances. These events are interrelated and influence each other, therefore they do not act as independent factors. This review is focused on new evidence showing the pathological process of sepsis-associated encephalopathy.

Delayed awakening in neurocritical care

Delayed awakening is defined as a persistent disorder of arousal or consciousness 48 to 72h after sedation interruption in critically ill patients. Delayed awakening is either a component of coma or delirium. It results in longer hospital stays and increased mortality. It is therefore a diagnostic, therapeutic and prognostic emergency. In severe brain injured patients, delayed awakening may be related to the primary neurological injury or to secondary systemic insults related to organ failure associated with intensive care. In the present review, we propose diagnostic, therapeutic and prognostic algorithms for managing delayed awaking in neuro-ICU brain injured patients.

Pediatric Delirium: Evaluation, Management, and Special Considerations

Delirium describes a syndrome of acute brain dysfunction with severe consequences on patient outcomes, medical cost, morbidity, and mortality. It represents a final common pathway of numerous pathophysiologic disturbances disrupting cerebral homeostasis. The diagnosis is predicated on recognition of the clinical features of the syndrome through ongoing clinical assessment. Early identification can be aided by routine screening, particularly in high-risk populations. Evaluation and management are continuous and simultaneous processes involving a multidisciplinary care team including child psychiatry consultation. Prevention, early identification and management are critical in alleviating symptoms, improving outcomes, and reducing distress for patients, families, and care teams. This review highlights our current understanding regarding pediatric delirium, its mechanisms, clinical manifestations, detection and management.

Renal-Dose Dopamine: From Hypothesis to Paradigm to Dogma to Myth and, Finally, Superstition?

Acute renal failure (ARF) is common in the critically ill and is associated with a high mortality rate. Its pathogenesis is not understood. Because animal models use ischemia to induce experimental ARF, there is the widespread belief that lack of blood flow is responsible for ARF. Low-dose dopamine (LDD) has been shown to increase renal blood flow in animal and in human volunteers. Thus, it has been administered to humans for almost 3 decades in the belief that it would lead to renal arterial vasodilation and increase renal blood flow (RBF). However, the etiology of ARF in critical illness is likely multifactorial, and the contribution of hypovolemia and reduced renal perfusion is unknown. Furthermore, interindividual variation in the pharmacokinetics of dopamine typically results in poor correlation between blood levels and administered dose, making accurate and reliable delivery of LDD difficult. Finally, dopamine is a proximal tubular diuretic that increases Na+ delivery to tubular cells, thus increasing their oxygen demands. Accordingly, even if LDD were able to preferentially increase RBF, there is no guarantee that it would restore renal parenchymal oxygen homeostasis. More important, 2 meta-analyses and a large double-blind, prospective, multiple-center, randomized controlled trial have failed to demonstrate that dopamine protects the kidney in critically ill patients with ARF. Currently, there is insufficient evidence to support the use of renal-dose dopamine in the intensive care unit.

High prolactin levels are associated with more delirium in septic patients

PURPOSES

We investigated whether high prolactin levels were associated with delirium in septic patients because neuropsychiatric disorders are frequently associated with hyperprolactinemia.

MATERIALS AND METHODS

Prolactin levels were measured daily for 4 days in 101 patients with sepsis. Delirium was assessed using the Richmond Agitation Sedation Scale and the Confusion Assessment Method in the ICU.

RESULTS

Delirium developed in 79 patients (78%) and was more common in patients older than 65 years. Prolactin levels were higher in patients with delirium than in those without over the 4 days of observation (P = .032). In patients with delirium, higher prolactin levels were associated with a lower incidence of nosocomial infection (P = .006). Multivariable logistic regression showed that the Sequential Organ Failure Assessment score at intensive care unit admission (odds ratio, 1.24; 95% confidence interval, 1.04-1.48; P = .002) and the combined effect of prolactin levels with age (odds ratio, 1.018; 95% confidence interval, 1.01-1.031; P = .006) were associated with the development of delirium.

CONCLUSIONS

High prolactin levels may be a risk factor for delirium in septic patients.

Muscarinic M1 receptors modulate endotoxemia-induced loss of synaptic plasticity

Septic encephalopathy is associated with rapid deterioration of cortical functions. Using magnetic resonance imaging (MRI) we detected functional abnormalities in the hippocampal formation of patients with septic delirium. Hippocampal dysfunction was further investigated in an animal model for sepsis using lipopolysaccharide (LPS) injections to induce endotoxemia in rats, followed by electrophysiological recordings in brain slices. Endotoxemia induced a deficit in long term potentiation which was completely reversed by apamin, a blocker of small conductance calcium-activated potassium (SK) channels, and partly restored by treatment with physostigmine (eserine), an acetylcholinesterase inhibitor, or TBPB, a selective M1 muscarinic acetylcholine receptor agonist. These results suggest a novel role for SK channels in the etiology of endotoxemia and explain why boosting cholinergic function restores deficits in synaptic plasticity. Drugs which enhance cholinergic or M1 activity in the brain may prove beneficial in treatment of septic delirium in the intensive care unit.

Dopamine Administration is a Risk Factor for Delirium in Patients Undergoing Coronary Artery Bypass Surgery

BACKGROUND

Delirium is an important morbidity following heart surgery. We sought to determine whether dopamine infusion is associated with increased risk of delirium in patients undergoing coronary artery bypass grafting.

METHODS

A total of 137 patients (mean age; 61.02±7.83, 105 males) were included in the study. Patients undergoing isolated coronary artery bypass grafting were considered eligible and those with preoperative neurological deficit or significant neurocognitive disorders, dementia or psychiatric disorders were excluded. Primary outcome measure was occurrence of delirium within 72 hours after operation. The diagnosis of delirium was made using confusion assessment method for the intensive care unit questionnaire. Both administration of dopamine as a dichotomised variable and the total amount of dopamine per kg body-weight were included in two different logistic regression models.

RESULTS

Delirium occurred in 18 (13.1%) patients. Age adjusted Mantel-Haenszel relative risk for delirium with receiving dopamine was 4.62. Relative risk was 2.37 (0.18 to 31.28, 95% CI, p=0.51) in total doses over 10mg whereas it was 3.55 (1.16 to 10.89 95% CI, p=0.02) in total doses over 30 mg per kg body-weight. Older age (p=0.03), dopamine administration (OR: 9.227 95% CI, 2.688-32.022, p<0.001) and the amount of dopamine administered (OR: 1.072, 95% CI, 1.032-1.115, p<0.001) were independent predictors for delirium 72 hours after surgery.

CONCLUSION

Along with older age, dopamine infusion--even in low doses but more probably in higher doses--emerged as an independent risk factor for delirium in patients undergoing CABG. Further study is needed to confirm the validity of results presented.

Delirium detection based on monitoring of blinks and eye movements

OBJECTIVE

To investigate whether delirious patients differ from nondelirious patients with regard to blinks and eye movements to explore opportunities for delirium detection.

METHODS

Using a single-center, observational study in a tertiary hospital in the Netherlands, we studied 28 delirious elderly and 28 age- and gender-matched (group level) nondelirious elderly, postoperative cardiac surgery patients. Patients were evaluated for delirium by a geriatrician, psychiatrist, or neurologist using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria. Blinks were automatically extracted from electro-oculograms and eye movements from electroencephalography recordings using independent component analysis. The number and duration of eye movements and blinks were compared between patients with and without delirium, based on the classification of the delirium experts described above.

RESULTS

During eyes-open registrations, delirious patients showed, compared with nondelirious patients, a significant decrease in the number of blinks per minute (median: 12 [interquartile range {IQR}: 5-18] versus 18 [IQR: 8-25], respectively; p = 0.02) and number of vertical eye movements per minute (median: 1 [IQR: 0-13] versus 15 [IQR: 2-54], respectively; p = 0.01) as well as an increase in the average duration of blinks (median: 0.5 [IQR: 0.36-0.95] seconds versus 0.34 [IQR: 0.23-0.53] seconds, respectively; p <0.01). During eyes-closed registrations, the average duration of horizontal eye movements was significantly increased in delirious patients compared with patients without delirium (median: 0.41 [IQR: 0.15-0.75] seconds versus 0.08 [IQR: 0.06-0.22] seconds, respectively; p <0.01).

CONCLUSION

Spontaneous eye movements and particularly blinks appear to be affected in delirious patients, which holds promise for delirium detection.

Incidence, prevalence, risk factor and outcome of delirium in intensive care unit: a study from India

OBJECTIVE

To evaluate the incidence, prevalence, risk factors and outcome of delirium in the respiratory intensive care unit of a tertiary care hospital.

METHODS

Consecutive patients admitted to an eight-bed respiratory intensive care unit were screened for presence of delirium by a psychiatrist. Patients found to have delirium were evaluated using univariate techniques for their clinical profiles, risk factors for delirium, Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, duration of stay (in days) and outcome at discharge from intensive care unit besides evaluation on Delirium Rating Scale-Revised 98 version (DRS-R-98).

RESULTS

Incidence and prevalence rate of delirium were 24.4% and 53.6% respectively. Univariate analyses revealed that the prevalence of delirium was higher (64%) in mechanically ventilated patients. The predisposing risk factors identified for delirium in univariate analysis were higher age; higher Glasgow Coma Scale score; increased APACHE II score; hyperuricemia; hypoalbuminemia; presence of acidosis; abnormal alkaline transferase levels; use of mechanical ventilation; higher number of total medication received and use of sedative, steroids and insulin. Univariate analysis showed that patients who were diagnosed with delirium had significantly longer duration of intensive care unit (ICU) stay and higher mortality rates. Age, multiple organ failure, hypoactive delirium and higher DRS-R-98 scores were significant risk factors for mortality in patients with delirium.

CONCLUSIONS

Delirium is highly prevalent in the ICU setting and delirium is associated with longer ICU stay and higher mortality.

An open trial of aripiprazole for the treatment of delirium in hospitalized cancer patients

Objective:

The purpose of this study was to examine the efficacy and safety of aripiprazole in the treatment of delirium in hospitalized cancer patients, and to examine differential responses based on delirium subtypes.

Method:

We conducted an analysis of 21 hospitalized cancer patients at Memorial Sloan-Kettering Cancer Center (MSKCC) who had been evaluated and treated for delirium with aripiprazole, using an MSKCC Institutional Review Board (IRB) approved Clinical Delirium Database. Measures used were the Memorial Delirium Assessment Scale (MDAS), the Karnofsky Scale of Performance Status (KPS), and side effect rating at baseline (T1), 2–3 days (T2), and 4–7 days (T3). All measurements were integrated into the routine clinical care of patients. Doses of aripiprazole were adjusted based on clinical response.

Results:

Patients treated for delirium with aripiprazole experienced significant improvement and resolution of delirium, with MDAS scores declining from a mean of 18.0 at baseline (T1) to mean of 10.8 at T2 and a mean of 8.3 at T3. KPS scores improved from 28.1 at baseline (T1) to 35.2 at T2 and 41 at T3. Delirium resolved (based on MDAS < 10) in 52.4% of cases at T2 and in 76.2% at T3. The mean dosage of aripiprazole required was 18.3 mg (range of 5–30) daily at T3. In our cohort of patients with hypoactive delirium, we observed a delirium resolution rate of 100% compared to the cohort of patients with hyperactive delirium (58.3% rate of delirium resolution). MDAS scores improved from 15.6 at T1 to 5.7 at T3 in hypoactive delirium and from 19.9 at T1 to 10.2 at T3 in hyperactive delirium. In patients with pre-morbid cognitive deficits and the hyperactive subtype of delirium, we observed a more limited treatment response to aripiprazole treatment for delirium. There were no clinically significant side effects noted.

Significance of results:

Aripiprazole is effective and safe in the treatment of delirium in hospitalized cancer patients. These preliminary finding suggest that aripiprazole may be most effective in resolving delirium of the hypoactive subtype.

A screening, prevention, and restoration model for saving the injured brain in intensive care unit survivors

We face a profound and emerging public health problem in the form of acute and chronic brain dysfunction. This affects both young and elderly intensive care unit survivors and is altering the landscape of society. Two-thirds of intensive care unit patients develop delirium, and this is associated with longer stays, increased costs, and excess mortality. In addition, over half of intensive care unit survivors suffer a dementia-like illness that impacts their physical and cognitive functional abilities and which appears to be related to the duration of their intensive care unit delirium. A new paradigm of how intensivists handle the brain is required. We propose a three-step approach to address this emerging epidemic, which includes Screening, Prevention, and Restoration of brain function (SPR). Screening combines risk factor identification and delirium assessment using validated instruments. Prevention of acute and chronic brain dysfunction requires implementation of a core model of care that combines evidence-based practices: awakening and breathing, coordination with target-based sedation, delirium monitoring, and exercise/early mobility (ABCDE). Restoration introduces strategies of ongoing screening and treatment for intensive care unit survivors at high risk of ongoing brain dysfunction. This practical system applying many evidence-based concepts incorporates personalized medicine, systems-based practice, and continuing research and development toward improving acute and chronic cognitive outcomes.

Ghrelin in central neurons

Ghrelin, an orexigenic peptide synthesized by endocrine cells of the gastric mucosa, is released in the bloodstream in response to a negative energetic status. Since discovery, the hypothalamus was identified as the main source of ghrelin in the CNS, and effects of the peptide have been mainly observed in this area of the brain. In recent years, an increasing number of studies have reported ghrelin synthesis and effects in specific populations of neurons also outside the hypothalamus. Thus, ghrelin activity has been described in midbrain, hindbrain, hippocampus, and spinal cord. The spectrum of functions and biological effects produced by the peptide on central neurons is remarkably wide and complex. It ranges from modulation of membrane excitability, to control of neurotransmitter release, neuronal gene expression, and neuronal survival and proliferation. There is not at present a general consensus concerning the source of ghrelin acting on central neurons. Whereas it is widely accepted that the hypothalamus represents the most important endogenous source of the hormone in CNS, the existence of extra-hypothalamic ghrelin-synthesizing neurons is still controversial. In addition, circulating ghrelin can theoretically be another natural ligand for central ghrelin receptors. This paper gives an overview on the distribution of ghrelin and its receptor across the CNS and critically analyses the data available so far as regarding the effects of ghrelin on central neurotransmission.

Pharmacological treatment for the prevention of delirium: review of current evidence

OBJECTIVE

Delirium is a very common and serious disorder with high morbidity and mortality. Despite symptomatic treatment the outcome can be poor for some especially when no underlying cause is identified. As a result, various strategies for delirium prevention have been assessed. Pharmacological agents such as antipsychotics, acetylcholinesterase inhibitors, sleep-wake cycle regulators, anti-inflammatories and others have been advocated for a potential role in delirium prevention. The aim of this paper is to review the available evidence for their use in the prevention of delirium.

METHODS

An electronic search was carried out using Medline, EMBASE and Cochrane for randomised controlled trials (RCTs) and other studies. The words delirium, prevention, intervention, pharmacological, prophylactic, antipsychotics, acetylcholinesterase inhibitors, sleep and anti-inflammatories were used. References from selected papers were also searched.

RESULTS

No multi-centre RCT has been identified. Few trials and other studies have been published so far assessing the prophylactic role of antipsychotics, acetylcholinesterase inhibitors, hypnotics, melatonin, and gabapentin. As these studies tested different drugs, regimes and protocols in diverse populations no meaningful comparison can be made.

CONCLUSION

To date there is conflicting and inconsistent data regarding the efficacy of pharmacological treatment for delirium prevention. Positive reports in few of the studies justify further assessment of the potential for some pharmacological agents in the prevention of delirium. Well designed and appropriately powered RCTs are now needed. However, based on available evidence so far, no recommendation can be made to justify the routine clinical prophylactic use of any pharmacological agent in the prevention of delirium.

Sleep and delirium in ICU patients: a review of mechanisms and manifestations

Sleep deprivation and delirium are conditions commonly encountered in intensive care unit patients. Sleep in these patients is characterized by sleep fragmentation, an increase in light sleep, and a decrease of both slow wave sleep and rapid eye movement sleep. The most common types of delirium in this population are hypoactive and mixed-type. Knowledge about the mechanisms of sleep and delirium has evolved over time, but these phenomena are not yet well understood. What is known, however, is that different areas in the brainstem transmit information to the thalamus and cortex necessary for sleep-wake regulation. Delirium is related to an imbalance in the synthesis, release, and inactivation of some neurotransmitters, particularly acetylcholine and dopamine. The relationship between sleep deprivation and delirium has been studied for many years and has been viewed as reciprocal. The link between them may be ascribed to shared mechanisms. An imbalance in neurotransmitters as well as alteration of melatonin production may contribute to the pathogenesis of both phenomena. A better understanding of the mechanisms and factors that contribute to sleep deprivation and delirium can guide the development of new methods and models for prevention and treatment of these problems and consequently improve patient outcomes.

Pathoetiological model of delirium: a comprehensive understanding of the neurobiology of delirium and an evidence-based approach to prevention and treatment

Delirium is the most common complication found in the general hospital setting. Yet, we know relatively little about its actual pathophysiology. This article contains a summary of what we know to date and how different proposed intrinsic and external factors may work together or by themselves to elicit the cascade of neurochemical events that leads to the development delirium. Given how devastating delirium can be, it is imperative that we better understand the causes and underlying pathophysiology. Elaborating a pathoetiology-based cohesive model to better grasp the basic mechanisms that mediate this syndrome will serve clinicians well in aspiring to find ways to correct these cascades, instituting rational treatment modalities, and developing effective preventive techniques.

Delirium, cognitive dysfunction and posttraumatic stress disorder

PURPOSE OF REVIEW

In the critically ill patient, disease and the therapies we use impact on brain function. Simple tools are now available to recognise such problems. This review highlights neuropsychiatric and cognitive observations that have direct relevance to patient care and outcome.

RECENT FINDINGS

Delirium is a common event, especially the hypoactive forms in the elderly. The recognition of significant cognitive dysfunction is worrying since it has profound implications for how we treat and manage patients within intensive care and beyond. The most important message is that the 'awake' intensive care unit patient is not necessarily free of significant brain dysfunction. There is also the added complication of psychological disturbances related to real or imagined delusional experiences underlying the importance of memory and recall. Longer-term implications, particularly debilitating conditions such as posttraumatic stress disorder, mean that there is a need for improved post-intensive care unit rehabilitation care.

SUMMARY

Health professionals working with the critically ill must routinely include the assessment of brain cognitive function. While some of the consequences may be unavoidable, we need to reassess our sedation and care practices to ensure we are not confounding the problem. Practical options to improve outcome are being developed and emphasise that the recovery from critical illness is psychological as well as physical.

Bench-to-bedside review: critical illness-associated cognitive dysfunction--mechanisms, markers, and emerging therapeutics

Cognitive dysfunction is common in critically ill patients, not only during the acute illness but also long after its resolution. A large number of pathophysiologic mechanisms are thought to underlie critical illness-associated cognitive dysfunction, including neuro-transmitter abnormalities and occult diffuse brain injury. Markers that could be used to evaluate the influence of specific mechanisms in individual patients include serum anticholinergic activity, certain brain proteins, and tissue sodium concentration determination via high-resolution three-dimensional magnetic resonance imaging. Although recent therapeutic advances in this area are exciting, they are still too immature to influence patient care. Additional research is needed if we are to understand better the relative contributions of specific mechanisms to the development of critical illness-associated cognitive dysfunction and to determine whether these mechanisms might be amenable to treatment or prevention.

Clinical review: agitation and delirium in the critically ill--significance and management

Agitation is a psychomotor disturbance characterized by a marked increase in motor and psychological activity in a patient. It occurs very frequently in the intensive care setting. It may be isolated, or accompanied by other mental disorders, such as severe anxiety and delirium. Frequently, agitation is a sign of brain dysfunction and, as such, may have adverse consequences, for at least two reasons. First, agitation can interfere with the patient's care and second, there is evidence demonstrating that the prognosis of agitated (and delirious) patients is worse than that of non-agitated (non-delirious) patients. These conditions are often under-diagnosed in the intensive care unit (ICU). Consequently, a systematic evaluation of this problem in ICU patients should be conducted. Excellent tools are presently available for this purpose. Treatment, including prevention, must be undertaken without delay, and the ICU physician should follow logical, strict and systematic rules when applying therapy.

Brain dysfunction in critically ill patients--the intensive care unit and beyond

Critical care physicians often find themselves prognosticating for their patients, attempting to predict patient survival as well as disability. In the case of neurologic injury, this can be especially difficult. A frequent cause of coma in the intensive care unit is resuscitation following cardiac arrest, for which mortality and severe neurologic disability remain high. Recent studies of the clinical examination, of serum markers such as neuron-specific enolase, and of somatosensory evoked potentials allow accurate and specific prediction of which comatose patients are likely to suffer a poor outcome. Using these tools, practitioners can confidently educate the family for the majority of patients who will die or remain comatose at 1 month. Delirium is a less dramatic form of neurologic injury but, when sought, is strikingly prevalent. In addition, delirium in the intensive care unit is associated with increased mortality and poorer functional recovery, prompting investigation into preventative and therapeutic strategies to counter delirium. Finally, neurologic damage may persist long after the patient's recovery from critical illness, as is the case for cognitive dysfunction detected months and years after critical illness. Psychiatric impairment including depression or post-traumatic stress disorder may also arise. Mechanisms contributing to each of these entities are reviewed.

[Recall and memory after intensive care unit stay. Development of posttraumatic stress disorder]

BACKGROUND AND OBJECTIVE

The intensive care unit (ICU) confers a stress on patients and may affect the memory. The aim of the study was to examine the memory after critical care and the relationship with therapy and the development of posttraumatic stress disorder.

PATIENTS AND METHOD

Prospectively study conducted between December 2001 and June 2003. Patients were excluded if language difficulties or had a neurologic or psychiatric disease. We collected data on gender and age, length of stay in the ICU, severity of acute illness, diagnoses and medical treatment with mechanical ventilation, propofol, midazolam and dopamine during the ICU stay. 12 months after ICU eligible patients were contacted to assess memory. The ICUM (Intensive Care Memory) tool and IES (Impact Event Scale) were used to assess memory and posttraumatic stress disorder.

RESULTS

A total of 169 patients were included. The incidence of memory was 77.6%. 41 patients recalled delusional memories and these patients had higher IES after discharge. The logistic regression suggested a relationship with propofol, dopamine and length of stay.

CONCLUSIONS

ICU treatment may be related more to recall of delusions. The delusional memory is associated with posttraumatic stress disorder symptoms after ICU.

Potential mechanisms and markers of critical illness-associated cognitive dysfunction

PURPOSE OF REVIEW

To review the current understanding of the potential mechanisms of critical illness-associated cognitive dysfunction and to provide insight into markers that could be used to evaluate the influence of specific mechanisms in individual patients.

RECENT FINDINGS

Cognitive dysfunction is common in critically ill patients, not only during the acute illness but also long after its resolution. Several pathophysiologic mechanisms are thought to underlie critical illness-associated cognitive dysfunction, including neurotransmitter abnormalities and occult diffuse brain injury. Markers that could be used to evaluate the influence of specific mechanisms in individual patients include serum anticholinergic activity, certain brain proteins, and tissue sodium concentration determination by way of high-resolution three-dimensional magnetic resonance imaging.

SUMMARY

Although recent advances in this area are exciting, they are still too immature to influence patient care. Additional research is needed to provide a better understanding of the relative contribution of specific mechanisms to the development of critical illness-associated cognitive dysfunction and to determine whether these mechanisms might be amenable to treatment or prevention.