Hypothalamic-pituitary-adrenal axis dysfunction in critically ill patients with traumatic brain injury: incidence, pathophysiology, and relationship to vasopressor dependence and peripheral interleukin-6 levels

The Unique Relationship between Neuro-Critical Care and Critical Illness-Related Corticosteroid Insufficiency : Implications for Neurosurgeons in Neuro-Critical Care

The brain houses vital hormonal regulatory structures such as the hypothalamus and pituitary gland, which may confer unique susceptibilities to critical illness-related corticosteroid insufficiency (CIRCI) in patients with neurological disorders. In addition, the frequent use of steroids for therapeutic purposes in various neurological conditions may lead to the development of steroid insufficiency. This abstract aims to highlight the significance of understanding these relationships in the context of patient care and management for physicians. Neurological disorders may predispose patients to CIRCI due to the role of the brain in hormonal regulation. Early recognition of CIRCI in the context of neurological diseases is essential to ensure prompt and appropriate intervention. Moreover, the frequent use of steroids for treating neurological conditions can contribute to the development of steroid insufficiency, further complicating the clinical picture. Physicians must be aware of these unique interactions and be prepared to evaluate and manage patients with CIRCI and steroid insufficiency in the context of neurological disorders. This includes timely diagnosis, appropriate steroid administration, and careful monitoring for potential adverse effects. A comprehensive understanding of the interplay between neurological disease, CIRCI, and steroid insufficiency is critical for optimizing patient care and outcomes in this complex patient population.

Neurons and glial cells acquire a senescent signature after repeated mild traumatic brain injury in a sex-dependent manner

Mild traumatic brain injury (mTBI) is an important public health issue, as it can lead to long-term neurological symptoms and risk of neurodegenerative disease. The pathophysiological mechanisms driving this remain unclear, and currently there are no effective therapies for mTBI. In this study on repeated mTBI (rmTBI), we have induced three mild closed-skull injuries or sham procedures, separated by 24 h, in C57BL/6 mice. We show that rmTBI mice have prolonged righting reflexes and astrogliosis, with neurological impairment in the Morris water maze (MWM) and the light dark test. Cortical and hippocampal tissue analysis revealed DNA damage in the form of double-strand breaks, oxidative damage, and R-loops, markers of cellular senescence including p16 and p21, and signaling mediated by the cGAS-STING pathway. This study identified novel sex differences after rmTBI in mice. Although these markers were all increased by rmTBI in both sexes, females had higher levels of DNA damage, lower levels of the senescence protein p16, and lower levels of cGAS-STING signaling proteins compared to their male counterparts. Single-cell RNA sequencing of the male rmTBI mouse brain revealed activation of the DNA damage response, evidence of cellular senescence, and pro-inflammatory markers reminiscent of the senescence-associated secretory phenotype (SASP) in neurons and glial cells. Cell-type specific changes were also present with evidence of brain immune activation, neurotransmission alterations in both excitatory and inhibitory neurons, and vascular dysfunction. Treatment of injured mice with the senolytic drug ABT263 significantly reduced markers of senescence only in males, but was not therapeutic in females. The reduction of senescence by ABT263 in male mice was accompanied by significantly improved performance in the MWM. This study provides compelling evidence that senescence contributes to brain dysfunction after rmTBI, but may do so in a sex-dependent manner.

Trauma-related electrolyte disturbances: From resuscitation to rhabdomyolysis

Traumatic injury results in drastic changes to a patient's normal physiology. The hormonal stress response, as well as some treatment strategies, lead to significant disruptions in electrolyte homeostasis that are important for clinicians to understand. In addition, advances in fluid resuscitation and modern transfusion practices have led to their own unique set of consequences, which we are just beginning to appreciate. Special attention is placed on rhabdomyolysis, as this distinct entity represents an extreme example of injury induced electrolyte derangements. This review describes the physiologic response to trauma and highlights some of the important electrolyte abnormalities that can be encountered while caring for the injured patient.

The role of the stress system in recovery after traumatic brain injury: A tribute to Bruce S. McEwen

Traumatic brain injury (TBI) represents a major public health concern. Although the majority of individuals that suffer mild-moderate TBI recover relatively quickly, a substantial subset of individuals experiences prolonged and debilitating symptoms. An exacerbated response to physiological and psychological stressors after TBI may mediate poor functional recovery. Individuals with TBI can suffer from poor stress tolerance, impairments in the ability to evaluate stressors, and poor initiation (and cessation) of neuroendocrine stress responses, all of which can exacerbate TBI-mediated dysfunction. Here, we pay tribute to the pioneering neuroendocrinologist Dr. Bruce McEwen by discussing the ways in which his work on stress physiology and allostatic loading impacts the TBI patient population both before and after their injuries. Specifically, we will discuss the modulatory role of hypothalamic-pituitary-adrenal axis responses immediately after TBI and later in recovery. We will also consider the impact of stressors and stress responses in promoting post-concussive syndrome and post-traumatic stress disorders, two common sequelae of TBI. Finally, we will explore the role of early life stressors, prior to brain injuries, as modulators of injury outcomes.

Biofluid Biomarkers in Traumatic Brain Injury: A Systematic Scoping Review

Emerging evidence suggests that biofluid-based biomarkers have diagnostic and prognostic potential in traumatic brain injuries (TBI). However, owing to the lack of a conceptual framework or comprehensive review, it is difficult to visualize the breadth of materials that might be available. We conducted a systematic scoping review to map and categorize the evidence regarding biofluid-based biochemical markers of TBI. A comprehensive search was undertaken in January 2019. Of 25,354 records identified through the literature search, 1036 original human studies were included. Five hundred forty biofluid biomarkers were extracted from included studies and classified into 19 distinct categories. Three categories of biomarkers including cytokines, coagulation tests, and nerve tissue proteins were investigated more than others and assessed in almost half of the studies (560, 515, and 502 from 1036 studies, respectively). S100 beta as the most common biomarker for TBI was tested in 21.2% of studies (220 articles). Cortisol was the only biomarker measured in blood, cerebrospinal fluid, urine, and saliva. The most common sampling time was at admission and within 24 h of injury. The included studies focused mainly on biomarkers from blood and central nervous system sources, the adult population, and severe and blunt injuries. The most common outcome measures used in studies were changes in biomarker concentration level, Glasgow coma scale, Glasgow outcome scale, brain computed tomography scan, and mortality rate. Biofluid biomarkers could be clinically helpful in the diagnosis and prognosis of TBI. However, there was no single definitive biomarker with accurate characteristics. The present categorization would be a road map to investigate the biomarkers of the brain injury cascade separately and detect the most representative biomarker of each category. Also, this comprehensive categorization could provide a guiding framework to design combined panels of multiple biomarkers.

Diabetes exacerbates brain pathology following a focal blast brain injury: New role of a multimodal drug cerebrolysin and nanomedicine

Blast brain injury (bBI) is a combination of several forces of pressure, rotation, penetration of sharp objects and chemical exposure causing laceration, perforation and tissue losses in the brain. The bBI is quite prevalent in military personnel during combat operations. However, no suitable therapeutic strategies are available so far to minimize bBI pathology. Combat stress induces profound cardiovascular and endocrine dysfunction leading to psychosomatic disorders including diabetes mellitus (DM). This is still unclear whether brain pathology in bBI could exacerbate in DM. In present review influence of DM on pathophysiology of bBI is discussed based on our own investigations. In addition, treatment with cerebrolysin (a multimodal drug comprising neurotrophic factors and active peptide fragments) or H-290/51 (a chain-breaking antioxidant) using nanowired delivery of for superior neuroprotection on brain pathology in bBI in DM is explored. Our observations are the first to show that pathophysiology of bBI is exacerbated in DM and TiO₂-nanowired delivery of cerebrolysin induces profound neuroprotection in bBI in DM, not reported earlier. The clinical significance of our findings with regard to military medicine is discussed.

Pituitary dysfunction after traumatic brain injury: prevalence and screening strategies

INTRODUCTION

Pituitary gland is vulnerable to traumatic brain injury (TBI). As a result a series of neuroendocrine changes appear after head injury; in many occasions they reverse with time, while occasionally new late onset changes may develop.

AREAS COVERED

In this review, we focus on the prevalence of anterior and posterior pituitary hormonal changes in the acute and chronic post-TBI period in both children and adults. Moreover, we present evidence supporting the need for evaluating pituitary function along with the current suggestions for the most appropriate screening strategies. We attempted to identify all published literature and we conducted an online search of PubMed, from January 1970 to June 2020.

EXPERT OPINION

Adrenal insufficiency and water metabolism disorders are medical emergencies and should be promptly recognized. Awareness for long-term hormonal derangements is necessary, as they may lead to a series of chronic health issues and compromise quality of life. There is a need for well-designed prospective long-term studies that will estimate pituitary function during the acute and chronic phase after head injury.

A study of serum cortisol levels in acute head injury patients

Introduction Adrenal insufficiency has a great impact on the prognosis of patients with traumatic brain injury. In healthy persons during normal day-to-day activity, the concentration of plasma cortisol is high in the morning, decreases during the day and rises again during night. But this diurnal rhythm is abolished in long-term unconscious patients and in those with disturbed sleep cycles. In addition, patients with central nervous system disease, who are conscious but have lesions in the temporal lobe, and the pretectal or hypothalamus area, demonstrate abnormal rhythms. Methods This cross-sectional study recruited 33 consecutive patients attending emergency medical departments of Prathima Institute of Medical Sciences Hospital between July 2017 and April 2018 with mild to severe traumatic head injury within 6 h of injury. The selected patients were mainly divided into three groups depending on the Glasgow Coma Scale (GCS) [mild head injury (14-15); moderate head injury (9-13); severe head injury (3-8)]. In each group, 11 patients were selected. GCS was calculated at the time of admission. The adrenal function of the patients was assessed by using the serum cortisol tests. Results In this comparative study of acute head injury among three groups, males are more prone to injury than females, with 81%, 90% and 72% in mild, moderate and severe injuries, respectively. The result mainly shows that the mean cortisol levels estimated were significantly increased in mild head injury and were with greater increase in cases of moderate & severe head injuries. Statistically significant positive correlation was observed between serum cortisol & GCS levels. Conclusions In this study of serum cortisol levels in head injury patients, we observed that there is increase in the serum cortisol level immediately after trauma. The increase is linearly related with the severity of head injury. Hence performing serum cortisol test is recommended for the assessment of adrenal function in patients with traumatic head injury.

Sepsis-associated encephalopathy: a vicious cycle of immunosuppression

Sepsis-associated encephalopathy (SAE) is commonly complicated by septic conditions, and is responsible for increased mortality and poor outcomes in septic patients. Uncontrolled neuroinflammation and ischemic injury are major contributors to brain dysfunction, which arises from intractable immune malfunction and the collapse of neuroendocrine immune networks, such as the cholinergic anti-inflammatory pathway, hypothalamic-pituitary-adrenal axis, and sympathetic nervous system. Dysfunction in these neuromodulatory mechanisms compromised by SAE jeopardizes systemic immune responses, including those of neutrophils, macrophages/monocytes, dendritic cells, and T lymphocytes, which ultimately results in a vicious cycle between brain injury and a progressively aberrant immune response. Deep insight into the crosstalk between SAE and peripheral immunity is of great importance in extending the knowledge of the pathogenesis and development of sepsis-induced immunosuppression, as well as in exploring its effective remedies.

The blockade of corticotropin-releasing factor 1 receptor attenuates anxiety-related symptoms and hypothalamus-pituitary-adrenal axis reactivity in mice with mild traumatic brain injury

Recent studies have shown that mild traumatic brain injury (mTBI) is associated with higher risk for anxiety-related disorders. Dysregulation in the hypothalamus-pituitary-adrenal (HPA) axis following mTBI has been proposed to be involved in the development of neurobehavioral abnormalities; however, the underlying mechanisms are largely unknown. The aim of this study was to determine whether the corticotropin-releasing-factor-1 (CRF-1) receptor is involved in the regulation of anxiety-related symptoms in a mouse model of mTBI. Animals with or without mTBI received intracerebroventricular injections of a CRF-1 receptor agonist (CRF; 0.01 nmol/mouse) or antagonist (antalarmin; 1 µg/mouse) for 5 days, and then the animals were subjected to anxiety tests (light-dark box and zero maze). The levels of adrenocorticotropic hormone and corticosterone, the most important markers of HPA axis, were also measured after behavioral tests. Our results indicated that mTBI-induced anxiety-related symptoms in mice through increased levels of adrenocorticotropic hormone and corticosterone, showing HPA axis hyperactivity. Interestingly, activation of CRF receptor by a subthreshold dose of CRF resulted in significant increases in anxiety-like behaviors and HPA axis response to stress, whereas blockade of CRF receptors by a subthreshold dose of antalarmin decreased anxiety-related symptoms and HPA axis response to stress in mTBI-induced mice. Collectively, these findings suggest that the CRF-1 receptor plays an important role in the regulation of anxiety-related behaviors following mTBI induction in mice and support the hypothesis that blockade of the CRF-1 receptor may be a promising therapeutic target for anxiety-related disorders in patients with TBI.

[Critical illness - related corticosteroid insufficiency in patients after cardiac surgery and cardiologic emergencies]

Critical illness - related corticosteroid insufficiency (CIRCI) is associated with elevated level of circulating biomarkers of inflammation, pro - coagulant effects, deterioration of systemic inflammatory response syndrome (SIRS) and, consequently, prolonged in - hospital stay and increased mortality of intensive care patients. Incidence of CIRCI widely varies depending on specific patient's population and applied diagnostic thresholds being as high as 30% among postoperative patients on inotropes. CIRCI is a complex clinical and pathophysiological condition with substantial influence on immediate survival and prognosis. Clinical impact of CIRCI as well as pathogenetically based therapy arouse keen interest of intensive care specialists and clinical pathologists. The specific issues of CIRCI in patients after cardiac surgery and cardiology emergencies remain largely under - recognized, so further scrutinization is needed.

Traumatic brain injury induced neuroendocrine changes: acute hormonal changes of anterior pituitary function

PURPOSE

It is estimated that approximately 69 million individuals worldwide will sustain a TBI each year, which accounts for substantial morbidity and mortality in both children and adults. TBI may lead to significant neuroendocrine changes, if the delicate pituitary is ruptured. In this review, we focus on the anterior pituitary hormonal changes in the acute post-TBI period and we present the evidence supporting the need for screening of anterior pituitary function in the early post-TBI time along with current suggestions regarding the endocrine assessment and management of these patients.

METHODS

Original systematic articles with prospective and/or retrospective design studies of acute TBI were included, as were review articles and case series.

RESULTS

Although TBI may motivate an acute increase of stress hormones, it may also generate a wide spectrum of anterior pituitary hormonal deficiencies. The frequency of post-traumatic anterior hypopituitarism (PTHP) varies according to the severity, the type of trauma, the time elapsed since injury, the study population, and the methodology used to diagnose pituitary hormone deficiency. Early neuroendocrine abnormalities may be transient, but additional late ones may also appear during the course of rehabilitation.

CONCLUSIONS

Acute hypocortisolism should be diagnosed and managed promptly, as it can be life-threatening, but currently there is no evidence to support treatment of acute GH, thyroid hormones or gonadotropins deficiencies. However, a more comprehensive assessment of anterior pituitary function should be undertaken both in the early and in the post-acute phase, since ongoing hormone deficiencies may adversely affect the recovery and quality of life of these patients.

Catastrophic Non-Survivable Brain Injury Care-Role 2/3

A catastrophic brain injury is defined as any brain injury that is expected to result in permanent loss of all brain function above the brain stem level. These clinical recommendations will help stabilize the patient so that they may be safely evacuated from theater. In addition to cardiovascular and hemodynamic goals, special attention must be paid to their endocrine dysfunction and its treatment-specifically steroid, insulin and thyroxin (t4) replacement while evaluating for and treating diabetes insipidus. Determining the futility of care coupled with resource management must also be made at each echelon. Logistical coordination and communication is paramount to expedite these patients to higher levels of care so that there is an increased probability of reuniting them with their family.

Mechanisms underlying vulnerabilities after repeat mild traumatic brain injuries

Traumatic brain injury (TBI) has drawn national attention for its high incidence and mechanistic complexity. The majority of TBI cases are "mild" in nature including concussions and mild TBI (mTBI). Concussions are a distinct form of mTBI where diagnosis is difficult, quantification of the incidence is challenging and there is greater risk for subsequent injuries. While concussions occur in the general population, it has become a hallmark injury consistently observed among adolescent and young adult athletes and the risks for repeat TBI (rTBI) is significant. Clinical and experimental evidence shows that the magnitude and duration of deficits is dependent on the number and the interval between injuries. Several studies suggest that metabolic vulnerabilities after injury may contribute to the window for cerebral vulnerability from rTBI. In addition to metabolism, this review addresses how age, sex and hormones also play an important role in the response to repeat concussions. Understanding how these factors collectively contribute to concussion and rTBI recovery is critically important in establishing age/sex appropriate return to play guidelines, injury prevention, therapeutic interventions and mitigation of long-term consequences of rTBI.

Serum electrolyte imbalance and prognostic factors of postoperative death in adult traumatic brain injury patients: A prospective cohort study

Electrolyte imbalances are common in traumatic brain injury. It shares the cause of perioperative morbidity and mortality. Types of intravenous fluid resuscitation, osmotic diuretics, massive blood loss, and intracranial pathology were considered as the potential factors to worsen electrolyte abnormalities in these patients. The aims of this study were to report the incidence of electrolyte imbalance in traumatic brain injured patients and to assess the association between electrolyte imbalance and other prognostic factors to death within 24 hours of the injury.The study was carried out in the northern university, tertiary-care hospital of Thailand. The patients aged from 18 to 65 years old, presented with traumatic brain injury, and needed for emergency craniotomy were included. We excluded the patients who had minor neurosurgical procedures, pregnancy, and undergone cardiopulmonary resuscitation from the Emergency Department.Among 145 patients recruited, 101 (70%) had Glasgow Coma Scale (GCS) score ≤ 8, 25 (17%) had GCS score 9 to 12, and 19 (13%) had GCS score 13 to 15. The most common diagnosis were subdural hematoma and epidural hematoma, 51% and 36%, respectively. Hypokalemia was the most common electrolyte imbalance at 65.5%. The results of the use of a multivariable logistic regression model show that the odds of postoperative death in TBI patients were increased with high levels of blood glucose, hypernatremia, and acidosis.Hypokalemia was the most common electrolyte imbalance in TBI patients. Hypernatremia, acidosis, and hyperglycemia significantly increased the odds ratio of death in the first 24 hours post TBI.

Hydrocortisone therapy in a cat with vasopressor-refractory septic shock and suspected critical illness-related corticosteroid insufficiency

A 27‐month‐old female cat was presented with septic peritonitis secondary to a ruptured pyometra and subsequent pyothorax. Vasopressor‐refractory septic shock led to a suspicion of critical illness‐related corticosteroid insufficiency, successfully treated with intravenous hydrocortisone. Previous megestrol acetate administration may have played a role in the development of adrenocortical dysfunction.

Hepatic alterations are accompanied by changes to bile acid transporter-expressing neurons in the hypothalamus after traumatic brain injury

Annually, there are over 2 million incidents of traumatic brain injury (TBI) and treatment options are non-existent. While many TBI studies have focused on the brain, peripheral contributions involving the digestive and immune systems are emerging as factors involved in the various symptomology associated with TBI. We hypothesized that TBI would alter hepatic function, including bile acid system machinery in the liver and brain. The results show activation of the hepatic acute phase response by 2 hours after TBI, hepatic inflammation by 6 hours after TBI and a decrease in hepatic transcription factors, Gli 1, Gli 2, Gli 3 at 2 and 24 hrs after TBI. Bile acid receptors and transporters were decreased as early as 2 hrs after TBI until at least 24 hrs after TBI. Quantification of bile acid transporter, ASBT-expressing neurons in the hypothalamus, revealed a significant decrease following TBI. These results are the first to show such changes following a TBI, and are compatible with previous studies of the bile acid system in stroke models. The data support the emerging idea of a systemic influence to neurological disorders and point to the need for future studies to better define specific mechanisms of action.

Systemic complications of traumatic brain injury

PURPOSE OF REVIEW

Increased understanding of the pathophysiology in traumatic brain injury (TBI) has resulted in the development of core physiological targets and therapies to preserve cerebral oxygenation, and in doing so prevent secondary insult. This review addresses the many systemic complications of TBI that make achieving these targets challenging and can influence outcome.

RECENT FINDINGS

There are a wide range of systemic complications following TBI. Complications involve the cardiovascular, respiratory, immunological, haematological and endocrinological systems amongst others, and can influence early management and long-term outcomes.

SUMMARY

Effective management of TBI should go beyond formulaic-based pursuit of physiological targets and requires a detailed understanding of the multisystem response of the body.

Does low-dose hydrocortisone therapy prevent ventilator-associated pneumonia in trauma patients?

The incidence of ventilator-associated pneumonia (VAP) is particularly high in trauma patients. Immediate acute inflammation response is one of the hallmarks of multiple trauma. This phenomenon is associated with an immunosuppression state and may increase the risk of VAP. In our study, we aimed to evaluate whether low-dose steroids prevent VAP onset in multiple trauma patients. All adult patients admitted in our intensive care unit (ICU) for multiple trauma with predicted duration of mechanical ventilation over 48 hours were included. We compared 2 different periods: a retrospective cohort of patients who did not receive low-dose steroids for VAP prevention and a prospective cohort of patients who received hydrocortisone with a dose of 100 mg/8 hours for a scheduled period of 7 days. We included 175 patients: 92 in the steroids (-) group and 83 in the steroids (+) group. The incidence of VAP was not different between the 2 studied groups (29.3% and 26.5%; P = 0.676). When predictive factors of VAP onset were studied in multivariate analysis, steroids had no preventive effect on VAP [OR = 1.6; 95% confidence interval, 0.73-3.6; P = 0.234]. We did not find any difference between the 2 groups, neither in terms of ICU length of stay (respectively, 11 ± 9.7 days vs. 12.3 ± 10.7 days; P = 0.372) nor in terms of ICU mortality (29.3% vs 24.1%; P = 0.434).

Brain-lung crosstalk: Implications for neurocritical care patients

Major pulmonary disorders may occur after brain injuries as ventilator-associated pneumonia, acute respiratory distress syndrome or neurogenic pulmonary edema. They are key points for the management of brain-injured patients because respiratory failure and mechanical ventilation seem to be a risk factor for increased mortality, poor neurological outcome and longer intensive care unit or hospital length of stay. Brain and lung strongly interact via complex pathways from the brain to the lung but also from the lung to the brain. Several hypotheses have been proposed with a particular interest for the recently described “double hit” model. Ventilator setting in brain-injured patients with lung injuries has been poorly studied and intensivists are often fearful to use some parts of protective ventilation in patients with brain injury. This review aims to describe the epidemiology and pathophysiology of lung injuries in brain-injured patients, but also the impact of different modalities of mechanical ventilation on the brain in the context of acute brain injury.

Impaired Pituitary Axes Following Traumatic Brain Injury

Pituitary dysfunction following traumatic brain injury (TBI) is significant and rarely considered by clinicians. This topic has received much more attention in the last decade. The incidence of post TBI anterior pituitary dysfunction is around 30% acutely, and declines to around 20% by one year. Growth hormone and gonadotrophic hormones are the most common deficiencies seen after traumatic brain injury, but also the most likely to spontaneously recover. The majority of deficiencies present within the first year, but extreme delayed presentation has been reported. Information on posterior pituitary dysfunction is less reliable ranging from 3%-40% incidence but prospective data suggests a rate around 5%. The mechanism, risk factors, natural history, and long-term effect of treatment are poorly defined in the literature and limited by a lack of standardization. Post TBI pituitary dysfunction is an entity to recognize with significant clinical relevance. Secondary hypoadrenalism, hypothyroidism and central diabetes insipidus should be treated acutely while deficiencies in growth and gonadotrophic hormones should be initially observed.

Adrenal inhibition following a single dose of etomidate in intubated traumatic brain injury victims

Background:

Etomidate is frequently used to intubate traumatic brain injury (TBI) victims, even though it has been linked to adrenal insufficiency (AI) in some populations. Few studies have explored the risk of prolonged etomidateinduced AI among TBI victims.

Objective:

To determine the risk and the length of AI induced by etomidate in patients intubated for moderate and severe TBI.

Methods:

Participants in this observational study were moderate to severe intubated TBI victims aged ≥ 16 years. The anesthetic used (etomidate versus others) was determined solely by the treating emergency physician. Adrenocorticotropic hormone (ACTH) stimulation tests (250 µg) were performed 24, 48, and 168 hours after intubation. AI was defined as an increase in serumcortisol 1 hour post–ACTH test (delta cortisol) of less than 248.4 nmol/L.

Results:

Forty subjects (participation 42.6%) underwent ACTH testing. Fifteen received etomidate, and 25 received another anesthetic. There were no statistically significant differences between groups as to the cumulative incidence of AI at any measurement time. However, at 24 hours, exploratory post hoc analyses showed a significant decrease in delta cortisol (adjusted means: etomidate group: 305.1 nmol/L, 95% CI 214.7–384.8 versus other anesthetics: 500.5 nmol/L, 95% CI 441.8–565.7). This decrease was not present at 48 and 168 hours.

Conclusion:

In TBI victims, although a single dose of etomidate does not increase the cumulative incidence of AI as defined, it seems to decrease the adrenal response to an ACTH test for 24 hours. The clinical impacts of this finding remain to be determined.

Systemic manifestations of traumatic brain injury

Traumatic brain injury (TBI) affects functioning of various organ systems in the absence of concomitant non-neurologic organ injury or systemic infection. The systemic manifestations of TBI can be mild or severe and can present in the acute phase or during the recovery phase. Non-neurologic organ dysfunction can manifest following mild TBI or severe TBI. The pathophysiology of systemic manifestations following TBI is multifactorial and involves an effect on the autonomic nervous system, involvement of the hypothalamic-pituitary axis, release of inflammatory mediators, and treatment modalities used for TBI. Endocrine dysfunction, electrolyte imbalance, and respiratory manifestations are common following TBI. The influence of TBI on systemic immune response, coagulation cascade, cardiovascular system, gastrointestinal system, and other systems is becoming more evident through animal studies and clinical trials. Systemic manifestations can independently act as risk factors for mortality and morbidity following TBI. Some conditions like neurogenic pulmonary edema and disseminated intravascular coagulation can adversely affect the outcome. Early recognition and treatment of systemic manifestations may improve the clinical outcome following TBI. Further studies are required especially in the field of neuroimmunology to establish the role of various biochemical cascades, not only in the pathophysiology of TBI but also in its systemic manifestations and outcome.

Longitudinal assessment of adrenal function in the early and prolonged phases of critical illness in septic patients: relations to cytokine levels and outcome

CONTEXT

Adrenal dysfunction remains a controversial issue in critical care. The long-stay intensive care unit (ICU) population may be at increased risk of adrenal insufficiency.

OBJECTIVE

We aimed to determine whether adrenal dysfunction develops during the course of sepsis.

DESIGN

This is a prospective observational longitudinal study.

SETTING

The study was conducted in the ICU of a secondary/tertiary care hospital.

PATIENTS

We studied 51 consecutive mechanically ventilated patients with sepsis.

INTERVENTION

We measured cortisol, ACTH, cortisol-binding globulin, cytokines, and cortisol 30 minutes after 1 μg ACTH(1-24), upon sepsis diagnosis and every 3 to 4 days, until Day 30 or until recovery or death.

MAIN OUTCOME MEASURES

We looked for changes in baseline and stimulated cortisol levels and its relationship to ACTH levels, sepsis severity or survival.

RESULTS

Baseline and stimulated cortisol levels did not vary significantly. Septic patients with shock had higher baseline (20 ± 6 vs 17 ± 5 μg/dL, P = .03) and stimulated cortisol levels (26 ± 5 vs 23 ± 6 μg/dL, P = .04), compared with those without shock. On Day 1, ACTH levels could not predict cortisol levels (R(2) = 0.06, P = .08). ACTH levels increased significantly after Day 10 and, at this time point, they related to cortisol levels (R(2) = 0.35, P < .001). Development of septic shock, or resolution from it, was not associated with changes in baseline, stimulated cortisol levels, or the cortisol increment. There was much inpatient variability in the diagnosis of adrenal dysfunction at different time points.

CONCLUSIONS

Total cortisol levels relate both to the severity and outcome of sepsis and remain fairly unchanged during the course of illness. Initially, cortisol levels are largely ACTH independent, whereas ACTH increases and correlates with cortisol levels later on. Adrenal dysfunction does not seem to be a major problem during the prolonged phase of sepsis. Although not significant, the variation in cortisol levels may be such that classification of patients varies, questioning the utility of arbitrary cut-offs to define adrenal dysfunction in septic patients.

Endocrinological disorders affecting neurosurgical patients: An intensivists perspective

Management of critically ill neurosurgical patients is often complicated by the presence or development of endocrinological ailments which complicate the clinical scenario and adversely affect the prognosis of these patients. The anatomical proximity to the vital centers regulating the endocrinological physiology and alteration in the neurotransmitter release causes disturbances in the hormonal homeostasis. This paves the way for development of diverse disorders where single or multiple hormones may be involved which can have deleterious effect on the different organ system. Understanding and awareness of these disorders is important for the treating intensivist to recognize these changes early in their course, so that appropriate and timely therapeutic measures can be initiated along with the treatment of the primary malady.

The incidence of critical-illness-related-corticosteroid-insufficiency is associated with severity of traumatic brain injury in adult rats

Traumatic brain injury (TBI) causes deleterious critical-illness-related-corticosteroid-insufficiency (CIRCI), leading to high mortality and morbidity. However, the incidence of CIRCI following different TBI severities is not fully defined. This study was designed to investigate mechanistically the effects of injury severity on corticosteroid response and the development of CIRCI in a rat model of experimentally controlled TBI. Adult male Wistar rats were randomly assigned to sham, mild injury, moderate injury or severe injury groups. TBI was induced using a fluid percussion device at magnitudes of 1.2-1.4 atm (mild injury), 2.0-2.2 atm (moderate injury), and 3.2-3.5 atm (severe injury). We first assessed the effects of injury severity on the mortality and CIRCI occurrence using electrical stimulation test to assess corticosteroid response. We also investigated a series of pathological changes in the hypothalamus, especially in the paraventricular nuclei (PVN), among different injury group including: apoptosis detected by a TUNEL assay, blood-brain-barrier (BBB) permeability assessed by brain water content and Evans Blue extravasation into the cerebral parenchyma, and BBB integrity evaluated by CD31 and Claudin-5 expression and transmission electron microscopy. We made the following observations. First, 6.7% of mild-injured, 13.3% of moderate-injured, and 68.8% of severe-injured rats developed CIRCI, with a peak incidence on post-injury day 7. Second, TBI-induced CIRCI is closely correlated with injury severity. As the injury severity rises both the incidence of CIRCI and mortality surge; Third, increased level of injury severity reduces the expression of endothelial tight junction protein, aggravate BBB permeability and exacerbate the ensuing neural apoptosis in the PVN of hypothalamus. These findings indicate that increased severity of TBI aggravate the incidence of CIRCI by causing damage to tight junctions of vascular endothelial cells and increasing neuronal apoptosis in the PVN of hypothalamus.

A new way of thinking: hydrocortisone in traumatic brain-injured patients

Data suggest that treatment of critical illness-related corticosteroid insufficiency after traumatic brain injury (TBI) with a stress dose of hydrocortisone may improve the neurological outcome and the mortality rate. The mineralocorticoid properties of hydrocortisone may reduce the rate of hyponatremia and of brain swelling. The exaggerated inflammatory response may cause critical illness-related corticosteroid insufficiency by altering the function of the hypothalamic–pituitary–adrenal axis, and hydrocortisone is able to restore a balanced inflammatory response rather than inducing immunosuppression. Hydrocortisone could also prevent neuronal apoptosis. Considering side effects, corticosteroids are not equal; when a high dose of synthetic corticosteroids seems detrimental, a strategy using a stress dose of hydrocortisone seems attractive. Finally, results from a large multicenter study are needed to close the debate regarding the use of hydrocortisone in TBI patients.

Role of intravenous levetiracetam in seizure prophylaxis of severe traumatic brain injury patients

Traumatic brain injury (TBI) can cause seizures and the development of epilepsy. The incidence of seizures varies from 21% in patients with severe brain injuries to 50% in patients with war-related penetrating TBI. In the acute and sub-acute periods following injury, seizures can lead to increased intracranial pressure and cerebral edema, further complicating TBI management. Anticonvulsants can be used for seizure prophylaxis according to the current Parameters of Practice and Guidelines in a subset of severe TBI patients, and for a limited time window. Phenytoin is the most widely prescribed anticonvulsant in these patients. Intravenous levetiracetam, made available in 2006, is now being considered as a viable option in acute care settings if phenytoin is unavailable or not feasible due to side-effects. We discuss current data regarding the role of intravenous levetiracetam in seizure prophylaxis of severe TBI patients and the need for future studies.

Hormonal dysfunction in neurocritical patients

PURPOSE OF REVIEW

Acute brain injury results in widespread systemic endocrine dysfunction and affects how we care for patients. We review the existing literature on incidence, type and duration of endocrine dysfunction with special focus on the pituitary dependent function.

RECENT FINDINGS

Acute studies document widespread alterations of the hypothalamic-pituitary-adrenal axis, disruption of the anterior hypothalamus related hormones, and alteration of regulation of sodium and fluid balance. Diagnostic testing and therapeutic intervention are outlined in this review. Relative adrenal insufficiency and cerebral salt wasting are the two main forms of endocrine dysfunction in neurocritical care patients.

SUMMARY

Surveillance for endocrine dysfunction and early treatment with hormonal replacement may be life-saving in neurologic critically ill patients.

Stress-dose hydrocortisone reduces critical illness-related corticosteroid insufficiency associated with severe traumatic brain injury in rats

Introduction

The spectrum of critical illness-related corticosteroid insufficiency (CIRCI) in severe traumatic brain injury (TBI) is not fully defined and no effective treatments for TBI-induced CIRCI are available to date. Despite growing interest in the use of stress-dose hydrocortisone as a potential therapy for CIRCI, there remains a paucity of data regarding its benefits following severe TBI. This study was designed to investigate the effects of stress-dose hydrocortisone on CIRCI development and neurological outcomes in a rat model of severe traumatic brain injury.

Methods

Rats were subjected to lateral fluid percussion injury of 3.2-3.5 atmosphere. These rats were then treated with either a stress-dose hydrocortisone (HC, 3 mg/kg/d for 5 days, 1.5 mg/kg on day 6, and 0.75 mg on day 7), a low-dose methylprednisolone (MP, 1 mg/kg/d for 5 days, 0.5 mg/kg on day 6, and 0.25 mg on day 7) or control saline solution intraperitoneally daily for 7 days after injury.

Results

We investigated the effects of stress-dose HC on the mortality, CIRCI occurrence, and neurological deficits using an electrical stimulation test to assess corticosteroid response and modified neurological severity score (mNSS). We also studied pathological changes in the hypothalamus, especially in the paraventricular nuclei (PVN), after stress-dose HC or a low dose of MP was administered, including apoptosis detected by a TUNEL assay, blood–brain barrier (BBB) permeability assessed by brain water content and Evans Blue extravasation into the cerebral parenchyma, and BBB integrity evaluated by CD31 and claudin-5 expression. We made the following observations. First, 70% injured rats developed CIRCI, with a peak incidence on post-injury day 7. The TBI-associated CIRCI was closely correlated with an increased mortality and delayed neurological recovery. Second, post-injury administration of stress-dose HC, but not MP or saline increased corticosteroid response, prevented CIRCI, reduced mortality, and improved neurological function during the first 14 days post injury dosing. Thirdly, these beneficial effects were closely related to improved vascular function by the preservation of tight junctions in surviving endothelial cells, and reduced neural apoptosis in the PVN of hypothalamus.

Conclusions

Our findings indicate that post-injury administration of stress-dose HC, but not MP reduces CIRCI and improves neurological recovery. These improvements are associated with reducing the damage to the tight junction of vascular endothelial cells and blocking neuronal apoptosis in the PVN of the hypothalamus.

Pituitary dysfunction after aneurysmal subarachnoid hemorrhage

Patients recovering from aneurysmal SAH often complain about weakness, fatigue and impaired cognitive skills. Pituitary dysfunction might be one possible reason for these complaints, as in patients with traumatic brain injury, hypopituitarism is known to be a common complication. There are only a few studies dealing with this problem in SAH patients, but these studies suggest that pituitary disturbances are very frequent after aneurysmal SAH. But anterior pituitary lobe disturbances might not be the only one responsible for some complaints or complications in patients suffering from aneurysmal SAH. Hyponatremia in the early state after SAH could be a hint for posterior pituitary lobe dysfunction.

Common endocrine issues in the pediatric intensive care unit

Thyroid hormone is central to normal development and metabolism. Abnormalities in thyroid function in North America often arise from autoimmune diseases, but they rarely present as critical illness. Severe deficiency or excess of thyroid hormone both represent life-threatening disease, which must be treated expeditiously and thoroughly. Such deficiencies must be considered, because presentation may be nonspecific.

The effects of three specific conditions related to critical care on adrenal function in children

PURPOSE

To evaluate the effects of three specific conditions related to critical care on adrenal function with special regard to the levels of serum cortisol, corticotropin (ACTH), dehydroepiandrosterone sulfate, and cytokines.

METHODS

The study enrolled a total of 74 children who were divided into three groups. Group 1 comprised 23 patients who had acute critical illness (ACI) associated with severe sepsis/septic shock. Group 2 comprised 27 patients who had ACI without sepsis. Group 3 comprised 24 patients who underwent major surgery. Blood samples were obtained for baseline measurements and a low-dose ACTH stimulation test (LD-ST) was performed. Serial ACTH and cortisol levels were measured with an interval of 3 days and LD-ST was repeated on day 14 for all groups.

RESULTS

Baseline cortisol, ACTH, and dehydroepiandrosterone sulfate levels were significantly higher in patients with adrenal insufficiency (AI) than those of without AI. AI was detected in four patients in group 1, seven in group 2, and ten in group 3. Consecutive cortisol and ACTH levels did not differ significantly among the groups. On day 14, the recovery rate in patients with AI was 82 % in the whole group. Patient's age and interleukin-10 level were found to be independent predictors of AI.

CONCLUSIONS

A considerable proportion of patients in these three groups had AI with a high spontaneous recovery rate in 2 weeks. The presence of sepsis was not associated with an increased risk of AI. Our serial cortisol and ACTH values in these different groups could be used as reference values for further studies.

Validation of a low-dose ACTH stimulation test in healthy adult horses

OBJECTIVE

To determine the lowest ACTH dose that would induce a maximum increase in serum cortisol concentration in healthy adult horses and identify the time to peak cortisol concentration.

DESIGN

Evaluation study.

ANIMALS

8 healthy adult horses.

PROCEDURES

Saline (0.9% NaCl) solution or 1 of 4 doses (0.02, 0.1, 0.25, and 0.5 μg/kg [0.009, 0.045, 0.114, and 0.227 μg/lb]) of cosyntropin (synthetic ACTH) were administered IV (5 treatments/horse). Serum cortisol concentrations were measured before and 30, 60, 90, 120, 180, and 240 minutes after injection of cosyntropin or saline solution; CBCs were performed before and 30, 60, 120, and 240 minutes after injection.

RESULTS

For all 4 doses, serum cortisol concentration was significantly increased, compared with the baseline value, by 30 minutes after administration of cosyntropin; no significant differences were detected among maximum serum cortisol concentrations obtained in response to administration of doses of 0.1, 0.25, and 0.5 μg/kg. Serum cortisol concentration peaked 30 minutes after administration of cosyntropin at a dose of 0.02 or 0.1 μg/kg, with peak concentrations 1.5 and 1.9 times, respectively, the baseline concentration. Serum cortisol concentration peaked 90 minutes after administration of cosyntropin at a dose of 0.25 or 0.5 μg/kg, with peak concentrations 2.0 and 2.3 times, respectively, the baseline concentration. Cosyntropin administration significantly affected WBC, neutrophil, and eosinophil counts and the neutrophil-to-lymphocyte ratio.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that in healthy horses, administration of cosyntropin at a dose of 0.1 μg/kg resulted in maximum adrenal stimulation, with peak cortisol concentration 30 minutes after cosyntropin administration.

Endocrine function following acute SAH

Disruption of the hypothalamic-pituitary-adrenal axes may occur after aneurysmal subarachnoid hemorrhage, resulting in hypopituitarism. An electronic literature search was conducted to identify articles with English-language abstracts published between 1980 and March 2011, which addressed hypothalamic-pituitary-adrenal axis insufficiency and hormone replacement. A total of 18 observational and prospective, randomized studies were selected for this review. Limited data are available, evaluating pituitary effects during the acute stage after subarachnoid hemorrhage, with inconsistent results being reported. Overall, after acute subarachnoid hemorrhage, cortisol levels may initially be supranormal, decreasing toward normal levels over time. During the months to years after subarachnoid hemorrhage, pituitary deficiency may occur in one out of three patients. Limited data suggest modest outcome benefits with fludrocortisone and no benefit or harm from corticosteroids.

SAH pituitary adrenal dysfunction

Disruption of the hypothalamic-pituitary-adrenal axis may occur after aneurysmal subarachnoid hemorrhage, resulting in hypopituitarism. An electronic literature search was conducted to identify articles with English-language abstracts published between 1980 and March 2011 that addressed hypothalamic-pituitary-adrenal axis insufficiency and hormone replacement. A total of 18 observational and prospective, randomized studies were selected for this review. Limited data are available evaluating pituitary effects during the acute stage after subarachnoid hemorrhage, with inconsistent results reported. Overall, acutely after subarachnoid hemorrhage, cortisol levels may initially be supranormal, decreasing toward normal levels over time. During the months to years after subarachnoid hemorrhage, pituitary deficiency may occur in up to one in three patients. Limited data suggest modest outcome benefits with fludrocortisone and no benefit or harm from corticosteroids.

Incidence and Outcomes of Critical Illness-Related Corticosteroid Insufficiency in Trauma Patients

The spectrum of critical illness-related corticosteroid insufficiency (CIRCI) in trauma is not fully defined. This study describes our trauma experience with hydrocortisone-treated patients experiencing CIRCI. We conducted a 5-year retrospective analysis from a Level II trauma center using biochemical and clinical criteria for adrenal insufficiency. Seventy patients met the inclusion criteria for CIRCI. There was a 34 per cent mortality rate despite therapy. Nonsurvivors were older with larger admission base deficits and experienced higher rates of sepsis, bacteremia, and pneumonia. Nonsurvivors had prolonged vent days (mean 53 ± 64 days) when compared with survivors (mean 30 ± 22 days; P = 0.029). Renal replacement therapy was a strong predictor of mortality. Spinal cord-injured patients had high Injury Severity Scores (mean 34 ± 18), elevated baseline Cortisol levels (mean 56 ± 84 vs 18 ± 14; P = 0.004), and required prolonged duration of steroid therapy (30 ± 52 vs 15 ± 15 days; P = 0.080) when compared with the nonspinal cord-injured group. Our data suggest that CIRCI in trauma is associated with significant mortality and morbidity even when patients are treated appropriately.

Analytic review: Interleukin-6 in surgery, trauma, and critical care: part I: basic science

A variety of cytokines play a role in the response to an inflammatory stimulus. The interleukin-6 (IL-6)-type cytokines are released in response to tissue injury or an inflammatory stimulus. They act locally and systemically to generate a variety of physiologic responses, principal among them is the acute phase response. The IL-6 type cytokines demonstrate pleiotropy and redundancy of actions. This is made possible by the distinctive characteristics of the IL-6 receptor complex, which contains an ubiquitous subunit that is shared by most IL-6-type cytokines, as well as a cytokine-specific subunit.

Sodium, potassium and glucose management in organ transplantation

PURPOSE OF REVIEW

To present current knowledge about the metabolic management of patients undergoing solid organ transplantation, and potential organ donors.

RECENT FINDINGS

Appropriate management of electrolytes and glucose improves outcome after transplantation, although conflicting evidence exists. Patients with cirrhosis-induced hyponatremia can be successfully transplanted but are at increased risk of postoperative complications. A new class of drugs, the vaptans, that antagonizes arginine vasopressin may be an effective treatment for hyponatremia in transplant candidates. Recent literature has documented the implications, predictors and potential therapies for perioperative hyperkalemia in the transplant population. The debate over appropriate targets for serum glucose in perioperative and critically ill patients has been lively. The documented risk of hypoglycemia associated with 'intensive insulin therapy' has led to the adoption of more conservative glycemic targets. Studies of glycemic control in transplant recipients are limited.

SUMMARY

In patients undergoing solid organ transplants, sodium management should aim to minimize an acute change in sodium concentration. Vaptans may be of future use in optimizing patients with cirrhosis prior to transplantation. Pending further studies, a perioperative 'middle ground' target glucose of between 140 and 180 mg/dl seems reasonable at this time.

Serum cytokines and critical illness-related corticosteroid insufficiency

PURPOSE

Little information exists regarding the association of specific cytokine levels and different subgroups of patients with critical illness-related corticosteroid insufficiency (CIRCI).

METHODS

Data from a previous prospective study on adrenal function in the ICU were used in this study. CIRCI was diagnosed when either the basal cortisol was less than 10 μg/ml or the Δ cortisol was less than 9 μg/ml. The patients with CIRCI were further divided into a low basal cortisol (LBC) group (basal cortisol < 10 μg/ml), and low Δ cortisol (LDC) group (basal cortisol ≥ 10 μg/ml and Δ cortisol < 9 μg/ml). Serum cytokine levels were compared among the normal (NOM), LBC, and LDC groups.

RESULTS

The serum of 82 out of 123 (67%) patients included in the previous study was available for analysis; these patients were included in the present study. The overall incidence of CIRCI was 43.9% (36 out of 82 patients). Among patients with CIRCI, 16 (44.4%) were classified as the LBC group and 20 (55.6%) as the LDC group. The LDC group had significantly higher levels of IL-6 and IL-10 compared to both the NOM and LBC groups (p < 0.01). The LDC group also had significantly increased TNF-α (p = 0.002) compared to the LBC group. There were no significant differences in any of the cytokine levels between the NOM and LBC groups.

CONCLUSIONS

Elevated cytokines were associated with adrenal dysfunction in a subset of patients meeting the criteria for CIRCI (normal or high basal cortisol and low Δ cortisol).

Drug-induced endocrine disorders in the intensive care unit

The neuroendocrine response to critical illness is key to the maintenance of homeostasis. Many of the drugs administered routinely in the intensive care unit significantly impact the neuroendocrine system. These agents can disrupt the hypothalamic-pituitary-adrenal axis, cause thyroid abnormalities, and result in dysglycemia. Herein, we review major drug-induced endocrine disorders and highlight some of the controversies that remain in this area. We also discuss some of the more rare drug-induced syndromes that have been described in the intensive care unit. Drugs that may result in an intensive care unit admission secondary to an endocrine-related adverse event are also included. Unfortunately, very few studies have systematically addressed drug-induced endocrine disorders in the critically ill. Timely identification and appropriate management of drug-induced endocrine adverse events may potentially improve outcomes in the critically ill. However, more research is needed to fully understand the impact of medications on endocrine function in the intensive care unit.

Contemporary pharmacologic issues in the management of traumatic brain injury

Traumatic brain injury (TBI) is a major cause of death and disability in the United States. While there are no pharmacotherapeutic options currently available for attenuating the neurologic injury cascade after TBI, numerous pharmacologic issues are encountered in these critically ill patients. Adequate fluid resuscitation, reversal of coagulopathy, maintenance of cerebral perfusion, and treatment of intracranial hypertension are common interventions early in the treatment of TBI. Other deleterious complications such as venous thromboembolism, extremes in glucose concentrations, and stress-related mucosal disease should be anticipated and avoided. Early provision of nutrition and prevention of drug or alcohol withdrawal are also cornerstones of routine care in TBI patients. Prevention of infections and seizures may also be helpful. Clinicians caring for TBI patients should be familiar with the pharmacologic issues typical of this vulnerable population in order to develop optimal strategies of care to anticipate and prevent common complications.

Correlation between brain interstitial and total serum cortisol levels in traumatic brain injury. A preliminary study

INTRODUCTION

Brain cortisol availability has never been evaluated in patients with traumatic brain injury (TBI). Cerebral microdialysis is a well-established technique for monitoring brain metabolism in neurocritically ill patients, which may be used to measure interstitial cortisol. The objective of this preliminary study was to measure brain interstitial cortisol and its correlation with total serum cortisol in patients with TBI.

METHODS

We prospectively studied 6 patients with severe TBI admitted to the Intensive Care Unit of our tertiary University Hospital in which multimodal neuromonitoring including cerebral microdialysis with a high cut-off of 100 k-Da and 20-mm long membrane was used. Serum and brain interstitial cortisol microdialysis samples were obtained every 8 h and analyzed afterwards.

RESULTS

Linear regression analysis of total serum cortisol and brain interstitial cortisol in the whole population showed a moderate correlation (R2=0.538, p<0.001, no.=118). However, intra-individual correlation showed a great variability, with correlation coefficients ranging from a R2=0.091 to R2=0.680.

CONCLUSION

Our prospective and preliminary study showed a moderate correlation of brain interstitial cortisol and total serum cortisol values in patients with diffuse TBI. However, intra-individual analysis showed a great variability. These results suggest that total serum cortisol may not reflect brain cortisol availability in half of TBI patients.

A prospective study on the incidence and predictive factors of relative adrenal insufficiency in Korean critically-ill patients

This study was undertaken to evaluate the incidence and risk factors associated with relative adrenal insufficiency (RAI) in Korean critically-ill patients. All patients who were admitted to the Medical Intensive Care Unit (MICU) of Samsung Medical Center between January 1, 2006 and April 30, 2007 were prospectively evaluated using a short corticotropin stimulation test on the day of admission. RAI was defined as an increase in the serum cortisol level of <9 microg/dL from the baseline after administration of 250 microg of corticotropin. In all, 123 patients were recruited and overall the incidence of RAI was 44% (54/123). The presence of septic shock (P=0.001), the Simplified Acute Physiology Score (SAPS) II (P=0.003), the Sequential Organ Failure Assessment (SOFA) score (P=0.001), the mean heart rate (P=0.040), lactate levels (P=0.001), arterial pH (P=0.047), treatment with vasopressors at ICU admission (P=0.004), and the 28-day mortality (P=0.041) were significantly different between patients with and without RAI. The multivariate analysis showed that the SOFA score was an independent predictor of RAI in critically-ill patients (odd ratio=1.235, P=0.032). Our data suggest that RAI is frequently found in Korean critically-ill patients and that a high SOFA score is an independent predictor of RAI in these patients.

Effects of the neurological wake-up test on intracranial pressure and cerebral perfusion pressure in brain-injured patients

OBJECTIVE

To evaluate the effects of the neurological "wake-up test" (NWT), defined as interruption of continuous propofol sedation and evaluation of the patient's level of consciousness, on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in patients with severe subarachnoid hemorrhage (SAH) or traumatic brain injury (TBI).

METHODS

A total of 127 NWT procedures in 21 severely brain-injured adult patients with either TBI (n = 12) or SAH (n = 9) were evaluated. ICP and CPP levels prior to, during and after the NWT procedure were recorded.

RESULTS

During the NWT, ICP increased from 13.4 +/- 6 mmHg at baseline to 22.7 +/- 12 (P < 0.05) and the CPP increased from 75.6 +/- 11 to 79.1 +/- 21 mmHg (P < 0.05) in TBI patients. Eight patients showed a reduced CPP during the NWT due to increased ICP. In SAH patients, ICP increased from 10.6 +/- 5 to 16.8 +/- 8 mmHg (P < 0.05) and the CPP increased from 76.9 +/- 13 to 84.6 +/- 15 mmHg (P < 0.05).

CONCLUSION

When continuous propofol sedation was interrupted and NWT was performed in severely brain-injured patients, the mean ICP and CPP levels were modestly increased. A subset of patients showed more pronounced changes. To date, the role of the NWT in the neurointensive care of TBI and SAH patients is unclear. Although the NWT is safe in the majority of patients and may provide useful clinical information about the patient's level of consciousness, alternate monitoring methods are suggested in patients showing marked ICP and/or CPP changes during NWT.