The adrenal response after severe trauma

Immune regulation of the gut-brain axis and lung-brain axis involved in ischemic stroke

Local ischemia often causes a series of inflammatory reactions when both brain immune cells and the peripheral immune response are activated. In the human body, the gut and lung are regarded as the key reactional targets that are initiated by brain ischemic attacks. Mucosal microorganisms play an important role in immune regulation and metabolism and affect blood-brain barrier permeability. In addition to the relationship between peripheral organs and central areas and the intestine and lung also interact among each other. Here, we review the molecular and cellular immune mechanisms involved in the pathways of inflammation across the gut-brain axis and lung-brain axis. We found that abnormal intestinal flora, the intestinal microenvironment, lung infection, chronic diseases, and mechanical ventilation can worsen the outcome of ischemic stroke. This review also introduces the influence of the brain on the gut and lungs after stroke, highlighting the bidirectional feedback effect among the gut, lungs, and brain.

The ultra-acute steroid response to traumatic injury: a cohort study

OBJECTIVE

Trauma-induced steroid changes have been studied post-hospital admission, resulting in a lack of understanding of the speed and extent of the immediate endocrine response to injury. The Golden Hour study was designed to capture the ultra-acute response to traumatic injury.

DESIGN

We conducted an observational cohort study including adult male trauma patients <60 years, with blood samples drawn ≤1 h of major trauma by pre-hospital emergency responders.

METHODS

We recruited 31 adult male trauma patients (mean age 28 [range 19-59] years) with a mean injury severity score (ISS) of 16 (IQR 10-21). The median time to first sample was 35 (range 14-56) min, with follow-up samples collected 4-12 and 48-72 h post-injury. Serum steroids in patients and age- and sex-matched healthy controls (HCs) (n = 34) were analysed by tandem mass spectrometry.

RESULTS

Within 1 h of injury, we observed an increase in glucocorticoid and adrenal androgen biosynthesis. Cortisol and 11-hydroxyandrostendione increased rapidly, whilst cortisone and 11-ketoandrostenedione decreased, reflective of increased cortisol and 11-oxygenated androgen precursor biosynthesis by 11β-hydroxylase and increased cortisol activation by 11β-hydroxysteroid dehydrogenase type 1. Active classic gonadal androgens testosterone and 5α-dihydrotestosterone decreased, whilst the active 11-oxygenated androgen 11-ketotestosterone maintained pre-injury levels.

CONCLUSIONS

Changes in steroid biosynthesis and metabolism occur within minutes of traumatic injury. Studies that address whether ultra-early changes in steroid metabolism are associated with patient outcomes are now required.

Hypothermia in the Combat Trauma Population

BACKGROUND

The MARCH (Massive hemorrhage, Airway, Respirations, Circulation, and Hypothermia/Head injuries) algorithm taught to military medics includes interventions to prevent hypothermia. As possible sequelae from major trauma, hypothermia is associated with coagulopathy and lower survival. This paper sought to define hypothermia within our combat trauma population using an outcomes-based method, and determine clinical variables associated with hypothermia.

METHODS

This is a secondary analysis of a previously described dataset from the Department of Defense Trauma Registry focused on casualties who received prehospital care. A receiver operating curve was constructed and Youden's index was used to define hypothermia within the predetermined population based on mortality risk. A multivariable regression model was used to identify associations.

RESULTS

There were 23,243 encounters that met the inclusion criteria for this study with patients having received prehospital care and documentation of at least one emergency department temperature. An optimal threshold of 36.2° C was found to predict mortality; 3,159 casualties had temperatures below this threshold (14%). Survival to discharge was lower among casualties with hypothermia (91% versus 98%). Hypothermic casualties were less likely to undergo blanket application (38% versus 40%). However, they had higher proportions with Hypothermia Prevention and Management Kit application (11% versus 7%) and radiant warming (2% versus 1%). On multivariable regression modeling, none of the hypothermia interventions were associated with a decreased likelihood of hypothermia. Non-hypothermia interventions associated with hypothermia included prehospital intubation (OR 1.57, 95% CI 1.45-1.69) and blood product administration.

CONCLUSIONS

Hypothermia, including a single recorded low temperature in the patient care record, was associated with worse outcomes in this combat trauma population. Prehospital intubation was most strongly associated with developing hypothermia. Prehospital warming interventions were not associated with a reduction in hypothermia risk. Our dataset suggests that current methods for prehospital warming are inadequate.

Lipid changes during the perioperative period in patients with early breast cancer: a real-world retrospective analysis

Background

Surgery remains the major treatment for early breast cancer (BC), but surgery itself is also a trauma which might induce alterations in lipid metabolism. The aim of this study was to investigate the changes in lipid profiles and to explore factors associated with lipid changes pre- and postoperation.

Methods

We retrospectively analyzed the pre- and postoperative serum lipid profiles of 1934 BC patients.

Results

The levels of triglycerides (TG) (p < 0.001) and low-density lipoprotein cholesterol (LDL) (p < 0.001) were significantly elevated after surgery, while the levels of high-density lipoprotein cholesterol (HDL) (p < 0.001) were significantly decreased. After surgery, 27.76% of patients with preoperative ortholiposis developed dyslipidemia. Postmenopausal BC patients had a higher incidence of dyslipidemia (32.31%) after surgery than premenopausal BC patients (26.07%; p = 0.041). Additionally, patients with BMI > 24 (34.92%) had a higher incidence of dyslipidemia than patients with BMI ≤ 24 (24.84%; p = 0.001). Moreover, the magnitudes of the TG increase (p < 0.001), cholesterol (TC) increase (p = 0.013) and LDL increase (p = 0.015) in the premenopausal group were all greater than those in the postmenopausal group. After adjusting for multiple baseline covariates, preoperative hyperlipidemia and progesterone receptor (PR)-positive status were significantly associated with elevated TG, TC and LDL levels after surgery.

Conclusions

Serum lipid profiles of BC patients may increase after surgery, especially premenopausal patients. Additionally, postmenopausal and overweight patients may have a higher risk of being diagnosed with dyslipidemia after surgery. Therefore, lipid monitoring, dyslipidemia prevention and corresponding interventions should be taken into consideration during the perioperative period.

Immunopathophysiology of trauma-related acute kidney injury

Physical trauma can affect any individual and is globally accountable for more than one in every ten deaths. Although direct severe kidney trauma is relatively infrequent, extrarenal tissue trauma frequently results in the development of acute kidney injury (AKI). Various causes, including haemorrhagic shock, rhabdomyolysis, use of nephrotoxic drugs and infectious complications, can trigger and exacerbate trauma-related AKI (TRAKI), particularly in the presence of pre-existing or trauma-specific risk factors. Injured, hypoxic and ischaemic tissues expose the organism to damage-associated and pathogen-associated molecular patterns, and oxidative stress, all of which initiate a complex immunopathophysiological response that results in macrocirculatory and microcirculatory disturbances in the kidney, and functional impairment. The simultaneous activation of components of innate immunity, including leukocytes, coagulation factors and complement proteins, drives kidney inflammation, glomerular and tubular damage, and breakdown of the blood-urine barrier. This immune response is also an integral part of the intense post-trauma crosstalk between the kidneys, the nervous system and other organs, which aggravates multi-organ dysfunction. Necessary lifesaving procedures used in trauma management might have ambivalent effects as they stabilize injured tissue and organs while simultaneously exacerbating kidney injury. Consequently, only a small number of pathophysiological and immunomodulatory therapeutic targets for TRAKI prevention have been proposed and evaluated.

Crosstalk between brain, lung and heart in critical care

Extracerebral complications, especially pulmonary and cardiovascular, are frequent in brain-injured patients and are major outcome determinants. Two major pathways have been described: brain-lung and brain-heart interactions. Lung injuries after acute brain damages include ventilator-associated pneumonia (VAP), acute respiratory distress syndrome (ARDS) and neurogenic pulmonary œdema (NPE), whereas heart injuries can range from cardiac enzymes release, ECG abnormalities to left ventricle dysfunction or cardiogenic shock. The pathophysiologies of these brain-lung and brain-heart crosstalk are complex and sometimes interconnected. This review aims to describe the epidemiology and pathophysiology of lung and heart injuries in brain-injured patients with the different pathways implicated and the clinical implications for critical care physicians.

Prospective evaluation of admission cortisol in trauma

Background

A low cortisol level has been shown to occur soon after trauma, and is associated with increased mortality. The purpose of this study was to investigate the impact of low cortisol levels in acute critically ill trauma patients. We hypothesized that patients would require increase vasopressor use, have a greater blood product administration, and increased mortality rate.

Methods

A blinded, prospective observational study was performed at an American College of Surgeons verified Level I trauma center. Adult patients who met trauma activation criteria, received initial treatment at Community Regional Medical Center and were admitted to the intensive care unit were included. Total serum cortisol levels were measured from the initial blood draw in the emergency department. Patients were categorized according to cortisol ≤15 µg/dL (severe low cortisol, SLC), 15.01–25 µg/dL (relative low cortisol, RLC), or >25 µg/dL (normal cortisol, NC) and compared on demographics, injury severity score, initial vital signs, blood product usage, vasopressor requirements, and mortality.

Results

Cortisol levels were ordered for 280 patients; 91 were excluded and 189 were included. Penetrating trauma accounted for 19% of injuries and blunt trauma for 81%. 22 patients (12%) had SLC, 83 (44%) had RLC, and 84 (44%) had NC. This study found patients with admission SLC had higher rates of vasopressor requirements, required more units of blood, and had a higher mortality rate than both the RLC and NC groups.

Conclusion

Low cortisol level can be identified acutely after severe trauma. Trauma patients with SLC had larger blood product requirements, vasopressor use, and increase mortality. Initial cortisol levels are useful in identifying these high-risk patients.

Level of evidence

Prognostic/epidemiologic study, level III

Surgical and immune reconstitution murine models in bone marrow research: Potential for exploring mechanisms in sepsis, trauma and allergy

Bone marrow, the vital organ which maintains lifelong hemopoiesis, currently receives considerable attention, as a source of multiple cell types which may play important roles in repair at distant sites. This emerging function, distinct from, but closely related to, bone marrow roles in innate immunity and inflammation, has been characterized through a number of strategies. However, the use of surgical models in this endeavour has hitherto been limited. Surgical strategies allow the experimenter to predetermine the site, timing, severity and invasiveness of injury; to add or remove aggravating factors (such as infection and defects in immunity) in controlled ways; and to manipulate the context of repair, including reconstitution with selected immune cell subpopulations. This endows surgical models overall with great potential for exploring bone marrow responses to injury, inflammation and infection, and its roles in repair and regeneration. We review three different murine surgical models, which variously combine trauma with infection, antigenic stimulation, or immune reconstitution, thereby illuminating different aspects of the bone marrow response to systemic injury in sepsis, trauma and allergy. They are: (1) cecal ligation and puncture, a versatile model of polymicrobial sepsis; (2) egg white implant, an intriguing model of eosinophilia induced by a combination of trauma and sensitization to insoluble allergen; and (3) ectopic lung tissue transplantation, which allows us to dissect afferent and efferent mechanisms leading to accumulation of hemopoietic cells in the lungs. These models highlight the gain in analytical power provided by the association of surgical and immunological strategies.

Postinjury Inflammation and Organ Dysfunction

The development of organ dysfunction (OD) is related to the intensity and balance between trauma-induced simultaneous, opposite inflammatory responses. Early proinflammation via innate immune system activation may cause early OD, whereas antiinflammation, via inhibition of the adaptive immune system and apoptosis, may induce immunoparalysis, impaired healing, infections, and late OD. Patients discharged with low-level OD may develop the persistent inflammation-immunosuppression catabolism syndrome. Although the incidence of multiple organ failure has decreased over time, it remains morbid, lethal, and resource intensive. However, single OD, especially acute lung injury, remains frequent. Treatment is limited, and prevention remains the mainstay strategy.

Sugar or salt? The relative roles of the glucocorticoid and mineralocorticoid axes in traumatic shock

BACKGROUND

Glucocorticoid deficiency (GD) has been proposed as a key contributor to shock states, but the presence and role of acute mineralocorticoid deficiency may be of equal or greater significance. We sought to analyze the incidence and degree of acute mineralocorticoid deficiency and GD in an animal model of severe hemorrhage and shock.

METHODS

Fifty-seven swine underwent 35% volume-controlled hemorrhage followed by aortic cross-clamping for 50 minutes to induce truncal ischemia-reperfusion. Protocol-guided resuscitation was performed. Laboratory analysis included cortisol, aldosterone, and plasma renin activity. The aldosterone-to-renin ratio (ARR) was calculated at each time point, and changes were correlated to markers of perfusion.

RESULTS

Mean baseline cortisol levels were 5.8 μg/dL. Following hemorrhage, there was a significant increase in mean cortisol to 9.2 μg/dL (p < 0.001). After 1 hour of reperfusion, there was no change in mean cortisol levels (9.8 μg/dL, p = 0.12). Mean baseline aldosterone was 13.3 pg/mL. Aldosterone levels before cross-clamp removal increased significantly to 115.1 pg/mL (p < 0.001) and then rapidly declined to 49.2 pg/mL (p < 0.001) after 1 hour of reperfusion. Conversely, baseline plasma renin activity was 0.75 ng/mL per hour and increased significantly before cross-clamp removal (1.8) and at 1 hour (8.9, both p < 0.001). The ARR at baseline was 96.1 and increased to 113.5 (p = 0.68) before cross-clamp removal but significantly declined following 1 hour of reperfusion to 7.6 (p < 0.001). Overall, this represented a 93% reduction in mean ARR following reperfusion. The degree of aldosterone deficiency correlated with degree of systemic shock as measured by arterial base deficit (r = 0.47, p = 0.04), while cortisol showed no correlation.

CONCLUSION

Hemorrhagic shock with ischemia-reperfusion injury resulted in only modest impact on the glucocorticoid axis, but major dysfunction of the mineralocorticoid axis and severe hyperreninemic hypoaldosteronism. The degree of aldosterone deficiency may provide prognostic information or offer potential targets for pharmacologic intervention.

LEVEL OF EVIDENCE

Diagnostic study, level III.

Increased Total Serum Random Cortisol Levels Predict Mortality in Critically Ill Trauma Patients

Dysfunction in the hypothalamopituitary adrenal axis is thought to exist; however, there continues to be controversy about what level of serum cortisol corresponds to adrenal insufficiency. Few studies have focused on the significance of serum random cortisol in the critically ill trauma patient. Trauma patients with total serum random cortisol levels drawn in the intensive care unit within the first seven days of hospitalization were retrospectively reviewed. The primary outcome measured was in-hospital mortality. Two hundred forty-two patients were analyzed. Non-survivors had significantly higher mean cortisol levels than survivors (28.7 ± 15.80 mg/dL vs 22.9 ± 12.35 mg/dL, P = 0.01). Patients with cortisol 30 mg/dL or greater were more likely to die with odds ratio of 2.7 (95% confidence interval [CI], 1.5 to 5). The odds ratio increased to 4.0 and 3.8 (95% CI, 1.4 to 11.4 and 1.3 to 10.9) when cortisol was drawn on hospital Day 2 and Days 3 through 7, respectively. Among nonsurvivors, patients with an injury severity score less than 25 had significantly higher cortisol levels than patients with an Injury Severity Score 25 or higher (35.3 ± 19.21 mg/dL vs 25.7 ± 13.21 mg/dL, P = 0.009). Patients with massive transfusion, traumatic brain injury, spinal cord injury, or solid organ injury did not have significantly different cortisol levels. The covariate-adjusted area under the receiver operating characteristic curve indicated that cortisol level has a 77 per cent accuracy in differentiating survivors from nonsurvivors. Higher cortisol levels were predictive of mortality in critically ill trauma patients. Whether serum cortisol level is a marker that can be modified remains an area of interest for future study.

Adrenal response after trauma is affected by time after trauma and sedative/analgesic drugs

BACKGROUND

The adrenal response in critically ill patients, including trauma victims, has been debated over the last decade. The aim of this study was to assess the early adrenal response after trauma.

METHODS

Prospective, observational study of 50 trauma patients admitted to a level-1-trauma centre. Serum and saliva cortisol were followed from the accident site up to five days after trauma. Corticosteroid binding globulin (CBG), dehydroepiandrosterone (DHEA) and sulphated dehydroepiandrosterone (DHEAS) were obtained twice during the first five days after trauma. The effect of time and associations between cortisol levels and; severity of trauma, infusion of sedative/analgesic drugs, cardiovascular dysfunction and other adrenocorticotropic hormone (ACTH) dependent hormones (DHEA/DHEAS) were studied.

RESULTS

There was a significant decrease over time in serum cortisol both during the initial 24 h, and from the 2nd to the 5th morning after trauma. A significant decrease over time was also observed in calculated free cortisol, DHEA, and DHEAS. No significant association was found between an injury severity score ≥ 16 (severe injury) and a low (< 200 nmol/L) serum cortisol at any time during the study period. The odds for a serum cortisol < 200 nmol/L was eight times higher in patients with continuous infusion of sedative/analgesic drugs compared to patients with no continuous infusion of sedative/analgesic drugs.

CONCLUSION

Total serum cortisol, calculated free cortisol, DHEA and DHEAS decreased significantly over time after trauma. Continuous infusion of sedative/analgesic drugs was independently associated with serum cortisol < 200 nmol/L.

Etomidate increases susceptibility to pneumonia in trauma patients

PURPOSE

To investigate the impact of etomidate on the rate of hospital-acquired pneumonia (HAP) in trauma patients and the effects of hydrocortisone in etomidate-treated patients.

METHODS

This was a sub-study of the HYPOLYTE multi-centre, randomized, double-blind, placebo-controlled trial of hydrocortisone in trauma patients (NCT00563303). Inclusion criterion was trauma patient with mechanical ventilation (MV) of ≥48 h. The use of etomidate was prospectively collected. Endpoints were the results of the cosyntropin test and rate of HAP on day 28 of follow-up.

RESULTS

Of the 149 patients enrolled in the study, 95 (64 %) received etomidate within 36 h prior to inclusion. 79 (83 %) of 95 patients receiving etomidate and 34 of the 54 (63 %) not receiving etomidate had corticosteroid insufficiency (p = 0.006). The administration of etomidate did not alter basal cortisolemia (p = 0.73), but it did decrease the delta of cortisolemia at 60 min (p = 0.007). There was a correlation between time from etomidate injection to inclusion in the study and sensitivity to corticotropin (R (2) = 0.19; p = 0.001). Forty-nine (51.6 %) patients with etomidate and 16 (29.6 %) patients without etomidate developed HAP by day 28 (p = 0.009). Etomidate was associated with HAP on day 28 in the multivariate analysis (hazard ratio 2.48; 95 % confidence interval 1.19-5.18; p = 0.016). Duration of MV with or without etomidate was not significantly different (p = 0.278). Among etomidate-exposed patients, 18 (40 %) treated with hydrocortisone developed HAP compared with 31 (62 %) treated with placebo (p = 0.032). Etomidate-exposed patients treated with hydrocortisone had fewer ventilator days (p < 0.001).

CONCLUSIONS

Among the patients enrolled in the study, etomidate did not alter basal cortisolemia, but it did decrease reactivity to corticotropin. We suggest that in trauma patients, etomidate is an independent risk factor for HAP and that the administration of hydrocortisone should be considered after etomidate use.

Mineralocorticoid deficiency in hemorrhagic shock

BACKGROUND

In the critically ill, mineralocorticoid deficiency (MD) is associated with greater disease severity, the development of acute renal insufficiency, and increased mortality. We hypothesized that severely injured trauma patients presenting with hemorrhagic shock would demonstrate a high degree of MD. We also hypothesized that MD in these patients would be associated with increased length of stay, hypotension, fluid requirements, and acute kidney injury (AKI).

MATERIALS AND METHODS

Thirty-two trauma patients in hemorrhagic shock on admission to the trauma bay (SBP <90 mm Hg × 2) were enrolled. Blood samples were obtained on ICU admission and 8, 16, 24, and 48 hours later. Plasma aldosterone (PA) and renin (PR) were assayed by radioimmunoassay. MD was defined as a ratio of PA/PR ≤2. Demographic data, injury severity score, ICU and hospital length of stay, fluid requirements, mean arterial pressure, serum sodium, hypotension, and risk for AKI were compared for patients with and without MD.

RESULTS

At ICU admission, 48% of patients met criteria for MD. Patients with MD were significantly more likely to experience hypotension (MAP ≤60 mm Hg) during the study period. MD patients required significantly more units of blood in 48 h than non-MD patients (13 [7-22] versus 5 [2-7], P = 0.015) and had increased crystalloid requirements (18L [14-23] versus 9L [6-10], P < 0.001). MD patients were at higher risk for AKI according to RIFLE and AKIN criteria.

CONCLUSIONS

MD is a common entity in trauma patients presenting in hemorrhagic shock. Patients with MD required a more aggressive resuscitative effort, were more likely to experience hypotension, and had a higher risk of AKI than non-MD patients. Future studies are needed to fully understand the impact of MD following trauma and the potential role for hormonal replacement therapy.

Toll-like receptors in the inflammatory response during open and laparoscopic colectomy for colorectal cancer

BACKGROUND

Surgical interventions activate a cascade of reactions that result in an aseptic inflammatory reaction. This inflammatory response initiates the organism's innate immunity. Laparoscopic surgery reduces the trauma, and patients benefit from diminished surgical trauma and maintained immune function. Cytokine levels and C-reactive protein (CRP) are related to the magnitude of surgical trauma and surgical stress. Toll-like receptors (TLRs) 2 and 4 are the first sensor-recognition receptors of the invading pathogens for the innate immune response. This study aimed to compare the inflammatory response and then the stress response during laparoscopic and open colectomy for cancer by calculating TLR-2 and TLR-4 as the first sensor-recognition receptors together with interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and high-sensitivity CRP (hsCRP).

METHODS

A total 40 patients with colorectal cancer were randomized in two groups: group A (open colectomy, n = 20) and group B (laparoscopic colectomy, n = 20). An epidural catheter was placed in all patients 1 h preoperatively. Rupivocaine was administered perioperatively and 48 h postoperatively. Blood samples were taken for calculation of IL-6, TNF-α, hsCRP, TLR-2, and TLR-4 preoperatively and 5 min after deflation of pneumoperitoneum (group B) or 5 min after division of the colon (group A), then 6 and 24 h postoperatively.

RESULTS

The mean operative time was 115 for group A and 142 min for group B. The mean blood loss was respectively 240 and 105 ml (P < 0.001), and the mean hospital stay was respectively 8 and 5 days (P < 0.05). The IL-6 level was significant higher in group A than in group B at 6 and 24 h postoperatively (P < 0.0001), and the hsCRP level was significant higher in group A than in group B at 24 h postoperatively (P < 0.001). The TNF-α values did not differ between the two groups. The TLR-2 level was significantly higher in group A than in group B at 5 min (P = 0.013) and 24 h (P = 0.007) postoperatively. The TLR-4 level was significant higher in group A than in group B at 5 min postoperatively (P = 0.03).

CONCLUSION

The inflammatory response and the resultant stress response are significantly less during laparoscopic colectomy than during open colectomy for colorectal cancer. This is an obvious short-term clinical benefit for the patient, providing tinder for further study to investigate the long-term results of laparoscopic colectomy versus open colectomy for colorectal cancer.

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.

Assessment of the hypothalamic-pituitary-adrenal axis in critical illness

Cortisol is the main corticosteroid secreted from the human adrenal cortex, and it has a crucial role for survival in stressful conditions. An adequate increase in levels of cortisol helps patients to cope with the severity of the disease in the acute phase of critical illness. Either higher or lower than expected cortisol levels were found to be related to increased mortality. Prolonged activation of the hypothalamic-pituitary-adrenal (HPA) axis can result in hypercortisolemia or hypocortisolemia; both can be detrimental to recovery from critical illness. Primary and secondary adrenal insufficiency, relative adrenal insufficiency, tissue resistance to glucocorticoids, adrenocorticotrophic hormone deficiency and immune-mediated inhibition of the HPA axis can be the cause of the impairment of the secretion or action of cortisol in critically ill patients. Recently, some authors offered the term 'critical illness-related corticosteroid insufficiency' to better point out the relative adrenal insufficiency that is seen during critical illness. Patients with critical illness-related corticosteroid insufficiency not only have insufficient circulating cortisol but also have impaired cellular utilization of cortisol. In this article, how adrenal dysfunction presents in critical illness and how appropriate diagnosis and management can be achieved in the critical care setting will be discussed.

Immunosuppression following surgical and traumatic injury

Severe sepsis and organ failure are still the major causes of postoperative morbidity and mortality after major hepatobiliary pancreatic surgery. Despite recent progress in understanding the immune conditions of abdominal sepsis, the postoperative incidence of septic complications after major visceral surgery remains high. This review focuses on the clinical and immunological parameters that determine the risk of the development and lethal outcome of postoperative septic complication following major surgery and trauma. A review of the literature indicates that surgical and traumatic injury profoundly affects the innate and adaptive immune responses, and that a marked suppression in cell-mediated immunity following an excessive inflammatory response appears to be responsible for the increased susceptibility to subsequent sepsis. The innate and adaptive immune responses are initiated and modulated by pathogen-associated molecular-pattern molecules and by damage-associated molecular-pattern molecules through the pattern-recognition receptors. Suppression of cell-mediated immunity may be caused by multifaceted cytokine/inhibitor profiles in the circulation and other compartments of the host, excessive activation and dysregulated recruitment of polymorphonuclear neutrophils, induction of alternatively activated or regulatory macrophages that have anti-inflammatory properties, a shift in the T-helper (Th)1/Th2 balance toward Th2, appearance of regulatory T cells, which are potent suppressors of the innate and adaptive immune system, and lymphocyte apoptosis in patients with sepsis. Recent basic and clinical studies have elucidated the functional effects of surgical and traumatic injury on the immune system. The research studies of interest may in future aid in the selection of appropriate therapeutic protocols.

Cosyntropin as a diagnostic agent in the screening of patients for adrenocortical insufficiency

Adrenocortical insufficiency occurs when there is inadequate release of cortisol from the adrenal cortex. Disturbances of the hypothalamic-pituitary-adrenal axis are common following trauma, surgical stress, and critical illness. While this is often a protective mechanism, these responses may become "uncoupled" or maladaptive resulting in an exacerbation of organ failure and higher mortality rates. In these clinical settings, the patient presents with a persistent systemic inflammation state, a hyperdynamic cardiovascular response, and vasopressor dependent shock. As such, the occurrence of adrenal insufficiency in the setting of critical illness is most appropriately termed critical illness-related corticosteroid insufficiency. In these settings, recent data suggests that these patients may benefit from a short course of low-dose steroid replacement therapy. Cosyntropin, a synthetic derivative of adrenocorticotropic hormone, is being used with increased frequency in the evaluation and diagnosis of adrenocortical insufficiency in this patient population. A random cortisol level is checked before a 250-μg injection of cosyntropin and then 30-60 minutes later. The cortisol levels and response to cosyntropin may be interpreted to identify an insufficient adrenal response. Of note, the setting of critical illness can greatly affect the cosyntropin test sensitivity on identifying adrenal insufficiency. Changes in the stress response during critical illness combined with the resuscitation and management of these patients greatly disturbs serum protein levels, especially those of albumin and transcortin. Common intensive care unit (ICU) diagnoses such as sepsis and malnutrition can increase baseline levels and blunt the cortisol response to cosyntropin stimulation, respectively. As well, numerous pharmacological agents routinely used in the ICU have been shown to interfere with cortisol levels and cosyntropin responsiveness. While steroids have a place in the ICU, specific dosing and length of administration remain inconsistent.

Acute Adrenal Insufficiency May Affect Outcome in the Trauma Patient

Acute adrenal insufficiency in the trauma patient is underrecognized and the impact poorly understood. Our hypothesis was that the identification and treatment of acute adrenal insufficiency reduces mortality in trauma patients. Institutional Review Board approval for the retrospective review of a prospective database from a Level 1 trauma center for 2002 to 2004 was obtained. The study population included patients receiving a cosyntropin stimulation test (250 μg) and/or random Cortisol level based on our practice management guideline and an intensive care unit stay longer than 24 hours. Demographic, acuity, and outcome data were collected. The nonresponders had baseline Cortisol levels less than 20 μg/dL or poststimulation rise less than 9 μg/dL. Independent t tests and χ2 statistics were used. One hundred thirty-seven patients had cosyntropin stimulation tests performed. Eighty-two (60%) patients were nonresponders of which 66 were treated with hydrocortisone and 16 went untreated as a result of the discretion of the attending physician. The 55 (40%) responders showed no statistical differences in outcome variables whether or not they received hydrocortisone. The untreated adrenal-insufficient patients had significantly higher mortality, longer hospital length of stay, intensive care unit days, and ventilator-free days. Conclusions were: 1) treatment of acute adrenal insufficiency reduces mortality by almost 50 per cent in the trauma patient; and 2) acute adrenal insufficiency recognized by low random Cortisol levels or nonresponse to a stimulation tests should be considered for treatment.

Medication-related complications in the trauma patient

Trauma patients are twice as likely to have adverse reactions to medication as nontrauma patients. The need for medication in trauma patients is high. Surgery is often necessary, and immunosuppression and hypercoagulability may be present. Adverse drug events can be caused in part by altered pharmacokinetics, drug interactions, and polypharmacy. Medications may also have serious long-term adverse effects, which must be considered. It is not the purpose of this review article to discuss all adverse effects of all medications. This article will discuss the more common adverse effects of medications for trauma patients in the acute care setting, in the following categories: pain control, sedation, antibiotics, seizure prophylaxis in head trauma, atrial fibrillation, deep vein thrombosis and pulmonary embolism prophylaxis, hemodynamic support, adrenal insufficiency, factor VIIa.

Time-course changes in nuclear translocation of hepatic glucocorticoid receptor in rats after burn trauma and its pathophysiological significance

Nuclear translocation is a determining step for the glucocorticoid receptor (GR) to exert its functions in response to traumatic conditions. This study was designed to observe the nuclear translocation changes of hepatic GR in severely burned rats during early postburn stage, and to explore the effects of high-dose dexamethasone on GR nuclear translocation. Rats with 35% total body surface area full-thickness burn injury, parallelized with a sham-burn group, were killed at consecutive time points to examine the changes in plasma corticosterone and expression of hepatic GR at both whole-cell and nuclear levels. The effects of high-dose dexamethasone on GR nuclear translocation and suppression of proinflammatory cytokine overproduction were subsequently analyzed. In burned rats, plasma corticosterone increased remarkably soon after burn injury. On the contrary, the hepatic GR levels showed an initial phase of decrease as measured in both whole-cell and nucleus by Western blot, followed by a rapid elevation in the nucleus but a slow recovery at whole-cell level. By comparing the changes of GR in both whole-cell and nuclear levels, we found that GR nuclear translocation was relatively enhanced in the early postburn period. High-dose dexamethasone administered at 1 or 48 h postburn did not further elevate GR nuclear translocation, neither did it restrain the increased release of proinflammatory cytokines such as TNF-alpha and IL-1 beta. These studies suggest that although the whole-cell level of hepatic GR is decreased, GR nuclear translocation is relatively enhanced at early postburn stage. High-dose exogenous glucocorticoids may not promote more nuclear translocation of GR to reinforce its functions.

Impact of stressors in a natural context on release of cortisol in healthy adult humans: a meta-analysis

Increased hypothalamic-pituitary-adrenal (HPA) activation, culminating in elevated circulating cortisol levels is a fundamental response to stressors. In animals, this neuroendocrine change is highly reliable and marked (approximately 5-10-fold elevations), whereas in humans, the increase of cortisol release is less pronounced, and even some potent life-threatening events (anticipation of surgery) only elicit modest cortisol increases. Meta-analysis of factors that influenced the increase of cortisol release in a laboratory context pointed to the importance of social evaluative threats and stressor controllability in accounting for the cortisol rise. The present meta-analysis, covering the period from 1978 through March 2007, was undertaken to identify the factors most closely aligned with cortisol increases in natural settings. It appeared that stressor chronicity was fundamental in predicting cortisol changes; however, this variable is often confounded by the stressor type, the stressor's controllability, as well as contextual factors, making it difficult to disentangle their relative contributions to the cortisol response. Moreover, several experiential factors (e.g. previous stressor experiences) may influence the cortisol response to ongoing stressors, but these are not readily deduced through a meta-analysis. Nevertheless, there are ample data suggesting that stressful events, through their actions on cortisol levels and reactivity, may influence psychological and physical pathology.

Are Adrenal Injuries Predictive of Adrenal Insufficiency in Patients Sustaining Blunt Trauma?

Adrenal insufficiency (AI) is an uncommon life-threatening development in trauma patients. The aim of this study was to determine if adrenal injury sustained during blunt trauma is associated with an increased risk of AI. A single-institution retrospective cohort review was performed over a 3-year period on all patients with blunt trauma requiring intensive care admission and mechanical ventilation for longer than 24 hours. Adrenal injuries were identified on admission CT scan. All patients with AI were identified as noted by practice management guidelines. Patients were stratified by Injury Severity Score (ISS) as less than 16, 16 to 25, and greater than 25 and relative risks were calculated. Multiple logistic regression was performed using age, race, sex, Glasgow Coma Scale, ISS, length of hospitalization, and adrenal injury as covariates with AI as the outcome of interest. A secondary analysis was then performed with adrenal injury classified as bilateral versus unilateral or no adrenal injury and relative risks were calculated for ISS strata. A total of 2072 patients were identified with 71 developing AI. Adrenal injuries were noted in 113 patients with eight subsequently developing AI. Multiple logistic regression model (P < 0.01) showed that age (P < 0.01) and increasing ISS (P = 0.02) were predictive of AI. Adrenal injury was not an independent predictor of AI (P = 0.12). After controlling for age and ISS, adrenal injury was not an independent predictor of the development of AI. Adrenal insufficiency should be considered with increasing injury severity and age in the intensive care setting after blunt trauma.

Adrenal insufficiency in critical illness

One of the more controversial areas in critical care in recent decades relates to the issue of adrenal insufficiency and its treatment in critically ill patients. There is no consensus on which patients to test for adrenal insufficiency, which tests to use and how to interpret them, whether to use corticosteroids, and, if so, who to treat and with what dose. This review illustrates the complexity and diversity of pathophysiological changes in glucocorticoid secretion, metabolism, and action and how these are affected by various types of illness. It will review adrenal function testing and give guidance on corticosteroid replacement regimens based on current published literature. There remain inherent difficulties in interpreting the effects of glucocorticoid replacement during critical illness because of the diversity of effects of glucocorticoids on various tissues. Investigation and treatment will depend on whether the likely cause of corticosteroid insufficiency is adrenal or central in origin.

Relative adrenal insufficiency: an identifiable entity in nonseptic critically ill patients?

OBJECTIVE

To determine whether relative adrenal insufficiency (RAI) can be identified in nonseptic hypotensive patients in the intensive care unit (ICU).

DESIGN

Retrospective study in a medical-surgical ICU of a university hospital.

PATIENTS

One hundred and seventy-two nonseptic ICU patients (51% after trauma or surgery), who underwent a short 250 microg ACTH test because of > 6 h hypotension or vasopressor/inotropic therapy.

MEASUREMENTS

On the test day, the Simplified Acute Physiology Score II (SAPS II) and Sequential Organ Failure Assessment (SOFA) score were calculated to estimate disease severity. The ICU mortality until day 28 was recorded. Best discriminative levels of baseline cortisol, increases and peaks were established using receiver operating characteristic curves. These and corticosteroid treatment (in n = 112, 65%), among other variables, were examined by multiple logistic regression and Cox proportional hazard regression analyses to find independent predictors of ICU mortality until day 28.

RESULTS

ICU mortality until day 28 was 23%. Nonsurvivors had higher SAPS II and SOFA scores. Baseline cortisol levels correlated directly with albumin levels and SAPS II. In the multivariate analyses, a cortisol baseline > 475 nmol/l and cortisol increase < 200 nmol/l predicted mortality, largely dependent on disease severity but independent of albumin levels. Corticosteroid (hydrocortisone) treatment was not associated with an improved outcome, regardless of the ACTH test results.

CONCLUSION

In nonseptic hypotensive ICU patients, a low cortisol/ACTH response and treatment with corticosteroids do not contribute to mortality prediction by severity of disease. The data thus argue against RAI identifiable by cortisol/ACTH testing and necessitating corticosteroid substitution treatment in these patients.

Surgical Trauma-Induced Adrenal Insufficiency is Associated with Postoperative Inflammatory Responses

The hypothalamic-pituitary-adrenal axis is an essential component for the maintenance of homeostasis following trauma. Major surgical trauma often induces overwhelming inflammatory responses leading to sepsis and organ dysfunction. This study was designed to evaluate the adrenal responses both before and after various degrees of surgical trauma and to determine the incidence of postoperative relative adrenal insufficiency resulting in the marked inflammatory response often associated with postoperative complications. Fifty-one surgical patients were divided into groups who underwent major, moderate, and minor surgeries. Before the operation and during resting conditions, a short corticotropin (ACTH) stimulation test was performed in each patient. The postoperative concentrations of serum cortisol, interleukin (IL)-6, IL-10, C-reactive protein (CRP), and plasma ACTH were measured. Fifty of 51 patients were identified as responders to ACTH. The postoperative cortisol levels were the same as those obtained by ACTH stimulation in highly and moderately stressful surgeries. The increases in postoperative IL-6 and CRP levels were greatest with major surgery, intermediate with moderate surgery, and least with minor surgery. Furthermore, plasma ACTH levels increased after major and moderate surgeries; however, there was no significant differences in postoperative serum IL-10 levels. Systemic inflammatory response syndrome (SIRS) was found in 11 of 17 patients (64.7%) who underwent major surgery and in 4 of 16 patients (25%) who underwent moderate surgery (p=0.037). The duration of SIRS was significantly longer in patients undergoing major surgery (62+/-20 hrs) than in patients undergoing moderate surgery (21+/-3 hrs, p=0.038). Postoperative complications were more frequent in patients undergoing major surgery (41.2%) than in patients undergoing moderate surgery (6.3%, p=0.039). Furthermore, there were significant differences in the length of the postoperative stay among the three groups (p<0.01). One nonresponder had serious postoperative inflammatory complications. These results suggest that a short ACTH stimulation test performed preoperatively is a helpful method for determining the maximal cortisol response to surgical trauma and to identify high-risk individuals and that a relative postoperative adrenal insufficiency may be closely related to the decreased cortisol secretion following major surgical trauma.

Metabolic changes after polytrauma: an imperative for early nutritional support

Major trauma induces marked metabolic changes which contribute to the systemic immune suppression in severely injured patients and increase the risk of infection and posttraumatic organ failure. The hypercatabolic state of polytrauma patients must be recognized early and treated by an appropriate nutritional management in order to avoid late complications. Clinical studies in recent years have supported the concept of "immunonutrition" for severely injured patients, which takes into account the supplementation of Ω-3 fatty acids and essential aminoacids, such as glutamine. Yet many aspects of the nutritional strategies for polytrauma patients remain controversial, including the exact timing, caloric and protein amount of nutrition, choice of enteral versus parenteral route, and duration. The present review will provide an outline of the pathophysiological metabolic changes after major trauma that endorse the current basis for early immunonutrition of polytrauma patients.

Relative adrenal insufficiency after cardiac arrest: impact on postresuscitation disease outcome

The purpose of this study is to prospectively evaluate the cortisol response and determine the relative adrenal insufficiency after return of spontaneous circulation (ROSC).

METHODS

This is a prospective cohort study describing the prevalence of relative adrenal insufficiency in consecutive patients admitted to an intensive care unit following ROSC (>24 hours) after cardiac arrest. The study institution is a 1,300-bed urban hospital with an annual intensive care unit census of 80. Descriptive statistics is used to report results.

RESULTS

This study included 30 patients over a 1-year period. The mean patient age was 52 years, and there were 15 (50%) males. The most common etiology for cardiac arrest was unknown, and the most common initial rhythm was asystole. There were 16 (53%) witnessed arrests. The mean time from arrest to cardiopulmonary resuscitation was 8 minutes, and the mean time from arrest to ROSC was 23 minutes. Relative adrenal insufficiency (incremental response to corticotrophin test < 9 microg/dL) at initial 12 to 24 hours and >24 to 48 hours occurred in 13 (43%) and 10 (33%) patients, respectively. All basal cortisol values were normal to high. Nineteen (58%) patients survived. The mean cortisol values at the initial 12 to 24 hours and >24 to 48 hours were similar among survivors and nonsurvivors. Relative adrenal insufficiency was present in only 5 (26%) survivors.

CONCLUSION

Relative adrenal insufficiency may be associated with the increased mortality rate in patients with return of circulation after cardiac arrest. Although basal cortisol values were normal to high, treatment of relative adrenal insufficiency with corticosteroids may decrease the mortality rate. Additional studies are needed to confirm this association and to determine the effectiveness of treating relative adrenal insufficiency.

Circulating Cytokines, Chemokines, and Stress Hormones are Increased in Patients with Organ Dysfunction Following Liver Resection

BACKGROUND

Humoral mediators are potentially involved in the pathogenesis of postoperative complications following surgery. The aim of the present study is to evaluate the postoperative responses of circulating cytokines, chemokines, and stress hormones following liver resection, and their effects on postoperative infectious complications and organ dysfunction.

PATIENTS AND METHODS

Perioperative plasma concentrations of interleukin (IL)-6, IL-10, IL-4, IL-8, macrophage chemoattractant protein (MCP)-1, cortisol, macrophage migration inhibitory factor (MIF), and leptin were measured by immunoassays in 128 consecutive patients undergoing liver resection.

RESULTS

Forty-three patients had postoperative infection and 11 had infection-related organ dysfunction. Plasma levels of all mediators except for IL-4 increased postoperatively. Postoperative levels of IL-6, IL-10, IL-8, MCP-1, cortisol, and leptin were significantly higher in patients with organ dysfunction than in those without organ dysfunction (P < 0.05). However, postoperative MIF levels were not affected by postoperative infection or organ dysfunction. Plasma levels of IL-6, IL-10, IL-8, and MCP-1 were positively correlated with operation time (P < 0.0001) or blood loss (P < 0.0001), and higher in patients with jaundiced liver (P < 0.05). In univariate logistic regression analyses, elevated IL-6, IL-10, IL-8, and MCP-1, advanced age, large volume of blood loss, long operation time, long hepatic ischemia time, and major liver resection were significantly correlated with postoperative infection (P < 0.05). In multivariate analyses, IL-6 and IL-10 were significant predisposing factors for postoperative infection (P < 0.05), and blood loss and IL-6 for organ dysfunction (P < 0.01).

CONCLUSIONS

These results suggest that IL-6, IL-10, IL-8, MCP-1, cortisol, and leptin are released after liver resection in response to surgical stress and correlated with postoperative infection and organ dysfunction, and that of these circulating mediators, IL-6 and IL-10, have a close relationship to the complications.

Adrenal Insufficiency in the Critically Ill Trauma Population

Acute adrenal insufficiency has been demonstrated in a number of patients with shock. This study was designed to evaluate the rate of occult adrenal insufficiency in the critically ill trauma population and to determine the impact of hypoproteinemia on the use of random cortisol levels as a marker for adrenal insufficiency. Forty-four patients were prospectively enrolled on admission to the trauma intensive care unit, with three excluded, for a total n of 41. Random total serum cortisol and albumin levels were drawn on hospital Days 1, 4, 8, and 14. Occult adrenal insufficiency was defined as a cortisol less than 25 mcg/dL in the setting of an albumin greater than 2.5 g/dL. The prevalence of cortisol less than 25 mcg/dL ranged from 51 to 81 per cent during the study period, and peaked on Days 4 and 8. Albumin 2.5 g/dL or less ranged from 37 to 60 per cent, and this prevalence also peaked on Days 4 and 8. The patients with a low albumin had a high prevalence of low cortisol, ranging from 67 to 100 per cent. The prevalence of adrenal insufficiency, with low cortisol and normal albumin, ranged from 41 to 82 per cent during the study period. None of our patients with occult adrenal insufficiency were treated with steroids, which was a decision made by the treating physicians. Among the patients with occult adrenal insufficiency, survival was 100 per cent. Occult adrenal insufficiency is common in critically ill trauma patients, and is a dynamic entity that can be acquired and even resolved during critical illness. Random cortisol of 25 mcg/dL may actually not be an adequate marker of occult adrenal insufficiency. Low albumin predicts a low cortisol. Hemodynamically stable occult adrenal insufficiency should not be treated with steroid replacement in the critically ill trauma patient, as survival in our series was 100 per cent without replacement.

Prehepatic portal hypertension induces alterations in cytochrome oxidase activity in the rat adrenal gland

One approach to assess neuroendocrine response to portal hypertension in short-term portal vein-stenosed rats consists in studying metabolic and functional activity patterns in adrenal glands using mitochondrial enzyme cytochrome c oxidase (COX) as a histochemical marker. Male Wistar rats were divided into two groups: a control group (Group I; n = 8), in which the animals did not undergo any operative intervention, and a triple calibrated portal vein stenosis group (TPVS) (Group II; n = 7). The sections of suprarenal glands were histochemically stained for COX and the optical densitometry was measured by a computer image analyzer attached to a microscope. In TPVS rats, COX activity in the adrenal gland cortex is lower than in control rats and affects the fascicular (52.30, 47.16-60.98, vs. 67.12, 60.31-73.89, p = .002), glomerular (49.68, 46.19-53.56 vs. 70.47, 64.64-73.51, p < .001), and reticular (47.35, 35.63-54.39, vs. 55.37, 49.76-58.97; p < .05) layers. In contrast, COX activity in the adrenal gland medulla is similar in TPVS rats and in control rats (29.91, 29.54-31.18, vs. 29.67, 28.95-30.23). The changes in adrenocortical COX activity in short-term-TPVS rats could constitute a pathogenic factor for both splanchnic and systemic hyperdynamic circulations, described in this experimental model of prehepatic portal hypertension.

Relative adrenal insufficiency among trauma patients in a community hospital

BACKGROUND

The integrity of the hypothalamic-pituitary-adrenal (HPA) axis is a major determinant of the host response to stress. Recent studies have proven that low doses of hydrocortisone and fludrocortisone can significantly reduce mortality in patients with relative adrenal insufficiency (RAI) without increasing adverse events.

STUDY DESIGN

This study was a retrospective chart review of patients in a community hospital who carried the diagnosis of both adrenal insufficiency and trauma.

RESULTS

Over a 16-month period, the incidence of RAI among severely injured patients (injury severity score >/= 13) was 3%. Only 1 patient had the classic electrolyte findings of adrenal insufficiency, but all had vasopressor-dependent hypotension. Our patients had an average intensive care unit day stay of 37 days and were not tested for RAI on average until day 20 of their intensive care unit stay. Random cortisol levels did not correlate with injury severity. Six patients (75%) had a positive hemodynamic response to steroids.

CONCLUSIONS

Relative adrenal insufficiency after trauma is rare. In RAI, clear signs and symptoms are usually absent. The clinical diagnostic clue may be the unexplained hypotension and the resistance to inappropriately high doses of inotropes and vasoactive agents. The hemodynamic profile often shows a hyperdynamic state of high cardiac output and a low systemic vascular resistance. Baseline serum cortisol levels did not correlate with injury severity scores in this group of patients, which suggests a defect in the HPA axis. An intensive care unit day stay of greater than or equal to 20 days, ventilator dependence/acute respiratory distress syndrome, and a hyperdynamic state mandates consideration of endocrine testing to exclude RAI. Physiologic doses of hydrocortisone can reverse this potentially life-threatening syndrome.

Neuroendocrine responses mediate macrophage function after trauma

BACKGROUND

Clearly understanding the interactions between macrophage (M phi)-generated inflammatory mediators and the neuroendocrine system in regulating immune function after traumatic injury may aid in reversing trauma-mediated immune dysfunction and diminish the incidence and severity of infection in the traumatized patient.

METHODS

Trauma consisted of an open femur fracture and 40% retro-orbital hemorrhage (Trauma) or anesthesia alone (Control). Female Balb/C mice (6-8 weeks) with intact adrenal glands (Intact) or a bilateral adrenalectomy (ADX) were used. For glucocorticoid studies, corticosterone or a vehicle was administered via intraperitoneal (ip) injection 2 hours before the trauma. Splenic M phis were harvested and prostaglandin E(2) (PGE(2)) and interleukin-6 (IL-6) production, and mRNA, cyclooxygenase-2 (COX-2) protein, and nuclear factor kappa B (NF-kappa B) activity were measured.

RESULTS

M phi, PGE(2) and IL-6 production in Trauma+Intact mice was significantly increased compared with Control+Intact mice. Adrenalectomy decreased these levels to Control levels. Similar changes were observed for COX-2 and IL-6 expression. M phi nuclear NF-kappa B levels were increased in Trauma+Intact mice compared with controls. Adrenalectomy abrogated this increase. Treating Trauma+Intact mice with RU-486 did not restore PGE(2) and IL-6 production or COX-2 and IL-6 messenger RNA to control levels. Administering exogenous glucocorticoid to Intact mice did not increase PGE(2) and IL-6 production or COX-2 and IL-6 mRNA to Trauma levels.

CONCLUSIONS

The neuroendocrine system upregulates certain M phi inflammatory mediators, including PGE(2), IL-6, and NF-kappa B, after trauma. This upregulation does not seem to be mediated via glucocorticoids and possibly may be mediated via catecholamines. Elucidation of the interactions between the neuroendocrine system, the immune system, and inflammatory mediator secretion might provide novel therapeutic strategies for the injured patient.

Reprogramming of the immune system during zinc deficiency

Thymic atrophy, lymphopenia, and compromised cell- and antibody-mediated responses that cause increased rates of infections of longer duration are the immunological hallmarks of zinc deficiency (ZD) in humans and higher animals. As the deficiency advances, a reprogramming of the immune system occurs, beginning with the activation of the stress axis and chronic production of glucocorticoids that accelerate apoptosis among pre-B and -T cells. This reduces lymphopoiesis and causes atrophy of the thymus. In contrast, myelopoiesis is preserved, thereby providing protection for the first line of immune defense or innate immunity. Changes in gene expression for cytokines, DNA repair enzymes, zinc transporters, signaling molecules, etc., suggest that cells of the immune system are attempting to adapt to the stress of suboptimal zinc. Better understanding of the molecular and cellular changes made in response to inadequate zinc should lead to the development of immunotherapeutic interventions.

Impaired basal glucose effectiveness but unaltered fasting glucose release and gluconeogenesis during short-term hypercortisolemia in healthy subjects

Excess cortisol has been demonstrated to impair hepatic and extrahepatic insulin action. To determine whether glucose effectiveness and, in terms of endogenous glucose release (EGR), gluconeogenesis, also are altered by hypercortisolemia, eight healthy subjects were studied after overnight infusion with hydrocortisone or saline. Glucose effectiveness was assessed by a combined somatostatin and insulin infusion protocol to maintain insulin concentration at basal level in the presence of prandial glucose infusions. Despite elevated insulin concentrations (P < 0.05), hypercortisolemia resulted in higher glucose (P < 0.05) and free fatty acid concentrations (P < 0.05). Furthermore, basal insulin concentrations were higher during hydrocortisone than during saline infusion (P < 0.01), indicating the presence of steroid-induced insulin resistance. Postabsorptive glucose production (P = 0.64) and the fractional contribution of gluconeogenesis to EGR (P = 0.33) did not differ on the two study days. During the prandial glucose infusion, the integrated glycemic response above baseline was higher in the presence of hydrocortisone than during saline infusion (P < 0.05), implying a decrease in net glucose effectiveness (4.42 +/- 0.52 vs. 6.65 +/- 0.83 ml.kg-1.min-1; P < 0.05). To determine whether this defect is attributable to an impaired ability of glucose to suppress glucose production, to stimulate its own uptake, or both, glucose turnover and "hot" (labeled) indexes of glucose effectiveness (GE) were calculated. Hepatic GE was lower during cortisol than during saline infusion (2.39 +/- 0.24 vs. 3.82 +/- 0.51 ml.kg-1.min-1; P < 0.05), indicating a defect in the ability of glucose to restrain its own production. In addition, in the presence of excess cortisol, glucose disappearance was inappropriate for the prevailing glucose concentration, implying a decrease in glucose clearance (P < 0.05). The decrease in glucose clearance was confirmed by the higher increment in [3-3H]glucose during hydrocortisone than during saline infusion (P < 0.05), despite the administration of identical tracer infusion rates. In conclusion, short-term hypercortisolemia in healthy individuals with normal beta-cell function decreases insulin action but does not alter rates of EGR and gluconeogenesis. In addition, cortisol impairs the ability of glucose to suppress its own production, which due to accumulation of glucose in the glucose space results in impaired peripheral glucose clearance. These results suggest that cortisol excess impairs glucose tolerance by decreasing both insulin action and glucose effectiveness.