Adrenal failure in the critically ill

Vitamin C: The next step in sepsis management?

Sepsis is a life-threatening medical condition, affecting approximately 26 million people worldwide every year. The disease is a continuum, marked by dysregulated inflammation and hemodynamic instability leading to shock, multi-system organ dysfunction, and death. Over the past decades, there has been a focus on the early identification and treatment of sepsis primarily with bundled and goal directed therapy. Despite these advances, morbidity and mortality has remained high, prompting investigation into novel therapies. Vitamin C is a water-soluble vitamin that plays a role in mediating inflammation through antioxidant activities and is also important in the synthesis of cortisol, catecholamines, and vasopressin, which are key mediators in the disease process. Emerging evidence provides cursory data in support of the administration of vitamin C in addition to standard therapy to ameliorate the effects of inflammation and improve hemodynamic stability in patients with sepsis and septic shock; however, further evidence is needed to support this practice. This review discusses the physiologic role of vitamin C as well as the recent literature and evidence for the use of vitamin C in patients presenting with sepsis.

Effect of high-dose Ascorbic acid on vasopressor's requirement in septic shock

Objective:

Effects of ascorbic acid on hemodynamic parameters of septic shock were evaluated in nonsurgical critically ill patients in limited previous studies. In this study, the effect of high-dose ascorbic acid on vasopressor drug requirement was evaluated in surgical critically ill patients with septic shock.

Methods:

Patients with septic shock who required a vasopressor drug to maintain mean arterial pressure >65 mmHg were assigned to receive either 25 mg/kg intravenous ascorbic acid every 6 h or matching placebo for 72 h. Vasopressor dose and duration were considered as the primary outcomes. Duration of Intensive Care Unit (ICU) stay and 28-day mortality has been defined as secondary outcomes.

Findings:

During the study period, 28 patients (14 in each group) completed the trial. Mean dose of norepinephrine during the study period (7.44 ± 3.65 vs. 13.79 ± 6.48 mcg/min, P = 0.004) and duration of norepinephrine administration (49.64 ± 25.67 vs. 71.57 ± 1.60 h, P = 0.007) were significantly lower in the ascorbic acid than the placebo group. No statistically significant difference was detected between the groups regarding the length of ICU stay. However, 28-day mortality was significantly lower in the ascorbic acid than the placebo group (14.28% vs. 64.28%, respectively; P = 0.009).

Conclusion:

High-dose ascorbic acid may be considered as an effective and safe adjuvant therapy in surgical critically ill patients with septic shock. The most effective dose of ascorbic acid and the best time for its administration should be determined in future studies.

Ascorbate-dependent vasopressor synthesis: a rationale for vitamin C administration in severe sepsis and septic shock?

Severe systemic inflammatory response to infection results in severe sepsis and septic shock, which are the leading causes of death in critically ill patients. Septic shock is characterised by refractory hypotension and is typically managed by fluid resuscitation and administration of catecholamine vasopressors such as norepinephrine. Vasopressin can also be administered to raise mean arterial pressure or decrease the norepinephrine dose. Endogenous norepinephrine and vasopressin are synthesised by the copper-containing enzymes dopamine β-hydroxylase and peptidylglycine α-amidating monooxygenase, respectively. Both of these enzymes require ascorbate as a cofactor for optimal activity. Patients with severe sepsis present with hypovitaminosis C, and pre-clinical and clinical studies have indicated that administration of high-dose ascorbate decreases the levels of pro-inflammatory biomarkers, attenuates organ dysfunction and improves haemodynamic parameters. It is conceivable that administration of ascorbate to septic patients with hypovitaminosis C could improve endogenous vasopressor synthesis and thus ameliorate the requirement for exogenously administered vasopressors. Ascorbate-dependent vasopressor synthesis represents a currently underexplored biochemical mechanism by which ascorbate could act as an adjuvant therapy for severe sepsis and septic shock.

What is the rationale for hydrocortisone treatment in children with infection-related adrenal insufficiency and septic shock?

Recent studies show that children who die from fulminant meningococcaemia have very low cortisol:adrenocorticotrophic hormone (ACTH) ratios within the first 8 h of presentation to emergency facilities compared with survivors. This observation supports the possibility that adrenal insufficiency may contribute to rapid cardiovascular collapse in these children. In recent years, the use of hydrocortisone treatment has become increasingly popular in the care of adult and paediatric patients with septic shock. In this review, the classical adrenal insufficiency literature is presented and the existing rationale for using titrated hydrocortisone treatment (2-50 mg/kg/day) to reverse catecholamine-resistant shock in children who have absolute adrenal insufficiency (defined by peak cortisol level <18 microg/dl after ACTH challenge) or pituitary, hypothalamic or adrenal axis insufficiency is provided. In addition, the concept of relative adrenal insufficiency (basal cortisol >18 microg/dl but a peak response to ACTH <9 microg/dl) is reviewed. Although there is a good rationale supporting the use of 7 days of low-dose hydrocortisone treatment (about 5 mg/kg/day) in adults with this condition and catecholamine resistant septic shock, the paediatric literature suggests that it is prudent to conduct more studies before recommending this approach in children.

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.

Hemodynamic effects of rescue protocol hydrocortisone in neonates with low cardiac output syndrome after cardiac surgery

OBJECTIVE

To assess the hemodynamic effects and safety of hydrocortisone in neonates with low cardiac output syndrome requiring high levels of inotropic support and fluid resuscitation after cardiac surgery.

DESIGN

Retrospective chart review.

SETTING

Fifteen-bed pediatric cardiovascular intensive care unit.

PATIENTS

Twelve neonates with low cardiac output syndrome after cardiac surgery to whom hydrocortisone was administered according to one of two dosing regimens (100 mg/[m.day] for 2 days, 50 mg/[m.day] for 2 days, and 25 mg/[m.day] for 1 day or 100 mg/[m.day] for 1 day, 50 mg/[m.day] for 2 days, and 25 mg/[m.day] for 2 days) were identified from the Department of Pharmacy database between September 2002 and January 2004.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The mean and systolic blood pressure increased significantly 3 hrs after hydrocortisone treatment from the values preceding hydrocortisone administration. The mean blood pressure increased from 44.0+/-3.0 to 55.4+/-2.3 mm Hg (p=.01) and the systolic blood pressure increased from 64.2+/-4.7 to 78.3+/-3.4 mm Hg (p=.04). Comparable beneficial changes were also seen in the heart rate, which decreased from 168.3+/-4.6 to 148.3+/-5.6 beats/min (p=.004) after 24 hrs of hydrocortisone administration and remained at this level during the 72 hrs of follow-up. Significant weaning of epinephrine infusions was possible, from a mean dose of 0.16 to 0.06 microg/(kg.min) (p=.008), within 24 hrs after the initiation of steroid administration, and this reduction was not offset by increases in other inotropic agents. hydrocortisone administration caused nonsignificant increases in mean blood glucose concentration (from 116.2+/-20.6 to 156.0+/-25.6 mg/dL; p=.64), mean white blood cell count (from 16.6+/-1.6 to 18.9+/-2.6 x 10 U/L; p=.35), and sodium level (from 144.7+/-1.3 to 145.3+/-1.3 mmol/L; p=.51). Ten of the 12 patients (83.3%) survived.

CONCLUSION

Most of the hemodynamically compromised neonates who were unresponsive to high doses of inotropic agents and fluid resuscitation after heart surgery responded to hydrocortisone with improvement of hemodynamic parameters and a decrease in inotropic requirements.

Stress-dose corticosteroid therapy for sepsis and acute lung injury or acute respiratory distress syndrome in critically ill adults

Sepsis and acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) are associated with high mortality rates despite recent therapeutic advances. Both disease states involve uncontrolled host defense responses that lead to inflammation, endothelial damage, enhanced coagulation, diminished fibrinolysis and fibroproliferation to produce microthrombi, and relative adrenal insufficiency. Corticosteroids inhibit the host defense response and may offer an inexpensive therapeutic option. Results of several randomized, double-blind studies demonstrated no survival benefit and higher secondary infection rates when supraphysiologic doses of corticosteroids were administered for less than 24 hours. Recently, the emphasis of research for corticosteroid therapy has involved adrenocortical replacement dosage regimens administered for several days to weeks, with doses corresponding to the stress level of the disease. Stress-dose therapy with hydrocortisone in patients with septic shock who require vasopressor support, especially if adrenal insufficiency is present, accelerates hemodynamic stability and reduces mortality. The frequency of gastrointestinal hemorrhage was higher with corticosteroid therapy than with placebo, but the occurrence of secondary infections was similar to that of placebo. The only randomized, double-blind study that evaluated stress-dose methylprednisolone therapy for ARDS was terminated early after only 24 patients were enrolled because therapy with methylprednisolone was associated with enhanced survival despite higher secondary infection rates. A multicenter study investigating stress-dose methylprednisolone for ARDS is under way and should provide valuable information. Sufficient data support stress-dose hydrocortisone therapy for vasopressor-dependent septic shock. Stress-dose methylprednisolone therapy for ALI-ARDS requires further study but may be warranted in cases of refractory infection-induced ARDS when impending mortality is likely.

Relative adrenal failure in intensive care: an identifiable problem requiring treatment?

Adequate adrenocortical function is essential to survive critical illness. Most critically ill patients display an elevated plasma cortisol level, reflecting activation of the pituitary-adrenal axis, which is considered to be a homeostatic adaptation. In the setting of critical illness, the failure of an appropriate neuroendocrine response can lead to the picture of vasopressor-dependent refractory hypotension. This state of relative or functional adrenal insufficiency is characterized by an inadequate production of cortisol in relation to an increased demand during periods of severe stress, particularly prolonged critical illness such as multi-organ failure. This clinical entity, however, lacks clear-cut diagnostic criteria. What are the appropriate cortisol concentrations in the critically ill? Should base-line and adrenocorticotropic hormone-stimulated cortisol concentrations be assessed? The classical adrenocorticotropic hormone stimulation test is often used, but there are problems with interpreting its results. Other diagnostic tools, such as the low-dose adrenocorticotropic hormone test and relative eosinophilia, are promising but also lack proper criteria. A prompt response to hydrocortisone treatment is a major clue to the diagnosis. Recent studies with stress doses of hydrocortisone in sepsis and septic shock have shown a marked haemodynamic improvement, but whether patients with relative adrenal dysfunction benefit most from this treatment and whether there is definitely an effect on outcome is still undecided.

Hypopituitarism after surgical clipping of a ruptured cerebral aneurysm

OBJECTIVE

The causes of hypopituitarism in adult life are most frequently cerebral tumors, pituitary infarction, head trauma, pituitary surgery, or irradiation. We report a case of hypopituitarism after surgical clipping of a ruptured cerebral aneurysm. Two previous cases after the rupture of a cerebral aneurysm have been reported.

DESIGN

Case report.

PATIENTS

One 42-yr-old man.

MEASUREMENTS AND MAIN RESULTS

A 42-yr-old man was admitted as an emergency for unconsciousness. The computed tomography showed a massive subarachnoid hemorrhage, and specific angiography showed an aneurysm in the internal carotid. The aneurysm was successfully clipped through craniotomy. The patient's hospital course was marked by a few episodes of pulmonary infection, and a tracheotomy was performed. The patient was transferred to the rehabilitation unit; he received a rating of 9 on the Glasgow Coma Scale. Seven months after rupture of the aneurysm, the patient was readmitted to the intensive care unit for septic shock, with pulmonary infection associated with vomiting and diarrhea. Despite standard therapy and inotropic support, there was no improvement of his clinical condition. Adrenal failure was then suspected. Treatment was started immediately with hydrocortisone (50 mg) four times a day. Within hours, his clinical condition improved. The following month, the patient was weaned off his tracheotomy and had nearly recovered. Endocrine tests confirmed the cortisol insufficiency but also hypothyroidism and hypogonadotropic hypogonadism secondary to hypopituitarism.

CONCLUSION

Our case is the first one reported of hypopituitarism after surgical clipping of a ruptured cerebral aneurysm.

Adrenal insufficiency during the late stage of polymicrobial sepsis

OBJECTIVES

Although studies have indicated that adrenal insufficiency occurs after severe trauma and hemorrhagic shock, it remains controversial whether adrenal function is depressed during the late stage of polymicrobial sepsis.

DESIGN

Prospective, controlled animal study.

SETTING

A university research laboratory.

SUBJECTS

Male rats (275-325 g) were subjected to polymicrobial sepsis by cecal ligation and puncture (CLP) or sham operation followed by the administration of normal saline solution.

MEASUREMENTS AND MAIN RESULTS

Systemic blood samples were taken at 20 hrs after CLP (i.e., a late stage of sepsis) or sham operation to measure plasma levels of corticosterone and corticotropin as well as adrenal contents of corticosterone. Additional groups of animals were utilized to examine corticotropin-stimulated plasma corticosterone release as well as adrenal levels of cyclic adenosine monophosphate (cAMP, the second messenger of corticotropin action). The results indicate that despite a 75% (p < .05) higher concentration in plasma corticotropin at 20 hrs after the onset of sepsis, plasma corticosterone levels were similar to those in sham-operated animals. In addition, adrenal contents of corticosterone were reduced by 42% (p < .05) in septic animals. Moreover, the plasma corticosterone and adrenal cAMP responses to corticotropin were reduced by 53% and 27% (p < .05), respectively, at 20 hrs after CLP.

CONCLUSIONS

These findings suggest that, despite high plasma levels of endogenous corticotropin, adrenal dysfunction, as indicated by the reduction of corticotropin-induced plasma corticosterone release and adrenal contents of cAMP as well as the decreased adrenal levels of corticosterone, occurs during the late stage of polymicrobial sepsis. Therefore, the recognition of adrenal insufficiency and interventions to improve adrenal responsiveness may be beneficial in improving the outcome during late sepsis.

Testosterone receptor blockade after trauma and hemorrhage attenuates depressed adrenal function

Although the testosterone receptor antagonist flutamide restores the depressed immune function in males after trauma and hemorrhage, it remains unknown whether this agent has any salutary effects on adrenal function. To study this, male rats underwent laparotomy and were bled to and maintained at a blood pressure of 40 mmHg until 40% of the shed blood volume was returned in the form of Ringer lactate. Animals were then resuscitated and flutamide (25 mg/kg body wt) was administered subcutaneously. Plasma adrenocorticotropic hormone (ACTH) and corticosterone, as well as adrenal corticosterone and cAMP were measured 20 h after resuscitation. In additional animals, ACTH was administered and ACTH-induced corticosterone release and adrenal cAMP were determined. The results indicate that adrenal contents of corticosterone and cAMP were significantly decreased and morphology was altered after hemorrhage. Administration of flutamide improved corticosterone content, restored cAMP content, and attenuated adrenal morphological alterations. Flutamide also improved the diminished ACTH-induced corticosterone release and adrenal cAMP response at 20 h after hemorrhage and resuscitation. Furthermore, the diminished corticosterone response to ACTH stimulation in the isolated adrenal preparation was improved with flutamide. These results suggest that flutamide is a useful adjunct for improving adrenal function in males following trauma and hemorrhage.

The metabolic and nutritional response to critical illness

The metabolic response to critical illness promotes catabolism, which mobilizes substrates for energy. Initially the hypothalamic-pituitary-adrenal axis is stimulated, but later there appears to be anterior pituitary depression. Despite this, the early increase in plasma cortisol levels is usually maintained by means independent of (falling) corticotropin levels. Some patients, however, develop acute adrenal insufficiency and appear to benefit from replacement exogenous glucocorticoid. However, identifying such patients is often difficult. The replacement of other deficiencies may not be in the patients' interests. For example, leptin, a stress-related hormone, has multiple effects, some seemingly advantageous and others detrimental in critical illness. Its overall influence and significance remains unclear.The health of gut mucosa and the inflammatory response might be improved or influenced to the (presumed) benefit of the patient by agents such as glutamine, arginine, some eicosanoids, and exogenous nucleic acids. Such "immunonutrition" appears to improve mortality and other measures of outcome in surgical intensive care unit patients and those with sepsis.

Adrenocortical function in critically ill patients 24 h after a single dose of etomidate

We compared the effects of single doses of etomidate and thiopentone on adrenocortical function in a randomised controlled clinical trial involving 35 critically ill patients who needed a general anaesthetic. Just before induction of anaesthesia, a baseline blood cortisol sample was taken. Twenty-four hours later we performed a short adrenocorticotrophic hormone stimulation test. No patient had a low cortisol level (< 160 nmol.l-1) at any time during the study. Baseline, pre-ACTH and post-ACTH cortisol levels were similar in the two groups. However, significantly more patients in the etomidate group had an ACTH-stimulated cortisol increment < 200 nmol.l-1. The clinical significance of these findings is not clear, but we conclude that single doses of etomidate may interfere with cortisol synthesis for at least 24 h in the critically ill.