Jennifer Cole is a Critical Care and Internal Medicine Pharmacy Specialist at the Veterans Health Care System of the Ozarks in Fayetteville, Arkansas. Correspondence: Jennifer Cole (jennifer.cole@va.gov)
Author disclosures The author reports no actual or potential conflicts of interest with regard to this article.
Disclaimer The opinions expressed herein are those of the author and do not necessarily reflect those of Federal Practitioner, Frontline Medical Communications Inc., the US Government, or any of its agencies. This article may discuss unlabeled or investigational use of certain drugs. Please review the complete prescribing information for specific drugs or drug combinations—including indications, contraindications, warnings, and adverse effects—before administering pharmacologic therapy to patients.
Steroids are commonly used in the ICU and affect nearly every critically ill population. Common indications for steroids in the ICU include anaphylaxis, airway edema, septic shock, asthma and COPD exacerbations, pneumocystis pneumonia, adrenal crisis, antiemetic treatment, elevated intracranial pressure from tumors, autoimmune disorders, and stress doses needed for chronic steroid users before invasive procedures.26 Whether divided into glucocorticoid or mineralocorticoid subgroups, corticosteroids offer therapeutic benefit from their pharmacologic similarity to endogenously produced cortisol, which includes anti-inflammatory, immunosuppressive, antiproliferative, and vasoconstrictive effects.
Steroid receptors are present in most human tissue, and in varying degrees of binding affinity produce a wide variety of effects. After passive diffusion across cell membranes, steroid-receptor activation binds to various DNA sites, called glucocorticoid regulatory elements, which either stimulates or inhibits transcription of multiple nearby genes.
At the cellular level, corticosteroids inhibit the release of arachidonic acid through upstream production of lipocortin peptides and antagonism of phospholipase A2. This action decreases subsequent inflammatory mediators, including kinins, histamine, liposomal enzymes, and prostaglandins. Steroids also inhibit NF-κB, which further decreases expression of proinflammatory genes while promoting interleukin-10 and its anti-inflammatory properties. Antiproliferative effects of steroids are seen by triggering cell apoptosis and inhibition of fibroblast proliferation.27,28
By binding to mineralocorticoid receptors, steroids cause sodium retention coupled with hydrogen and potassium excretion in the distal renal tubule. Steroids also promote vasoconstriction by upregulating the production and sensitivity of β receptors in the endothelium while suppressing the production of vasodilators. Although rarely used for these physiologic effects, steroids also are involved in a number of metabolic pathways, including calcium regulation, gluconeogenesis, protein metabolism, and fat distribution. Given the similar structure to cortisol, exogenous steroids depress the hypothalamic-pituitary axis (HPA) and decrease the release of adrenocorticotropic hormone (ACTH). Tapering doses of steroid regimens is often required to allow natural androgen and cortisol synthesis and prevent steroid withdrawal.27,28
The potency of various exogenous steroids closely parallels their ability to retain sodium (Table 2). Prolonged activation of steroid receptors can have numerous systemic AEs, including unwanted neurocognitive effects (Table 3). Insomnia and psychosis are commonly described in corticosteroid clinical trials, and in one meta-analysis, both are associated with high costs per episode per year.29
Steroid-Induced Sleep Disruption and Psychosis
Sleep disruption caused by exogenous administration of steroids is thought to trigger other psychostimulant effects, such as mood swings, nervousness, psychoses, and delirium.30 Similarly, the SCCM PADIS guidelines included an ungraded statement: “although an association between sleep quality and delirium occurrence exists in critically ill adults, a cause-effect relationship has not been established.”17 For this review, these AEs will be discussed as related events.
The medical literature proposes 3 pathways primarily responsible for neurocognitive AEs of steroids: behavior changes through modification of the HPA axis, changes in natural sleep-wake cycles, and hyperarousal caused by modification in neuroinhibitory pathways (Figure).
HPA Axis Modification
Under either physical or psychological stress, neural circuits in the brain release corticotropin-releasing hormone (CRH), dehydroepiandrosterone (DHEA), and arginine vasopressin, which go on to activate the sympathetic nervous system and the HPA axis. CRH from the hypothalamus goes on to stimulate ACTH release from the pituitary. ACTH then stimulates cortisol secretion from the adrenal glands. Circulating cortisol feeds into several structures of the brain, including the pituitary, hippocampus, and amygdala. Steroid-receptor complexes alter gene transcription in the central nervous system (CNS), affecting the production of neurotransmitters (eg, dopamine, serotonin) and neuropeptides (eg, somatostatin, β-endorphin). Feedback inhibition ensues, with downregulation of the HPA axis, which prevents depletion of endogenous production of steroids.31 DHEA has protective effects against excessive cortisol activity, but DHEA secretion declines with prolonged cortisol exposure. Exogenous steroids may have different effects than endogenous steroids, and neurocognitive sequelae stem from disruption and imbalance of these physiologic mechanisms.32,33
