The stress response and critical illness: a review

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.

The long-term effects of postoperative complications

PURPOSE OF REVIEW

This review examines the long-term influence of postoperative complications on survival. Although it is intuitive that complications after surgery worsen short-term outcomes, it is not clear to what extent and why a longer-term relationship may exist.

RECENT FINDINGS

Most studies have focused on outcomes after cancer surgery. Despite mixed results in smaller cohorts, large multicentre analyses consistently identify an association between postoperative complications and long-term mortality. In part, this phenomenon may be due to unmeasured confounding factors or insufficient separation of short and long-term consequences. Nevertheless, functional and biological imprints established during postoperative complications are likely to be relevant, and are the subject of ongoing research.

SUMMARY

Patients that develop postoperative complications and survive the immediate risk period, demonstrate worsened long-term mortality. The field of perioperative medicine is increasingly mandated to identify vulnerable individuals, develop and implement strategies to prevent and treat complications, and provide better care pathways after hospital discharge.

Pain in Intensive Care: A Personalised Healthcare Approach

For patients admitted to intensive care, pain is a common experience with potentially significant consequences. Pain management needs to evolve from the traditional ‘one-size-fits-all’ plan to a more personalised approach. This can be achieved by appreciating the numerous potential causes of pain, using appropriate assessment tools, utilising a range of potential treatment options and addressing the challenges associated with pain management in this heterogeneous population. At this point a truly multimodal, multidisciplinary management plan can be implemented, aimed at improving pain control and ultimately patient outcomes.

Hormesis and Cellular Quality Control: A Possible Explanation for the Molecular Mechanisms that Underlie the Benefits of Mild Stress

In contrast to the detrimental action of severe stress conditions, the beneficial effects of mild stress, known as hormesis, is increasingly discussed and studied. A variety of applications for hormesis in risk assessment processes, anti-ageing strategies and clinical therapies have been proposed. The molecular mechanisms underlying the phenomenon of hormesis, however, are not yet fully understood. A possible mechanism that has been proposed for hormesis, the homoeostasis overshoot hypothesis, assumes that an overshoot of repair- and self-recovery mechanisms in response to mild damage can be held responsible for the beneficial effects of hormesis. The present paper proposes 'cellular quality control' as a further explanation of the molecular mechanisms underlying the benefits observed after exposure to mild stress. The most important quality control mechanisms are outlined and their known and hypothesised actions in hormesis are discussed. As an example, different aspects of protein quality control will be described in more detail, which includes the reaction of the cell upon stress-induced protein damage and -aggregation. The regulation of Heat Shock Proteins and components from the ubiquitin proteasome system as part of cellular quality control is described in relation to its beneficial role in hormesis.