Endocrine dysregulation in aneurysmal subarachnoid haemorrhage.

INTRODUCTION: Aneurysmal Subarachnoid haemorrhage (aSAH) is one of the most common causes of neurocritical care admission. Consistent evidence has been suggestive of endocrine dysregulation in aSAH. This review aims to provide an up-to-date presentation of the available evidence regarding endocrine dysregulation in aneurysmal subarachnoid haemorrhage. METHODS: A comprehensive literature search was performed using PubMed database. All available evidence related to endocrine dysregulation in hypothalamic-pituitary hormones, adrenal hormones and natriuretic peptides after aSAH, published since 2010, were reviewed. RESULTS: There have been reports of varying prevalence of dysregulation in hypothalamic-pituitary and adrenal hormones in aSAH. The cause of this dysregulation and its pattern remain unclear. Hypothalamic-pituitary and adrenal dysregulation have been associated with higher incidence of poor neurological outcome and increased mortality. Whilst there is evidence that long-term dysregulation of these axes may also develop, it appears to be less frequent than the acute-phase dysregulation and transient in pattern. Increased levels of catecholamines have been reported in the hyper-acute phase of aSAH with reported inconsistent correlation with the outcomes and the complications of the disease. There is growing evidence that of a causal link between the endocrine dysregulation and the development of hyponatraemia and delayed cerebral ischaemia, in the acute phase of aSAH. However, the pathophysiological mechanism and pattern of endocrine dysregulation which could be causally associated with these complications still remain debatable. CONCLUSION: The evidence, mainly from small observational and heterogeneous in methodology studies, is suggestive of adverse effects of the endocrine dysregulation on the outcome and the incidence of complications of the disease. However, the cause of this dysregulation and a pathophysiological mechanism that could link its presence with the development of acute complications and the outcome of the aSAH remain unclear. Further research is warranted to elucidate the clinical significance of endocrine dysregulation in subarachnoid haemorrhage.

A narrative review of the clinical application of pressure reactiviy indices in the neurocritical care unit.

Pressure reactivity indices are used in clinical research as a surrogate marker of the ability of the cerebrovasculature to maintain cerebral autoregulation. The use of pressure reactivity indices in patients with neurological injury represents a potential to move away from population-based physiological targets used in guidelines to individualized physiological targets. The aim of this review is to describe the underlying principles and development of pressure reactivity indices, alongside a critique of how they have been used in clinical research, including their limitations. The primary source literature was identified from a database search of PUBMed and OVID online using the search terms "pressure reactivity index" and "pressure reactivity indices". The evidence base regarding pressure reactivity indices currently remains Level III. Pressure reactivity indices rely on the correlation (-1 to +1) between the arterial blood pressure and intracranial pressure, with negative values indicating intact cerebral autoregulation and positive values indicating dysfunctional cerebral autoregulation. Meaningful data is taken from summary measures and trends. The traumatic brain injury population feature most prominently in the literature. There is limited description of the potential confounding factors that may affect pressure reactivity indices, including physiological parameters and therapeutic interventions. Plotting a pressure reactivity index against a cerebral perfusion pressure can indicate an optimal cerebral perfusion pressure to individualise patient care. There is potential to over interpret optimal cerebral perfusion pressure targets when the values of pressure reactivity indices are close to zero. There is an association between pressure reactivity indices and neurological outcomes, however the use of pressure reactivity indices as a prognostication tool is to be challenged. Average values of cerebral perfusion pressure that are not close to averaged values of optimal cerebral perfusion pressure are also associated with poor outcome. Further research is required to ascertain whether targeting an optimal cerebral perfusion pressure may alter outcome.

Early versus late readmission of subarachnoid haemorrhage patients into neurocritical care.

INTRODUCTION: Subarachnoid haemorrhage (SAH) patients will typically require monitoring in a specialised Neurocritical Care Unit (NCCU) regardless of the primary treatment modality. Once discharged from NCCU, readmission within 48 h is regarded as a "failed" discharge. The aims of this study are to (1) Evaluate the readmission rate of SAH patients into NCCU, (2) Identify the indications for readmission, (3) Analyse clinical parameters on discharge between patients readmitted early and late. MATERIALS AND METHODS: Retrospective observational study of the Intensive Care National Audit and Research Centre (ICNARC) database of patients from our unit diagnosed with SAH from January 2009-December 2014, who were readmitted into NCCU. Demographic data, World Federation of Neurosurgical Societies (WFNS) grade, Fisher grade, length of initial and subsequent NCCU stay, time of readmission, indication for readmission, and mortality rate data were collected. Patients were categorised by early (<48 h) and late (>48 h) readmission, and their clinical parameters on NCCU discharge were statistically analysed. RESULTS: Five hundred and seventy-five SAH patients were admitted into NCCU, of which 49 patients (9%) were readmitted after discharge to ward-level care. The mean age of readmitted patients was 64.1 ± 11.6 years old. The most common indications were delayed cerebral ischaemia (DCI) (50%) and infection (19%). Readmitted SAH patients were typically WFNS grade I-II (n = 22) and Fisher grade III-IV (n = 44). 17 (35%) patients were readmitted early, and were older (p = 0.0049) with a lower GCS (p = 0.0077) compared to patients readmitted later. White cell count and C-reactive protein were higher in patients readmitted early, but did not reach statistical significance (p = 0.09, p = 0.07). CONCLUSION: DCI and infection were the most common indications for NCCU readmission in SAH patients. "Failed" discharged patients from NCCU are typically older with a lower GCS than patients readmitted after 48 h, and therefore clinicians should be more cautious in discharging these patients prematurely.

Nosocomial infection in trauma intensive care.

This editorial examines the epidemiology of nosocomial infection in trauma intensive care. Specifically, ventilator-associated pneumonia, central line-associated blood stream infection, and catheter-associated urinary tract infection rates are described. Two important trends are observed. Firstly, nosocomial infection rates have fallen with time. This trend is evident in all intensive care populations and is thought to be principally due to the adoption of preventative bundle strategies. Secondly, rates remain consistently higher in trauma patients than in other intensive care populations. The reasons for this are likely to be multifactorial. Recognizing the particular vulnerability of this patient group should prompt especially rigorous efforts at prevention, early diagnosis, and management.