Clinical benefits of tight glycaemic control: effect on the kidney

Acetate supplementation improves neurological outcomes by preventing hyperglycemia and suppressing Serpina3n expression in CA1 region after cardiac arrest and cardiopulmonary resuscitation

BACKGROUND

Hyperglycemia is common after cardiac arrest and cardiopulmonary resuscitation (CA/CPR). More importantly, it is associated with a worse neurological outcome after CA/CPR. Acetate has been proven to be of great value to reprogram glucose metabolism in the whole body. Nevertheless, the impact of acetate on hyperglycemia and neurological outcomes after CA/CPR remains largely unexplored.

METHODS

Glucose metabolism-related parameters were examined to assess the changes of glucose metabolism in our CA/CPR model. Survival and neurological function were measured after return of spontaneous circulation. Acetate supplementation was achieved by gavage to assess the impact of acetate on CA/CPR-induced hyperglycemia. Proteomics investigation of the changes in proteins of the CA1 region were performed to explore the differences of protein expression. The correlation between acetate supplementation and improvement of neurological outcomes after CA/CPR was elucidated by Serpina3n over-expression and knockdown in CA1 region.

RESULTS

CA/CPR induces hyperglycemia, hyperinsulinemia, glucose intolerance, and insulin resistance with upregulation of Serpina3n in CA1 region. Acetate supplementation could attenuate hyperglycemia, reduce protein levels of Serpina3n in CA1 region, and improves neurological outcomes after CA/CPR. Mechanistically, the acetate-dependent improvement of neurological outcomes after CA/CPR and attenuation of CA/CPR-induced hyperglycemia were correlated with the down-regulation of Serpina3n in CA1 region.

CONCLUSIONS

Our findings suggest that acetate supplementation improves neurological outcomes of CA/CPR mice by maintaining glucose homeostasis in the whole body and suppression of Serpina3n expression in CA1 region.

Kidney Dysfunction After Traumatic Brain Injury: Pathophysiology and General Management

Traumatic brain injury (TBI) remains a major cause of mortality and morbidity, and almost half of these patients are admitted to the intensive care unit. Of those, 10% develop acute kidney injury (AKI) and 2% even need kidney replacement therapy (KRT). Although clinical trials in patients with TBI who have AKI are lacking, some general principles in this population may apply. The present review is an overview on the epidemiology and pathophysiology of AKI in patients with TBI admitted to the intensive care unit who are at risk for or who have developed AKI. A cornerstone in severe TBI management is preventing secondary brain damage, in which reducing the intracranial pressure (ICP) and optimizing the cerebral perfusion pressure (CPP) remain important therapeutic targets. To treat episodes of elevated ICP, osmolar agents such as mannitol and hypertonic saline are frequently administered. Although we are currently awaiting the results of a prospective randomized controlled trial that compares both agents, it is important to realize that both agents have been associated with an increased risk of developing AKI which is probably higher for mannitol compared with hypertonic saline. For the brain, as well as for the kidney, targeting an adequate perfusion pressure is important. Hemodynamic management based on the combined use of intravascular fluids and vasopressors is ideally guided by hemodynamic monitoring. Hypotonic albumin or crystalloid resuscitation solutions may increase the risk of brain edema, and saline-based solutions are frequently used but have a risk of hyperchloremia, which might jeopardize kidney function. In patients at risk, frequent assessment of serum chloride might be advised. Maintenance of an adequate CPP involves the optimization of circulating blood volume, often combined with vasopressor agents. Whether individualized CPP targets based on cerebrovascular autoregulation monitoring are beneficial need to be further investigated. Interestingly, such individualized perfusion targets are also under investigation in patients as a strategy to mitigate the risk for AKI in patients with chronic hypertension. In the small proportion of patients with TBI who need KRT, continuous techniques are advised based on pathophysiology and expert opinion. The need for KRT is associated with a higher risk of intracranial hypertension, especially if osmolar clearance occurs fast, which can even occur in continuous techniques. Precise ICP and CPP monitoring is mandatory, especially at the initiation of KRT.

Stress hyperglycemia, cardiac glucotoxicity, and critically ill patient outcomes current clinical and pathophysiological evidence

Stress hyperglycemia is a transient increase in blood glucose during acute physiological stress in the absence of glucose homeostasis dysfunction. Its's presence has been described in critically ill patients who are subject to many physiological insults. In this regard, hyperglycemia and impaired glucose tolerance are also frequent in patients who are admitted to the intensive care unit for heart failure and cardiogenic shock. The hyperglycemia observed at the beginning of these cardiac disorders appears to be related to a variety of stress mechanisms. The release of major stress and steroid hormones, catecholamine overload, and glucagon all participate in generating a state of insulin resistance with increased hepatic glucose output and glycogen breakdown. In fact, the observed pathophysiological response, which appears to regulate a stress situation, is harmful because it induces mitochondrial impairment, oxidative stress-related injury to cells, endothelial damage, and dysfunction of several cellular channels. Paradigms are now being challenged by growing evidence of a phenomenon called glucotoxicity, providing an explanation for the benefits of lowering glucose levels with insulin therapy in these patients. In the present review, the authors present the data published on cardiac glucotoxicity and discuss the benefits of lowering plasma glucose to improve heart function and to positively affect the course of critical illness.

Tight glycemic control in critically ill pediatric patients: a systematic review and meta-analysis

Background

Hyperglycemia is prevalent in patients in the pediatric intensive care unit. The purpose of this study was to describe the benefits and risks of tight glucose control (TGC) in critically ill children.

Methods

A systemic review and meta-analysis of the literature was carried out on randomized controlled trials of TGC in critically ill children admitted to the pediatric intensive care unit. The databases searched were Medline, Embase, and CENTRAL databases until May 1, 2017. Paired reviewers independently screened citations, assessed risk of bias of included studies, and extracted data. A random-effects model was used to report all outcomes. The Grading of Recommendations Assessment, Development and Evaluation system was used to quantify absolute effects and quality of evidence. The primary outcome was hospital mortality. The secondary outcomes were hypoglycemia (any, severe), sepsis, new need for dialysis, and seizures.

Results

A total of 4030 patients were included from six studies. All six studies were rated as at low risk of bias. Our meta-analysis showed that TGC did not result in a decrease in risk of hospital mortality (odds ratio (OR), 0.95; 95% confidence interval (CI), 0.62–1.45; I² = 40%; moderate quality), sepsis (OR, 0.82; 95% CI, 0.63–1.08), or seizures (OR, 0.98; 95% CI, 0.59–1.63). TGC was associated with a decrease in new need for dialysis (OR, 0.63; 95% CI, 0.45–0.86). However, TGC was associated with a significant increase in any hypoglycemia (OR, 4.39; 95% CI, 2.39–8.06) and severe hypoglycemia (OR, 4.11; 95% CI, 2.67–6.32).

Conclusions

Among critically ill children with hyperglycemia, TGC does not result in a decrease in hospital mortality, but appears to reduce a new need for dialysis. However, TGC is associated with higher incidence of hypoglycemia.

Systematic review registration

PROSPERO registration number CRD42017074039.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-1976-2) contains supplementary material, which is available to authorized users.

Stress hyperglycemia in pediatric critical illness: the intensive care unit adds to the stress!

Stress hyperglycemia (SH) commonly occurs during critical illness in children. The historical view that SH is beneficial has been questioned in light of evidence that demonstrates the association of SH with worse outcomes. In addition to intrinsic changes in glucose metabolism and development of insulin resistance, specific intensive care unit (ICU) practices may influence the development of SH during critical illness. Mechanical ventilation, vasoactive infusions, renal replacement therapies, cardiopulmonary bypass and extracorporeal life support, therapeutic hypothermia, prolonged immobility, nutrition support practices, and the use of medications are all known to mediate development of SH in critical illness. Tight glucose control (TGC) to manage SH has emerged as a promising therapy to improve outcomes in critically ill adults, but results have been inconclusive. Large variations in ICU practices across studies likely resulted in inconsistent results. Future studies of TGC need to take into account the impact of commonly used ICU practices and, ideally, standardize protocols in an attempt to improve the accuracy of conclusions from such studies.