Miet Schetz

Intensive Insulin Therapy in Critically Ill Patients: NICE-SUGAR or Leuven Blood Glucose Target?

CONTEXTnHyper- and hypoglycemia are associated with increased mortality of critically ill patients, but whether this association is causal remains unclear. Early randomized-controlled studies compared insulin infusion targeting age-normal blood glucose levels, labeled intensive insulin therapy, with an approach that considered hyperglycemia as a beneficial adaptation. These studies found benefits with maintaining normoglycemia. A recent large multicenter study, NICE-SUGAR, compared a similar age-normal with an intermediate glucose target and found the intermediate target superior. These results require explanation.nnnEVIDENCE ACQUISITIONnAll published randomized controlled studies on glucose control in ICU were reviewed. The methodological differences between the repeat studies, most specifically NICE-SUGAR, and the original proof-of-concept studies, were systematically analyzed.nnnEVIDENCE SYNTHESISnThere were important methodological differences, possibly explaining different outcomes. These comprised different target ranges for blood glucose in control and intervention groups, different routes for insulin administration and types of infusion-pumps, different sampling sites, and different accuracies of glucometers, as well as different nutritional strategies and varying levels of expertise.nnnCONCLUSIONSnThese differences do not permit confident recommendations for a single optimal glucose target in variable ICU settings. Respecting the primum non nocere principle, it appears safe not to embark on targeting age-normal levels in ICUs that are not equipped to accurately and frequently measure blood glucose and have not acquired extensive experience with iv insulin administration using a customized guideline. A simple overall fall-back position could be to maintain blood glucose levels as close to normal as possible without evoking unacceptable fluctuations, hypoglycemia, and hypokalemia.

Bench-to-bedside review: Metabolism and nutrition

Acute kidney injury (AKI) develops mostly in the context of critical illness and multiple organ failure, characterized by alterations in substrate use, insulin resistance, and hypercatabolism. Optimal nutritional support of intensive care unit patients remains a matter of debate, mainly because of a lack of adequately designed clinical trials. Most guidelines are based on expert opinion rather than on solid evidence and are not fundamentally different for critically ill patients with or without AKI. In patients with a functional gastrointestinal tract, enteral nutrition is preferred over parenteral nutrition. The optimal timing of parenteral nutrition in those patients who cannot be fed enterally remains controversial. All nutritional regimens should include tight glycemic control. The recommended energy intake is 20 to 30 kcal/kg per day with a protein intake of 1.2 to 1.5 g/kg per day. Higher protein intakes have been suggested in patients with AKI on continuous renal replacement therapy (CRRT). However, the inadequate design of the trials does not allow firm conclusions. Nutritional support during CRRT should take into account the extracorporeal losses of glucose, amino acids, and micronutrients. Immunonutrients are the subject of intensive investigation but have not been evaluated specifically in patients with AKI. We suggest a protocolized nutritional strategy delivering enteral nutrition whenever possible and providing at least the daily requirements of trace elements and vitamins.

Do we have reliable biochemical markers to predict the outcome of critical illness

Current outcome prediction in critically ill patients relies on the art of clinical judgement and/or the science of prognostication using illness severity scores. The biochemical processes underlying critical illness have increasingly been unravelled. Several biochemical markers reflecting the process of inflammation, immune dysfunction, impaired tissue oxygenation and endocrine alterations have been evaluated for their predictive power in small subpopulations of critically ill patients. However, none of these parameters has been validated in large populations of unselected ICU patients as has been done for the illness severity and organ failure scores. A simple biochemical predictor of ICU mortality will probably remain elusive because the processes underlying critical illness are very complex and heterogeneous. Future prognostic models will need to be far more sophisticated.