Postoperative metabolic support in the ICU

Patients admitted to the intensive care unit (ICU) after major surgery frequently develop anorexia, feeding intolerance, and hyperglycaemia in response to the severe stress. Although observational studies have associated accumulation of a caloric deficit with poor outcome, randomised controlled trials (RCTs) have shown that early nutrition support induces dose-dependent harm in ICU patients, which has been attributed to aggravation of hyperglycaemia and associated metabolic damage, as well as suppressed cellular repair mechanisms. Hence, early full nutrition support, including early parenteral nutrition, should be avoided. The ideal blood glucose control target depends on the context. Tight blood glucose control (TGC) may be superior, but should only be performed when it can be achieved with a protocol that avoids hypoglycaemia. Safe TGC requires a protocol that includes regular, accurate blood glucose measurements and avoidance of insulin boluses. In the absence of such protocol, at least severe hyperglycaemia and hypoglycaemia should be avoided.