Effective glucose control in the intensive care unit (ICU) has been shown to decrease morbidity across a large range of conditions and also to decrease mortality. Studies supporting the role of glycemic control have used continuous infusion of insulin and glucose. With this protocol, glucose should be monitored frequently after initiation of the protocol (every 30 to 60 minutes) and on a regular basis (every 4 hours) once the blood glucose concentration has stabilized.
Hyperglycemia, caused by insulin resistance in the liver and muscle, is a common finding in ICU patients. It can be considered an adaptive response, providing glucose for the brain, red blood cells, and wound healing, and is generally only treated when blood glucose increases to > 215 mg/dL (>12 mmol/L). Conventional wisdom in the ICU has been that hyperglycemia is beneficial and that hypoglycemia is dangerous and should be avoided. This concept has been challenged recently, and controlling blood glucose levels by intensive insulin therapy decreased mortality and morbidity in surgical critically ill patients.
Van den Berghe et al. demonstrated that controlling blood glucose levels by intensive insulin therapy dramatically decreased mortality and morbidity in critically ill patients. [Van den Berghe et al. Outcome benefit of intensive insulin therapy in the critically ill: Insulin dose versus glycemic control. Critical Care Medicine. 2003;31(2):359–366.] The trial was a large single-center study of postoperative surgical patients. The design employed a continuous infusion of insulin to maintain glucose between 80 and 110 mg/dL (4.4–6.1 mmol/L) (94 guidelines). Exogenous glucose was begun simultaneously with insulin with frequent monitoring of glucose (every 1 hour) and intensity of monitoring was greatest at the time of initiation of insulin.
This protocol was provided by the investigators as an appendix and can be found on the website of the New England Journal of Medicine. In brief, this proceeding leads to a strategy of maintaining normoglycemia with insulin (0.04 units·kg-1·hour-1) during normal intake of glucose (9 g/hr) and calories (19 kcal·kg-1·day-1).
Benefits of Intensive Insulin Therapy:
A total of 35 of 765 patients (4.6 percent) in the intensive insulin group died in the ICU in Van den Berghe et al., compared with 63 patients (8.0 percent) in the conventional therapy group.
Intensive insulin therapy halved the prevalence of:
- Blood stream infections
- Prolonged inflammation
- ARF requiring dialysis or hemofiltration
- Critical illness polyneuropathy
- Transfusion requirements
Patients receiving intensive insulin therapy were also less likely to require prolonged mechanical ventilation and intensive care. Rigorous insulin treatment reduced the number of deaths from multiple-organ failure with sepsis, regardless of whether there was a history of diabetes or hyperglycemia.
Surgical vs. Medical Patients:
In medical septic patients, such a tight control of glycemia targeted to obtain normal blood glucose levels has not yet been adequately studied. However, there is no reason to believe that this strategy is not applicable to medical patients. Because medical patients tend to stay in the ICU longer than surgical patients, we suspect that the results from such a study will indicate that this intervention is even more favorable in medical ICU patients.
