Conventional Versus Tight Glycemic Control in Critically Ill Patients

Wednesday, May 15, 2013

Featured Article

{Insert Alt Tag Here}

Technology Spotlight

Please check out our Clinical Diagnostics section to find manufacturers that sell these products

Hyperglycemia is common in critically ill patients, whether or not they have a history of diabetes. It can be caused by stress, infection, steroid therapy, other medications, physical inactivity, and diet. Patients in the intensive care unit (ICU) who develop hyperglycemia have increased morbidity and mortality.

Targeting Blood Glucose Ranges in the ICU

In 2001, a prospective randomized trial studying patients in a surgical ICU, where only 13% of patients had a history of diabetes, found that intensive maintenance of normoglycemia (blood glucose between 80 and 110 mg/dL) with insulin infusions reduced mortality in patients remaining in the ICU for more than 5 days by 48%.1 It also greatly decreased the incidence of acute renal failure, septicemia, and critical-illness polyneuropathy. The impressive results led to the development of numerous intravenous insulin protocols, as well as to the generation of new studies evaluating tight glycemic control in other critically ill hospital populations.

However, additional clinical trials have not confirmed that intensive insulin therapy leads to a significant drop in mortality compared to conventional treatment (maintenance of blood glucose between 180 and 200 mg/dL). Some trials have also shown increased rates of hypoglycemia-associated mortality as a result of intensive insulin therapy for critically ill patients. A large international randomized trial (NICE-SUGAR study)2 in 2009 found slightly increased mortality with tight glucose control versus conventional control, along with significantly more severe hypoglycemia. The results of this study led to decreased use of intravenous insulin therapy for critically ill patients, although experts believe that there are subsets of patients who should routinely undergo continuous intravenous therapy.3 The Society of Thoracic Surgeons has endorsed the routine use of intravenous insulin for patients undergoing open cardiac surgery,4 and intravenous insulin is also thought to be useful for diabetic patients who are refractory to conventional insulin therapy or are being treated with steroids. The optimal target range for blood glucose levels in these critically ill patients has not yet been established.3

Blood Glucose Tests Should Be Rapid and Accurate

Bedside glucose monitors enable rapid testing, which is needed to prevent the development of hypoglycemia in those patients needing intravenous glucose therapy. However, accuracy is very important when intravenous glucose protocols are used. Factors affecting the accuracy of point-of-care glucose monitors include type of sample measured, sampling site, amount of sample applied to a glucometer strip, presence of anemia or peripheral hypoperfusion, or presence in the blood of substances that affect the accuracy of glucose measurement.

Although continuous glucose monitoring systems (CGMS) theoretically provide the optimal solution for avoiding hypoglycemia and reducing the nursing workload in the ICU, they are still being evaluated in pilot studies. There are a few CGMS approved by the FDA for home use, provided they are calibrated daily with a glucose meter on fingerstick blood. CGMS measure the amount of glucose in the interstitial fluid by means of a sensor in the form of a wire that sticks into the skin and is connected to a transmitter.

Blood Glucose Monitoring Systems for Use in the ICU

  • Nova Biomedical Corp. (Waltham, MA) offers StatStrip® glucose monitoring systems, which feature handheld, point-of-care Connectivity and Xpress analyzers. They are used with StatStrip Glucose Strips. The Multi-Well Technology of the test strip measures and corrects hematocrit interference, electrochemical interferences, as well as interferences from acetaminophen, bilirubin, uric acid, ascorbic acid, maltose, galactose, xylose, and oxygen. The system uses 1.2 μL of blood and can deliver a result in 6 sec. The Connectivity Meter can store up to 1000 patient and 200 QC tests and has a built-in barcode scanner. The Xpress meter stores a total of 400 patient and QC tests, and has data transfer capability.
  • HemoCue® America (Cypress, CA) offers the HemoCue Glucose Systems, which consist of a small, dedicated analyzer and unique, disposable microcuvettes that automatically draw a precise specimen volume. These systems can be used for diagnosing or monitoring blood glucose levels in the adult as well as neonate. Measurement is based on a glucose dehydrogenase method. The HemoCue Glucose 201 DM system provides modern data management. By means of a wide range of settings and definable options, the system can be made to prompt the operator for identification, lot numbers, quality control, and other required information during analysis. These data can then be transmitted to clinical information systems. The analyzer can measure glucose in 5 μL of capillary, venous, or arterial whole blood, and results are available in 40–240 sec, depending on blood glucose concentration.
  • Roche Diagnostics, North America (Indianapolis, IN), offers the Accu-Chek® Inform System, a bedside unit intended for use in the quantitative determination of glucose concentration in whole blood samples, and for use by health-care professionals. The system consists of a meter, base unit, and accessory container for the meter and supplies. It performs blood glucose and quality control tests. Data are transferred from the meter to a data management system or LIS via the base unit. The glucose test system uses Accu-Chek Comfort CurveTest Strips and is based on the glucose dehydrogenase method. Results appear in 26 sec.

References

  1. Van den Berghe, G.; Wouters, P. et al. Intensive insulin therapy in critically ill patients. N. Engl. J. Med.  2001, 345, 1359–67.
  2. NICE-SUGAR Study Investigators. Intensive versus conventional glucose control in critically ill patients. N. Engl. J. Med. 2009, 360, 1283–97.
  3. Medscape Reference, Feb 11, 2013. Intravenous Insulin Therapy. Guy W. Soo Hoo, M.D., M.P.H.; Chief Editor: George T. Griffing, M.D.
  4. Lazar, H.L.; McDonnell, M.; et al. The Society of Thoracic Surgeons practice guideline series: blood glucose management during adult cardiac surgery. Ann. Thorac. Surg. 2009, 87, 663–9.

Please check out our Clinical Diagnostics section to find manufacturers that sell these products