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Hyperglycemia ≠- an excess of sugar in the blood – is often linked to worse outcomes in many types of cerebral injuries, according to both animal and human data. A group of Emory University researchers looked at the prevalence of hyperglycemia in critically-ill patients being cared for in a neurointensive care unit (NICU), a unit designated for the sickest neurological and neurosurgical patients, and compared two methods of achieving tighter glycemic control. This is the first study of its kind. The findings were presented at the American Academy of Neurology (AAN) 55th Annual Meeting in Honolulu, Hawaii on April 3.
"We think hyperglycemia and brain injuries are directly related," says Mustapha Ezzeddine, MD, an assistant professor of neurology and neurosurgery, Emory University School of Medicine. "When the brain is injured, the body releases catecholamines, the natural mediators that increase hormones and neurotransmitters. When this happens, the body also increases insulin resistance and blood glucose levels. Weíve found that an increase in glucose levels can cause an injury to worsen."
Research has shown that hyperglycemia can cause worse outcomes following a subarachnoid hemorrhage (bleeding between the brain and the membranes that cover it), intracranial hemorrhage (bleeding in the brain caused by a ruptured blood vessel) and ischemic stroke (cutting off the blood supply to a part of the brain), closed head injury and head trauma injury. "But we donít know if controlling blood glucose levels by giving insulin therapy following a cerebral injury can make a difference in a patientís outcome," says Dr. Ezzeddine. "We do know, however, the results of a recently published study that showed that general critically-ill patients in a surgical ICU, who also developed hyperglycemia, when treated aggressively with insulin, had a reduced mortality."
Emory researchers, lead by Dr. Ezzeddine and Owen Samuels, MD, assistant professor of neurology and neurosurgery and director of the Division of Neurointensive Care at Emory, retrospectively reviewed all available charts of patients admitted for more than 24 hours to the NICU at Emory University Hospital during a period of three months (July-September 2002). The researchers recorded the primary diagnosis, insulin use, glucose levels and discharge disposition, among other things. Most patients were given insulin to treat hyperglycemia most likely brought on by the cerebral event. Some received the standard injection method of giving insulin, which is subcutaneously or just under the skin. Patients with persistent hyperglycemia were treated in a different, more aggressive manner using a continuous intravenous insulin drip to maintain blood glucose levels. This different approach of administering insulin directly into the vein provides much more control when giving insulin.
Out of 33 NICU cases reviewed, 12 patients (36 percent) were treated with an intravenous infusion of insulin (Group I). Of the remaining patients (Group II), most received subcutaneous insulin at least once during their stay (17/21). Admission diagnoses in Group I were one stroke, one brain tumor, six intracerebral hemorrhages and four others. In Group II, there were five brain tumors, 10 intracerebral hemorrhages and six others.
"In Group I, we were able to achieve really tight control of glucose levels in patients treated with intravenous insulin, almost in the close range of normal," Dr. Ezzeddine explains. "We also were able to measure the glucose levels hourly when giving insulin intravenously, rather than three to six hours when administering insulin subcutaneously."
"This type of treatment is not common practice yet, because outcome data are not available at this time," says Dr. Ezzeddine. "General ICUs are looking at using intravenous insulin injections to help reduce infection rates in critically-ill patients, but the approach is not common in neurointensive care units. We plan to continue our research at Emory, but larger, multi-site, placebo-controlled studies are needed to determine outcomes in relation to improved glycemic control in neurocritical patients."
Emory University Hospital is the only hospital in the state of Georgia with a neurocritical care unit and two fellowship-trained neurointensivists on board. Dr. Ezzeddine completed his internship and residency at Duke University Medical Center after receiving his MD. In addition, Dr. Ezzeddine did a fellowship in neurointensive care and stroke at Massachusetts General Hospital in Boston. After receiving his MD, Dr. Samuels completed his internship and residency training at the University of Rochester Medical Center. He then completed a cerebrovascular disease fellowship at Emory University and a second fellowship in neurointensive care medicine at the University of Pennsylvania.