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The Use of Insulin Infusions to Improve Outcomes in Critically Ill Patients
Surgery can be a stressful experience for the body, and one of the potential complications that can occur after surgery is high blood sugar levels. High blood sugar, also known as hyperglycemia, can have detrimental effects on the body’s overall health and slow down the healing process. Luckily, there are effective ways to manage this condition and improve outcomes in critically ill patients.
Insulin: Beyond Glucose-Lowering Effects
Insulin is currently the primary therapy available for treating acute hyperglycemia. Apart from its ability to lower blood sugar levels, insulin also has various metabolic and cellular actions that can significantly benefit patients. For instance, insulin plays a crucial role in maintaining normal cell metabolism by increasing glucose uptake and adenosine triphosphate (ATP) production through glycolysis. Additionally, insulin provides protection against endothelial dysfunction, reducing the risk of organ failure and death. It also has anti-inflammatory, anti-thrombotic, and anti-atherogenic properties. Insulin treatment causes arterial vasodilation, improves myocardial perfusion, and even exhibits direct cardioprotective effects that are independent of glucose concentrations.
The Role of Insulin Infusions
The use of insulin infusions to improve outcomes during critical illness originally began with the use of glucose-insulin-potassium (GIK) infusions for the treatment of myocardial ischemic events. GIK infusions were found to increase myocardial glucose uptake and utilization, which improves myocardial efficiency and contractile function following acute myocardial ischemia. Additionally, GIK inhibits fatty acid oxidation, leading to improved myocardial oxygen consumption and decreased production of arrhythmogenic substrates.
Studies investigating the use of GIK have reported improved outcomes after myocardial infarction and cardiac surgery. However, some investigations did not find a beneficial effect, possibly due to the adverse effects of hyperglycemia that may occur with GIK. Nevertheless, further research on glucose control using conventional insulin infusions focused on critically ill patients and patients who recently underwent cardiac surgery.
Intensive Insulin Therapy: A Game Changer
In 2001, a landmark investigation reported significant decreases in morbidity and mortality in critically ill and cardiac surgical patients when intensive insulin therapy was used to achieve normoglycemia (glucose target between 80 and 110 mg/dL). This approach, also known as “tight” glucose control, resulted in lower risks of bloodstream infections, renal failure, critical illness polyneuropathy, and a 30% decrease in mortality. The results were met with enthusiasm and led to the establishment of tight glucose control as the standard of care in many institutions.
However, subsequent randomized controlled trials and meta-analyses presented conflicting results. Some trials found no benefit in mortality rates or organ failure scores when using tight glucose control, and the risk of hypoglycemia was significantly higher. A large randomized controlled trial called NICE SUGAR even reported increased mortality in patients who received intensive insulin therapy.
Rethinking Glucose Control
The reasons behind these different outcomes compared to the initial landmark investigation are not entirely clear. It is possible that the standard of care for glucose management has evolved over the years, resulting in less severe hyperglycemia and, consequently, less severe outcomes in control groups. Nevertheless, most experts now believe that tight glucose control does not have a beneficial effect on mortality and may instead increase the risk of serious adverse events, including hypoglycemia.
When blood sugar levels are high after surgery, it is essential to work closely with healthcare professionals to develop an individualized treatment plan. This plan may include insulin therapy, dietary adjustments, and regular blood sugar monitoring. Managing blood sugar levels effectively can help improve post-surgery outcomes and facilitate a speedy recovery.
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