Introduction:
Perioperative hyperglycemia increases the risk of complications post-operatively and the mortality rate. Long-term and perioperative glycemic control is essential for patients undergoing surgery for a better outcome. Increased blood glucose level impairs the functioning of neutrophils which causes increased production of free fatty acids, reactive oxygen species, and inflammatory mediators. These will cause vascular, cellular, and direct cellular dysfunction. Thus perioperative hyperglycemia management is mandatory to provide better surgical outcomes like delayed wound healing, increased hospital stay, increased chances of infections, and reduced mortality rate.
The stress during surgery or type of anesthesia also has an impact on perioperative hyperglycemia. It will increase the secretion of certain hormones like glucagon, cortisol, and growth hormones that will reduce insulin secretion, decrease the peripheral uptake of glucose, and increase resistance towards insulin, lipolysis, and proteolysis are increased. As a result of this, gluconeogenesis and glycogenolysis will increase this condition and worsens hyperglycemia; thus, it is called stress hyperglycemia. Hyperglycemia also disrupts electrolyte and fluid balance and increases pro-inflammatory cytokines, which will result in mitochondrial injury, and dysfunction of the endothelium. As a result of all these following perioperative hyperglycemia results in poor surgical outcomes.
What Are the Metabolic Consequences of Surgical Stress and Anesthesia?
Surgical stress and anesthesia induce hyperglycemia by altering hepatic glucose production and glucose utilization in peripheral tissues. Increased secretion of hormones like cortisol, glucagon, and growth hormone, which are counter-regulatory hormones, causes increased secretion of inflammatory cytokines. Cortisol (stress hormone) increases hepatic glucose production (liver) and promotes gluconeogenesis(a process that converts non-carbohydrate substances into glucose), resulting in increased blood glucose levels.
An increase in stress hormones causes lipolysis (breakdown of fat) and increases free fatty acid levels. These increased free fatty acids prevent insulin-stimulated uptake of glucose. Preoperative carbohydrate loading is done in surgeries because it counteracts the insulin resistance that occurs in response to stress and anesthesia. The enhanced recovery and surgery (ERAS) program induce having a carbohydrate-rich drink at least two hours before surgery. This will increase insulin sensitivity and reduce the risk of hyperglycemia. Types of anesthesia used in surgeries also have an impact on hyperglycemia during surgery because it increases the level of cortisol and glucagon more than epidural anesthesia.
What Is the Prevalence of Hyperglycemia and Diabetes in Surgical Patients?
Approximately 12 % - 30 % of patients who did not have diabetes experienced hyperglycemia during surgery. Stress hyperglycemia is caused by the stress hormone released during surgeries. It will resolve when the stress hormone level is normal. HbA1C is a test done before surgery in patients to differentiate between stress hyperglycemia and patients who have undiagnosed diabetes. A value of 6.5 % or higher confirms diabetes. The joint commission suggests nutritional assessment should be done in all hospital-appointed surgery ongoing patients. It should be done twenty-four hours before the surgery.
What Are the Preoperative Glycemic Management Measures?
Treatment of type 2 diabetes using home medications is done after evaluating a lot of factors. It depends upon the type of diabetes, nature of the surgical procedure, time of preoperative and postoperative fasting, daily medications, etc. Taking oral medications should be considered. Certain medications can be continued on the day of surgery, but a few drugs, like sulfonylurea, should be stopped if they increase the risk of hyperglycemia. Medicines like metformin in diabetic patients should be stopped one day before surgery and continued on the day of surgery when a normal diet is started.
Due to the risk of diabetic ketoacidosis in patients of sodium glucose-cotransporter 2(SGLT-2)inhibitor therapy. Recommendations for this include stoppage of medicine in patients undergoing emergency surgery and holding the medicine 24 hours before elective surgery. In a patient with type2 diabetes who is already on insulin, the therapy dosage is adjusted before and after surgery accordingly. Patients with type1 diabetes require an extra dosage of insulin to prevent the risk of hyperglycemia or diabetic ketoacidosis. Because stress may induce it, these patients should receive 80 % of basal insulin in the evening before surgery and in the morning to prevent the risk of hypoglycemia.
What Are the Intraoperative Glycemic Management Measures?
The value of perioperative glucose level depends on various factors. It includes the duration of the surgical procedure, type of anesthesia used, type of invasive surgical procedure, and when to restart the oral and daily routine anti-diabetic therapy. According to the endocrine society and SAMBA, intraoperative blood sugar should be maintained at a level of less than 18omg/dL. Mostly hyperglycemia is treated with subcutaneous rapid-acting insulin or intravenous infusion. Patients undergoing short-duration surgeries are perfect for this subcutaneous infusion.
The advantages of this infusion are its action in controlling hyperglycemia, its ease of administration, and its low rate of hypoglycemia. In this, blood glucose levels should be monitored every 2 hours. Rapid-acting insulin should not be used more than every two hours to prevent the complication of insulin stacking. The shorter duration of action of a rapid-acting insulin analog limits the side-effect of insulin stacking in repeated doses. Thus limiting the dose to two in four hours will reduce the side effect of hypoglycemia.
Intravenous infusion is given in patients whose surgery causes expected temperature changes(hypothermia), the shift in fluid, anticipated hemodynamic changes, and more than 4 hours of lengthy operation time. These alter the subcutaneous insulin absorption. Due to these reasons, intravenous infusion is done in critically ill patients and cardiac surgery patients. The short half-life of IV insulin allows sudden changes in drug delivery. It has short-lasting effects.
What Are Postoperative Glycemic Management for Non-ICU Patients?
Subcutaneous insulin is used in controlling hyperglycemia in non -ICU and non-critical patients. Blood glucose levels should be monitored every 2 hours in diabetic and non-diabetic patients under insulin. Insulin dose is calculated based on body weight or dose taken at home. The use of oral anti-diabetic drugs is not recommended in hospitalized patients.
How Is Glucose Monitored in the Perioperative Period?
Glucose is monitored by various methods like central laboratory technique, blood gas analysis, and POC-capillary point-of-care testing. Central laboratory technique provides accurate blood glucose levels. The immediate turnaround time of POC provides anesthesia providers and surgeons to make quick decisions.
Conclusion
Increased blood glucose level(hyperglycemia) is common in ongoing surgery patients. Perioperative control of hyperglycemia is very important as it affects the surgery outcome and length of hospital stay, and also to avoid certain complications like delayed wound healing, infection, etc., valid tests should be done on an inpatient who is not diabetic also to check the hyperglycemia. The selection of subcutaneous or intravenous insulin infusion also depends on the patient's individual factors and type of surgery. Blood glucose levels higher than 180 mg/dL or higher should be treated with insulin. Proper care should be given, and multiple teams should work together for screening, monitoring, and treating hyperglycemia cases to avoid complications and provide better care.
