Perioperative Management of Blood Glucose
Diabetes is so prevalent that it very common to be managing patients perioperatively with this chronic disorder. I felt that a post was necessary because there are reasons why tight glucose control is important and also multiple methods to managing blood glucose. Studies have shown that there is a decreased morbidity (decreased risk of infection, cardiovascular complications...) with blood glucose control. Blood glucose levels can be difficult to control during surgery and anesthesia, however, due to an increase in counterregulatory hormones (epinephrine, glucagon, cortisol, cytokines and interluekins) which will lead to insulin resistance and decreased peripheral utilization causing hyperglycemia. Pts are NPO before surgery which can lead to difficulty managing blood glucose levels.
The goals of perioperative managment in diabetic patients include...
I checked on uptodate and there are actually no clear optimal guidelines for the glucose range but it was recommended to keep the glucose readings between 140-200. The article stated that trying to get the glucose levels to a normal value was not associated with a reduction of post op infections or cardiac events but was associated with an increase in hypoglycemic episodes.
Strategies to maintain the target ranges for glucose (again, there is no optimal range set as of now) have been proposed and are described below.
Type 2 diabetes treated with diet alone
These patients do not need any therapy perioperatively unless their glucose levels climb out of the target range. If correction is needed, the pt can be treated with rapid-acting (lispro, aspart or glusine) or short-acting (regular). Short surgeries (2 hours or less) can check the blood glucose before and after surgery. Longer than 2 hours, you can check the blood glucose every 1-2 hours intraoperatively.
Type 2 diabetes patient's treated with oral hypoglycemic agents or non-insulin injectables (not insulin)
Pt can continue their normal medication regimen but hold their oral diabetic medication the morning of surgery. If the patient climbs to the out of target range, they can be treated with short or rapid-acting insulin. Pt can restart medication after pt is able to eat with the exception of metformin which can be restarted after the patient has documented adequate renal function. Sulfonylureas have a side effect of hypoglycemia and should only be restarted once it is documented that the pt can eat. Thiazolidinediones should not be used if the patients develop CHF, edema or liver function abnomalities.
Insulin dependent diabetes
If the procedure is not long or complex (transplant, bypass surgery or neurosurgery) the patient can be treated with subcutaneous insulin. For longer, more complex operations, the patient will need IV insulin drip. IV insulin requires close monitoring and should be checked about every hour. The amount of insulin to give in units/hour can be calculated by this helpful algorithim...
Blood glucose/100 = Units/hour
Example- blood glucose = 210 210/100 = 2.1 = 2.1 Units of Insulin/hour should be given
Interesting point came up in surgery today. We had a patient with insulin dependent diabetes and also had a bad history of post-op n/v so we wanted to give her plenty of anti-emetics but we did not give her dexamethasone because of its side effect of hyperglycemia. I read in uptodate though that small doses of dexamethasone, 4-8mg, had a very small hyperglycemic effect. I am unsure if a dose that small would be helpful with anti-emetic action.
I wanted to give myself a little overview of the management but because there are still no optimal guidelines set in place I believe that the management will vary depending on the hospital.
- Avoidance of hypoglycemia (<40 can cause arrythmias or cognitive defects)
- Maintain a balance of electrolytes (hyperosmolar states can causes osmotic diuresis)
- Avoidance of hyperglycemia
- Prevention of ketoacidosis
I checked on uptodate and there are actually no clear optimal guidelines for the glucose range but it was recommended to keep the glucose readings between 140-200. The article stated that trying to get the glucose levels to a normal value was not associated with a reduction of post op infections or cardiac events but was associated with an increase in hypoglycemic episodes.
Strategies to maintain the target ranges for glucose (again, there is no optimal range set as of now) have been proposed and are described below.
Type 2 diabetes treated with diet alone
These patients do not need any therapy perioperatively unless their glucose levels climb out of the target range. If correction is needed, the pt can be treated with rapid-acting (lispro, aspart or glusine) or short-acting (regular). Short surgeries (2 hours or less) can check the blood glucose before and after surgery. Longer than 2 hours, you can check the blood glucose every 1-2 hours intraoperatively.
Type 2 diabetes patient's treated with oral hypoglycemic agents or non-insulin injectables (not insulin)
Pt can continue their normal medication regimen but hold their oral diabetic medication the morning of surgery. If the patient climbs to the out of target range, they can be treated with short or rapid-acting insulin. Pt can restart medication after pt is able to eat with the exception of metformin which can be restarted after the patient has documented adequate renal function. Sulfonylureas have a side effect of hypoglycemia and should only be restarted once it is documented that the pt can eat. Thiazolidinediones should not be used if the patients develop CHF, edema or liver function abnomalities.
Insulin dependent diabetes
If the procedure is not long or complex (transplant, bypass surgery or neurosurgery) the patient can be treated with subcutaneous insulin. For longer, more complex operations, the patient will need IV insulin drip. IV insulin requires close monitoring and should be checked about every hour. The amount of insulin to give in units/hour can be calculated by this helpful algorithim...
Blood glucose/100 = Units/hour
Example- blood glucose = 210 210/100 = 2.1 = 2.1 Units of Insulin/hour should be given
Interesting point came up in surgery today. We had a patient with insulin dependent diabetes and also had a bad history of post-op n/v so we wanted to give her plenty of anti-emetics but we did not give her dexamethasone because of its side effect of hyperglycemia. I read in uptodate though that small doses of dexamethasone, 4-8mg, had a very small hyperglycemic effect. I am unsure if a dose that small would be helpful with anti-emetic action.
I wanted to give myself a little overview of the management but because there are still no optimal guidelines set in place I believe that the management will vary depending on the hospital.
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