Diabetes Mellitus
Anesthesia Implications
Anesthesia Implications
Preoperative assessment – should include determining how much insulin is normally required to control blood glucose (BG) along with any acute and/or chronic conditions associated with DM
Monitor regularly – There are multiple methods/theories on proper blood glucose control, but the prevailing emphasized point is to regularly monitor the blood glucose levels (recommended every 30-60 minutes) with correction if necessary.
Difficult airway risk – Patients with diabetes mellitus should be anticipated difficult airways. The “prayer sign”, a symptom of stiff joint syndrome (or diabetic scleredema), would be further indication of a difficult airway and long-standing diabetes.
Consider RSI – Delayed GI motility predisposes these patients to aspiration during induction, so diabetics should be treated as if they have a full stomach. Preoperative treatment should include drugs that inhibit secretion and neutralize gastric acid.
Drug considerations – Drugs that raise blood glucose (e.g. Decadron) are generally avoided in diabetic patients. Beta blockers may mask the signs/symptoms of hypoglycemia in diabetic patients. Insulin dependent patients are more prone to anaphylaprotamine sulfatectic reactions to protamine sulfate.
Give sufficient oxygen – diabetes negatively affects oxygen transport by glucose covalently binding to hemoglobin. This alters the way oxygen binds to hemoglobin and may decrease O2 saturation and RBC O2 transport.
Careful positioning – Diabetic patients are much more susceptible to compression and stretch nerve injuries.
Immunocompromise – Diabetes is also a cause of immunocompromise. These patients will have a higher risk for delayed recovery and infection.
Watch for arrhythmias – Diabetes (especially insulin dependent) is a strong contributor to ischemic heart disease. These patients will be at a much higher risk of developing an acute MI during surgery than patients without diabetes.
Considerations of Diabetics With Autonomic Dysfunction
Degree of severity – The corrected QT interval on the ECG will correlate with the severity of autonomic dysfunction
Aspiration risk – Gastroparesis, decreased cough reflex threshold, and higher incidence of obstructive sleep apnea (OSA).
Keep normothermic – delayed compensation for changes in temperature
Delayed hemodynamic compensation – Hydrate and be ready to pharmaceutically correct swings in BPs
Drugs – Autonomic dysfunction is predictive of the need for a vasopressor during general anesthesia. Delayed or blunted reactions to drugs such as atropine and beta blockers.
Myocardial Infarction – Pain may be mild or absent if there is an acute myocardial infarction. An MI will exhibit ST elevation or a new LBBB
Diagnosis
Diagnosis is made based on any ONE of the following:
A1C ≥ 6.5%. This test assesses glucose control over the last 2-3 months
Fasting plasma glucose ≥ 126 mg/dL. This requires no caloric intake for at least 8 hours
Two-hour plasma glucose ≥ 200 mg/dL. 75 g of anhydrous glucose is administered PO
Symptoms of hyperglycemia with random BG ≥ 200 mg/dL
Pathophysiology
Considered a metabolic disorder
Diabetes mellitus type 1 is typically caused by an autoimmune destruction of pancreatic beta cells. Diabetes type 2 is caused by a combination of a cellular resistance to insulin (this is the primary cause) and decreased insulin release. Gestational diabetes mellitus is diabetes that is first diagnosed during pregnancy. More than 75% of patients with diabetes type 2 may find resolution of the disease simply by losing weight.
Retinal and renal nerve cells do not require insulin for glucose to pass into the cells. Hyperglycemia will cause a buildup of cellular sorbitol. Sorbitol will increase intracellular osmolarity, which results in nerve dysfunction.
Three major complications can result from diabetes: Diabetic ketoacidosis (type 1 DM), hyperglycemic non-ketotic state (type 2 DM), and hypoglycemia.
Blood glucose control is best determined using the glycosylated hemoglobin A1C, which will assess glucose control over the last 2-3 months.
Diabetes contributes to the development of atherosclerosis, peripheral arterial disease, ischemic heart disease, heart failure (both diastolic and systolic), aortic stenosis, atrial fibrillation, stroke, cognitive dysfunction, nonalcoholic fatty liver disease
Conditions that can cause or contribute to the development of diabetes: Cystic fibrosis, gout, hemochromatosis, and obesity
Additional Notes:
Diabetes causes increased fasting serum gastrin levels.
Hines. Stoelting’s anesthesia and co-existing disease. 7th edition. 2018. p. 70-73, 83, 85, 162, 324, 350, 364, 367, 382-384, 388, 399, 367,
Chestnut. Chestnut’s obstetric anesthesia principles and practice. 5th edition. 2014. p. 118-120, 148, 158, 168, 195, 201, 555, 828, 838, 888, 1003-1012
