Today, we discussed a case of diabetic ketoacidosis (DKA) in a patient with a new diagnosis of diabetes. DKA is characterized by an absolute or relative deficiency of insulin in which ketone acids accumulate in blood so as to cause a fall in arterial pH to less than 7.25 or a decrease in serum bicarbonate to less than 10 mEq per liter (or both).
It is always important to think about what the precipitant is for DKA, so here is a little mnemonic to help you remember the eight major causes that all start with the letter I:
- Infection (think UTI, pneumonia, strep throat)
- Inflammation (like pancreatitis)
- Initial diagnosis
- Infarction or ischemia (like an MI or stroke)
- Insulin deficiency (patient not taking at all, not taking enough for their physiologic needs)
- Infant (pregnancy)
- Illegal drugs (cocaine, meth, etc)
- Iatrogenic (mainly drug interactions, such as starting prednisone)
The cornerstones of management are:
1) Rapid intravascular volume repletion with IVF
- Start with normal saline bolus, then continue at ~20mL/kg/hr
- Switch to half isotonic saline if the *corrected* sodium is normal or elevated (corrected= for every 100 above normal glucose, add ~2 mEq of Na to the serum sodium level)
- Add dextrose (can do D5 half NS) once the serum glucose is less than 200
2) Correction of hyperglycemia and acidosis with insulin drip. Only start if the K is > 3.3, otherwise replete first. The standard is an insulin drip often with 0.1 units/kg IV bolus, then start a continuous IV infusion 0.1 units/kg per hour. Stop the drip when: the patient's anion gap is closed, the patient is eating, and 1-2 hours after you have given SC insulin.
3) Electrolyte replacement as needed, particularly potassium. That is, regardless of the initial measured serum potassium, patients with DKA have a large total body potassium deficit.
• IfK+ is <3.3 mEq/L, hold insulin and give potassium chloride 20 to 40 mEq/hour IV until K is >3.3 mEq/L (avoid life-threatening muscle weakness and cardiac arrhythmias)
• If K+ is 3.3 - 5.3 mEq/L, give potassium chloride 20 to 30 mEq per liter IV fluid; goal K+ 4 to 5
• If K+ is > 5.3 mEq/L, do not give potassium
4) Monitoring: CBGs every hour, basic chemistry every 2 hours