Diabetic Ketoacidosis (DKA)
Diabetic ketoacidosis is a condition that occurs when the body is deprived of the ability to use glucose as an energy source. Usually this is due to a lack of insulin. Insulin is used to uptake glucose into the cells to be used for energy. If there is no insulin or the cells are resistant to insulin, the blood sugar levels increase to dangerous levels for the patient. It seems counter intuitive that the patient wouldn't have energy with such high levels of glucose, but this glucose is essentially unusable without insulin. Because your body needs energy to survive, it starts turning to alternative fuel sources (fat). Fat cells start breaking down and, as a result, release ketones (which are acidic) into the bloodstream. Hence the name: diabetic ketoacidosis.
The most common causes of DKA are not getting enough insulin, having a severe infection, becoming dehydrated, or a combination of these issues. It seems like it occurs mainly in patients with type one diabetes.
Some of the symptoms that people experience with DKA include the following:
- Excessive thirst and urination (more water is pulled into the urine as a result of high ketone loss in the urine)
- Breathing very quickly (patients have a very high level of acids in their bloodstream and they try to "blow" off carbon dioxide by breathing quickly)
- A fruity odor on their breath (ketones have a fruity smell)
- Nausea and vomiting (the body tries to get rid of acids any way it can-even stomach acid!)
- Blurred vision
- Decreased perspiration (in line with the excessive urination...patients are very dehydrated)
As more ketones accumulate in the blood and are passed through the urine, more sodium and potassium electrolytes are removed with them. Watch for electrolyte imbalances!
Severe DKA requires admission to an ICU for frequent monitoring, lab draws, and blood glucose checks. Patients in my ICU are placed on an insulin IV drip which is closely monitored. We check hourly blood sugars and then titrate the insulin drip to the level. An ideal amount for someone blood sugar to drop is 50-100 mg/dL per hour. More than that and the patient can experience cerebral edema and demyelination as a result.
Electrolytes are also of huge concern with DKA patients. Here is a pretend patient's BMP upon admission for DKA:
- Potassium: 5.5 (normal range: 3.5-5.5)
- Anion Gap: Unable to calculate (AKA greater than 30; normal range: 6-14)
- Glucose: 925 (normal range: 70-120)
- Magnesium: 1.6 (normal range:1.4-2.6)
- Phosphorus: 1.8 (normal range: 2.3-5.6)
- Bicarbonate (same as CO2 on a BMP): Less than 5 (normal range 20-30)
We are frequently monitoring the patient's electrolytes (usually every four hours) to be sure that they do not either get too high or too low. Remember that as insulin is used to pull sugar into the cells, potassium is also used at the same time!When a patient is severely hyperkalemic, doctors will sometimes order D50 (pretty much straight sugar) and insulin to be given because using insulin decreased potassium levels. Be sure not to bottom out your patient's potassium as you are normalizing their sugar. The electrolytes all work hand in hand so monitor magnesium and phosphorus as well.
The anion gap is a good judge of how well the DKA is resolving. The anion gap is calculated on your BMP. If you wanted to calculate it manually (which we never do), it is a measurement of the number of chloride and bicarbonate anions together subtracted from the number of sodium and potassium cations. You can see why it's a good measure because as your DKA resolves your electrolytes become more stable and your anion gap returns to normal.
The bicarbonate is also a good measurement of how the DKA is progressing. As your acid level rises in your body (due to the acidic ketones), the bicarbonate is used as a buffer to try and relieve some of the acidity. This depletes the bicarbonate. Sometimes in severe cases of DKA the doctors will put the patients on a bicarbonate IV drip to try and help neutralize the patient's acids. The patient will naturally try and expel extra acids by breathing quickly and blowing off carbion dioxide (which is an acid). Their venous blood gas is going to be UGLY! An example is as follows: pH 7.06, pCO2 20, and bicarb 5. UGLY! Don't freak out though. This will resolve as the ketones are expelled and the bicarb increases.
As the patient recovers from DKA, the anion gap will decrease and the bicarbonate will increase. The patient's sugar will begin to resolve as you give insulin and everything else usually follows suit. Once the blood sugar has resolved, we usually supplement the patient's IV fluids with D5. The maintenance fluid of choice is generally Lactated Ringers at 200 mL/hr until the blood sugar reaches less than 200; then we change the fluid over to D5/LR. The insulin helps with resolving the DKA so we supplement with sugar to continue the insulin until the DKA is finished. Once the labs have resolved, we give Lantus (long-acting insulin) about 3-4 hours before we discontinue the insulin drip. Patients are usually feeling much better at this point and get transfer orders for a general medical unit.
Other relevant articles include: