A 22-year-old man is brought to the emergency department by his roommate due to progressive lethargy, diffuse abdominal pain, and repeated vomiting for the past 24 hours. He has a history of type 1 diabetes mellitus but ran out of his insulin prescriptions three days ago. On examination, he is obtunded. Temperature is (), blood pressure is , pulse is , and respirations are and deep. Mucous membranes are extremely dry.
Laboratory results show:
| Laboratory Test | Result |
|---|---|
| Serum glucose | |
| Serum sodium | |
| Serum potassium | |
| Serum chloride | |
| Serum bicarbonate | |
| Blood urea nitrogen | |
| Serum creatinine | |
| Arterial pH |
Arrange the following interventions in the most appropriate chronological sequence for the management of this patient.
- 1Administration of rapid isotonic intravenous fluids
- 2Administration of intravenous potassium chloride
- 3Initiation of continuous intravenous regular insulin infusion
- 4Addition of 5% dextrose to maintenance intravenous fluids
- 5Transition to a subcutaneous basal-bolus insulin regimen
Answer
The correct sequence is: Administration of rapid isotonic intravenous fluids, followed by Administration of intravenous potassium chloride, then Initiation of continuous intravenous regular insulin infusion, followed by Addition of 5% dextrose to maintenance intravenous fluids, and finally Transition to a subcutaneous basal-bolus insulin regimen.
The management of diabetic ketoacidosis (DKA) follows a strict, step-wise algorithm to prevent complications such as cerebral edema, severe hypoglycemia, and fatal arrhythmias.
1. Intravenous Fluids: The absolute first step is aggressive volume expansion with 0.9% normal saline. Patients with DKA have a massive total body water deficit due to osmotic diuresis. This patient is profoundly hypotensive, making rapid fluid resuscitation paramount.
2. Potassium Replacement: Although total body potassium is depleted in DKA, initial serum potassium can be normal, high, or low due to extracellular shifts from acidosis. This patient's serum potassium is dangerously low (). Because insulin drives potassium into cells, administering insulin immediately could cause profound hypokalemia and cardiac arrest. Therefore, potassium must be repleted (to ) *before* initiating insulin therapy.
3. Intravenous Insulin: Once potassium is safe (), a continuous IV regular insulin infusion is started. Insulin is essential to halt ketogenesis, resolve the acidosis, and lower glucose levels.
4. Addition of 5% Dextrose: As insulin works, serum glucose falls faster than ketones clear. When glucose reaches approximately , 5% dextrose must be added to the IV fluids. This prevents hypoglycemia while allowing the insulin infusion to continue until the anion gap is closed.
5. Subcutaneous Insulin: When the ketoacidosis has resolved (anion gap , pH ) and the patient is awake and able to eat, they are transitioned to a subcutaneous basal-bolus insulin regimen. The IV infusion is continued for 1-2 hours after the first subcutaneous dose to prevent rebound ketoacidosis.
1. Intravenous Fluids: The absolute first step is aggressive volume expansion with 0.9% normal saline. Patients with DKA have a massive total body water deficit due to osmotic diuresis. This patient is profoundly hypotensive, making rapid fluid resuscitation paramount.
2. Potassium Replacement: Although total body potassium is depleted in DKA, initial serum potassium can be normal, high, or low due to extracellular shifts from acidosis. This patient's serum potassium is dangerously low (). Because insulin drives potassium into cells, administering insulin immediately could cause profound hypokalemia and cardiac arrest. Therefore, potassium must be repleted (to ) *before* initiating insulin therapy.
3. Intravenous Insulin: Once potassium is safe (), a continuous IV regular insulin infusion is started. Insulin is essential to halt ketogenesis, resolve the acidosis, and lower glucose levels.
4. Addition of 5% Dextrose: As insulin works, serum glucose falls faster than ketones clear. When glucose reaches approximately , 5% dextrose must be added to the IV fluids. This prevents hypoglycemia while allowing the insulin infusion to continue until the anion gap is closed.
5. Subcutaneous Insulin: When the ketoacidosis has resolved (anion gap , pH ) and the patient is awake and able to eat, they are transitioned to a subcutaneous basal-bolus insulin regimen. The IV infusion is continued for 1-2 hours after the first subcutaneous dose to prevent rebound ketoacidosis.
Step-by-Step Solution
Key Concept
In the acute management of diabetic ketoacidosis (DKA), fluid resuscitation is the initial priority. Crucially, if serum potassium is , insulin therapy must be delayed until potassium is repleted to prevent life-threatening hypokalemia.