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Difficulty: HardGeneral Internal Medicine

A 22-year-old man with type 1 diabetes mellitus is brought to the emergency department with abdominal pain, nausea, and confusion. He recently had a respiratory infection. His blood pressure is 90/60 mm Hg, and heart rate is 122/min. Point-of-care capillary blood glucose is 550 mg/dL. An arterial blood gas reveals a pH of 7.15 and a bicarbonate of 10 mEq/L. The remainder of his laboratory results, including a basic metabolic panel, are pending. Arrange the following management steps in the most appropriate chronological order for this patient.

  1. 1Administer rapid intravenous fluid resuscitation with 0.9% normal saline
  2. 2Verify that the serum potassium concentration is ≥3.3\geq 3.3 mEq/L
  3. 3Initiate a continuous intravenous infusion of regular insulin
  4. 4Add 5% dextrose to the intravenous fluid composition
  5. 5Transition to a subcutaneous insulin regimen

Answer

The correct sequence is: Administer rapid intravenous fluid resuscitation with 0.9% normal saline, verify that the serum potassium concentration is ≥3.3\geq 3.3 mEq/L, initiate a continuous intravenous infusion of regular insulin, add 5% dextrose to the intravenous fluid composition, and finally transition to a subcutaneous insulin regimen.
The correct chronological sequence for managing diabetic ketoacidosis (DKA) prioritizes physiological stabilization and avoids iatrogenic complications. Severe volume depletion must be addressed immediately with intravenous normal saline to restore perfusion. Before insulin can be administered to halt ketogenesis, the serum potassium level must be verified as ≥3.3\geq 3.3 mEq/L to prevent fatal intracellular shifts. Once safe, a continuous regular insulin infusion is started. As the blood glucose falls below 200 mg/dL, 5% dextrose is added to the fluids to prevent hypoglycemia while the insulin continues to close the anion gap. Finally, once the anion gap is closed and the patient can eat, they are transitioned to a subcutaneous insulin regimen.

Step-by-Step Solution

1
Identify the patient's primary diagnosis and immediate life-threatening physiological derangement.
The patient has diabetic ketoacidosis (DKA) with significant volume depletion, evidenced by hypotension (90/60 mm Hg) and tachycardia.
Severe dehydration and acidosis must be addressed first to restore tissue perfusion.
2
Select the first line of acute management.
Administer rapid intravenous fluid resuscitation with 0.9% normal saline.
Restoring intravascular volume is the most critical initial step, which also helps lower blood glucose by improving renal perfusion and glucose excretion.
3
Determine the prerequisite for insulin therapy.
Verify that the serum potassium concentration is ≥3.3\geq 3.3 mEq/L from the pending basic metabolic panel.
DKA causes a total body potassium deficit. Insulin drives potassium intracellularly; giving insulin to a hypokalemic patient can trigger fatal arrhythmias.
4
Initiate therapy to halt ketogenesis.
Initiate a continuous intravenous infusion of regular insulin.
Once potassium levels are confirmed safe, insulin is required to stop lipolysis, halt ketone production, and close the anion gap.
5
Determine how to prevent hypoglycemia during continued insulin therapy.
Add 5% dextrose to the intravenous fluid composition when blood glucose drops below 200 mg/dL.
Insulin must be continued to close the anion gap even after blood glucose normalizes. Adding dextrose prevents iatrogenic hypoglycemia during this process.
6
Plan the long-term transition out of the acute crisis.
Transition to a subcutaneous insulin regimen.
Once the anion gap is closed, the patient is clinically stable, and can eat, they can safely be transitioned off the continuous intravenous infusion.

Key Concept

The management of diabetic ketoacidosis follows a strict protocol prioritizing volume resuscitation, verification of potassium stores to prevent fatal arrhythmias, insulin administration to close the anion gap, and eventual addition of dextrose to prevent hypoglycemia.
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General Internal Medicine

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