Diabetic Ketoacidosis Induced increased Tidal Volume USMLE Step 2 CK

What’s happening to the girl?

• She has diabetic ketoacidosis (DKA), a serious complication of type 1 diabetes.

• Her body does not have enough insulin, so it starts breaking down fat for energy.

• This leads to acid buildup (ketones) in the blood, causing the symptoms.

Clues from the question:

• Excessive thirst & urination (polydipsia, polyuria) → Classic signs of diabetes.

• Weight loss → Her body is burning fat instead of using sugar.

• Fruity breath smell → Due to ketones, a sign of DKA.

• Vomiting, nausea, and abdominal pain → Common symptoms of DKA.

• Fatigue but still alert → She’s sick but not yet in a coma.

Why is the answer "Increased tidal volume" (C)?

• DKA causes high acid levels in the blood (metabolic acidosis).

• The body tries to fix this by breathing faster & deeper (Kussmaul breathing) to remove excess acid (CO₂).

• Tidal volume = amount of air taken in with each breath.

• In DKA, tidal volume increases as the body breathes deeply to compensate for the acidosis.

Why not the other options?

• A) Exophthalmos (bulging eyes) → Seen in Graves' disease (hyperthyroidism), not diabetes.

• B) Hypertension (high blood pressure) → DKA usually causes low blood pressure due to dehydration.

• D) Neutropenia (low white blood cells) → No link to DKA; usually seen in infections or chemotherapy.

• E) Thrombocytopenia (low platelets) → Not related to diabetes or DKA.

Conclusion:

• The best answer is "Increased tidal volume" (C) because of Kussmaul breathing in DKA.

• This deep, fast breathing helps remove acid from the body.