A 55-year-old man is evaluated in the post-anesthesia care unit due to altered mental stat… — USMLE Step 3

A $55$ -year-old man is evaluated in the post-anesthesia care unit due to altered mental status, tachypnea, and hypotension. Two hours ago, he underwent an elective laparoscopic cholecystectomy for symptomatic cholelithiasis. His past medical history includes type 2 diabetes mellitus, hypertension, and a pulmonary embolism $4$ months ago. Home medications include metformin, empagliflozin, lisinopril, and rivaroxaban. He was instructed to hold all oral medications on the morning of surgery.

Vital signs show a temperature of $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), blood pressure of $78/48\text{ mmHg}$ , heart rate of $128\text{/min}$ , and respiratory rate of $28\text{/min}$ . Physical examination reveals dry mucous membranes, clear lungs, and delayed capillary refill. The abdomen has appropriately placed, dry surgical dressings. A Foley catheter has drained $30\text{ mL}$ of urine over the last $2$ hours.

Laboratory results are as follows:

Test	Result
Sodium	$136\text{ mEq/L}$
Potassium	$4.8\text{ mEq/L}$
Chloride	$98\text{ mEq/L}$
Bicarbonate	$12\text{ mEq/L}$
Blood urea nitrogen	$32\text{ mg/dL}$
Creatinine	$1.5\text{ mg/dL}$
Glucose	$168\text{ mg/dL}$
Lactate	$1.5\text{ mmol/L}$ (Normal: $0.5\text{--}2.2\text{ mmol/L}$ )
Hemoglobin	$13.2\text{ g/dL}$ (preoperative: $13.5\text{ g/dL}$ )

An arterial blood gas on room air reveals a pH of $7.18$ , pCO $_2$ of $24\text{ mmHg}$ , and pO $_2$ of $92\text{ mmHg}$ .

Aggressive intravenous fluid resuscitation with isotonic crystalloid is initiated. Which of the following is the most appropriate targeted pharmacologic intervention for this patient's underlying condition?

Intravenous regular insulin and $5\%$ dextrose infusionCevap
B
Intravenous regular insulin infusion in $0.9\%$ sodium chloride
C
Intravenous andexanet alfa
D
Intravenous sodium bicarbonate infusion
E
Intravenous hydrocortisone

Cevap

The most appropriate targeted pharmacologic intervention is the simultaneous administration of an intravenous regular insulin infusion and a dextrose-containing fluid (e.g.,

5\%

dextrose).

The patient is presenting with euglycemic diabetic ketoacidosis (euDKA), a known complication of sodium-glucose cotransporter-2 (SGLT2) inhibitors like empagliflozin. This condition is frequently precipitated by physiological stress and fasting, such as surgery. euDKA is characterized by a high anion gap metabolic acidosis (in this case, an anion gap of

26

) with a blood glucose level typically

< 250\text{ mg/dL}

. The treatment fundamentally requires intravenous regular insulin to suppress lipolysis and halt ketogenesis. However, because the patient's blood glucose is already normal or near-normal (

168\text{ mg/dL}

), administering an insulin infusion alone would rapidly precipitate severe, life-threatening hypoglycemia. Therefore, clinical guidelines mandate the simultaneous initiation of a dextrose infusion (e.g., D5W) alongside the insulin until the anion gap closes.

Adım Adım Çözüm

Calculate the anion gap to determine the etiology of the severe metabolic acidosis.

The anion gap is

26\text{ mEq/L}

(

136 - 98 - 12

), indicating a primary high anion gap metabolic acidosis (HAGMA).

Identifying the presence of a HAGMA narrows the differential diagnosis for the patient's severe acid-base derangement.

Evaluate the HAGMA in the context of the patient's other laboratory values and clinical presentation.

The normal lactate (

1.5\text{ mmol/L}

) and stable hemoglobin effectively rule out lactic acidosis secondary to hypoperfusion (from cardiogenic or septic shock) or massive hemorrhage.

This step prevents premature closure and ensures the hypotension is not misinterpreted as the primary driver of the acidosis.

Synthesize the clinical history with the remaining metabolic lab findings.

The patient is fasting post-surgery, has type 2 diabetes, takes an SGLT2 inhibitor (empagliflozin), and has a HAGMA with normal blood glucose (

168\text{ mg/dL}

), confirming euglycemic diabetic ketoacidosis (euDKA).

SGLT2 inhibitors increase renal glucose excretion and glucagon-to-insulin ratios, promoting lipolysis and ketogenesis, especially during physiological stress.

Determine the appropriate pharmacologic management protocol for euDKA.

Intravenous regular insulin is required to halt ketogenesis, but because blood glucose is already

< 250\text{ mg/dL}

, a dextrose infusion must be started simultaneously to prevent hypoglycemia.

Standard DKA protocols delay dextrose until glucose drops, but euDKA requires immediate dextrose supplementation alongside insulin.

Anahtar Kavram

Euglycemic diabetic ketoacidosis (euDKA) is a severe complication of SGLT2 inhibitors (e.g., empagliflozin), especially during physiological stress or fasting. It requires treatment with both intravenous insulin to clear ketones and intravenous dextrose to prevent hypoglycemia.

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