Anesthesiology APPLIED Exam › Endocrine, renal, hepatic and metabolic

Acute kidney injury

Endocrine, renal, hepatic and metabolic·~4 min read· Physician-reviewed✓ Sourced · 2

Stem

A 72-year-old man, 80 kg, with hypertension and a baseline creatinine of 1.1 mg/dL, is on postoperative day 1 after open repair of an abdominal aortic aneurysm that needed a suprarenal clamp for 28 minutes. Over the last 8 hours his urine output has averaged 25 mL/h. Creatinine this morning is 1.8 mg/dL. Blood pressure is 104/62 on no pressors, heart rate 96, and his abdomen is tense.

Question

Does he have acute kidney injury, and how will you manage it?

Ideal answer

HeadlineYes: creatinine up 0.7 mg/dL in under 48 hours and urine about 0.3 mL/kg/h for 8 hours meet KDIGO.¹ I hunt for a reversible cause.

Stage it: stage 1 now, heading to stage 2, at 1.6 times baseline with oliguria under 12 hours.¹
Obstruction first: flush the catheter, scan the bladder, the quickest reversible cause to exclude.
Bladder pressure for abdominal compartment syndrome, because his abdomen is tense after aortic repair; that needs decompression.
Dynamic measures and echo; if fluid-responsive, isotonic crystalloid, not colloid, and no starch;¹^,2 a vasopressor with fluid rather than flooding him, because his pressure is low for a hypertensive man.¹
Stop nephrotoxins: NSAIDs, aminoglycosides, avoidable contrast, dosing to current renal function; no low-dose dopamine, diuretic only for overload.¹

Watch for: hourly urine, creatinine and potassium daily or sooner, dialysis indications.

Breaking down the answer

Define and stage out loud — KDIGO uses a creatinine rise of ≥0.3 mg/dL in 48 hours, ≥1.5 times baseline within 7 days, or urine below 0.5 mL/kg/h for 6 hours.¹ Staging shows organization.
Prerenal, renal, postrenal by reversibility — a blocked catheter is the fastest fix; suprarenal clamping and hypotension point toward ischemic injury.
Compartment syndrome after aortic surgery — a tense abdomen with oliguria changes management from fluids to decompression; this is the adaptability examiners want, and repeated boluses before checking it is the classic error.
Why no starch — hydroxyethyl starch is used only when no adequate alternative exists, because it is linked to kidney injury and death.¹^,2
Pressure, not just volume — in vasomotor shock KDIGO recommends vasopressors together with fluids.¹
Drop the myths — low-dose dopamine does not prevent or treat AKI, and diuretics do not prevent it.¹

Follow-up question

Thirty-six hours later he has made 60 mL of urine in 12 hours. Potassium is 6.6 mmol/L with peaked T waves, pH 7.18, and he has crackles with SpO2 90% on 6 L/min. What do you do?

Follow-up answer

HeadlineSevere oliguric AKI, at least stage 2 and heading to dialysis, with life-threatening hyperkalemia, acidosis and overload. I call nephrology and ICU now.

KDIGO calls for emergent renal replacement therapy when life-threatening fluid, electrolyte or acid-base changes exist.¹ While the dialysis catheter goes in, IV calcium stabilizes the myocardium, insulin and dextrose shift potassium, and noninvasive ventilation or intubation supports oxygenation if he tires. A diuretic trial is reasonable because he is overloaded, but it must not delay dialysis.¹ I stop potassium-containing fluids, choose continuous therapy if he becomes unstable, and reassess potassium, gas and ECG hourly until dialysis runs.

Pitfalls that cost points

Using furosemide to "turn on" the kidneys.
Waiting for a creatinine threshold to start dialysis when hyperkalemia or pulmonary edema already exists.

Rapid-fire

Q: What defines stage 3 AKI? A: Creatinine 3 times baseline or ≥4.0 mg/dL, starting RRT, urine below 0.3 mL/kg/h for 24 hours, or anuria for 12 hours.¹

Q: How do you prevent contrast-associated AKI in a high-risk patient? A: IV volume expansion with isotonic saline or sodium bicarbonate, not oral fluids alone.¹

Q: What glucose target does KDIGO suggest in critically ill patients? A: 110–149 mg/dL.¹

Q: Which amphotericin formulation is preferred? A: Lipid formulations over conventional amphotericin B.¹

Q: Should you start dialysis on a creatinine number alone? A: No; KDIGO asks for the broader clinical picture and trends, not single urea and creatinine thresholds.¹

Numbers to know

Item	Value
AKI definition, creatinine	≥0.3 mg/dL in 48 h or ≥1.5× baseline in 7 days¹
AKI definition, urine	<0.5 mL/kg/h for 6 h¹
Stage 1	1.5–1.9× baseline; <0.5 mL/kg/h for 6–12 h¹
Stage 2	2.0–2.9× baseline; <0.5 mL/kg/h for ≥12 h¹
Stage 3	3× baseline, ≥4.0 mg/dL or RRT; <0.3 mL/kg/h for 24 h or anuria 12 h¹
ICU glucose target	110–149 mg/dL¹

Sources

1.KDIGO Clinical Practice Guideline for Acute Kidney Injury · KDIGO, 2012 · kdigo.org
2.Labeling Changes on Mortality, Kidney Injury, and Excess Bleeding with Hydroxyethyl Starch Products · FDA, 2021 · fda.gov

Facts on this page were checked against these sources on Oct 15, 2026. Guidelines change; confirm doses against current institutional protocols.