The Real-World Boards: Question #14
A 76-year-old man with heart failure who develops renal failure during diuresis
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A 76-year-old man was admitted to the intermediate unit 5 days ago after presenting to the ED with dyspnea and leg edema. He has heart failure with reduced ejection fraction and was reportedly nonadherent with outpatient medications and a low-sodium diet.
He was diagnosed with decompensated heart failure. Furosemide 40 mg and then 80 mg b.i.d. IV was provided. He initially had high urine output with net volume losses, but urine output has declined to 500 mL in the past 24 hours. His baseline creatinine is 1.9 mg/dL and has increased to 2.5 mg/dL.
BP is 110/75, heart rate 101/min. He initially required 4 L/min nasal cannula oxygen but now requires high-flow nasal cannula oxygen at 40% FiO2 at 40 L/min, alternating with noninvasive ventilation. Respirations are 28/min with mildly increased work of breathing. He has pitting edema in both legs and distended neck veins.
Other medications include metoprolol, lisinopril, aspirin, and atorvastatin.
Notable labs include:
Cardiorenal syndrome is a common complication of decompensated heart failure. The pathophysiology is complex, and involves:
Impaired renal perfusion due to reduced forward flow (cardiac output) and increased venous congestion;
Increased neurohumoral tone (activation of the renin-angiotensin-aldosterone and sympathetic nervous systems);
Decreased effective arterial blood volume with reduced sodium delivery to the renal tubules, which interpret the above signals as underfilling and therefore remain sodium-avid, reducing the efficacy of loop diuretics.