Chapter 26: Acute Kidney Injury and Renal Replacement Therapy
A 70-year-old man presents with peritonitis from a ruptured diverticulum and has an urgent partial colectomy. Postoperatively, he requires vasopressors and multiple liters of IV fluid.
His medical history includes stage 4 CKD from hypertension. His usual medications include lisinopril 20 mg daily, amlodipine 10 mg daily, and furosemide 80 mg twice daily.
On the first postoperative day, his temperature is 101°F, heart rate (HR) is 90 beats/min, and his blood pressure (BP) is 120/60 mmHg. His urine output declines to 5 mL/h despite continued IV fluids and repeat doses of IV furosemide boluses. His abdomen is mildly distended, quiet, and tender to palpation. He has pitting edema of the hands and lower legs. Bladder pressure is 10 cm H2O. His labs showed the following:
|Na ||125 mEq/L |
|K ||6.4 mEq/L |
|Cl ||100 mEq/L |
|BUN ||50 mg/dL |
|CO2 ||18 mEq/L |
|Crea ||4.5 mg/dL |
His urine sediment shows granular casts and cellular debris. An electrocardiogram (ECG) shows tall T waves in precordial leads and a shortened QT interval.
In addition to intravenous calcium, insulin, and dextrose, which the following is the next most appropriate treatment?
A. Furosemide drip at 10 mg/h
B. Sodium zirconium cyclosilicate
C. Sodium polystyrene sulfonate
Emergent indications for hemodialysis are severe metabolic acidosis, hyperkalemia, significant uremia causing altered mental status, pericardial rub and uremic frost, hypervolemia, and toxin removal. Hemodialysis is the most reliable way to address life-threatening hyperkalemia in a patient with severely impaired renal function. Other methods to lower serum potassium are temporary, delayed, and/or require intact renal or gastrointestinal function to be effective.
A furosemide (Lasix) drip would be ineffective (choice A). The patient is almost anuric despite receiving multiple doses of IV furosemide without increase of urine output. Sodium zirconium cyclosilicate is a novel cation exchanger that appears to be effective and have a reasonable onset of action (within 4 hours) but has not been extensively studied, particularly in patients with severe hyperkalemia and ECG changes (choice B). Its safety and efficacy in a patient with recent bowel surgery have not been established. Currently, this agent is approved only for chronic hyperkalemia. Sodium polystyrene sulfonate (Kayexalate) can be given orally or rectally to remove potassium via the gastrointestinal tract (choice C). It is contraindicated in patients with recent bowel surgery due to an increased risk for intestinal necrosis.
A 37-year-old cirrhotic woman undergoes esophagogastroduodenoscopy after developing significant hematemesis and melena at home. The ...