RENAL8: Hypertonic Bicarbonate during Continuous Renal Replacement Therapy in Acute Liver Failure

Abstract

Introduction: Acute liver failure (ALF) is particularly alarming when presenting with vasodilated shock and multi-organ system failure. Standard manufactured hemofiltration fluid (sodium [Na+] = 140 mEq/L) would result in hyponatremia in vivo. We present a case study of hypertonic NaHCO3 infusion to address simultaneous serum Na+ target and correction of acidemia during continuous therapy. Case Presentation: A 42-year-old female with a history of seizures, and heavy alcohol use presented from outside the hospital for evaluation of stroke-like symptoms and subsequent mechanical fall. Urgent head CT was non-contributory. She was found to be in acute liver failure with total bilirubin 4.7, AST: 15,525 ALT: 5,727, ammonia 267 umol/L [reference range: 18-72], acetaminophen level 29 mcg/mL [reference range 10-30], Na+ 128 mEq/L, lactate >20 mmol/L, PT INR 8.1, PH 7.0 on blood gas and a negative ethanol level/salicylate/urine drug screen. After emergent intubation for encephalopathy and multiorgan system failure, she required multiple vasopressors (epinephrine, vasopressin, and norepinephrine), and received N-acetylcysteine protocol, with intravenous bicarbonate infusion and broad-spectrum antibiotic. High dose continuous veno-venous hemodiafiltration (CVVHDF) was initiated via Baxter PrisMax platform and global effluent dosing of 58mL/kg/hr with post-filter 3% NaCl at a rate of 100 mL/hr to reach goal serum sodium of 140 mEq/dL. [3% NaCl infusion rate calculation: (target infused Na – 140 mEq/L)/ (513 mEq/L – 140 mEq/L) x hemofiltration rate (mL/h)]. She also received Therapeutic Plasma Exchange for ALF for 5 daily sessions using fresh frozen plasma. She continued to have ongoing acidosis with a lactate of 11.7 mmol/L, and serum bicarbonate of 17 mEq/L. On Hospital Day 6, 3% NaCl was changed to hypertonic NaHCO3 drip [4.2% NaHCO3 solution (500 mEq/L in 1L of D5W) at a rate of 100 mL/hr, replacing 3% NaCl on a 1:1 ratio mL/mL]. After 24 hours she had improvement in metabolic acidosis with improvement in serum bicarbonate from 17 to 24 mEq/L, pH of 7.34 to 7.40; pCO2 32 to 42, HCO3 17 to 25 mmHg and serum Na 133 to 140 mEq/L. Unfortunately, on hospital day 8 developed worsening shock requiring vasopressors; a repeat abdominal imaging noted high-grade small bowel obstruction with ischemic bowel and pneumatosis intestinalis and was transitioned to comfort care. Discussion: While CVVHDF can address elevated ammonia in ALF, infused standard therapy fluid (Na+ = 140 mEq/L) would equilibrate serum Na+ to 133 - 135 mEq/L, in the presence of plasma proteins. Post-filter hypertonic saline infusion during CVVHDF would enable simultaneous clamping of serum Na+ to the appropriate target level. Due to heavier molecular size, 4.2% NaHCo3 results in identical Na+ delivery of 3% saline along with the added benefit of improving acidosis. Clinical studies are desirable to define optimal serum Na+ concentrations during CVVDF in various clinical settings.