title: Low-flow CO₂ removal integrated into a renal-replacement circuit can reduce acidosis and decrease vasopressor requirements.
abstract: BACKGROUND
  Lung-protective ventilation in patients with ARDS and multiorgan failure, including renal failure, is often paralleled with a combined respiratory and metabolic acidosis. We assessed the effectiveness of a hollow-fiber gas exchanger integrated into a conventional renal-replacement circuit on CO₂ removal, acidosis, and hemodynamics.
  
  
  METHODS
  In ten ventilated critically ill patients with ARDS and AKI undergoing renal- and respiratory-replacement therapy, effects of low-flow CO₂ removal on respiratory acidosis compensation were tested by using a hollow-fiber gas exchanger added to the renal-replacement circuit. This was an observational study on safety, CO₂-removal capacity, effects on pH, ventilator settings, and hemodynamics.
  
  
  RESULTS
  CO₂ elimination in the low-flow circuit was safe and was well tolerated by all patients. After 4 hours of treatment, a mean reduction of 17.3 mm Hg (-28.1%) pCO₂ was observed, in line with an increase in pH. In hemodynamically instable patients, low-flow CO₂ elimination was paralleled by hemodynamic improvement, with an average reduction of vasopressors of 65% in five of six catecholamine-dependent patients during the first 24 hours.
  
  
  CONCLUSIONS
  Because no further catheters are needed, besides those for renal replacement, the implementation of a hollow-fiber gas exchanger in a renal circuit could be an attractive therapeutic tool with only a little additional trauma for patients with mild to moderate ARDS undergoing invasive ventilation with concomitant respiratory acidosis, as long as no severe oxygenation defects indicate ECMO therapy.
authors.forename: Christian
authors.initials: C
authors.lastname: Forster
authors.forename: Jens
authors.initials: J
authors.lastname: Schriewer
authors.forename: Stefan
authors.initials: S
authors.lastname: John
authors.forename: Kai-Uwe
authors.initials: KU
authors.lastname: Eckardt
authors.forename: Carsten
authors.initials: C
authors.lastname: Willam
mesh_terms: D000138:Acidosis / Q000097:blood* / Q000517:prevention & control*; D000368:Aged; D001784:Blood Gas Analysis / Q000295:instrumentation / Q000379:methods; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000295:instrumentation / Q000379:methods*; D017582:Renal Replacement Therapy / Q000295:instrumentation / Q000379:methods; D014662:Vasoconstrictor Agents / Q000008:administration & dosage*
chemical_list: D014662:Vasoconstrictor Agents; D002245:Carbon Dioxide