title: Respiratory dialysis: reduction in dependence on mechanical ventilation by venovenous extracorporeal CO2 removal.
abstract: OBJECTIVE
  Mechanical ventilation is injurious to the lung. Use of lung-protective strategies may complicate patient management, motivating a search for better lung-replacement approaches. We investigated the ability of a novel extracorporeal venovenous CO2 removal device to reduce minute ventilation while maintaining normocarbia.
  
  
  METHODS
  Prospective animal study.
  
  
  METHODS
  Government laboratory animal intensive care unit.
  
  
  METHODS
  Seven sedated swine.
  
  
  METHODS
  Tracheostomy, volume-controlled mechanical ventilation, and 72 hrs of round-the-clock intensive care unit care. A 15-F dual-lumen catheter was inserted in the external jugular vein and connected to the Hemolung, an extracorporeal pump-driven venovenous CO2 removal device. Minute ventilation was reduced, and normocarbia (Paco2 35-45 mm Hg) maintained. Heparinization was maintained at an activated clotting time of 150-180 secs.
  
  
  RESULTS
  Minute ventilation (L/min), CO2 removal by Hemolung (mL/min), Hemolung blood flow, O2 consumption (mL/min), CO2 production by the lung (mL/min), Paco2, and plasma-free hemoglobin (g/dL) were measured at baseline (where applicable), 2 hrs after device insertion, and every 6 hrs thereafter. Minute ventilation was reduced from 5.6 L/min at baseline to 2.6 L/min 2 hrs after device insertion and was maintained at 3 L/min until the end of the study. CO2 removal by Hemolung remained steady over 72 hrs, averaging 72 ± 1.2 mL/min at blood flows of 447 ± 5 mL/min. After insertion, O2 consumption did not change; CO2 production by the lung decreased by 50% and stayed at that level (p < .001). As the arterial PCO2 rose or fell, so did CO2 removal by Hemolung. Plasma-free hemoglobin did not change.
  
  
  CONCLUSIONS
  Venovenous CO2 removal enabled a 50% reduction in minute ventilation while maintaining normocarbia and may be an effective lung-protective adjunct to mechanical ventilation.
authors.affiliation: US Army Institute of Surgical Research, Brooke Army Medical Center, Fort Sam Houston, San Antonio, TX, USA. andriy.batchinsky@amedd.army.mil
authors.forename: Andriy I
authors.initials: AI
authors.lastname: Batchinsky
authors.forename: Bryan S
authors.initials: BS
authors.lastname: Jordan
authors.forename: Dara
authors.initials: D
authors.lastname: Regn
authors.forename: Corina
authors.initials: C
authors.lastname: Necsoiu
authors.forename: William J
authors.initials: WJ
authors.lastname: Federspiel
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Morris
authors.forename: Leopoldo C
authors.initials: LC
authors.lastname: Cancio
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D002405:Catheterization, Central Venous; D004867:Equipment Design; D005112:Extracorporeal Circulation / Q000295:instrumentation*; D005260:Female; D006440:Hemofiltration / Q000295:instrumentation*; D012131:Respiratory Insufficiency / Q000097:blood / Q000628:therapy*; D013552:Swine; D015300:Ventilator Weaning / Q000295:instrumentation*
chemical_list: D002245:Carbon Dioxide