title: The effect of pumpless extracorporeal CO2 removal on regional perfusion of the brain in experimental acute lung injury.
abstract: BACKGROUND
  Lung-protective mechanical ventilation with low tidal volumes (V(T)) is often associated with hypercapnia (HC), which may be unacceptable in patients with brain injury. CO2 removal using a percutaneous extracorporeal lung assist (pECLA) enables normocapnia despite low V(T), but its effects on regional cerebral blood flow (rCBF) remain ambiguous. We hypothesized that reversal of HC by pECLA impairs rCBF in a porcine lung injury model.
  
  
  METHODS
  Lung injury was induced in 9 anesthetized pigs by hydrochloric acid aspiration. rCBF and systemic hemodynamics were measured by colored microsphere technique and transpulmonary-thermodilution during a randomized sequence of 4 experimental situations: pECLA shunt-on (1) with HC and (2) without HC, pECLA shunt-off (3) with HC and (4) without HC.
  
  
  RESULTS
  HC increased rCBF (P<0.05). CO2 removal with pECLA resulting in normocapnia, decreased rCBF to levels comparable to those without pECLA and normocapnia. HC resulted in increased cardiac output (+25.5%). Cardiac output was highest during HC with pECLA shunt (+44.9%). During pECLA with CO2 removal, cardiac output (+38.1%) decreased compared with pECLA without CO2 removal, but stayed higher than during normocapnia/no pECLA shunt (P<0.05).
  
  
  CONCLUSIONS
  In this animal model, mechanical ventilation with low V(T) was associated with HC and increased rCBF. CO2 removal by pECLA restored normocapnia, reduced rCBF to levels of normocapnia, but required a higher systemic blood flow for the perfusion of the pECLA device. If these results could be transferred to patients, extracorporeal CO2 removal might be an option for treatment of combined lung and brain injury in condition of a sufficient cardiac flow reserve.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn, Germany. stefan.kreyer@uni-bonn.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Kreyer
authors.forename: Thomas
authors.initials: T
authors.lastname: Muders
authors.forename: Henning
authors.initials: H
authors.lastname: Luepschen
authors.forename: Corinna
authors.initials: C
authors.lastname: Kricklies
authors.forename: Katharina
authors.initials: K
authors.lastname: Linden
authors.forename: Martin
authors.initials: M
authors.lastname: Soehle
authors.forename: Joerg
authors.initials: J
authors.lastname: Zinserling
authors.forename: Christian
authors.initials: C
authors.lastname: Putensen
authors.forename: Hermann
authors.initials: H
authors.lastname: Wrigge
mesh_terms: D000138:Acidosis / Q000503:physiopathology; D055371:Acute Lung Injury / Q000139:chemically induced / Q000503:physiopathology*; D000818:Animals; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000032:analysis*; D002302:Cardiac Output / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D015199:Extracorporeal Membrane Oxygenation / Q000009:adverse effects*; D006439:Hemodynamics / Q000502:physiology; D006851:Hydrochloric Acid; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000209:etiology / Q000503:physiopathology*; D008863:Microspheres; D015656:Respiratory Mechanics / Q000502:physiology; D013552:Swine
chemical_list: D002245:Carbon Dioxide; D006851:Hydrochloric Acid