title: Transmission of arterial oxygen partial pressure oscillations to the cerebral microcirculation in a porcine model of acute lung injury caused by cyclic recruitment and derecruitment.
abstract: BACKGROUND
  Cyclic recruitment and derecruitment (R/D) play a key role in the pathomechanism of acute lung injury (ALI) leading to respiration-dependent oscillations of arterial partial pressure of oxygen (Pa(O(2))). These Pa(O(2)) oscillations could also be forwarded to the cerebral microcirculation.
  
  
  METHODS
  In 12 pigs, partial pressure of oxygen was measured in the thoracic aorta (Pa(O(2))) and subcortical cerebral tissue (Pbr(O(2))). Cerebral cortical haemoglobin oxygen saturation (Sbr(O(2))), cerebral blood flow (CBF), and peripheral haemoglobin saturation (Sp(O(2))) were assessed by spectroscopy and laser Doppler flowmetry. Measurements at different fractions of inspired oxygen (F(I(O(2)))) were performed at baseline and during cyclic R/D.
  
  
  METHODS
  frequency domain analysis, the Mann-Whitney test, linear models to test the influence of Pa(O(2)) and systolic arterial pressure (SAP) oscillations on cerebral measurements.
  
  
  RESULTS
  Parameters [mean (SD)] remained stable during baseline. Pa(O(2)) oscillations [10.6 (8) kPa, phase(reference)], systemic arterial pressure (SAP) oscillations [20 (9) mm Hg, phase(Pa(O(2))-SAP) -33 (72)°], and Sp(O(2))oscillations [1.9 (1.7)%, phase(Pa(O(2))-Sp(O(2))) 264 (72)°] were detected during lung R/D at 1.0. Pa(O(2)) oscillations decreased [2.7 (3.5) kPa, P=0.0008] and Sp(O(2)) oscillations increased [6.8 (3.9)%, P=0.0014] at F(I(O(2))) 0.3. In the brain, synchronized Pbr(O(2)) oscillations [0.6 (0.4) kPa, phase(Pa(O(2))-Pbr(O(2))) 90 (39)°], Sbr(O(2)) oscillations [4.1 (1.5)%, phase(Pa(O(2))-Sbr(O(2))) 182 (54)°], and CBF oscillations [198 (176) AU, phase(Pa(O(2))-CBF) 201 (63)°] occurred that were dependent on Pa(O(2)) and SAP oscillations.
  
  
  CONCLUSIONS
  Pa(O(2)) oscillations caused by cyclic R/D are transmitted to the cerebral microcirculation in a porcine model of ALI. These cyclic oxygen alterations could play a role in the crosstalk of acute lung and brain injury.
authors.affiliation: Department of Anaesthesiology, Medical Center of the Johannes Gutenberg-University, Mainz, Germany. klaus.klein@meduniwien.ac.at
authors.forename: K U
authors.initials: KU
authors.lastname: Klein
authors.forename: S
authors.initials: S
authors.lastname: Boehme
authors.forename: E K
authors.initials: EK
authors.lastname: Hartmann
authors.forename: M
authors.initials: M
authors.lastname: Szczyrba
authors.forename: L
authors.initials: L
authors.lastname: Heylen
authors.forename: T
authors.initials: T
authors.lastname: Liu
authors.forename: M
authors.initials: M
authors.lastname: David
authors.forename: C
authors.initials: C
authors.lastname: Werner
authors.forename: K
authors.initials: K
authors.lastname: Markstaller
authors.forename: K
authors.initials: K
authors.lastname: Engelhard
mesh_terms: D055371:Acute Lung Injury / Q000150:complications* / Q000503:physiopathology*; D000768:Anesthesia, General; D000818:Animals; D001785:Blood Gas Monitoring, Transcutaneous; D001794:Blood Pressure / Q000187:drug effects; D001992:Bronchoalveolar Lavage Fluid; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003399:Craniotomy; D006439:Hemodynamics / Q000502:physiology; D017078:Laser-Doppler Flowmetry; D008168:Lung / Q000503:physiopathology*; D008833:Microcirculation / Q000502:physiology*; D010100:Oxygen / Q000097:blood*; D012121:Respiration, Artificial; D013552:Swine; D012122:Ventilators, Mechanical
chemical_list: D010100:Oxygen