title: Improved arterial oxygenation with biologically variable or fractal ventilation using low tidal volumes in a porcine model of acute respiratory distress syndrome.
abstract: We compared biologically variable ventilation (V (bv); n = 9) with control mode ventilation (V (c); n = 8) at low tidal volume (VT)--initial 6 ml/kg--in a porcine model of acute respiratory distress syndrome (ARDS). Hemodynamics, respiratory gases, airway pressures, and VT data were measured. Static P-V curves were generated at 5 h. Interleukin (IL)-8 and IL-10 were measured in serum and tracheal aspirate. By 5 h, higher Pa(O(2)) (173 +/- 30 mm Hg versus 119 +/- 23 mm Hg; mean +/- SD; p < 0.0001 group x time interaction [G x T]), lower shunt fraction (6 +/- 1% versus 9 +/- 3%; p = 0.0026, G x T) at lower peak airway pressure (21 +/- 2 versus 24 +/- 1 cm H(2)O; p = 0.0342; G x T) occurred with V (bv). IL-8 concentrations in tracheal aspirate and wet:dry weight ratios were inversely related; p = 0.011. With V (c), IL-8 concentrations were 3.75-fold greater at wet:dry weight ratio of 10. IL-10 concentrations did not differ between groups. In both groups, ventilation was on the linear portion of the P-V curve. With V (bv), VT variability demonstrated an inverse power law indicating fractal behavior. In this model of ARDS, V (bv) improved Pa(O(2)) at lower peak airway pressure and IL-8 levels compared with V (c).
authors.affiliation: Department of Anesthesiology, University of Manitoba, Winnipeg, Canada.
authors.forename: Abdulaziz
authors.initials: A
authors.lastname: Boker
authors.forename: M Ruth
authors.initials: MR
authors.lastname: Graham
authors.forename: Keith R
authors.initials: KR
authors.lastname: Walley
authors.forename: Bruce M
authors.initials: BM
authors.lastname: McManus
authors.forename: Linda G
authors.initials: LG
authors.lastname: Girling
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Walker
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Lefevre
authors.forename: W Alan C
authors.initials: WA
authors.lastname: Mutch
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D016207:Cytokines / Q000378:metabolism; D017709:Fractals; D006439:Hemodynamics; D008170:Lung Compliance; D011659:Pulmonary Gas Exchange; D011897:Random Allocation; D012121:Respiration, Artificial / Q000379:methods*; D012128:Respiratory Distress Syndrome / Q000628:therapy*; D013552:Swine; D013990:Tidal Volume
chemical_list: D016207:Cytokines