title: Effect of alveolar hypoxia on pulmonary fluid filtration in in situ dog lungs.
abstract: We have studied the effect of alveolar hypoxia on fluid filtration characteristics of the pulmonary microcirculation in an in situ left upper lobe preparation with near static flow conditions (20 ml/min). In six dogs (group 1), rate of edema formation (delta W/delta t, where W is weight and t is time) was assessed over a wide range of vascular pressures under two inspired O2 fraction (FIO2) conditions (0.95 and 0.0 with 5% CO2-balance N2 in both cases). delta W/delta t was plotted against vascular pressure, and the best-fit linear regression was obtained. There was no significant difference (paired t test) in either threshold pressure for edema formation [18.3 +/- 1.8 and 17.1 +/- 1.2 (SE) mmHg, respectively] or the slopes (0.067 +/- 0.008 and 0.073 +/- 0.017 g.min-1. mmHg-1.100g-1, respectively). In another seven dogs (group 2), delta W/delta t was obtained at a constant vascular pressure of 40 mmHg under four FIO2 conditions (0.95, 0.21, 0.05, and 0.0, with 5% CO2-balance N2). Delta W/delta t for the four conditions averaged 0.60 +/- 0.11, 0.61 +/- 0.11, 0.61 +/- 0.10, and 0.61 +/- 0.10 (SE) g.min-1.mmHg-1.100g-1, respectively. No significant differences (ANOVA for repeated measures) were noted. We conclude that alveolar hypoxia does not alter the threshold for edema formation or delta W/delta t at a given microvascular pressure.
authors.affiliation: Respiratory Investigation Unit, University of Manitoba, Winnipeg, Canada.
authors.forename: L A
authors.initials: LA
authors.lastname: Homik
authors.forename: Z
authors.initials: Z
authors.lastname: Bshouty
authors.forename: R B
authors.initials: RB
authors.lastname: Light
authors.forename: M
authors.initials: M
authors.lastname: Younes
mesh_terms: D000818:Animals; D001826:Body Fluids / Q000378:metabolism*; D004285:Dogs; D005374:Filtration; D000860:Hypoxia / Q000503:physiopathology*; D008833:Microcirculation; D011312:Pressure; D011650:Pulmonary Alveoli / Q000503:physiopathology*