title: Redistribution of blood flow and lung volume between lungs in lateral decubitus postures during unilateral atelectasis and PEEP.
abstract: The effect of left lung atelectasis on the regional distribution of blood flow (Q), ventilation (V(A)) and gas exchange on the right lung ventilated with 100% O2 was studied in anesthetized dogs in the lateral decubitus posture. Q and V(A) were measured in 1.7 ml lung volume pieces using injected and aerosolized fluorescent microspheres, respectively. Hypoxic pulmonary vasoconstriction (HPV) in the atelectatic lung shifted flow to the ventilated lung. The increased flow in the ventilated lung ensured adequate gas exchange, compensating for the hypoxemia due to shunt contributed by the atelectatic lung. Left lung atelectasis caused a compensatory increase in the ventilated lung FRC that was smaller in the right (RLD) than left (LLD) lateral posture, the effect of lung compression by the atelectatic lung and mediastinal contents in the RLD posture. The O2 deficit measured by (A-a)DO2 increased with left lung atelectasis and was exacerbated in the LLD posture by 10 cm H2O PEEP, a result of increased shunt caused by a shift in Q from the ventilated to the atelectatic lung. The PEEP-induced O2 deficit was eliminated with inversion to the RLD posture.
authors.affiliation: Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195, USA. hung@mail.ndmctsgh.edu.tw
authors.forename: Hung
authors.initials: H
authors.lastname: Chang
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lai-Fook
authors.forename: Karen B
authors.initials: KB
authors.lastname: Domino
authors.forename: Carmel
authors.initials: C
authors.lastname: Schimmel
authors.forename: Jack
authors.initials: J
authors.lastname: Hildebrandt
authors.forename: Shih-Chun
authors.initials: SC
authors.lastname: Lee
authors.forename: Chung-Cheng
authors.initials: CC
authors.lastname: Kao
authors.forename: Jane-Yi
authors.initials: JY
authors.lastname: Hsu
authors.forename: H Thomas
authors.initials: HT
authors.lastname: Robertson
authors.forename: Robb W
authors.initials: RW
authors.lastname: Glenny
authors.forename: Michael P
authors.initials: MP
authors.lastname: Hlastala
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D004285:Dogs; D011175:Positive-Pressure Respiration / Q000379:methods*; D011187:Posture; D001261:Pulmonary Atelectasis / Q000503:physiopathology* / Q000628:therapy*; D011652:Pulmonary Circulation; D012123:Pulmonary Ventilation; D013990:Tidal Volume; D016896:Treatment Outcome