title: Influence of mixed venous oxygen tension (PVO2) on blood flow to atelectatic lung.
abstract: The influence of mixed venous oxygen tension (PVO2) on blood flow to the atelectatic left lung was studied at normal and reduced cardiac outputs (CO) using extracorporeal veno-venous bypass in six pentobarbital anesthetized, mechanically ventilated dogs. Aortic and left pulmonary artery flows; airway, left atrial, central venous, pulmonary, and systemic arterial pressures; hemoglobin, arterial, and mixed venous blood gases were measured. The blood flow reduction observed in atelectasis was altered by the PVO2. Approximately 50% of blood flow was diverted away from atelectatic lung when PVO2 was low (24 +/- 2 mmHg) or normal (46 +/- 2 mmHg) (mean left lung blood flow [QL%] was 23.2 +/- 4.6% with low PVO2 and 19.0 +/- 3.4%, with normal PVO2). When PVO2 was increased to greater than 100 mmHg, diversion of blood flow away from atelectatic lung did not occur and QL% was nearly the flow expected for normoxic ventilated left lung (mean QL% = 40.4 +/- 5.9%). Shunt (QS/QT%) was significantly greater when PVO2 was high than when it was normal or low (mean QS/QT% = 51.7 +/- 5.6%, 31.0 +/- 3.1%, 26.0 +/- 3.4% with high, normal, and low PVO2, respectively). Mean PaO2 was significantly greater when PVO2 was high than when PVO2 was normal or low, despite the increase in QL% and QS/QT% (PaO2 = 327 +/- 25 mmHg, 220 +/- 32 mmHg, 115 +/- 21 mmHg with high, normal, and low PVO2, respectively). A 40% reduction in cardiac output significantly decreased transmural pulmonary artery pressure but did not affect PaO2, QS/QT%, or QL%.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001794:Blood Pressure; D002302:Cardiac Output; D004285:Dogs; D005260:Female; D010100:Oxygen / Q000097:blood*; D010313:Partial Pressure; D001261:Pulmonary Atelectasis / Q000503:physiopathology*; D011652:Pulmonary Circulation; D014692:Ventilation-Perfusion Ratio
chemical_list: D010100:Oxygen