Premium
Decreased Arterial PO 2 , not O 2 Content, Increases Blood Flow Through Intrapulmonary Arteriovenous Anastomoses at Rest
Author(s) -
Duke Joseph,
Ryan Benjamin,
Davis James,
Beasley Kara,
Petrassi Frank,
Miller June,
Hawn Jerold,
Lovering Andrew
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.1031.1
Subject(s) - hypoxia (environmental) , hemoglobin , arteriovenous anastomosis , blood volume , arterial blood , medicine , cardiology , hemodynamics , blood flow , anastomosis , anesthesia , chemistry , oxygen , surgery , organic chemistry
Alveolar hypoxia, not increased pulmonary artery pressure, causes increased blood flow through intrapulmonary arteriovenous anastomoses (Q IPAVA ) in humans. However, it is unknown whether the hypoxic stimulus for Q IPAVA is decreased arterial PO 2 (PaO 2 ) or arterial O 2 content (CaO 2 ). CaO 2 is known to regulate blood flow in the systemic circulation and it is suggested that Q IPAVA is regulated similar to the systemic vasculature. Thus, we hypothesized that reduced CaO 2 would be the stimulus for hypoxia‐induced Q IPAVA . Blood volume (BV) was measured using the optimized carbon monoxide rebreathing method in 8 healthy subjects, 1 female. Less than 5 days later subjects breathed 18%, 14%, and 12.5% O 2 for 30 min each, in a randomized order, before and after isovolemic hemodilution (IH; 10% of BV withdrawn and replaced with an equal volume of 5% human serum albumin). PaO 2 was obtained at the end of each trial and Q IPAVA was assessed using saline contrast echocardiography. Hemoglobin concentration was reduced from 14.2 ± 0.7 to 12.8 ± 0.5 g/dL with IH. PaO 2 did not change pre‐ and post‐IH at any FIO 2 , but CaO 2 was 10.1, 11.3, and 5.4% lower at 18, 14, and 12.5% O 2 , respectively. Q IPAVA was significantly increased as PaO 2 decreased and despite reduced CaO 2 , was similar at iso‐PO 2 . These data suggest that with alveolar hypoxia, low PaO 2 causes the hypoxia‐induced increase in Q IPAVA . Support: Department of Defense