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Quantification of reduced blood flow through intrapulmonary arteriovenous anastomoses in healthy humans during exercise breathing 100% O 2
Author(s) -
Laurie Steven,
Elliott Jonathan E.,
Duke Joseph W,
Goodman Randall D,
Gladstone Igor M,
Fish Mathews B,
Lovering Andrew T
Publication year - 2013
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.27.1_supplement.1141.4
Subject(s) - breathing , arteriovenous anastomosis , medicine , nuclear medicine , blood flow , venous blood , physical exercise , cardiology , lung , ventilation (architecture) , anastomosis , chemistry , anesthesia , surgery , mechanical engineering , engineering
Saline contrast echocardiography (SCE) data suggest that breathing 100% O 2 during exercise reduces blood flow through large diameter intrapulmonary arteriovenous anastomoses (Q IPAVA ), however this has not been quantified. We hypothesized that during exercise when breathing 100% O 2 , Q IPAVA would be reduced compared to exercise breathing 21% O 2 as quantified using Technetium‐99m macroaggregated albumin ( 99m Tc‐MAA). We filtered MAA through a 20μm filter prior to labeling with 99m Tc; quality control determined a binding efficiency >;99.8% prior to injection. Six subjects underwent whole body Gamma camera imaging post injection of filtered 99m Tc‐MAA on 3 separate visits: A) rest breathing 21% O 2 ; B) 85% max exercise breathing 21% O 2 ; and C) 85% max exercise breathing 100% O 2 . Shunt fractions were quantified as the ratio of counts outside the lung divided by total counts from the whole body, less the fraction due to freely circulating 99m Tc determined from a venous blood sample. During exercise breathing 21% O 2 the shunt fraction increased from 0% at rest to 1.1% during exercise, but was reduced during exercise breathing 100% O 2 to 0.4%. These data obtained using solid MAA suggest that breathing 100% O 2 during exercise reduces Q IPAVA , supporting data obtained using SCE. Funding: Eugene & Clarissa Evonuk Memorial Graduate Fellowship in Environmental, Exercise, or Stress Physiology.