| Autor: |
Duke, Joseph W., Elliott, Jonathan E., Laurie, Steven S., Voelkel, Thomas, Gladstone, Igor M., Fish, Mathews B., Lovering, Andrew T. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physiology; Dec2017, Vol. 123 Issue 6, p1592-1598, 7p |
| Abstrakt: |
Blood flow through intrapulmonary arteriovenous anastomoses (Q˙ IPAVA) increases in healthy humans breathing hypoxic gas and is potentially dependent on body position. Previous work in subjects breathing room air has shown an effect of body position when ̇ IPAVA is detected with transthoracic saline contrast echocardiography (TTSCE). However, the potential effect of body position oṅ IPAVA has not been investigated when subjects are breathing hypoxic gas or with a technique capable of quantifying ̇ IPAVA. Thus the purpose of this study was to quantify the effect of body position on ̇ IPAVA when breathing normoxic and hypoxic gas at rest. We studied ̇ IPAVA with TTSCE and quantified ̇ IPAVA with filtered technetium-99m-labeled macroaggregates of albumin (99mTc- MAA) in seven healthy men breathing normoxic and hypoxic (12% O2) gas at rest while supine and upright. On the basis of previous work using TTSCE, we hypothesized that the quantified ̇ IPAVA would be greatest with hypoxia in the supine position. We found that ̇ IPAVA quantified with 99mTc-MAA significantly increased while subjects breathed hypoxic gas in both supine and upright body positions (Δ̇ IPAVA = 0.7 ± 0.4 vs. 2.5 ± 1.1% of cardiac output, respectively). ̇ IPAVA detected with TTSCE increased from normoxia in supine hypoxia but not in upright hypoxia (median hypoxia bubble score of 2 vs. 0, respectively). Surprisingly, ̇ IPAVA magnitude was greatest in upright hypoxia, when ̇ IPAVA was undetectable with TTSCE. These findings suggest that the relationship between TTSCE and 99mTc-MAA is more complex than previously appreciated, perhaps because of the different physical properties of bubbles and MAA in solution. NEW & NOTEWORTHY Using saline contrast bubbles and radiolabeled macroaggregrates (MAA), we detected and quantified, respectively, hypoxia-induced blood flow through intrapulmonary arteriovenous anastomoses (Q˙ IPAVA) in supine and upright body positions in healthy men. Upright hypoxia resulted in the largest magnitude of ̇ IPAVA quantified with MAA but the lowest ̇ IPAVA detected with saline contrast bubbles. These surprising results suggest that the differences in physical properties between saline contrast bubbles and MAA in blood may affect their behavior in vivo. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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