Effect of initial gas bubble composition on detection of inducible intrapulmonary arteriovenous shunt during exercise in normoxia, hypoxia or hyperoxia.
Summary of "Effect of initial gas bubble composition on detection of inducible intrapulmonary arteriovenous shunt during exercise in normoxia, hypoxia or hyperoxia."
Concern has been raised that altering the fraction of inspired O(2) (FIO(2)) could accelerate or decelerate microbubble dissolution time within the pulmonary vasculature and thereby invalidate the ability of saline contrast echocardiography to detect intrapulmonary arteriovenous shunt in subjects breathing low or high oxygen gas mixtures. The current study determined if the gaseous component used for saline contrast echocardiography affects the detection of exercise-induced intrapulmonary arteriovenous shunt under varying FIO(2)'s. Twelve healthy human subjects (6 female) performed three, 11 min bouts of cycle ergometer exercise at 60% VO(2peak), in normoxia, hypoxia (FIO(2) = 0.14), and hyperoxia (FIO(2) = 1.0). Five different gases were used to create saline contrast microbubbles using two separate methods and were injected intravenously in the following order at 2 min intervals: room air, 100% N(2), 100% O(2), 100% CO(2) and 100% He. Breathing hyperoxia prevented exercise-induced intrapulmonary arteriovenous shunt whereas breathing hypoxia and normoxia resulted in a significant level of exercise-induced intrapulmonary arteriovenous shunt. During exercise, for any FIO(2), there was no significant difference in bubble score when using the different microbubble gas compositions made with either method. The current results support our previous work using saline contrast echocardiography and validate the use of room air as the gaseous component of saline contrast microbubbles to detect intrapulmonary arteriovenous shunt during exercise or at rest with subjects breathing any FIO(2). These results suggest that in vivo gas bubbles are less susceptible to changes in the ambient external environment than previously suspected.
Affiliation
1University of Oregon.
Journal Details
This article was published in the following journal.
Name: Journal of applied physiology (Bethesda, Md. : 1985)
ISSN: 1522-1601
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20847134
- DOI: http://dx.doi.org/10.1152/japplphysiol.00145.2010
Medical and Biotech [MESH] Definitions
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Congenital vascular anomalies in the brain characterized by direct communication between an artery and a vein without passing through the CAPILLARIES. The locations and size of the shunts determine the symptoms including HEADACHES; SEIZURES; STROKE; INTRACRANIAL HEMORRHAGES; mass effect; and vascular steal effect.
Arteriovenous Anastomosis
A vessel that directly interconnects an artery and a vein, and that acts as a shunt to bypass the capillary bed. Not to be confused with surgical anastomosis, nor with arteriovenous fistula.
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Arteriovenous Fistula
An abnormal direct communication between an artery and a vein without passing through the CAPILLARIES. An A-V fistula usually leads to the formation of a dilated sac-like connection, arteriovenous aneurysm. The locations and size of the shunts determine the degree of effects on the cardiovascular functions such as BLOOD PRESSURE and HEART RATE.
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