No effect of patent foramen ovale on acute mountain sickness and pulmonary pressure in normobaric hypoxia.

New Findings: What is the central question to this study? Is there a relationship between a patent foramen ovale and the development of acute mountain sickness and an exaggerated increase in pulmonary pressure in response to 7-10 h of normobaric hypoxia? What is the main finding and its importance? Patent foramen ovale presence did not increase susceptibility to acute mountain sickness or result in an exaggerated increase in pulmonary artery systolic pressure with normobaric hypoxia. This suggests hypobaric hypoxia is integral to the increased susceptibility to acute mountain sickness previously reported in those with patent foramen ovale, and patent foramen ovale presence alone does not contribute to the hypoxic pulmonary pressor response.

Abstract: Acute mountain sickness (AMS) develops following rapid ascent to altitude, but its exact causes remain unknown.

Impaired pulmonary gas exchange efficiency, but normal pulmonary artery pressure increases, with hypoxia in men and women with a patent foramen ovale.

New Findings: What is the central question of this study? Do individuals with a patent foramen ovale (PFO ) have a larger alveolar-to-arterial difference in ( ) than those without (PFO ) and/or an exaggerated increase in pulmonary artery systolic pressure (PASP) in response to hypoxia? What is the main finding and its importance? PFO had a greater while breathing air, 16% and 14% O , but not 12% or 10% O . PASP increased equally in hypoxia between PFO and PFO . These data suggest that PFO may not have an exaggerated acute increase in PASP in response to hypoxia.

AltitudeOmics: effect of reduced barometric pressure on detection of intrapulmonary shunt, pulmonary gas exchange efficiency, and total pulmonary resistance.

Blood flow through intrapulmonary arteriovenous anastomoses (Q) occurs in healthy humans at rest and during exercise when breathing hypoxic gas mixtures at sea level and may be a source of right-to-left shunt. However, at high altitudes, Q is reduced compared with sea level, as detected using transthoracic saline contrast echocardiography (TTSCE). It remains unknown whether the reduction in Q (i.

AltitudeOmics: impaired pulmonary gas exchange efficiency and blunted ventilatory acclimatization in humans with patent foramen ovale after 16 days at 5,260 m.

A patent foramen ovale (PFO), present in ∼40% of the general population, is a potential source of right-to-left shunt that can impair pulmonary gas exchange efficiency [i.e., increase the alveolar-to-arterial Po2 difference (A-aDO2)].

Sildenafil, nifedipine and acetazolamide do not allow for blood flow through intrapulmonary arteriovenous anastomoses during exercise while breathing 100% oxygen.

Blood flow through intrapulmonary arteriovenous anastomoses (IPAVAs) is known to increase in healthy humans during exercise while breathing room air, but is prevented or significantly reduced during exercise while breathing 100% O2, potentially due to vasoconstriction of IPAVAs. Thus, pharmacological interventions that target known pathways regulating the cardiopulmonary circulation may be able to prevent the hyperoxia-induced reduction in IPAVA blood flow (Q̇ IPAVA ) during exercise. In nine healthy human subjects, we investigated the effects of sildenafil (100 mg p.

Normal pulmonary gas exchange efficiency and absence of exercise-induced arterial hypoxemia in adults with bronchopulmonary dysplasia.

Cardiopulmonary function is reduced in adults born very preterm, but it is unknown if this results in reduced pulmonary gas exchange efficiency during exercise and, consequently, leads to reduced aerobic capacity in subjects with and without bronchopulmonary dysplasia (BPD). We hypothesized that an excessively large alveolar to arterial oxygen difference (AaDO2) and resulting exercise-induced arterial hypoxemia (EIAH) would contribute to reduced aerobic fitness in adults born very preterm with and without BPD. Measurements of pulmonary function, lung volumes and diffusion capacity for carbon monoxide (DLco) were made at rest.

Prevalence of left heart contrast in healthy, young, asymptomatic humans at rest breathing room air.

Our purpose was to report the prevalence of healthy, young, asymptomatic humans who demonstrate left heart contrast at rest, breathing room air. We evaluated 176 subjects (18-41 years old) using transthoracic saline contrast echocardiography. Left heart contrast appearing ≤3 cardiac cycles, consistent with a patent foramen ovale (PFO), was detected in 67 (38%) subjects.

Catecholamine-induced opening of intrapulmonary arteriovenous anastomoses in healthy humans at rest.

The mechanism or mechanisms that cause intrapulmonary arteriovenous anastomoses (IPAVA) to either open during exercise in subjects breathing room air and at rest when breathing hypoxic gas mixtures, or to close during exercise while breathing 100% oxygen, remain unknown. During conditions when IPAVA are open, plasma epinephrine (EPI) and dopamine (DA) concentrations both increase, potentially representing a common mechanism. The purpose of this study was to determine whether EPI or DA infusions open IPAVA in resting subjects breathing room air and, subsequently, 100% oxygen.