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DIFFERENCE IN STEADY-STATE CHEMOREFLEX DRIVE BETWEEN GROUPS WITH AND WIHTOUT A PATENT FORAMEN OVALE

Abstract

D. R. Zehner1, M. M. Scanagatta-Long1, R. Goodman2, J.E. Futral2, J.A. Hawn2, J.E. Elliott3, S.S. Laurie4, RC Roach5, T.A. Day6, and A.T. Lovering1

1University of Oregon, Eugene OR, USA; 2Oregon Heart and Vascular Institute, Springfield, OR, USA; 3VA Portland Health Care System, Portland, OR, USA; 4KBR, Cardiovascular and Vision Laboratory, NASA Johnson Space Center, Houston, TX, USA; 5Altitude Research Center, University of Colorado Anschutz Medical Campus, Denver, Colorado; 6Mount Royal University, Calgary, AB, Canada

Ventilatory acclimatization is a hallmark physiological response to high altitude. In ~30% of the population, a shunt located between the right and left atrium called patent foramen ovale (PFO) is present. People with a PFO have a reduced degree of ventilatory acclimatization which may contribute to their increased risk for high altitude illnesses. Recently, the development of a steady-state chemoreflex drive (SS-CD) index has provided a novel approach to assessing the overall ventilatory drive at altitude. PURPOSE: Using data from a previous high-altitude expedition (AltitudeOmics), the SS-CD index (SS-CD = Minute ventilation (VE), / (arterial partial pressure of carbon dioxide (PaCO2) / arterial oxygen saturation (SaO2))), was utilized to quantify differences in the degree of ventilatory acclimatization between groups with a PFO, ­­­­­(PFO+) and without a PFO, (PFO-). METHODS: Twenty-one participants (n=11 PFO+, n=10 PFO-) participated in a high-altitude study during which they spent 16 days at 5260 meters in Bolivia. VE, PaCO2, and SaO2 data were collected at sea level (SL), day 1 at 5260m (ALT1), and day 16 at 5260m (ALT16). VE was obtained using a pneumotach. PaCO2 and SaO2 were obtained from a radial artery catheter. A mixed-model 2 way repeat measure ANOVA was performed for statistical analysis, with Tukey’s multiple comparisons test. RESULTS: There was a main effect of time on the SS-CD (p2). Future research should aim to investigate this inconsistency in chemoreflex responses in PFO+ and PFO- subjects at altitude.

Funding: Department of Defense (W81XWH-11-2-0040 TATRC to R. C. Roach and W81XWH-10-2-0114 to A. T. Lovering).

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