Premium
The Effect of a Patent Foramen Ovale on Ventilatory Responses to Hypoxia
Author(s) -
Chang Alex J,
Boulet Lindsey M,
Davis James T,
Hardin Alyssa M,
Foster Glen E,
Lovering Andrew T
Publication year - 2017
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.31.1_supplement.1072.10
Subject(s) - patent foramen ovale , medicine , hypoxia (environmental) , population , cardiology , anesthesia , chemistry , oxygen , migraine , environmental health , organic chemistry
Approximately 35% of the general healthy population has a patent foramen ovale (PFO) (Woods et al., 2010; Marriott et al., 2013; Elliott et al., 2013). Previous work by our lab has shown that after 16 days of exposure to 5260 m, subjects with a PFO (PFO+) had blunted ventilatory acclimatization to high altitude compared to subjects without a PFO (PFO−), such that PFO+ subjects had a lower PaO 2 , higher PaCO 2 , and lower SaO 2 (Elliott et al., J Appl Physiol, 2015). However, in that study 7/11 PFO+ subjects were female whereas only 2/10 PFO− subjects were female and thus potential sex differences were not accounted for and it is known that sex hormones can affect ventilatory responses to O 2 and CO 2 (Schoene et al., 1986; Slatkovska et al., 2006). Thus, it remains unknown if PFO+ subjects exhibit blunted ventilatory responses to hypoxia compared to PFO− subjects, independent of sex. Therefore, the purpose of this study was to determine if the presence of a PFO affects ventilatory responses during acute exposure to either poikilocapnic hypoxia or isocapnic hypoxia. A total of 31 healthy, non‐smoking subjects matched for height, weight, sex and age completed the entire study: PFO+: age: 24 ± 5 yrs, height: 170 ± 11 cm, weight: 69 ± 14 kg, BSA: 1.8 ± 0.2 m 2 PFO−: age: 27 ± 9 yrs, height: 172 ± 10 cm, weight: 71 ± 16 kg, BSA: 1.8 ± 0.2 m 2 These 31 subjects included 15 PFO+ subjects (8 female) and 16 PFO – subjects (8 female). On the day of the test, the subjects came to the lab on a single visit and breathed 1) poikilocapnic hypoxia (P ET O 2 = 51.4 ± 6.5 mmHg) and 2) isocapnic hypoxia (P ET O 2 = 43.7 ± 4.4 mmHg, P ET CO 2 = 40.0 ± 3.4 mmHg), and these gases were administered using the AirForce breathing response system in a randomized and balanced order. Time points of interest were baseline resting ventilation while sitting comfortably in a chair and the time at which V E was greatest after 5 minutes of breathing the respective hypoxic gas. There was a 40 min break between hypoxia trials. Hypoxic ventilatory response (HVR) was calculated as the change in minute ventilation divided by the change in saturation (Δ V E /Δ SpO 2 ). There was no effect of PFO on HVR during exposure to either isocapnic hypoxia or poikilocapnic hypoxia (p > .05). There was no effect of PFO on SpO 2 , V E , V T , RR, P ET O 2 or P ET CO 2 during either the isocapnic hypoxia or poikilocapnic hypoxia trials (p > .05). These data suggest that HVR is not blunted in PFO+ subjects compared to PFO− subjects. Additionally, there were no sex differences in HVR in PFO+ subjects compared to PFO− subjects. Based on these findings, it is plausible that the blunted ventilatory acclimatization previously found by our group may be due in part to differences in responses to hypercapnia suggesting involvement of a central chemoreceptor rather than just a peripheral component (see accompanying poster Hardin et al 2016).