Patent foramen ovale (PFO) exacerbates intermittent hypoxia in moderate-to-severe obstructive sleep apnea (OSA)...

Both obstructive sleep apnea (OSA)and patent foramen ovale (PFO) can lead to changes in blood oxygen. However, it is unclear whether PFO exacerbates the blood oxygen indicators of OSA.

This case series study included patients who underwent contrast-enhanced transcranial Doppler (c-TCD) and polysomnography (PSG examination) between January 2017 to December 2023 at the Third Affiliated Hospital of Yan'an University. Based on c-TCD and PSG results, patients were categorized into two groups: OSA and PFO double-positive group (OSA + PFO), OSA single-positive group (OSA). Furthermore, both the OSA + PFO and OSA groups were further subdivided into mild (5 times/hour ≤ AHI < 15 times/hour), moderate (15 times/hour ≤ AHI < 30 times/hour) and severe (AHI ≥ 30 times/hour) groups according to their apnea-hypopnea index (AHI). This study compared the minimum oxygen saturation, oxygen desaturation index (ODI), the percentage of cumulative time with oxygen saturation < 90% in total sleep time (T90) among all groups.

A total of 509 patients were included (386 males,75.83%; 123females,24.17%), with an average age of 56.76 ± 10.23 years. The study cohort included 97 OSA + PFO cases (55.67% moderate to severe) and 412 OSA cases (63.35% moderate to severe). No significant differences were observed in minimum oxygen saturation (75.97 ± 12.70% vs. 76.34 ± 12.67%, respectively, P =0.607) and ODI (32.99 ± 24.16% vs. 34.31 ± 23.59%, respectively, P =0.173) between the OSA group and the OSA + PFO group. Similarly, no significant differences were found in T90 (14.20 ± 20.50% vs. 16.69 ± 21.62%, respectively, P =0.075) between the OSA group and the OSA + PFO group. However, the T90 values were significantly higher in the moderate-severe OSA + PFO group compared to the moderate-severe OSA group (26.21 ± 22.97% vs.18.68 ± 22.02%, respectively, P < 0.05).

Although PFO has no significant effect on minimum oxygen saturation and ODI, PFO further aggravates intermittent hypoxia in patients with moderate to severe OSA.