Patent foramen ovale in obstructive sleep apnoea and chronic obstructive pulmonary disease

The objective of this thesis was to determine the impact of right to left shunting (RLS) through patent foramen ovale (PFO) on oxygen saturation in obstructive sleep apnoea (OSA) and chronic obstructive pulmonary disease (COPD). The first aim was to determine the prevalence of PFO in severe OSA and whether PFO closure improves nocturnal oxygen saturation. The data showed that PFO with large shunts were more prevalent, however overall prevalence was not statistically different when compared to healthy controls. PFO closure did not reduce nocturnal desaturation. The second aim was to determine whether severe COPD patients with PaO2 ≤ 7.3kPa had a higher prevalence of PFO compared to patients with PaO2 > 8kPa, additionally to compare the prevalence of PFO in COPD with healthy controls. The data showed no difference in PFO prevalence in patients with PaO2 ≤ 7.3kPa compared to patients with PaO2 > 8kPa, however, intrapulmonary shunts were more prevalent in hypoxaemic patients. Similar to OSA, PFO with large shunts were more prevalent in severe COPD, however overall prevalence was not statistically different to healthy controls. The final aim was to determine whether patients with COPD and PFO developed RLS during exercise and whether this was associated with reduced oxygen saturation, reduced exercise endurance and increased intrathoracic pressure swings. The data showed that RLS through PFO increased from baseline during exercise and this was associated with increased swings in intrathoracic pressure. There was no difference in desaturation or exercise endurance when compared to patients with no PFO. In summary, this thesis shows that PFO with large shunts are more prevalent in both OSA and COPD. PFO closure in OSA did not reduce nocturnal desaturation. Furthermore, the presence of a PFO in COPD did not influence resting or exercise oxygen saturation despite the observed increase in RLS with exercise.EThOS - Electronic Theses Online ServiceGBUnited Kingdo