PREVALENCE OF PATENT FORAMEN OVALE AND ITS CONTRIBUTION TO HYPOXEMIA IN PATIENTS WITH OBSTRUCTIVE SLEEP-APNEA

Study objectives: The objectives of this study were (1) to assess the prevalence of patent foramen ovale (PFO) by means of contrast transeso phageal echocardiography (TEE) in patients with obstructive sleep apne a, and (2) to determine the potential contribution of right to left in teratrial shunting to systemic oxygen desaturation following the perfo rmance of Valsalva maneuver. Design: Performance of contrast TEE durin g Valsalva maneuver with simultaneous measurement of systemic arterial oxygen saturation (SaO(2)) by means of pulse oximetry in patients wit h obstructive sleep apnea and a control group. Setting: Government tea ching hospital, university hospital affiliate. Patients: Study group c omprised 48 patients with documented obstructive sleep apnea and 24 co ntrol subjects. Interventions: Sleep studies, contrast TEE, Valsalva m aneuver, pulse oximetry.Measurements and results: Thirty-three of 48 p atients with obstructive sleep apnea compared with 4 of 24 control pat ients had a detectable PFO (69% vs 17%; p<0.0001). All sleep apnea pat ients had comparable baseline SaO(2) regardless of the presence of a P FO (93.9+/-1.7% vs 95+/-1.2%; p=not significant). After performance of a Valsalva maneuver, however, a significantly greater fall in SaO(2) was observed in patients with obstructive sleep apnea and PFO compared with patients with obstructive sleep apnea without PFO (-2.4+/-1.5% v s -1.3+/-0.6%; p=0.007). A statistically significant fall in SaO(2) (d efined as >4 SD of recorded SaO(2) values after Valsalva maneuver in p atients without PFO) was found in one third of patients with sleep apn ea and PFO. Conclusion: We conclude that there is an increased prevale nce of PFO in patients with obstructive sleep apnea that could contrib ute to significant hypoxemia after a Valsalva maneuver in approximatel y one third of these patients.