Intrinsic Periodic Pattern of Breathing

We made a fortuitous observation of periodic breathing in a healthy subject coming to our outpatient mountain medicine consultation at Avicenne hospital in Bobigny (France). During this consultation, subjects perform a hypoxia exercise test, which allows a good prediction of their risk factors for severe high altitude illnesses. Surprisingly, breath-by-breath recording of the ventilation signal showed a periodic breathing pattern, which increased when the subject started to exercise in hypoxic conditions and was maintained during normoxic exercise. Therefore, our objective was to confirm this observation in a retrospective study led in 82 subjects who passed this test. We tested the hypothesis that subjects with a brisk ventilatory response to hypoxia might show a more pronounced periodic pattern of ventilation, due to a higher gain of the chemoreceptor feedback loop. Then, our objective is to investigate the mechanisms involved in the periodic pattern in healthy subjects, as a function of exercise intensity, altitude intensity, role of peripheral and central chemoreceptors to O2 and CO2. Finally, we want to investigate the possible role of this ventilatory instability in patients with obstructive or central apneas.