Cardiopulmonary Differences in Apnea Divers Breathing Isocapnic Normobaric Hypoxia By Mohini B.-E.

Описание: Presenter- Mohini Bryant-Ekstrand
2020 Human Physiology Poster Award Recipient
"Hypoxia (low oxygen), induces a reversible form of pulmonary hypertension which can be studied to elucidate the etiology of pulmonary hypertension and right heart dysfunction. Breath hold divers (BHD) routinely place themselves into extremely hypoxemic (low blood oxygen) conditions and therefore may repeatedly expose themselves to acute bouts of pulmonary hypertension and increased right heart work. A patent foramen ovale is a tunnel between the top chambers (atria) of the heart present in 35% of the populations that may exacerbate hypoxemia thereby worsening pulmonary hypertension. The purpose of this study was to 1) determine if pulmonary arterial pressure and right heart dysfunction in hypoxia was greater in BHD compared to controls, 2) determine if the presence of a PFO contributed to the responses measured and 3) determine the role of a pulmonary vasodilator in ameliorating the increased pulmonary pressure in response to hypoxia. Subjects (n=26, 13 BHD, 13 Control) completed two 30-minute hypoxic breathing challenges, after receiving either 50mg sildenafil or placebo, with a 48-hour minimum washout period between visits. Saline contrast echocardiography was used to detect PFO. Pulmonary pressure and right heart function measures were made using Doppler ultrasound. Compared to placebo, sildenafil produced vasodilation before hypoxia in BHD and after 30 minutes of hypoxia in controls. PFO had no effect. Our preliminary data suggests elite breath hold divers may have a chronic pulmonary vasoconstriction in room air that is prevented with administration of sildenafil, and these findings are independent of having a PFO. "