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Abstract

Physiological responses to hypoxia in children are incompletely understood. We aimed to characterize cerebrovascular and ventilatory responses to normobaric hypoxia in girls and women. Methods: Ten healthy girls (9.9 +/- 1.7y; mean +/- SD; Tanner stage 1 and 2) and their mothers (43.9 +/- 3.5y) participated. Internal carotid (ICA) and vertebral artery (VA) velocity, diameter and flow (Duplex ultrasound) was recorded pre- and post-1h of hypoxic exposure (FIO₂=0.126;~4000m) in a normobaric chamber. Ventilation (VE) and respiratory drive (VT/TI) expressed as delta change from baseline (∆%), and end-tidal carbon-dioxide (PETCO₂) were collected at baseline (BL) and 5, 30 and 60 minutes of hypoxia (5/30/60 HYP). Heart rate (HR) and oxygen saturation (SpO₂) were also collected at these time-points. Results: SpO₂ declined similarly in girls (BL-97%; 60HYP-80%, P