0901 An odd presentation of a hidden curse

Abstract Introduction Congenital central hypoventilation syndrome (CCHS) is a rare disorder of respiratory deficiency due to mutation in the PHOX2B gene. Clinical presentation may be mild certain individuals different levels ventilatory dysregulation. Methods We present findings exogenous challenge testing and polysomnography (PSG) performed on normocapnic adult female with late-onset (LO) CCHS patient. Results The patient was exposed four separate challenges. During exposure hyperoxia using 100% oxygen (O2) administration, showed an inconsistent response blunted delayed increase regional tissue saturation (rSO2). hyperoxic hypercapnia 5% carbon dioxide (CO2) 95% O2, she demonstrated reduced based rate tidal volume. hypoxic hypercapnia, 7% CO2 14% markedly attenuated response. Hypoxia; nitrogen inhalation did not result increased ventilation. Ve slope, change minute ventilation/change end-tidal (EtCO2), challenges 4.88, which lower than normal. Ventilatory EtCO2 threshold 36 mmHg. PSG apnea-hypopnea index 3.3 hypoxemia during rapid eye movement (REM), nadir 84%. baseline around 36, peak 50 associated REM-related apnea events. Arterial blood gas unremarkable. Conclusion characterized by abnormal testing. Hyperoxia silences peripheral chemoreceptors (PC) responsible for stimulating ventilation normal individuals. Hyperoxic PC but stimulates (CC). Hypoxic hyperventilation via both CC. Our responses all As expected, classic chemosensory parameter, hypercarbia reduced. However, fell well below typically observed CCHS. noted greater alveolar REM compared non-REM, also atypical In conclusion, derangements control typical Despite this, our had no evidence daytime threshold. This case illustrates phenotypic variability LO-CCHS. Support (if any)