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848 Refractory Hypoventilation in Congenital Central Hypoventilation Syndrome: A Case for Average Volume-Assured Pressure Support


 
 
 Congenital Central Hypoventilation Syndrome (CCHS) is a rare cause of alveolar hypoventilation in children resulting in lifelong ventilatory support. In older children requiring nocturnal support alone, the use of diaphragmatic pacing in conjunction with or independent of non-invasive ventilatory (NIV) support has been demonstrated to improve quality of life. We present a case of refractory hypoventilation despite escalation of NIV.
 
 
 
 20-year-old female with Hirschsprung’s disease and CCHS (20/26 polyalanine repeats) with history of invasive ventilation via tracheostomy who underwent bilateral diaphragmatic phrenic nerve stimulator placement at 13 years-of-age with subsequent tracheostomy decannulation. Diaphragmatic pacing was discontinued three years later in the setting of pneumonia and patient discomfort because of receiver positioning. At that time, she had improved subjective sleep quality and adequate ventilatory support on bi-level positive airway pressure (PAP) despite discontinuation of diaphragmatic pacing. Titration of bi-level PAP was done via polysomnogram four years later demonstrating nocturnal hypoventilation with transcutaneous CO2 values greater than 50 mmHg for 80% of the study and an oxygen nadir of 87% despite titration of inspiratory pressure and respiratory rate to maximize ventilatory assistance. The patient was subsequently admitted to the intensive care unit for transition to non-invasive average volume-assured pressure support (AVAPS) mode. Ventilation improved with nocturnal pCO2 values via capillary blood gas of 31 mmHg and 45 mmHg at 2 am and 6 am respectively. The patient was discharged on AVAPS therapy while undergoing evaluation to resume diaphragmatic pacing via cervical phrenic nerve stimulators for improved comfort.
 
 
 
 Several ventilatory strategies may be employed in the care of patients with CCHS, with individualization of support based on phenotype, comorbidities, and patient and family preference. This case highlights the unique challenges of adequately ventilating patients as they age. The use of NIV via an AVAPS mode in patients with CCHS has been infrequently reported in the literature, though is promising in reported efficacy with regards to ensured ventilation. This, in conjunction with diaphragmatic pacing, may allow patients to achieve appropriate ventilation while maintaining quality of life, and could be considered in patients with refractory hypoventilation despite other modes of NIV.
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