Positional impairment of gas exchange during diaphragm pacing alleviated by increasing amplitude settings in congenital central hypoventilation syndrome

Congenital Central Hypoventilation Syndrome: Optimizing Care with a Multidisciplinary Approach

Congenital central hypoventilation syndrome (CCHS) is a rare genetic disorder affecting respiratory control and autonomic nervous system function caused by variants in the paired-like homeobox 2B (PHOX2B) gene. Although most patients are diagnosed in the newborn period, an increasing number of patients are presenting later in childhood, adolescence, and adulthood. Despite hypoxemia and hypercapnia, patients do not manifest clinical features of respiratory distress during sleep and wakefulness. CCHS is a lifelong disorder. Patients require assisted ventilation throughout their life delivered by positive pressure ventilation via tracheostomy, noninvasive positive pressure ventilation, and/or diaphragm pacing. At different ages, patients may prefer to change their modality of assisted ventilation. This requires an individualized and coordinated multidisciplinary approach. Additional clinical features of CCHS that may present at different ages and require periodic evaluations or interventions include Hirschsprung’s disease, gastrointestinal dysmotility, neural crest tumors, cardiac arrhythmias, and neurodevelopmental delays. Despite an established PHOX2B genotype and phenotype correlation, patients have variable and heterogeneous clinical manifestations requiring the formulation of an individualized plan of care based on collaboration between the pulmonologist, otolaryngologist, cardiologist, anesthesiologist, gastroenterologist, sleep medicine physician, geneticist, surgeon, oncologist, and respiratory therapist. A comprehensive multidisciplinary approach may optimize care and improve patient outcomes. With advances in CCHS management strategies, there is prolongation of survival necessitating high-quality multidisciplinary care for adults with CCHS.

Annual Respiratory Evaluations in Congenital Central Hypoventilation Syndrome and Changes in Ventilatory Management

Background: Annual in-hospital respiratory evaluations (AREs) during wakefulness and sleep are recommended to assess ventilatory requirements in patients with congenital central hypoventilation syndrome (CCHS) aged ≥2-3 years based on expert consensus. This study aimed to determine if AREs in patients with CCHS led to changes in ventilatory management. Methods: Retrospective review of patients with CCHS who underwent AREs with or without polysomnography between 2017 and 2019 was conducted. Clinical symptoms, results of AREs, and subsequent changes in ventilatory management were analyzed. Results: We identified 10 patients with CCHS aged 4-20 years. All patients required assisted ventilation (AV) only during sleep delivered by positive pressure ventilation via tracheostomy (n = 7) or diaphragm pacing (n = 3). In total, 7 (70%) patients had abnormal oxygenation and/or ventilation requiring changes in ventilator settings or duration of AV. Six patients required an increase in settings and/or duration of AV, and only 1 patient required a decrease in ventilator settings. Two patients had awake hypercapnia during a routine outpatient visit that improved following increase in ventilator settings and a period of continuous AV. One patient who was previously ventilator-dependent only during sleep was identified to require 16 h per day of AV. All patients (n = 3) who reported symptoms such as headache or oxygen desaturations during sleep required an increase in ventilator settings. Conclusion: We report a high prevalence of changes in AV management following an ARE. Our results demonstrate the importance of regular AREs in patients with CCHS to assess their ventilatory requirements and optimize AV.

Images: Polysomnographic artifacts in a child with congenital central hypoventilation syndrome

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Diaphragm pacing (DP), a modality of ventilatory support in children with congenital central hypoventilation syndrome, generates respiration using the patient's own diaphragm as the respiratory pump. We report a 14-year-old boy with congenital central hypoventilation syndrome who uses DP with an uncapped tracheostomy during sleep. Polysomnography to titrate DP settings identified artifacts occurring in regular intervals coinciding with the onset of inspiration during all sleep stages in several channels including legs, snore, and electrocardiogram. Clinicians interpreting polysomnograms performed during DP should become familiar with the multichannel artifacts due to DP impulses. We also identified that our patient was hyperventilated on home DP settings that led to adjustment of DP settings during the polysomnogram to achieve optimal oxygenation and ventilation. Our case also highlights the utility of polysomnography to ensure optimal gas exchange during sleep in children with congenital central hypoventilation syndrome using DP.