Hypoxaemia and interstitial lung disease in an infant with hypothyroidism and hypotonia.

A 7-month-old-term male infant presented with cough, tachypnoea, hypoxaemia and post-tussive emesis. Clinical history was significant for respiratory failure and pulmonary hypertension in the neonatal period requiring assisted ventilation, congenital hypothyroidism, mild hypotonia, recurrent respiratory infections, hypoxaemia requiring supplemental oxygen and nasogastric tube feeds. Physical examination showed tachypnoea, coarse bilateral breath sounds and mild hypotonia. Chest radiograph revealed multifocal pulmonary opacities with coarse interstitial markings and right upper lobe atelectasis. Following antibiotic therapy for suspected aspiration pneumonia, chest CT scan was performed and showed multiple areas of pulmonary consolidation and scattered areas of bilateral ground-glass opacities. Genetic studies showed a large deletion of chromosome 14q13.1-14q21.1, encompassing the NK2 homeobox 1 (NKX2-1) gene consistent with a diagnosis of brain-thyroid-lung (BTL) syndrome. Our case highlights the importance of genetic studies to diagnose BTL syndrome in infants with hypothyroidism, hypotonia and lung disease.

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

NONE: 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.

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

None: Diaphragm pacing (DP) by phrenic nerve stimulation is a modality of chronic ventilatory support in individuals with congenital central hypoventilation syndrome (CCHS). We report a 9-year-old girl with CCHS who uses DP without tracheostomy during sleep. Her parents report hypoxemia and hypercapnia related to positional changes of the body during sleep requiring frequent adjustment of pacer settings. Overnight polysomnography was performed to titrate DP settings that showed adequate gas exchange in the supine position, but intermittent hypoxemia and hypercapnia were noted in the left decubitus position without obstructive sleep apnea occurring. Subsequently, the DP amplitude settings were increased during polysomnography, thereby identifying and treating positional hypoxemia and hypercapnia in various body positions. Our case emphasizes the importance of polysomnography in children with CCHS using DP to monitor for sleep-disordered breathing and titration of DP settings to achieve optimal oxygenation and ventilation with different body positions during sleep.