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Abstract

Case Reports: A 50 year old African-American male presented with recurrent hypercapnic respiratory failure. Past medical history included hypertension, hypothyroidism and central sleep apnea on home BiPAP, with a BMI of 26. He presented in 2009 and 2010 with episodes of hypercapnia requiring intubation and normal pulmonary compliance and resistance. There was no history of sedative or narcotic medication ingestion. CT angiography, spirometry and neurological examination were normal. A brain MRI showed T2 and flair signal hyperintensities in the white matter and pons but no acute infarcts. On both occasions the patient briefly required mechanical ventilation and was discharged home. In 2012 he returned with lethargy and hypercapnic respiratory failure requiring intubation, room air ABG of 7.15/128/110/44/98%. CXR and CT head were negative and he had not received any sedation or narcotics. He had a mild erythrocytosis. Pulmonary mechanics were normal and he was able to comfortably draw 8-10 mL/Kg of ideal body weight on pressure support of 8/5, so he was extubated to BiPAP. Within a few hours he became lethargic and hypercapnic, with a room air ABG of 7.19/103/115/39/98% and was reintubated. Neurological examination was normal. EMGs were suspicious for demyelinating polyneuropathy, however he did not respond to a 3 day course of intravenous immunoglobulin. A sonographic “sniff test” revealed normal diaphragmatic excursion. Tracheostomy was performed. He tolerated tracheal collar during the day but required pressure support at night due to frequent periods of apnea. Genetic testing for central congenital hypoventilation syndrome (CCHS), also known as “Ondine’s curse”, was performed and returned positive for a heterozygous PHOX2b gene mutation. He was transferred to a university center for diaphragmatic pacemaker placement. Late-onset congential hypoventialation (LO-CHS) is rare, with fewer than 20 cases reported. Awareness of and evaluation for LO-CHS in patients with unexplained hypercapnic respiratory failure may help to diagnose future cases.