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Background: Congenital central hypoventilation syndrome (CCHS) is a rare disorder affecting central control of breathing. Thus, patients require lifelong assisted ventilation. Diaphragm pacing (DP) may permit decannulation in those who are ventilator dependent only during sleep., Objective: The purpose of this study is to determine if patients with CCHS can be successfully ventilated by DP without tracheostomy., Methods: We reviewed the records of 18 CCHS patients (mean age 19.5 ± 10.1 years; 44% female) who were ventilated by DP only during sleep., Results: Prior to diaphragm pacer implantation surgery, 14 CCHS patients had been using home portable positive pressure ventilation (PPV) via tracheostomy, 1 had been on PPV via endotracheal tube, and 3 had been using noninvasive PPV (NPPV). Of the patients with tracheostomy prior to DP (n = 15), 11 (73%) were decannulated and ventilated successfully by DP without tracheostomy. Of all the patients reviewed (n = 18), 13 (72%) were successfully ventilated by DP without tracheostomy. Obesity prevented successful DP without tracheostomy in 1 patient, and upper airway obstruction prevented success in another patient. Snoring and/or obstructive apneas were present in some patients, but they were improved by diaphragm pacer changes, adenotonsillectomy, and/or use of nasal steroids., Conclusions: DP without tracheostomy can be successfully achieved in patients with CCHS. Snoring and obstructive apneas, when present, can be managed by diaphragm pacer changes and medical therapies. Obesity can pose a challenge to successful DP., (© 2015 S. Karger AG, Basel.)

The presence of pulmonary, cerebral, and/or peripheral edema in acute mountain sickness (AMS) implies a derangement in the body's handling of water. Previously, we demonstrated water retention and increased symptoms of AMS when hypocapnia was prevented in subjects exposed to simulated high altitude. This led us to the hypothesis that upon ascent to high altitude, those persons who fail to increase their ventilation adequately and hence do not become hypocapnic will retain water reflected as weight gain and will develop AMS. To test this hypothesis, we studied in Kathmandu, Nepal (1,377 m) 42 healthy western tourists; all were restudied in Pheriche (4,243 m) within 6 days of exposure to high altitude. Symptoms of AMS were highly correlated (p less than 0.001) with weight change, suggesting that persons becoming symptomatic retained fluid. On going from low to high altitude, those persons who lost weight and remained well increased their resting ventilation, whereas those who gained weight did not (p = 0.03). This relative hypoventilation in the latter group was confirmed by higher values of Pco2 (heated hand vein blood) and lower values of arterial saturation (ear oximeter) at Pheriche. Vital capacity measured in Kathmandu was correlated with arterial saturation at Pheriche (p = 0.02); persons with low vital capacity were more hypoxemic with more symptoms of AMS. We conclude that relative hypoventilation and weight gain appear early in the development of AMS suggesting links between altitude hypoxia, hyperventilation, hypocapnia, and the body's handling of water.

An unusual patient with hypoxemia, hypercapnia, and right ventricular failure is presented. Minimal skeletal muscle weakness, although present, cannot explain hypercapnia. Muscle biopsy revealed diabetic microangiopathy. Carbon dioxide stimulation demonstrated a diminished hypercapnic ventilatory response. The patient benefited from progesterone therapy. In this unusual patient, mild muscular weakness, caused by diabetes, and central alveolar hypoventilation have acted in synergism to cause abnormal ventilation and right ventricular failure.