Passive motion of the extremities modifies alveolar ventilation during sleep in patients with congenital central hypoventilation syndrome.

Passive motion of lower extremities (PMLE) elicits significant increases in alveolar ventilation (V A) in awake children with congenital central hypoventilation syndrome (CCHS), who have absent or near absent ventilatory responses to hypercapnia. We hypothesized that PMLE would improve V A during non-rapid eye movement (NREM) sleep. To study this, six patients with CCHS (0.2 to 7 yr of age) were disconnected from mechanical ventilatory support during Stage III-IV NREM, and their feet were passively moved at the ankle, either manually or with a motorized device strapped to their feet at 40 to 50 strokes/min. Holding of the feet without motion served as control (C). From a total of 74 successful trials not associated with sleep state changes, PET(CO(2)) decreased from 58.9 +/- 3.5 to 40.9 +/- 2.6 mm Hg with PMLE (n = 58; p < 0.001), whereas end-tidal carbon dioxide (PET(CO(2))) increased in C (n = 16; 58.8 +/- 3.1 to 60.3 +/- 3.7 mm Hg; PMLE versus C: p < 0.001). PMLE increased respiratory frequency from 10.2 +/- 1.9 to 21.2 +/- 2.7 breaths/min (p < 0.0001). We conclude that PMLE during NREM increases V A possibly via activation of mechanoreceptor-afferent pathways rather than by respiratory entrainment. We speculate that such effect may provide future noninvasive ventilatory support strategies in patients with CCHS and mild phenotypic expression of their disease.