[The usefulness of tracheostomy in Duchenne muscular dystrophy ventilated by a chest respirator].

The respiratory dysfunction in Duchenne muscular dystrophy (DMD) patients increases with age. We have attempted various methods of artificial respiration for them. Recently, a non-invasive positive pressure ventilation (NIPPV) became the first choice of respiration, but the chest respirator (CR) was still one of the choices. In our hospital, DMD patients with tracheostomy wearing a CR were alive for longer period, despite of respiratory dysfunction and complications. We studied 6 DMD patients with CR to evaluate nocturnal hypoxia index (NHI) by examining nocturnal periodic hypoxia, and measured oxygen saturation after 20 mg of clomipramine hydrochloride administration before sleep. Three patients had periodic nocturnal hypoxia which was prevented by the clomipramine administration. Two patients with tracheostomy did not exhibit hypoxia. We speculated that pharyngeal hypotonia during REM sleep induces periodic nocturnal hypoxia, therefore the tracheostomy would prevent hypoxia. Next, we examined the pharyngeal MRI on one DMD patient at the same disease stage who also had night NIPPV. We found that his soft palate and tongue shifted downward, which narrowed his pharynx during REM sleep. Consequently we have concluded that noctunnal periodic hypoxia is mainly caured by obstructive sleep apnea. For DMD patients with CR, the tracheostomy may be effective to prevent hypoxia during sleep.