Sleep and neuromuscular disease: bilevel positive airway pressure by nasal mask as a treatment for sleep disordered breathing in patients with neuromuscular disease

Abstract

OBJECTIVE Investigation of the therapeutic effects of bilevel positive airway pressure delivered by nasal mask in patients with neuromuscular disease.

METHODS 20 patients with neuromuscular disease were evaluated for symptoms of nocturnal sleep disruption. These symptoms included daytime tiredness, fatigue, sleepiness, and complaints of insomnia. The patients were studied with nocturnal polysomnograms and daytime multiple sleep latency tests (MSLT). Their immediate and long term responses to bilevel positive airway pressure were also investigated. The study took place at the Stanford University Sleep Disorders Clinic. Some of the polygraphic evaluations were performed with portable equipment in the patients’ homes. The reported population comprised 20 patients, all of whom had progressive neuromuscular disease. Five of the patients were women. Four patients had muscular dystrophy, six had myotonic dystrophy, and two patients each had mitochondrial myopathy and glycogen storage disease. Two patients had post-traumatic lesions, one bulbar and the other phrenic. The remaining patients had vascular myopathy, unclassified myopathy, syringomyelia, and slow evolving spinocerebellar degeneration.

RESULTS 19 of the 20 patients accepted some form of non-invasive ventilation. All but one of these were initially maintained on bilevel positive airway pressure spontaneous (S) mode, although one patient required a switch to the timed (T) mode within a year. The mean expiratory positive airway pressure (EPAP) used was 4.5 with a range of 4 to 5 cm H₂O. The mean inspiratory positive airway pressure (IPAP) was 11.5, range 9 to 14 cm H₂O. Before treatment the MSLTs were ≤ 8 minutes in 11 of the patients. The overall mean score was 8.2 (SD) 1.3 minutes. After long term treatment the mean MSLT was 12.5 (SD 2) minutes and the mean ESS score was 7 (SD 3). During the mean 3.5 years of follow up, three patients needed supplemental oxygen at a flow of 0.5 to 1.0 l/min bled into their masks. Three patients with myotonic dystrophy presented continued daytime somnolence despite apparent adequate treatment of their sleep disordered breathing. This required the addition of stimulant medication to their regimen. During this time three additional subjects had to be switched to nasal mask intermittent positive pressure ventilation delivered by traditional volume cycled home ventilator (volume controlled NIPPV).

CONCLUSIONS Bilevel positive airway pressure delivered by nasal mask may be used successfully to treat sleep disordered breathing associated with neuromuscular disease. This device can be employed to assist nocturnal ventilation by either the spontaneous or timed mode. In the United States it is less expensive and easier to institute than volume controlled NIPPV and may be as efficacious as this mode if close surveillance and regular re-evaluation of the patient’s status is maintained.