The efficacy of noninvasive mechanical ventilation on nocturnal hypoxaemia in Duchenne's muscular dystrophy

The aim of this 2 yr follow-up study was to evaluate the efficacy of nocturnal noninvasive mechanical ventilation in a group of 10 Duchenne's muscular dystrophy (DMD) patients who desaturated during the night but had normal daytime blood gases: mean (range) age 18.3 (15-22) yrs; mean (SD) vital capacity (VC) 752.5 (460-1,308) mL; mean time in bed (TIB) with arterial oxygen saturation (Sa,O2) < 90% 22.8% of total TIB (range: 16.6-32.0); mean arterial oxygen tension (Pa,O2) 10.3 (9.3-11.7) kPa (78 (70.0-87.8) mmHg); mean arterial carbon dioxide tension (Pa,CO2) 5.9 (4.8-6.5) kPa (44.3 (36.3-48.5) mmHg). All the patients were noninvasively ventilated during the night with a bilevel positive pressure ventilation (BiPAP) devise in spontaneous mode in order to correct the episodes of nocturnal desaturation. Nocturnal Sa,O2 values normalized during nocturnal noninvasive mechanical ventilation, and daytime sleep-disordered breathing disappeared, for the entire study period. No statistically significant differences were observed between baseline and follow-up daytime blood gas values, although a slight increase in Pa,O2 was found. During the follow-up, VC declined at a rate of 79.1 +/- 25 mL.yr-1, less than that generally reported in the past in untreated patients in the same age range. In conclusion, our data suggest that patients with advanced Duchenne's muscular dystrophy with pronounced nocturnal desaturation, not fulfilling criteria for imperative ventilation, could be successfully treated with "elective" nocturnal ventilation with immediate benefits consequent to the correction of the nocturnal blood gas anomalies and with long-term benefits related to the preservation of residual respiratory function, delay of development of chronic hypercapnia and thus the requirement for imperative mechanical ventilation.