Changes in Spirometry Over Time as a Prognostic Marker in Patients with Duchenne Muscular Dystrophy

Abstract

Duchenne muscular dystrophy (DMD) causes a progressive impairment of muscle function leading to hypercapnic respiratory failure. Most studies of respiratory function in DMD have been cross-sectional rather than longitudinal, and these data have not been related to survival. We retrospectively studied 58 patients with DMD with at least 2 yr of follow-up spirometry and known vital status. Spirometry was abnormal at entry: median FEV(1) 1.60 L (range 0.4 to 2.6 L), FVC 1.65 L (range 0.45 to 2.75 L), FVC 64% predicted (range 29 to 97%). Individual rates of change of vital capacity varied, with a median annual change of -0.18 L (range 0.04 to -0.74 L), -8.0% predicted FVC (range 2 to -39%). During the study 37 patients died; the median age of death, calculated by Kaplan-Meier analysis, was 21.5 yr (range 15 to 28.5 yr). The age when vital capacity fell below 1 L was a strong marker of subsequent mortality (5-yr survival 8%). The maximal vital capacity recorded and its rate of decline (however expressed) predicted survival time. Repeated spirometric measurement provides a simple and relatively powerful means of assessing disease progression in these patients and should be considered when planning treatment trials.

Decline in Lung Volume With Duchenne Muscular Dystrophy Is Associated With Ventilation Inhomogeneity

“…1 The degree of lung volume decline is monitored annually by spirometry, as it is the strongest predictor of mortality for DMD patients. 2,3 Progressive loss of lung volume and weakness of expiratory muscles result in declining peak expiratory pressure and cough peak flow (CPF), leading to impaired clearance of airway secretions, recurrent respiratory tract infection, and atelectasis. 4 Lung volume decline manifests as progressive hypoventilation, 5 that is treated effectively with noninvasive ventilation.…”

Not to Invade: A Better Strategy?

“…They report survival as long as 25 years on full-time NIV, 3 which is certainly a greater lifespan for individuals with Duchenne muscular dystrophy than one would expect without ventilatory support. 4 However, we do not know whether patients on full-time NIV live longer than those with tracheostomy, as Bach and Martinez had no control group. 3 It seems unlikely that a randomized controlled trial of fulltime NIV versus tracheostomy ventilation will be performed, because there may not be sufficient equipoise, at least at centers where full-time NIV is available.…”

Duchenne musküler distrofi’de üst ekstremite dinamik egzersizinin solunum fonksiyonu ve yaşam kalitesi üzerine etkisi

“…Pulmoner fonksiyonlardaki kayıp-lar ortalama 9-11 yaşlarında başlamaktadır. Zorlu vital kapasitenin (ZVK) yılda ortalama % 5-10 arasında düşmeye başlamasıyla beraber öksürme kuvveti yetersizdir ve zayıf öksürüğe bağlı havayollarından sekresyonun uzaklaştırılmasındaki bozukluk ilerleyen dönemde sık görülen bulgular arasındadır (12)(13)(14)(15). ZVK'deki progresif düşüş, gece hiperkapnisinin gündüzleri de görülmesi şeklinde ilerleyerek ciddi solunum yetmezliğinin gelişmesine zemin hazırlamaktadır (16).…”

“…Literatürde nöromusküler hastalığa sahip bireylerin solunum fonksiyonlarının korunmasında inspiratuar kas eğitiminin, günlük yaşam aktivitelerindeki bağımsızlığın arttırılması ve dolayısıyla yaşam kalitesinin iyileştirilmesinde ise özellikle alt ekstremite ve gövdeye yönelik egzersiz uygulamalarının etkinliği gösterilmiştir (14,16,19,20,21). Ancak hastalı-ğın erken dönemlerinden itibaren üst ekstremiteyi içeren egzersiz uygulamalarının bu hastaların fonksiyonlarına olan etkilerini gösteren yayınlar sınırlı-dır (6,9).…”