ABSTRACT
Decline in pulmonary function in Duchenne Muscular Dystrophy (DMD) contributes to significant morbidity and reduced longevity. Spirometry is a widely used and fairly easily performed technique to assess lung function, and in particular lung volume; however, the acceptability criteria from the American Thoracic Society (ATS) may be overly restrictive and inappropriate for patients with neuromuscular disease. We examined prospective spirometry data (Forced Vital Capacity [FVC] and peak expiratory flow [PEF]) from 60 DMD patients enrolled in a natural history cohort study (median age 10.3 years, range 5-24 years). Expiratory flow-volume curves were examined by a pulmonologist and the data were evaluated for acceptability using ATS criteria modified based on the capabilities of patients with neuromuscular disease. Data were then analyzed for change with age, ambulation status, and glucocorticoid use. At least one acceptable study was obtained in 44 subjects (73%), and 81 of the 131 studies (62%) were acceptable. The FVC and PEF showed similar relative changes in absolute values with increasing age, i.e., an increase through 10 years, relative stabilization from 10-18 years, and then a decrease at an older age. The percent predicted, FVC and PEF showed a near linear decline of approximately 5% points/year from ages 5 to 24. Surprisingly, no difference was observed in FVC or PEF by ambulation or steroid treatment. Acceptable spirometry can be performed on DMD patients over a broad range of ages. Using modified ATS criteria, curated spirometry data, excluding technically unacceptable data, may provide a more reliable means of determining change in lung function over time.
Subject(s)
Lung/physiopathology , Muscular Dystrophy, Duchenne/physiopathology , Adolescent , Child , Child, Preschool , Cohort Studies , Disease Progression , Forced Expiratory Volume , Glucocorticoids/therapeutic use , Humans , Male , Mobility Limitation , Muscular Dystrophy, Duchenne/drug therapy , Peak Expiratory Flow Rate , Prospective Studies , Respiratory Function Tests/methods , Spirometry , Vital Capacity , Walking , Young AdultABSTRACT
AIMS: Autonomic nervous system dysfunction is observed in Type 2 diabetes. As gestational diabetes is a potent risk factor of later Type 2 diabetes, we set out to determine whether autonomic nervous system imbalance could already be observed in women with this condition. Because activity of the sympathetic nervous system tends to be relatively stable in the nocturnal hours, we performed the study at night. RESEARCH DESIGN AND METHODS: We studied 41 women with gestational diabetes, 22 healthy pregnant controls and 14 non-pregnant controls. We assayed plasma noradrenaline at 24.00, 04.00 and 07.00 h and performed an overnight Holter recording for heart rate variability analysis. In addition, we assayed plasma adrenomedullin, a cardiovascular protective hormone. RESULTS: Compared with non-pregnant controls, plasma noradrenaline levels were increased at 04.00 and 07.00 h in the gestational diabetic (P = 0.003) and pregnant control (P = 0.002) groups, with no difference between them. Heart rate variability, very-low-frequency and low-frequency power were lower in pregnant groups compared to the non-pregnant controls. Heart rate variability remained unchanged between specified sampling times in the gestational diabetic group, in contrast to fluctuation seen in the control groups. CONCLUSIONS: Gestational diabetes, compared with normal pregnancy, seems not to be a state of overall sympathetic nervous system activation. At the heart level, however, an inhibitory effect on autonomic nervous system modulation was seen. Plasma noradrenaline and heart rate variability correlated well, supporting the use of this function in future studies of overall sympathetic activity during pregnancy.
