Postural vital capacity difference with aging in duchenne muscular dystrophy.
BACKGROUND
A change in vital capacity (VC) from standing to supine can be an index of diaphragm paralysis if it exceeds 25%. We aimed to verify whether the postural VC difference increases with age and reflects diaphragm weakness in DMD.


METHODS
VCs were measured in DMD. Postural VC difference and percentage were calculated from the VC data. Maximal inspiratory pressure (MIP) and MIP percentage were measured as an indirect index of diaphragm weakness.


RESULTS
A total of 220 patients and 544 measurements were collected. MIP and MIP percentage decreased significantly with age (P < 0.001 for both). Estimated postural VC difference and percentage also decreased (P < 0.001, P = 0.006, respectively). Age group comparisons showed a significant decrease in younger, but not older subjects.


CONCLUSIONS
This study shows that the postural VC difference tended to decrease with age and might not reflect diaphragmatic weakness in DMD; however, this should be interpreted cautiously.
Department of Physical Medicine and Rehabilitation, Research Institute of Clinical Medicine, and Institute for medical science, Chonbuk National University Medical School & Hospital, Korea.|Yonsei University Graduate School of Medicine, Seoul, Korea.
Yu Hui
YH
Won
Department of Rehabilitation Medicine, Gangnam Severance Hospital, Rehabilitation Institute of Neuromuscular Disease, Yonsei University College of Medicine, Seoul, Korea.
Won Ah
WA
Choi
Department of Rehabilitation Medicine, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea, 135-720.
Dong Hyun
DH
Kim
Yonsei University Graduate School of Medicine, Seoul, Korea.|Department of Rehabilitation Medicine, Gangnam Severance Hospital, Rehabilitation Institute of Neuromuscular Disease, Yonsei University College of Medicine, Seoul, Korea.
Seong-Woong
SW
Kang
D000293:Adolescent; D000328:Adult; D000375:Aging / Q000473:pathology* / Q000502:physiology*; D002648:Child; D005500:Follow-Up Studies; D006801:Humans; D007320:Inspiratory Capacity / Q000502:physiology; D008297:Male; D020388:Muscular Dystrophy, Duchenne / Q000175:diagnosis* / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D012132:Respiratory Muscles / Q000473:pathology / Q000503:physiopathology; D012189:Retrospective Studies; D014797:Vital Capacity / Q000502:physiology*; D055815:Young Adult
Duchenne muscular dystrophy; age; diaphragm; maximal inspiratory pressure; postural vital capacity difference