Am. J. Respir. Crit. Care Med., Vol 153, No. 4, 04 1996, 1314-1321.
The effect of the absence of abdominal muscles on pulmonary function and exercise
JM Ewig, NT Griscom and ME Wohl
Department of Pediatrics, Children's Hospital, Boston, Massachusetts, USA.
In order to determine the long-term sequelae of prune belly syndrome (PBS)
and whether the absence of abdominal wall musculature impairs exercise
performance we studied nine patients 6 to 31 yr of age with PBS.
Conventional spirometry, lung volumes, DLCO, and respiratory muscle
strength were measured. A progressive 1-min incremental exercise test was
performed on a cycle ergometer, and relative abdominal and chest wall
displacements were measured by respiratory inductive plethysmography (RIP).
Mean values of TLC, FRC, and RV were 94 +/- 12, 88 +/- 13, and 94 +/- 41%,
respectively. Mean values of PEFR, FEV1, and FEF25-75 were 83 +/- 24, 92
+/- 23, and 83 +/- 28%, respectively. Maximal expiratory pressures were
significantly reduced in seven of nine patients, with marked reduction in
four (>3 SD below the mean). Percent predicted maximal VO2 achieved, %
maximal work, and % maximal heart rate were 79 +/- 13, 78 +/- 14, and 87
+/- 2%, respectively. All seven subjects with absent abdominal musculature
had paradoxical motion of the abdomen during quiet respiration in the erect
or sitting position and while exercising. These subjects had synchronous
breathing at rest in the supine position. Although the etiology of the
relatively low work rates and VO2 achieved was multifactorial, we speculate
that the abdominal paradox in these subjects necessitates abnormally large
rib cage displacements during exercise, which may be a significant
contributing factor to exercise limitation in some of these subjects.
