Am. J. Respir. Crit. Care Med., Vol 154, No. 4, Oct 1996, 1045-1048.
Chest wall compliance in infants and children with neuromuscular disease
C Papastamelos, HB Panitch and JL Allen
Department of Pediatrics, St. Christopher's Hospital for Children, Philadelphia, Pennsylvania, USA.
Respiratory muscle weakness is the primary cause of respiratory dysfunction
in neuromuscular disease (NMD), but structural abnormalities of the chest
wall also play a role. In adults with NMD, restrictive lung disease is in
part caused by reduced chest wall compliance (C(W)), believed to reflect
stiffening of connective tissue resulting from chronically reduced chest
wall motion in the presence of respiratory muscle weakness. We hypothesized
that chronic limitation of chest wall motion in young children with NMD
leads to structural underdevelopment of the chest wall, and results in
increased, rather than decreased, C(W). In 18 subjects with NMD, ranging
from 3 mo to 3.8 yr of age, we compared C(W) with values obtained in
children without NMD. A modification of the Mead-Whittenberger technique
was used, with respiratory muscle relaxation provided by brief manual
ventilation. Respiratory system compliance (Crs) and lung compliance (C(L))
were calculated from airway opening pressure, transpulmonary pressure, and
tidal volume. C(W) was calculated as 1/C(W) = 1/Crs - 1/C(L) during manual
ventilation. C(W)/kg was higher in subjects with NMD than in controls, at
5.2 +/- 2.8 (mean +/- SD) versus 2.4 +/- 0.8 ml/cm H2O (p < 0.001). In
subjects who had normal lung compliance values during spontaneous breathing
(C(Lspont)), C(W)/C(Lspont) was significantly greater in subjects with NMD
(5.5 +/- 3.2) than in controls (1.9 +/- 1.0) (p < 0.001). By
predisposing to rib cage deformation and reduced end-expiratory lung
volume, abnormally high C(W) in infants and young children with NMD may
contribute to respiratory dysfunction.
