Table 2—

Effect of different patterns of respiratory muscle weakness on lung volumes and spirometry

ControlsUDW/BDWIMWCMW
VC % pred (L)101.8±14.7 (5.47±1.37)76.4±7.2* (2.97±1.14)49.6±13.6*,# (1.98±0.64)50.5±15.6*,# (2.03±0.74)
TLC % pred (L)107.3±7.0 (7.51±1.15)83.6±11.2* (5.87±1.52)68.9±12.1*,# (4.60±0.95)80.9±13.0* (4.94±1.74)
FRC % pred (L)101.1±13.9 (3.65±0.68)83.9±15.1 (3.06±0.70)83.6±17.2 (2.94±0.68)109.9±29.2#,¶ (3.45±1.35)
RV % pred (L)117.3±17.0 (2.02±0.47)102.6±20.6 (2.52±0.47)103.7±23.4 (2.55±0.63)157.4±48.6*,#,¶ (2.89±1.49)
FEV1/FVC %83.4±6.074.4±4.1*79.4±5.0#90.5±2.6*,#,¶
  • Data are presented as mean±sd

  • UDW/BDW: isolated unilateral and bilateral diaphragm weakness

  • IMW: generalised inspiratory muscle weakness

  • CMW: combined inspiratory and expiratory muscle weakness

  • VC: vital capacity

  • % pred: percentage of predicted normal value

  • TLC: total lung capacity

  • FRC: functional residual capacity

  • RV: residual volume

  • FEV1/FVC: forced expiratory volume in one second, normalised for the forced vital capacity

  • *: significant difference from control group, p<0.05

  • #: significant difference from UDW/BDW group, p<0.05

  • : significant difference from IMW group, p<0.05