Table 1—

Anthropometric characteristics and pulmonary function data of the normocapnic and hypercapnic patients with chronic obstructive pulmonary disease

Normocapnic patientsHypercapnic patientsp-value
Subjects n96
Age yrs66.9±3.066.5±3.40.93
Body mass index kg·m−224.7±1.729.5±2.50.12
FEV1 L0.94±0.060.80±0.130.39
FVC L2.46±0.142.00±0.270.12
FRC L7.12±0.586.92±0.450.81
RV L6.39±0.616.20±0.400.82
TLC L9.20±0.608.28±0.400.28
Pa,CO2 mmHg39.9±0.652.4±1.6<0.001
Pa,O2 mmHg69.6±2.057.7±4.00.01
Arterial bicarbonate content, mEq·L−125.6±0.631.2±1.1<0.001
Edyn cmH2O·L−14.37±0.709.62±1.66<0.05
Edyn/Pdi,max L−125.6±0.631.2±1.1<0.001
  • Values are expressed as mean+se

  • FEV1: forced expiratory volume in one second

  • FVC: forced vital capacity

  • FRC: Functional residual capacity

  • RV: residual volume

  • TLC: total lung capacity

  • Pa,CO2: arterial carbon dioxide tension

  • Pa,O2: arterial oxygen tension

  • Edyn: dynamic elastance

  • Pdi,max: maximal transdiaphragmatic pressure