Pulmonary function test

폐기능 검사(Pulmonary function test, PFT)

• TLC=IC(inspiratory capacity)+FRC(funtional residual capacity)=VC+RV=ERV+TV(tidal volume)+IRV+RV
• Restrictive pattern: FVC<80%, FVC가 작을수록 심함, TLC, VC, RV 모두 감소
  • parenchymal restrictive pattern: RV 감소
    • 질환: IPF, sarcoidosis
  • extraparenchymal restrictive pattern with limitation in inspiration and expiration: RV 증가
    • 질환: Neuromuscular disease, chest wall 이상
• Obstructive pattern: FEV1/FVC<70%, FEV1이 작을수록 심함
  • 질환: 천식, COPD, 기관지 확장증, Bronchiolitis
  • Extrathoracic obstruction은 흡기시, Intrathoracic obstruction은 호기시 장애

• BDR(bronchodilator responsiveness)
  • BDR = [(Post-bronchodilator FEV1 - Pre-bronchodilator FEV1) / Predicted FEV1] x 100%
  • Interpreting BDR
    • Based on the change in percent predicted FEV1, BDR can be categorized into five levels:
      • Negative BDR: ≤0%
      • Minimal BDR: 0-2%
      • Mild BDR: 2-4%
      • Moderate BDR: 4-8%
      • Marked BDR: >8%