pulmonary function tests

• physiology of pulmary
• TLDR-PFT
• normal value of pulmonary function tests 󰒗
• 常見的錯誤: 如果說 FVV1/FVC < 70%, 還是要想是不是 FVC 的問題，如果 FVC 小，可能要想是不是有 mix: 無力的限制
• 肺活量測定：評估阻塞性疾病
• Flow-volume loops: diagnose and/or localize obstruction：診斷和/或定位阻塞
• Bronchodilator: indicated if obstruction at baseline or asthma clinically suspected 支氣管擴張劑：適用於基線阻塞或臨床哮喘

Methacholine challenge: helps dx asthma if spirometry nl, >20% ↓ FEV {1} → asthma 乙酰甲膽鹼挑戰：如果肺活量測定 nl，>20% ↓ FEV1 → 哮喘，則有助於 dx

• Lung volumes: evaluate for hyperinflation or restrictive disease including NM causes

• DLCO: evaluates functional surface area for gas exchange; helps differentiate causes of obstructive and restrictive diseases and screens for vascular disease & early ILD

• DLCO：評估氣體交換的功能表面積；有助於區分阻塞性和限制性疾病的原因，並篩查血管疾病和早期 ILD

Approach to pulmonary function test

• 先從 FEV1/forced vital capacity<LLN 及 total lung capacity < 80%
  • 可以分是氣管塞住、還是限制性
    • 如何分是 Asthma or chronic obstructive pulm dis
      • forced expir vol in 1 sec 第一秒可以吹多少
        • 吸了 bronchodilator 可以吹很多，不是 COPD: 是 Asthma

Comparison of bronchodilator responsiveness in asthma and chronic obstructive pulmonary disease

• RV: residual volume,
• ERV: Exspiratory reserve volume,
• IRV: Inspiratory reserve volume
• FRC (Functional residual capacity) = ERV + RV
• FVC (Functional vital capacity) = IRV + TV+ ERV TLC (Total lung capacity) = IRV+ TV+ ERV +RV