Basic pulmonary function tests, such as diffusing capacity for carbon monoxide (DLCO), flow-volume loops, lung volumes, and spirometry
Lung volumes
| Definition | |
|---|---|
| TV | Normal breath, ~500 mL |
| IRV / ERV | Extra volume in / out beyond tidal |
| RV | Air remaining after maximal expiration - cannot be measured by spirometry |
| FRC = ERV + RV | Volume at end of a normal expiration; where elastic recoil in = chest wall recoil out |
| VC = IRV + TV + ERV | Max in to max out |
| TLC = VC + RV | Everything |
- RV, FRC and TLC require body plethysmography, helium dilution or nitrogen washout
- Plethysmography measures all intrathoracic gas including trapped gas; dilution/washout measure only communicating gas
- -> Plethysmographic TLC > dilutional TLC in severe obstruction - the difference is trapped gas
- RV inc with age and with air trapping in obstructive disease
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