Total Lung Capacity (TLC)

Total lung capacity can be measured by

• Helium dilution method
• Plethysmography
• Single breath Helium
• Radiological method (CXR)
• CT scan

In routine PFT interpretation we will be primarily be evaluating TLC by the first three methods.

Plethysmograhy: Measures Slow spaces (Blebs)
Helium dilution: May underestimate slow spaces.
Sinle breath: We will consider it under diffusion measurement.