Spirometry Lab — Lung Volumes & Capacities

Part 1Read & Calculate: TV, ERV, and VC

Patient A was tested 15 minutes after maximal exercise. Use the graph to identify the three key volume levels from his spirometry tracing. Hover over the traces and click to lock a reading. Enter the values below — the calculations update automatically.

Highest volume reached during quiet (tidal) breathing

L

Lowest volume during quiet (tidal) breathing — the resting baseline

L

Maximum volume reached during Maneuver A (maximal inhalation)

L

Calculations

TV = ? − ? = — L

ERV = ? − 1.2 (RV, given) = — L

VC = ? − 1.2 (RV, given) = — L

Part 2Set Up Equations: IRV, IC, FRC, and TLC

Now set up the capacity equations using Patient A's measured volumes. Choose variables and operators — the same equations apply for any patient; only the values change.

Inspiratory Reserve Volume

IRV

=

Term 1

Term 2

Term 3

Inspiratory Capacity

IC

=

Term 1

Term 2

Functional Residual Capacity

FRC

=

Term 1

Term 2

Total Lung Capacity

TLC

=

Term 1

Term 2

Part 3Calculate the Capacities

Your equations are filled in with Patient A's values. Review the calculated capacities and compare them with the normal values from the baseline lab — which are elevated? Which are reduced?

IRV——L

IC — —L

FRC——L

TLC——L

Clinical Interpretation — Compare to Normal Baseline:
Normal RV ≈ 1.2 L → Patient A: 1.8 L ↑ (air trapping)
Normal FRC ≈ 2.5 L → Patient A: 2.8 L ↑ (elevated resting lung volume)
Normal ERV ≈ 1.3 L → Patient A: 1.0 L ↓ (ERV compressed by elevated RV)
Normal IRV ≈ 3.0 L → Patient A: 2.6 L ↓ (less room to inhale with hyperinflated lungs)
Normal VC ≈ 4.8 L → Patient A: 4.0 L ↓ (reduced vital capacity — obstructive pattern)

Part 4Label the Spirometry Graph

Label the four volume regions on Patient A's spirometry graph. Type the correct abbreviation into each box, then click Check Labels.