LFT Algorithm

Question 1

Step 1

Is the FEV1 low

Answer 1

Yes
-Move onto step 2

No
-no serious problem but review other readings

Question 2

Step 2

Is the FER below 0.7

Answer 2

Yes

• Obstructive issue
• Is the TLCO/KCO low

No

• Restrictive issue
• Is the TLCO/KCO, RV, FRC low

Question 3

Step 3a

Is the TLCO/KCO low

Answer 3

Yes

• COPD with emphysema
• check if RV and TLC is high

No
-Asthma or COPD without predominant emphysema

Question 4

Step 3b

Is the TLCO/KCO, RV, FRC low

Answer 4

Yes
-Intrinsic lung issue, stiff lungs?

No
-Extrinsic lung issue, chest wall, muscle issue

Question 5

Step 3ai

Is there marked reversibility with BD

Answer 5

Yes, change in FEV1 greater than 12%
-Asthma

No
-COPD