Page 717 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat

RespiRatoRy ` RESPIRATORY—PAThOlOgY RespiRatoRy ` RESPIRATORY—PAThOlOgY seCtioN iii 673

Flow-volume loops
FlOW-VOlUmE PARAmETER Obstructive lung disease Restrictive lung disease
RV  
FRC  
TlC  
FEV 1  
FVC  
FEV /FVC  Normal or 
1
FEV decreased more than FVC FEV decreased proportionately to FVC
1 1
OBSTRUCTIVE NORMAL RESTRICTIVE
Loop shifts to the left Loop shifts to the right
8 8 8
Expiration 4 4 4

Flow (L/sec) 8 6 4 2 0 8 6 4 2 0 8 6 4 2 0 Volume (L)

Inspiration 4 4 VC RV 4

8
8
TLC 8

FAS1_2019_16-Respiratory.indd 673 11/8/19 7:34 AM