Sunday, February 7, 2016

Pulmonology Review for Rotation Exams

Pulmonology for Rotation Exams
Peak Expiratory Flow - use a peak flow meter
  • If <350 L/min, perform PFTs to screen for obstruction
Pulmonary Function Testing
  • FEV1: amount of air that can be forced out of the lungs in 1 second
    • Airway obstruction diagnosed by: normal/increased TLC with decreased FEV1
      • FEV1/FVC < 0.7
Disease
FEV1
FVC
FEV1/FVC
FEF25-75
FET
Peak Exp Flow
Obstructive
Decreased
<80%
Normal
<80%
Decreased
< 0.7
Decreased
<60%
Increased
Low
Restrictive
Normal or
Decreased
<80%
Decreased
<80%
Normal or Increased
0.7
Normal
>60%
Normal
Normal
Mixed
Decreased
<80%
Decreased
<80%
Decreased
< 0.7
Decreased or Normal
<60%
Increased or Normal

    • Tiffeneau index (FEV1/FVC x 100): % of FVC expired in one second
    • FET = Forced Expiratory Time
  • Pay Attention Here: The important thing to know about how to differentiate an obstructive vs. restrictive lung disease is based on their TLC, not the vital capacity, which will be decreased in obstructive lung diseases (this can be misleading).
Disease
TLC
FRC
TV
RV
VC
Obstructive
Increased
Increased
N
Increased
Decreased
Restrictive
Decreased
Decreased
N
Decreased
Decreased
  • Total Lung Capacity: volume of air in lungs after maximum inspiration
  • Functional Residual Capacity: volume of air in lungs after normal expiration
  • Residual Volume: volume of air in the lungs at maximal expiration
  • Tidal Volume: volume of air breathed in and out of lungs during quiet breathing
  • Vital Capacity: volume of air expelled from the lungs during a maximum expiration
1221_lung_volume.gif