COPD/Emphysema

Emphysema is classified as an Obstructive lung disease and affects the lung structure, airways and alveoli. It is characterized by a loss of lung elasticity, hyperinflation (lung overinflation) and a loss of functional alveolar surface area. The loss of elasticity causes the airways to collapse during exhalation which reduces the rate at which air can flow. The hyperinflation decreases the turnover of fresh air in the lung during breathing and can limit how deep a breath that can be taken. The decrease in alveolar surface area reduces the ability of the lungs to transfer oxygen and carbon dioxide.

Emphysema status is best monitored by FEV1, DLCO and Oximetry.

A typical PFT pattern for Emphysema:

Spirometry FVC Normal or reduced
  FEV1 Reduced
  FEV1/FVC Ratio Reduced
  PEF Reduced
Lung Volumes TLC Normal
  RV Elevated
Diffusing Capacity DLCO Reduced
Oximetry SpO2 Reduced

The severity of obstruction is determined by the reduction in FEV1. When the FEV1 or FEV1/FVC ratio are reduced:

FEV1 >= 70% of predicted Mild
FEV1 <70% and >=60% of predicted Moderate
FEV1 <60% and >=50% of predicted Moderately severe
FEV1 <50% and >=35% of predicted Severe
FEV1 <35% of predicted Very severe

An additional factor that can be used to assess the severity of emphysema is the reduction in DLCO:

DLCO >=60% and <80% of predicted Mild reduction
DLCO >=40% and <60% of predicted Moderate reduction
DLCO <40% of predicted Severe reduction

 

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PFT Patient by Richard Johnston is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

2 thoughts on “COPD/Emphysema”

  1. I think that in Emphysema TLC will definitely increase. It is evident from Xray where we can see flattened diaphragm and hyper inflated lungs. since alveoli’s are destroyed there is more RV than normal. So, increase in TLC is obvious.

    1. Agreed, however there are different stages in emphysema and when mild TLC is usually normal. TLC usually doesn’t increase until emphysema is severe.

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