Abstract
Pulmonary function tests are designed to measure the mechanical properties of the
lung and to evaluate how well the body is performing its respiratory tasks. The carbon
monoxide diffusing capacity (DL
CO) test examines the transfer of gases from the alveolar capillary membrane to red
blood cell hemoglobin. This paper provides a brief overview of the physiological basis
for the test and an introduction to the technical challenges it presents.
DL
CO is frequently used in evaluating obstructive and restrictive lung diseases. It is
particularly useful in patients who report dyspnea but have normal spirometry and
a normal chest radiograph. It is important to keep in mind that many technical and
biological variables can alter DL
CO. Modern instruments are designed to deal with most of these issues and reliable measurements
can be obtained in clinical settings with modest effort.
Key Words:
diffusing capacity - DL
CO
- transfer factor - gas uptake - variability
