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0:00
Hello. My name is Charlie Irvin.
I'm a professor of medicine
and I'm also a professor of physiology and biophysics
here at the University of Vermont,
and I'm the Director of the Vermont Lung Center.
Today's lecture is on the
Physiology of Asthma and the Involvement of the Small Airways.
0:18
This diagram presents the common wisdom of the pathophysiology of asthma.
That is that asthma or the asthmatic has narrowed airways due to
smooth muscle contraction and accumulation of mucus within the airway lumen.
As we'll learn in this lecture,
this is far from the facts and many asthmatics and
the physiological changes that characterize the asthmatic are complex and varied.
0:44
This is the outline for the presentation today.
Asthma is a syndrome.
It's a syndrome that's characterized by airway inflammation and
a particular set of lung function abnormalities that are shown here.
Airflow limitation refers to the ability to bronchodilator,
periodicity of airflow limitation and airways hyper-responsiveness.
And it's these four topics that I'm going to be discussing,
because asthma is, after all,
defined by the physiological dysfunction,
so it's at this point, we do not have a biomarker or some other aspect of
the pathology that absolutely characterizes this particular syndrome and disease.
So let's first turn and discuss airflow limitation.
1:31
Airflow limitation or obstruction can be measured with a variety of techniques.
I will be discussing it at various points within this lecture.
Spirometry with the classic measurement of FEV1 and FVC.
And that's where we'll begin.
Flow volume loops, which are measurements of flow versus volume.
Other measurements of airflow limitation including
sGAW or conductance with the body with plethysmograph,
forced oscillations, peak flow recordings,
and the measurement of lung volume.
