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Breathing
through a small tube, with an increased resistance, evokes a qualitatively
distinct sensation from breathing carbon dioxide. The physiology
of these two stimuli is distinct as well. One involves a mechanical
load on the ventilatory pump. The other produces stimulation of
the chemoreceptors. In disease states such as asthma or emphysema,
there may be multiple physiological derangements interacting in
a way to produce one or more sensations under different circumstances.
| Table
3.1: Clusters of respiratory sensations described by
normal subjects who experienced breathing discomfort
in association with a range of respiratory tasks.
|
|---|
| Cluster
| Dsecriptors
| BrHo
| CO2
| DTV
| Res
| Elas
| FRC
| VT
| Exer
|
|---|
| 1.
Rapid |
14
|
|
X
|
|
|
|
X
|
X
|
X
|
| 2.
Exhalation |
18
|
|
|
|
|
|
X
|
|
|
| 3.
Concentration |
19
|
|
|
X
|
|
|
|
X
|
|
| 4.
Shallow |
1,
6, 15
|
|
|
|
|
|
|
X
|
|
| 5.
Work |
2,
9
|
|
X
|
|
X
|
|
|
|
|
| 6.
Suffocating | 3,
8, 10, 11, 13 | | | | | | | | |
| 7.
Hunger |
4,
17
|
X
|
|
X
|
X
|
X
|
|
|
|
| 8.
Heavy |
5,
16
|
|
|
|
|
|
|
|
X
|
| 9.
Gasping |
7,
12
| | | | | | | | |
BrHo
= breathholding
CO2 = steady state hypercapnia
DTV = driven targeted ventilation
Res = resistive load | Elas
= elastic load
FRC = increased functional residual capacity
VT = decreased tidal volume
Exer = exercise |
|
| Official
journal of the American Thoracic Society. © American
Lung Association. Reprinted with permission. |
|
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