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The first
premise when considering treatment of a patient suffering from
dyspnea is to attempt to correct the underlying medical condition
causing the symptom. Many chronic respiratory conditions, such
as emphysema, asthma, and pulmonary fibrosis, are not curable
and, even with optimal medical therapy, may lead to persistent
discomfort and morbidity. Unable to "fix the problem,"
physicians may be tempted to treat the symptoms, (particularly
if they are quite intense) in a non-specific way, typically by
using narcotics. Although narcotics may be very effective in blunting
the intensity of dyspnea, they also have significant side-effects
including alteration of consciousness, constipation, and suppression
of respiratory drive with the potential for acute hypoxemia and
hypercapnia. Faced with these dilemmas, researchers have begun
to explore interventions that target specific physiological mechanisms
believed responsible for dyspnea in a given condition.
Question
25.1
If the dissociation
between the efferent messages from the respiratory controller
and movement of the chest wall contributes to the dyspnea of COPD,
how might one alleviate the respiratory discomfort in a patient
with emphysema who is on maximal medical therapy?
 | Administer
nebulized lidocaine |
 | Suppress
the drive to breathe |
 | Stimulate
chest wall receptors |
| Figure
25.1: Effect of Chest Wall Vibration on Dyspnea at Rest
in 15 Patients with Chronic Respiratory Disease
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Official
Journal of the American Thoracic Society. © American
Lung Association.
Reprinted with permission. |
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This figure shows data
gathered in an attempt to determine if chest wall vibration would
relieve dyspnea in patients. In-phase chest wall vibration reduced
dyspnea at rest in patients with COPD. A subsequent study in patients
with COPD, however, showed no effect of chest wall vibration on
dyspnea during exercise although the dyspnea associated with acute
hypercapnia was ameliorated (Cristiano
and Schwartzstein, 1997). The difference in the results among
these studies may be due, in part, to the more intense discomfort
during exercise in the latter investigation. The effect of chest
wall vibration may be small and could be overwhelmed by the rapidly
rising discomfort during exercise.
The sequence of studies
outlined above demonstrates how researchers are beginning to approach
interventions to reduce dyspnea based on knowledge of specific
physiological mechanisms underlying the uncomfortable sensations.
Initially, studies are designed specifically to assess the intensity
of dyspnea. Of course, for a therapeutic intervention to become
widely accepted, additional outcomes, such as quality of life
of the patients, will also need to be addressed.
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