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Clinical Research on Dyspnea
Author Bios
What is Dyspnea?
What Provokes Dyspnea?
The Nature of Dyspnea
Language of Dyspnea
Clinical Application
Research Application
Variability in Sensations
Challenges in Study
Mechanical Loads and Sense of Effort
Chemoreceptors
Mechanoreceptors
Neuro-Mechanical Dissociation
Phase of Respiration and Dyspnea
Physiology of Dyspnea
Respiratory System
Cardiovascular System
Measuring Dyspnea
Scaling Issues
Currently selected section: Qualitative Aspects
Reliability and Validity Overview
Reliability and Validity
Sensitivity and Specificity
Scales
Sensation vs. Perception vs. Symptom
Treating Dyspnea
Why Measure?
Cluster Analysis
Statistical vs. Clinical Significance
Standard Error of Measurement
Measuring Fatigue
Measuring Depression
Measuring Anxiety and Hyperventilation
Measuring Quality of Life
Conclusion

 

Chapter 23: Dyspnea: Qualitative Aspects
        

We have outlined previously the need for and the development of dyspnea questionnaires to assist the clinician and researcher in efforts to approach the qualitative aspects of breathing discomfort in a systematic manner. These questionnaires have been shown to be reliable and discriminative for most, but not all, subjects (Elliott et al., 1991; Mahler et al., 1996).

Table 19.1: Example of a List of Descriptiors Utilized in Dyspnea Questionnaires
List of Descriptors
  1. My breath does not go in all the way.
  2. My breathing requires effort.
  3. I feel that I am smothering.
  4. I feel a hunger for more air.
  5. My breathing is heavy.
  6. I can not take a deep breath.
  7. I feel out of breath.
  8. My chest feels tight.
  9. My breathing requires more work.
  10. I feel that I am suffocating.
  11. I feel that my breath stops.
  12. I am gasping for breath.
  13. My chest is constricted.
  14. I feel that my breathing is rapid.
  15. My breathing is shallow.
  16. I feel that I am breathing more.
  17. I can not get enough air.
  18. My breath does not go out all the way.
  19. My breathing requires more concentration.

In administering questionnaires, we have found the following method to be most productive. First, subjects should be asked to describe in their own words the nature of their "breathing discomfort." We find this phrase to be the most general term one can use and the one least likely to bias the subject towards a particular response; the term "breathlessness" has also been used as a generic yet understandable term for non-physicians when one is inquiring about the quality of dyspnea. Second, we ask the subject to look at the list of phrases on the dyspnea questionnaire and to place a check-mark next to each of the phrases that applies to the breathing discomfort experienced during the circumstances under study. Third, we ask the subject to look only at the phrases with a check-mark and to mark a "1," "2," and"3" for the best, second best, and third best phrase that seems to capture the quality of the breathing discomfort. If the subject expressed or wishes to express a phrase not on the list, he or she should be encouraged to write it in on a blank line at the end of the questionnaire. A "cluster analysis," used to determine the groupings of phrases chosen by a population of subjects, is an involved statistical approach that has been described in several studies of the language of dyspnea (Simon et al., 1990; Elliott et al., 1991; Mahler et al., 1996).

When examining a specific physiologic mechanism responsible for dyspnea by provoking breathlessness with a particular stimulus, or when assessing the efficacy of an intervention to reduce breathlessness, one should be explicit in the instructions given to subjects about the sensation being measured. If one has a good idea about the relevant sensation that will be provoked or ameliorated, for example, the effort of breathing or chest tightness, or air hunger, you should instruct subjects to rate that sensation. If you are unsure about the quality of the sensation that will be provoked or if you are interested primarily in a global rating of dyspnea, subjects should be instructed to rate breathing discomfort. In this situation, however, it is important to debrief subjects at the end of the study to determine what they were actually rating. Seemingly inconsistent data may be explainable by the observation that different subjects were rating different sensations.

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