There is no universally accepted definition of dyspnea, but
everybody has experienced the sensation and thus has an
intuitive understanding of the phenomenon. At a symposium
on breathlessness in 1965, Julius H. Comroe1 outlined his
concept of dyspnea. It "is difficult, labored, uncomfortable
breathing; it is an unpleasant type of breathing, though it is
not painful in the usual sense of the word. It is subjective and,
like pain, it involves both perception of the sensation by the
patient and his reaction to the sensation." In his closing
remarks2 at the end of the symposium, he returned to this
issue.
We have learned here that there are five or six different grades or
types of this sensation. One is an awareness that there is a little
increase in ventilation. Another is a little shortness of breath ('harder
to get one's breath') and this may be slightly unpleasant. Another is
an