Without further information as :
What does dyspnea mean?
Shortness of breath — known medically as dyspnea — is often described as an intense tightening in the chest, air hunger, difficulty breathing, breathlessness or a feeling of suffocation. Very strenuous exercise, extreme temperatures, obesity and higher altitude all can cause shortness of breath in a healthy person.
This is usually a symptom of an underlying condition such as COPD or pneumonia for example.
R06 is Abnormalities of breathing
R06.00 Dyspnea, unspecified
R06.09 is Other forms of dyspnea