shortness of breathit is a subjective sensation

Question

Shortness of Breath

It is a subjective sensation of being unable too draw in enough air to breathe. Most often, this is associated with congestive cardiac failure and may accompany myocardial infraction.

This may be:

1. Dyspnoea on effort .(DOE) 
2. Orthopnea - inability to breath comfortably while lying flat. 
3. Paroxysmal Noctural Dypnoea (PND) Night time episodes of shortness of breath due to fluid movement into the lungs brought about lying flat and thereby increasing venous return.