Definition of Dyspnea

Dyspnea – Difficulty BREATHING or shortness of breath. There are numerous causes of dyspnea, most of which relate to cardiovascular or pulmonary disorders. Dyspnea occurs when the body does not receive enough oxygen. As oxygen is the fuel for cellular activity, lack of oxygen means cells cannot function properly. When oxygen insufficiency (HYPOXIA) is systemic (involves all the body) the body begins to conserve oxygen for vital uses. This concurrently slows activity of nonessential cells such as skeletal MUSCLE cells and sends signals to the LUNGS and HEART to increase their productivity.

Dyspnea may occur as a result of intense physical activity, such as exercise, in which case it generally diminishes with improved AEROBIC FITNESS. Dyspnea associated with cardiovascular or pulmonary disease may lessen slightly with pulmonary rehabilitation and improved physical conditioning but typically does not improve substantially unless the underlying disease condition improves. CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) and HEART FAILURE are the two most common causes of dyspnea. Doctors assess clinical dyspnea according to the degree to which it interferes with normal activities.

Grades of Dyspnea

GradeSeverityLevel of Impairment
grade 1minimalshortness of breath with exertion such as climbing multiple flights of stairs, short running such as to catch a bus, or walking uphill
grade 2mildshortness of breath with moderate exertion such as climbing a single flight of stairs or walking several blocks on the flat
grade 3moderateshortness of breath with mild exertion such as walking one block on the flat; must pause when climbing a single flight of stairs
grade 4significantshortness of breath with everyday physical activity; must pause when walking on the flat; must pause every few steps when climbing a flight of stairs
grade 5incapacitatingshortness of breath with any physical effort including dressing, undressing, showering or bathing; cannot walk more than a few steps without pausing; cannot climb steps


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