Pressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled gage pressure) is the pressure relative to the ambient pressure.
Cardiogenic pulmonary edema. Pulmonary edema that is due to a direct problem with the heart is called cardiogenic. Congestive heart failure is a common cause of cardiogenic pulmonary edema; in this condition, the left ventricle cannot pump out enough blood to meet the needs of the body. This causes a buildup of pressure in other parts of the circulatory system, forcing fluid into the air sacs of the lungs and other parts of the body.
Picture of the alveoli and lung. Pulmonary edema occurs when the alveoli fill up with excess fluid seeped out of the blood vessels in the lung instead of air. This can cause problems with the exchange of gas (oxygen and carbon dioxide), resulting in breathing difficulty and poor oxygenation of blood. Sometimes, this can be referred to as water in the lungs when describing the condition to patients. Pulmonary edema can be caused by many different factors.