Flash Pulmonary Edema is a misnomer for what is properly considered Acute Cardiovascular Insufficiency. The term pulmonary is misleading because this is a cardiovascular disease not a pulmonary disease. The origin of the illness and it progression is due to dysfunction of the cardiovascular system. Nor is it simply a dysfunction of the heart or heart failure but insufficiency of the entire cardiovascular system, the heart and also the blood vessels. It is not possible to create a proper understanding of the illness with this terminology. The wrong impression is inescapable because the visual appearance of the illness is so misleading.
It is a common misunderstanding the initiating event is the development of edema in the lungs. The circular reasoning that leads to this conclusion is propagated because of the incorrect naming of this condition as pulmonary edema. It is also erroneously believed that resolving the edema would resolve the illness also. This is also incorrect. Rather it is true that if the illness resolved, the edema would also. The edema is the result of the illness not the cause of it.
The term Acute Heart failure is misleading because this is a cardiovascular disease not a disease of only the heart. The vascular system is particularly important in this condition as high vascular resistance plays a key role. We don’t get this pathophysiology correct by renaming this Acute or Flash Pulmonary Edema as Acute or Flash Heart Failure. The word “Heart” has to be replace with the word “Cardiovascular”.
The essential facts are:
Edema of the lungs is easily observed. The flow of blood is not.
Blood pressure is easily measured. Too much reliance is placed on the observation of blood pressure. Monitoring of the blood pressure continuously or in real time does not solve this problem. In all setting outside the ICU, the insufficiency of blood flow cannot be observed. Cardiac output is not known.
The appearance of the most easily obtained image, the plain film chest X-ray is misleading. We need measurements of blood flow which we don’t have and as a practical matter can’t be obtained.
The heart can be imaged. The vascular tree cannot.
The insufficient delivery of oxygen to meet metabolic demand is the cause of shortness of breath not the edema of the lungs.
The importance of oxygen is at the tissue level not in blood of the arteries near the heart. When the flow is low the tissues will be starved of oxygen especially highly metabolic tissue like muscle.
When blood flow is low cyanosis may not be observed as the skin is not a highly metabolic tissue and the requirements for oxygen are not as high as the muscle and internal organs.
The introduction of non-invasive ventilation to treat acute cardiovascular insufficiency known by the colloquialism, flash pulmonary edema has contributed to the misunderstanding of the disease. The insufficiency of the cardiovascular system is the cause of the illness not the edema of the lungs.
The image of a patient severely short of breath with a mask connected to a ventilator paints a picture that is misleading. This is not a respiratory or pulmonary illness as it appears in this situation. Everyone in the room where this treatment is employed gets the wrong impression. It might be that only the doctor that knows that this is a cardiovascular disease. The cause of this illness despite the fact that edema of the lungs is a part of it, is insufficiency of the cardiovascular system. If we removed the edema of the lungs we would still have the inadequate flow, the tissues of the body would still be starved of the flow of blood and oxygen and there would still be the feeling of shortness of breath. The body feels a lack of oxygen at the tissue level. This still occurs if the oxygen in the arterial blood is normal or near normal. Edema of the lungs is the result of the problem not the proximate cause of the illness.