7 doctors weighed in:
How can decreased cardiac output be caused by abnormal fluid volume?
7 doctors weighed in

Dr. Islam Abudayyeh
Internal Medicine - Cardiology
6 doctors agree
In brief: Overloading
Low cardiac function may not be able to keep up with too much volume and the fluid backs up in places like the lung, neck, abdomen, and legs.
Too much volume can overwhelm a borderline heart already weak. When the heart cannot keep up the needed cardiac output (liters per min) and making the pump work harder increasing pressure inside the heart, and dilating the chamber getting into a bad cycle.

In brief: Overloading
Low cardiac function may not be able to keep up with too much volume and the fluid backs up in places like the lung, neck, abdomen, and legs.
Too much volume can overwhelm a borderline heart already weak. When the heart cannot keep up the needed cardiac output (liters per min) and making the pump work harder increasing pressure inside the heart, and dilating the chamber getting into a bad cycle.
Dr. Islam Abudayyeh
Dr. Islam Abudayyeh
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1 comment
Dr. Bennett Werner
I hadn't read Dr. Abudayyeh's answer when I answered but I agree with him. He and I are describing 2 ends of the spectrum and both cause low cardiac output: he describes a diseased, overloaded heart and I describe a normal, underloaded heart. In both cases, the heart cannot pump a normal amount of blood.
Dr. Bennett Werner
Internal Medicine - Cardiology
4 doctors agree
In brief: Physiology
The amount of blood the left ventricle can pump (stroke volume) is directly related to "preload" which is based on the venous return to the heart.
If volume is contracted from bleeding, diuresis, vasodilation, or poor intake, preload is reduced, venous return is reduced, stroke volume is reduced &, if increased heart rate can't compensate for the reduction, then cardiac output is also reduced.

In brief: Physiology
The amount of blood the left ventricle can pump (stroke volume) is directly related to "preload" which is based on the venous return to the heart.
If volume is contracted from bleeding, diuresis, vasodilation, or poor intake, preload is reduced, venous return is reduced, stroke volume is reduced &, if increased heart rate can't compensate for the reduction, then cardiac output is also reduced.
Dr. Bennett Werner
Dr. Bennett Werner
Thank
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