Quote from munchkin547
I am currently revising for a second yeaar nursing exam about renal, cardiac and respiratory complaints and I seem to be having a brain block!! I can't work out for the llife of me why cardiac failure and exacerbation of COPD causes oedema!? Think my brain has just stopped working from staring at the books for too long, but if anyone could help me out I'd be really grateful!!
Sounds like a realllll fun test!
Here's some basic info that might help you:
In cardiac failure, the heart's pumping ability is impaired. Depending on which side of the "pump" fails, you can get edema in different parts of the body. If the left side of the heart fails, where does the fluid back up?
Let's think about it...blood entering the left side of the heart is coming back from being oxygenated in the lungs, and is pumped to your extremities (& all those useful internal organs). If you've got lots of nice oxygenated blood in the lungs, but the left side is weak, fluid backs up in the lungs (pulmonary edema).
If the right side of the pump is failing, where does the fluid backup?
Blood coming into the right side of the heart is returning from peripheral circulation & being pumped to the lungs. If the right side of the pump fails, you may see edema at the extremities (i.e. swollen ankles)
COPD can aggravate right side failure as a result of pulmonary hypertension (an increase in blood pressure of lung blood vessels). Because of the pulmonary HTN, there's increased "back pressure" fighting against the right side of your heart. It would be like trying to blow up a balloon, while
a friend is squeezing the balloon. As a result, your heart can't pump the blood from the periphery to the lungs, and fluid backs up in the extremities (or sacral area for patients laying in bed).
Hope this helped & wasn't too confusing.