Congestive Heart Failure

[frdude1000]

Hey all, just a few questions on CHF.

First, how is there enough pressure to push fluid through the alveoli into the membranes of the lungs? I thought CHF is when the heart is weakened and unable to adequately circulate blood to meet the needs of the body, causing fluid to build up in the lungs and extremities.

Moving to capnography, what will the capnograph look like for a CHF pt. with SOB? Shark fin? High EtCo2?

 

[Handsome Robb]

Hey all, just a few questions on CHF.

First, how is there enough pressure to push fluid through the alveoli into the membranes of the lungs? I thought CHF is when the heart is weakened and unable to adequately circulate blood to meet the needs of the body, causing fluid to build up in the lungs and extremities.

Moving to capnography, what will the capnograph look like for a CHF pt. with SOB? Shark fin? High EtCo2?

Left-sided CHF causes pulmonary edema. The left side of the heart's inability to adequately pump blood causes a backup of blood. What comes before the left side of the heart? The lungs. The increased BP due to the backup of blood in the pulmonary vessels forces fluid into the aveoli. Super simple explanation. CHF *usually* starts on the left then eventually causes right sided failure since the right side is having to pump against such a high afterload. It can be on the right side too and eventually cause left sided failure. Look up Cor Pulmonale.

Correct me if I am wrong but the ETCO reading will be low due to poor gas exchange in the lungs. I need to do more work with ETCO and study it more, I haven't used it much :sad:

 

[NomadicMedic]

The ETCO2 waveform will look non obstructed, which is why it's a great tool when you have a CHF/COPD patient and you're not quite sure what's causing the dyspnea.

 

[DrankTheKoolaid]

The ETCO2 waveform will look non obstructed, which is why it's a great tool when you have a CHF/COPD patient and you're not quite sure what's causing the dyspnea.

Not exactly the case. Rales causing bronchospasm will appear like a copd'ers sharkfins. The difference there would be the baseline of the chf'er should go back to ~0 and the dyspneic copd'er typically will show a more elevated baseline along with the waveform deformity. At least this has been my experience

 

[Farmer2DO]

My experience with the sharkfin is that it's related to severe disease. I've only seen it a few times, and never on a CHF pt.

Also remember that typically, CHF patients have a hard time oxygenating, but will ventilate just fine. So that means that SPO2 is often a problem, but until they are in acute respiratory failure, ETCO2 is often low. On the reverse side, COPD patients often don't have a problem oxygenating, but they do have a problem ventilating. Again, unless they are in acute respiratory failure, or have some other problem with it (pulmonary edema or pneumonia), profound hypoxia is not usually a problem, but ventilation is an issue, meaning their ETCO2 can be exceedingly high.

And CHF =/= pulmonary edema. Pulmonary edema certainly can be seen with CHF, but it is a late presentation of, and a consequence of, heart failure. There are also other causes of pulmonary edema.

 

[DrankTheKoolaid]

Very true. The only CHF'ers ive had etco2 on were in extremis and vented. So they may have been the typical copder w/ chf along with it