# differentiating cardiac wheeze vs. obstructive airway wheeze using capno



## TYMEDIC (May 22, 2012)

Good day my fellow ALS providers. I need alittle input on a topic. Now lets say you have a LVF/CHF patient presenting with typical s/s. Lets say you hear rales all fields accompanied by diffuse expiratory wheeze. We all know its most likely cardiac wheeze. Now, beginning with trending tx. response with ETCO2, starting point. You "should" see upright/slightly narrowed wave form. because the alveoli are still, for the most part, emptying equally. I understand that alot of these diseases will accompany one another, but still...to see bronchospasming and or lung disease (B to C upstroke slope) shark fin. It kind of defeats the purpose using ETCO2 as a diagnostic tool to choose the right first line treatment. Standard of care is aggressive nitrates and CPAP for CHF and B-2 agonists ie (Albuterol) for obstructive airway disease. What do you guys think is the best way to help differentiate between the two using ETCO2?


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## 46Young (May 22, 2012)

A true shark-fin is a total loss of expiratory plateau. My concern is that the ETCO2 value will be higher than what the monitor is reading, and the pt is likely in autopeep (thanks to Bob Page). CPAP would defeat this autopeep and also promote air trapping, I would think. Since wheezing from cardiogenic pulmonary edema is from causes other than uneven alveolar emptying, the ETCO2 waveform should not be affected. If I had a small amount of slope towards the plateau I would be hesitant to initiate bronchodilators. CHF and COPD Hx are found together in a fair number of pts, so a small loss of plateau may be baseline for the pt.


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## usalsfyre (May 22, 2012)

While I'm not a "treat the patient not the monitor" kinda guy, ETCO2 should merely be confirming your initial suspicion. History is more useful in determining origin here.


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## jwk (May 23, 2012)

usalsfyre said:


> While I'm not a "treat the patient not the monitor" kinda guy, ETCO2 should merely be confirming your initial suspicion. History is more useful in determining origin here.



Hopefully you're looking at the patient before you treat the monitor.  One of my most memorable ER incidents was a patient whose EKG monitor lead popped off.  The paramedic in the room saw the flat line and defibbed the patient (back in the days when we shocked asystole).  The patient was not happy, and it took the medic just a few seconds to realize that screaming patients aren't in asystole and he noticed the disconnected lead.


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## Christopher (May 23, 2012)

TYMEDIC said:


> Good day my fellow ALS providers. I need alittle input on a topic. Now lets say you have a LVF/CHF patient presenting with typical s/s. Lets say you hear rales all fields accompanied by diffuse expiratory wheeze. We all know its most likely cardiac wheeze. Now, beginning with trending tx. response with ETCO2, starting point. You "should" see upright/slightly narrowed wave form. because the alveoli are still, for the most part, emptying equally. I understand that alot of these diseases will accompany one another, but still...to see bronchospasming and or lung disease (B to C upstroke slope) shark fin. It kind of defeats the purpose using ETCO2 as a diagnostic tool to choose the right first line treatment. Standard of care is aggressive nitrates and CPAP for CHF and B-2 agonists ie (Albuterol) for obstructive airway disease. What do you guys think is the best way to help differentiate between the two using ETCO2?



Why not put CPAP on that patient anyways? 2.5 to 5 cmH2O and an albuterol or two (plus ipratropium) sounds great for your struggling COPD patient.

Besides, you can have a nice little CHF exacerbation that makes their normally bronchospastic airways even worse. You'll likely still inline a neb Rx.

I'd look at it this way, regardless of your waveform your COPD exacerbation isn't going to have a diastolic of 110 or 120 mmHg. If they do have that, they likely have some CHF going on as well.

Nitro, titrate the CPAP up from 2.5 cmH2O, and inline a neb Rx once you get rid of the rhales and work yourself to the wheezes (if they even remain).

Here is an initial SpO2 and EtCO2 strip from a CHF/COPD patient with "tight" lungs that one medic said sounded like rhales and the other said sounded like wheezing. Low CO2, high respiratory rate, good looking boxes. COPD or CHF?


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## TYMEDIC (May 25, 2012)

Christopher said:


> Why not put CPAP on that patient anyways? 2.5 to 5 cmH2O and an albuterol or two (plus ipratropium) sounds great for your struggling COPD patient.
> 
> Besides, you can have a nice little CHF exacerbation that makes their normally bronchospastic airways even worse. You'll likely still inline a neb Rx.
> 
> ...





Not actually assessing the patient first hand and just looking at capno. I would suggest that was more CHF then an obstructive airway issue. the more upright plateau. Telling us that the alveoli are for the most part emptying effectivly. There would be an slant/ upslope otherwise.


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## TYMEDIC (May 25, 2012)

I personally just hate giving albuterol with the presence of rhales even diffuse rhonchi. Most of the time, we can do a thorough assessement and deem it an obstructive airway/broncho spasm or pump failure.


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