Monday, October 14, 2013

Dx of CHF in Dyspneic Pt: Need Echo?

53M PMH unknown 30 pack-year smoker presents with dyspnea to the ED. It's 2AM Saturday morning. The ED is PACKED with traumas, boarders, psychos… not to mention med students, residents & nurses strung out on caffeine or their stimulant of choice. Pt is desat'ing. Need to decide quick: Diuresis vs. Nebs? Diuresis won't help a dried out COPDer, and adrenergic nebs won't help a drowning CHFer. Echo Tech unavailable (this county hospital makes strategic budget cuts). 

How do you proceed?

NB: The H&P is very useful! Take the time to interview & examine the patient. Tell the med students & nurses to QUIET DOWN so you can hear that S3!

PV CHF LRs Collection:
Rivas CHF Dx Stats Collection:

NB2: Keep in mind that in CHF most findings are not conditionally independent  so usually cannot combine LRs for post-multiple-tests probabilities. Instead, rely on the most powerful finding you discover in that case (e.g. S3 to confirm dx or BNP less than 100 to exclude dx of CHF in dyspneic pt). Awesome free online course on Medical Decision Making btw. 

ROC Curves [BNP outperforms Echo EF%]



NB3: Here's the that shiny pearl you were waiting for…

CHF Dx Algorithm

NB4: This algorithm makes it look like H&P is useless. It's EXTREMELY useful (see LR tables above)! If you still can't make the diagnosis, obtain ECG & CXR. It should be the rare case when H&P+EKG+CXR is insufficient to make the diagnosis. In those scenarios, order BNP. Then, if BNP is indeterminate, perform bedside echo for Doppler MV Analysis for low Early/late (E/A) velocity ratio or short MV flow velocity Deceleration Time (DT) to cinch the diagnosis. Refer back to Rivas CHF Dx Stats. 

Explanation of MV E/A Ratio from Echo Doppler:

How to perform bedside Echo doppler MV assessment?
- Liz Turner from UC Irvine on FATE Exam: http://www.youtube.com/watch?v=9ybQ10m3uEY
- - That didn't quite answer my question, but came close. #FOAMed US gurus out there, help us out! Teach US!

Sources:
See losrivas EN Note


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