There are four types of shock: cardiogenic, distributive, obstructive, and hypovolemic. The study that I am taking apart here compared the NICOM monitor to a Swan-Ganz (Pulmonary artery) catheter in patients with cardiogenic shock.
I routinely make a big deal of volume resuscitation regarding septic shock which obviously falls under the distributive shock type. Part of the problem is that with all these well intentioned “Surviving Sepsis Campaigns”, I feel that we are under-recognizing cardiogenic shock which can also present with hypotension and an elevated lactic acid. When you provide 30cc/kg of IVF arbitrarily because the “sepsis screen” pops up on your EMR forcing you to give the fluids, you end up causing harm to your patients.
This is where the history and physical plays a huge role. The physical should include a quick targeted POCUS/bedside echo to make sure you’re not missing anything that’s staring you in the face. If you see an RVOT on the parasternal long axis that’s the size of a tennis ball, you’re not dealing with sepsis. If you see an LV on the apical four chamber that is barely moving, you’re likely not dealing with sepsis. Remember, if the patient is in septic shock, the systemic vascular resistance (SVR) hits the ground. There’s no afterload for the LV to deal with. The LV will be clapping happily like a bodybuilder curling a 10lb weight. The “eyeball test” on POCUS is widely criticized but it has some uses.
But once you make the diagnosis of cardiogenic shock, how do you manage that patient? This is where I feel you may have some value in trending a CVP. I know Swan-Ganz catheters are out of favor, but I feel they’re very useful if you know what to do with the numbers. Knowing how to apply the numbers clinically, though, takes some practice. Like everything else, you need to get your reps in.
I’m fortunate that I trained at an institution where all the post-op hearts came out with a Swan. It was very helpful in my training and allowed me the opportunity to see the value in it rather than just being a nay-sayer. The Swan does have its limitations, though. It’s not the easiest procedure to perform and it comes with some potential cardiac risks that I am not going to list here for the sake of my sanity. Is there something that we can use instead?
I will admit that I personally do not have any experience with the NICOM device. It would be nice to play with the technology one day. I like non-invasive things for my patients. I typically use another device which I will not name but I feel it is very helpful when used appropriately. No technology is perfect, not even the Swan. I was excited when I read this article because I was hoping for an out to not have to float Swans in this patient population. I also very much enjoyed how the authors conducted the study. Simultaneous measurements on the same patient was definitely the way to go and I applaud them on that.
Without boring you all with the details, the authors found that the NICOM correlates poorly with indirect Fick and therm-dilution measurements of cardiac output. The authors attribute it to the biorreactance technology being interfered with by pulmonary and interstitial edema. Makes sense to me. They also listed other factors as well which are on the full article. Nonetheless, what method do you use at your institution to manage cardiogenic shock?
-EJ
Citations:
Rali, A. S., Buechler, T., Van Gotten, B., Waters, A., Shah, Z., Haglund, N., & Sauer, A. (2019). Non-Invasive Cardiac Output Monitoring in Cardiogenic Shock – The NICOMTM Study. Journal of Cardiac Failure.
Link to Abstract
Great article for indirect Fick
De Maria AN, Raisinghani A. Comparative overview of cardiac output measurement methods: Has impedance cardiography come of age? Congestive Heart Failure. 2000;6:60–73.
Indirect Fick Abstract
Indirect Fick PDF
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