Cardiogenic Shock: NICOM vs. Swan-Ganz Catheter

There are four types of shock: cardiogenic, distributive, obstructive, and hypovolemic.

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. I look forward to playing 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



Link to Abstract

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.

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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HYPERION: 33 vs 37 for targeted temperature management in cardiac arrest

I am going to be all over the place with this takedown. I’m a bit upset at what may happen as a result of this publication. I really wanted it to be a good study but it’s not. You’ll see why shortly. 

The good news is that there’s no difference in adverse effects to the patient by cooling them, just a lot of added cost. That’s my tidbit for those physicians who are going to take this data and run with it as if it’s gospel. 

My practice prior to this article was to do a normothermia protocol of 36 degrees after the NEJM trial from 2013. Is this one going to change my ways... from the outset it appeared as if it will, but, spoiler alert, it won’t. 

The objective of this study was to sort out whether we should cool our patients to 33 or normothermia of 37 in patients who suffer cardiac arrest with a non-shockable rhythm. 

Within the methods, they excluded patients who were down for >10 minutes prior to chest compressions. This is hard to determine many times as families are never quite sure. I complement the 25 ICU’s who recruited 584 patients in this study. The fact that they allowed patients to be recruited for 300 minutes from their arrest time gives us insight that you don’t have to make the determination immediately on whether you have to cool the patient. Then again, such a high percentage did poorly that we don’t really know what’s the best time to get started. 

In how they rewarmed patients, it’s important to note from a practice standpoint that the sedation was tapered when the temp got above 36. That’s a nursing question I often hear. 

Within their outcomes, the primary was a favorable 90-day Cerebral Performance Scale where they wanted to see in particular if the patients had either a score of 1 or 2. A score of 1means Good cerebral performance or minor disability. A score of 2 means moderate disability. They called the patients or families on the telephone for follow up. People lie. I wish they would’ve had someone lay eyes on the patients. But people lie in both groups so this should be no big deal. should be. But it isn’t. You’ll see why. 

The secondary outcomes were all the typical ICU stuff: mortality, days on the vent, LOS in ICU and hospital, infections and adverse hematologic events. We know that cooling causes degrees of coagulopathy. 

With in the results, the authors assessed 2723 patients over the course of 4 years. That’s A LOT of cardiac arrests! Then again, 15 ICU’s. I imagine they’re all busy institutions. 

I was happy to see that an intravascular cooling catheter was only used in 14.8% of patients. I have always thought that they were a little too invasive for my tastes, especially if/when they start oozing. 

When looking at the actual outcomes, the best case scenarios still only had a 10.2% incidence of a CPC of 1 or 2. This is not a cure, team. Patients still do terribly. It’s helpful to let families know what to expect when a patient arrives in our ICUs in cardiac arrest. 

More than 80% of patients died in both groups. 81.3% vs. 83.2 in the 33 vs. 37 respectively. All of the secondary outcomes showed no difference. 

The supplementary text provides data as to how they handled withdrawal of care. Imaging was curiously nowhere to be seen anywhere in the paper. They do not mention abnormal CTs or any type of MRIs anywhere in this paper nor the supplementary text. I would be curious if they found anyone with loss of gray-white differentiation who did well. I wonder if they omitted that information so that they could collect a large enough sample size and families wouldn’t withdraw prior to completion of the study. Hmmmmm.  

I respect the heck out of the authors in the way they disclosed their limitations. They admitted that an outcome change in a single patient would make the primary outcome not significant. What am I supposed to do with that?!?! If one person lied about how well they were doing over the phone it would change the conclusions of the entire 4 years of work! This is why I don’t do research. 

The other caveat to the study is that they let the patients in the 37 degree group develop fevers. Correct me if I’m wrong but didn’t a subgroup analysis in the 33 vs 36 study from several years ago show that avoiding fever is the most important component in these patients? In my practice I discuss with the nurses that we need to be prepared for the fever and have meds on the medication list, not for if it will happen, but rather for when it will happen. Considering the study got started in 2014, this is something that hopefully they knew going into the study. 

I’m sticking with 36 in my practice. What do you all think? 

A hat tip to the authors. 

-EJ

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Transcatheter aortic valve replacement

A special shout out to the author of this article, Melody, who is one of the kick-ass nurses I have the pleasure of working with in the CVICU at my shop.

Link to Article

Link to PDF

Although great care has been taken to ensure that the information in this post is accurate, eddyjoemd, LLC shall not be held responsible or in any way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.