Pericardiocentesis

So let's say you have a patient--maybe they have a history of malignancy or renal failure or lupus or whatever--and the patient's having some trouble. Let's say they're dyspneic and hypotensive, and round out the classic Beck's Triad with some muffled heart sounds and distended neck veins (although only 33% of patients actually have all three of this point of medical masturbation).  You astutely throw on your ultrasound on the chest, and you see something that looks like this:

                           

Let's throw out the typical Procedures Club stem of "you're at a community hospital and there's no specialist around" blah blah blah and cut to the chase.  You're doing a pericardiocentesis today!

But before you do any poking, let's review the basics for a spell.  The pericardium is made of two layers, the visceral and parietal pericardia, with the potential pericardial space between them.  Physiologically, there should be about 20ish cc's of fluid there for shock absorbancy and lubrication.

Generally speaking, once you've got about 200 cc of fluid acutely in there, you start to see some systolic dysfunction.  Chronically, the space can accommodate quite well due to elasticity of the structures, so you could theoretically see a huge effusion with no symptoms as it has been there a while.  Here's a demonstration of how you can fall off the curve, based on animal studies:

Some other things to note: first off, are they stable?  If so, you might have enough time to treat what's causing the tamponade as opposed to the tap--i.e. if they're end stage renal, get them to HD.  If they're not stable, consider fluid boluses and pressors to buy you some time.  You do want to avoid positive pressure ventilation in these cases, however, as this may cause hemodynamic collapse.

In terms of preparation, you'll more or less need the following: an 18 G spinal needle, a 10 cc syringe, ECG wires with alligator clips, a guidewire, a pigtail catheter, a dilator, a stopcock, local anesthesia, sterile drape and wipes, and your trusty bedside ultrasound.  If you're in a pinch, just grab the 18G and the syringe and go go go.

There are a few ways to approach the pericardium,  The standard approach is subxiphoid, with you standing on the patient's right. After prepping and injecting some local anesthesia, you'll need to identify the left xiphocostal angle, and slide down about 1 cm.  This will be your entry point, where you'll come in at about 30 degrees, aimed at the left shoulder.  As with any other tap, you'll slowly aspirate as you go in.  NEVER move the needle in a side to side fashion, as you may lacerate the underlying epicardium. Once you're in, try to get a good 60 cc out.   If you've opted to attach your ECG wire, you can see if you hit epicardium by watching the waveform.  If you start seeing ST elevations, back up and watch for them to resolve.  After that, wire it and place your pigtail for continued drainage in an ICU setting.

If you have a legit tamponade, even a small amount of aspiration will cause a significant improvement in your patient.  Remember, how they showed on Downton Abbey?  Dr. Clarkson did that blind, in ONE POKE?  That's how they did it back in the day.

If it's a hemorrhagic tamponade, the traditional teaching is that you can distinguish it from ventricular blood by looking for clot--pericardial blood shouldn't have any due to the fibrinolytic activity.  However, this isn't totally reliable as you may just be tapping a brisk bleed.  You'll definitely want to check a post procedure CXR to make sure you didn't put any air somewhere air isn't supposed to be.

If you're doing it blind, cadaveric studies have shown that subxiphoid is probably the safest way to go, although it is not without complications. Here's the (unauthorized?) ATLS version for your perusal:

 If you have an ultrasound, however, you'll want to try a different route.  Specifically, you'll take a parasternal long axis view to identify the tamponade.  Your needle will be in plane with the probe.  The best part about this one is that you can see the effusion decrease in size in real time.

Academic Life in Emergency Medicine has a featured a fantastic primer on these based on a paper published by Dr. Arun Nagdev from UCSF. If you want to look particularly slick with this one, you can identify the interior mammary artery with your probe and mark the skin so that you don't hit it with your approach.

I couldn't find a YouTube demonstration of this (which is a bummer as it appears to be awesome), but here is a subxiphoid approach from the Ultrasound Podcast page:

As always, these writings are for EDUCATIONAL PURPOSES ONLY.  Would you want a family member to unnecessarily have a needle shoved in their pericardium by some overzealous scrub because "he always wanted to do one?"  Be smart!  Talk soon.

jps

Sources:

Roberts and Hedges' Clinical Procedures in Emergency Medicine, 6th Edition.  Chapter 16.

Loukas, M., Walters, A., Boon, J. M., Welch, T. P., Meiring, J. H., & Abrahams, P. H. (2012). Pericardiocentesis: A clinical anatomy review. Clinical Anatomy, 25(7), 872–881. doi:10.1002/ca.22032

MPH, P. C. I. M., & MD, S. L. (2013). Techniques and Procedures. Journal of Emergency Medicine, 44(3), 661–662. doi:10.1016/j.jemermed.2012.06.019

MD, A. N., & MD, D. M. (2013). American Journal of Emergency Medicine. American Journal of Emergency Medicine, 31(9), 1424.e5–1424.e9. doi:10.1016/j.ajem.2013.05.021

Life in the Fast Lane Blog: http://lifeinthefastlane.com/ccc/pericardiocentesis/

Academic Life in Emergency Medicine Blog: http://www.aliem.com/ultrasound-guided-pericardiocentesis/

Ultrasound Podcast YouTube Page