Soundings: Bradycardic and Blue

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image 1-1 RMHow bedside ultrasound can help bring a crashing patient into focus 

How bedside ultrasound can help bring a crashing patient into focus 


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They say things come in threes. Today seems to be a thoracic surgery day. You just got sign out of an elderly lady with a thoracic aortic stent graft that appears to be leaking. Next you saw a middle-aged man with hematemesis and chest pain after inducing vomiting because a large vitamin got stuck in his esophagus. Your next patient is a 67-year-old male with a history of coronary artery disease and gastritis who is here with abdominal and back pain associated with the urge to defecate. His wife called 911 when he became lethargic and started vomiting and she is providing most of the history because he is too lethargic to do much more than answer yes, no or I don’t know.

On exam he is lethargic but afebrile with a BP of 88/60 mmHg a pulse of 57 and respirations at 14. You are immediately concerned because in addition to the lethargy he is diaphoretic and a tad cyanotic from the chest up, which strikes you as unusual. His lungs are clear and his heart is regular but slow without murmur. His abdomen is obese but surprisingly non tender. You know this guy is sick, but what is going on?

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EKG shows a junctional rhythm at 51 with nonspecific ST changes – not enough to activate the cath lab; you’ll need more for a disposition . With abdominal and back pain associated with hypotension you are worried about his abdominal aorta, and for good reason, so you do a bedside ultrasound and take a look. You also ask the nurse to check the BP in the other arm, which is similarly low. On ultrasound, he is obese, which makes it challenging. His aorta is only minimally enlarged but doesn’t look right (image 1). What do you think? Since you can’t explain the upper body cyanosis you decide to do a quick echo of his heart as well. (Image 2) What does this image show?

Scroll down for answer.

 


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The Dx

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Image 1 is a longitudinal view of the abdominal aorta. On first glance it may appear normal, but on closer inspection one can see that the hyperechoic (white) posterior wall of the aorta is actually deep to a hyperechoic (white) dissection flap with an interposed echoic area which is suspicious for clotted blood. This may represent and aortic dissection. Image 2 shows the heart with what appears to be a normal sized left ventricle (LV) but a very small right ventricle (RV) that appears to be compressed by a hyperechoic structure which may represent clotted blood in the pericardium (later confirmed by CT). With this information in hand a stat call was placed to the on call thoracic surgeon, who was fortunately still in the hospital dealing with the other two cases, and the patient was bumped to the front of the CT queue to get a stat CT angiogram of the thoracic and abdominal aorta which confirmed a type A aortic dissection extending from aortic root to the left common femoral artery with a large pericardial hematoma compressing the right heart. In the meantime you had the BP checked. The other thoracic case had to “cool off” with antibiotics so this patient could be taken stat to the OR for repair of his aorta and drainage of his pericardium.

Remember to use bedside ultrasound when you are worried about a patient and want to get an early handle on exactly what is going on. You may still need to do a comprehensive ultrasound via radiology but a positive bedside ultrasound can trigger better and faster management of the critical ED patient. If the ultrasound is normal you may have a little more time to get your ducks in a row before calling a consult. In this case ultrasound not only expedited definitive care but prompted you to also have the BP checked in both legs prior to sending the patient to CT. It was in the 180’s in the right leg, despite a persistent BP of only 80’s to 90’s in the arms and the 120’s in the left leg. A nitroprusside drip was started and titrated to the BP in the right leg, which was presumably the only limb not affected by the dissection. Finally you had a plausible explanation for the blue hue in the upper body. Perhaps the aortic flap had compressed flow to both arms.

Pearls & Pitfalls for Cardiothoracic Ultrasound

  • Start with the abdominal aorta. Over 90% of aortic dissections will progress into the abdominal aorta and many will dissect into one leg. Start your scan in an area you are familiar with and look for a hyperechoic flap in the abdominal aorta. The false lumen may or may not be clotted off. Vessel wall and flap should appear hyperechoic (white), liquid blood should appear anechoic (black) and clotted blood should appear echoic (grey). A vascular flap within the abdominal aorta will usually move with each pulse if the false lumen has not clotted off. A vascular flap will not extend beyond the inner wall of the aorta. If it does, it is likely an artifact.
  • Next Look at the Heart. Check the sub-xyphoid and parasternal views for evidence of a pericardial effusion and if present, evidence of tamponade. Remember free flowing blood will appear black but clotted blood will appear gray and therefor may be missed if you are not looking for it.
  • Third, Look behind the Heart. Look at the descending thoracic aorta behind the heart. On the parasternal long axis view it will be seen in cross-section as a circle which normally should be less than 42mm in diameter. Rotate into the plane of the aorta to get a long axis view as you continue to check for a flap and any enlargement.
  • Check the Aortic Arch. Using the smallest probe you have, place it in the suprasternal notch to get a supra-sternal view of the aortic arch. Have the patient turn his or her head to the right and orient your probe in the plane of the aortic arch. With aortic dissection there is often some aneurysmal dilation which will make the aorta easier to visualize than in a normal patient. Again look for an intimal flap
  • Keep up your Skills. Consider a quick bedside echo in chest pain patients where there is some suspicion for dissection. If you do see a dissection or a pericardial effusion the heightened urgency it gives you may mean the difference between a good outcome and a bad one. The best way to minimize errors is through experience, so scan lots of normal anatomy. The more scans you do, the better you will be able to differentiate abnormal from normal, even when you may not be sure exactly what the abnormality is.


Brady Pregerson, MD 
(@TheSafetyDoc) manages a free online EM Ultrasound Image Library and is the editor of the Emergency Medicine Pocketbook series. For more info visit EMresource.org

Teresa Wu, MD (@TeresaWuMD) is an Associate Professor and Simulation Curriculum Director at the U of A-College of Medicine-Phoenix. She is the Director of the Ultrasound Program & Fellowships for the Maricopa EM Program and the creator of the app SonoSupport

1 Comment

  1. Great concept and image! We need as EP’s to start looking for aortic dissections better. In this case would have appreciated a diagram showing the descending aorta dimension as well. Also a comment at the sternal notch view looking at the aortic arch might have been helpful as well.

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