Now let’s talk about tightening up your right upper quadrant skills. We scan the right upper quadrant a lot in the ED; kidney, FAST, gallbladder, IVC, pleural effusion, etc. Everyone of these scans can be improved by knowing three simple landmarks. The anterior, mid, and posterior axillary lines are your window to scanning efficiently.

In the anterior axillary line is the gallbladder. In the mid axillary line you’ll find the IVC. In the posterior axillary line is the kidney. Because these three structures are stacked anterior to posterior in this order, you can guide your probe movement accordingly. If you’re looking for kidney and see gallbladder, simply sweep or fan posteriorly. If you’re looking for gallbladder and see IVC, just sweep or fan anteriorly. It’s as simple as that. When you’re looking for a structure, your movements should be purposeful and based on relative anatomy. Now that you know the right upper quadrant’s sonographic organization you can make purposeful movements guided by the surrounding anatomy to get images faster.

Happy scanning!

Even time you use too much depth a kitten dies…. or you greatly reduce your image quality and image the bed instead of the patient. Not only does it shrink the size of what you’re looking at, but it also moves your structure of interest out of the focal zone (you know the area of highest image resolution in the mid field of the ultrasound screen). Plus it adds poor quality images to the patient’s chart with your name, so don’t do it and think of the kittens.

Happy scanning everyone!

1. Descending thoracic aorta is associated with the left atrium
2. Look for left ventricular outflow tract/aortic valve in left ventricle
3. Tricuspid valve insertion onto septum is more apical
4. Tapered right ventricle shape
5. Moderator band is sometimes visible in the right ventricle

Happy scanning everyone!

Intro

Ultrasound is a lifesaver and luckily for a recent patient I mean this literally. Thanks to the early use of ultrasound a life was saved that would have been lost. A critical diagnosis was made within 5 minutes of arrival, preventing investment of precious time in ineffective treatments or delaying definitive care and making me look real slick in the process. The patient was successfully treated and admitted to the ICU. When I walk into work the next day, I find out the patient is not only alive but sitting up in bed talking to the team! With some simple ultrasound views and less than 2 minutes, the direction of our treatment completely changed and a man lived to see his family that I doubt would have otherwise. Two minutes to save a life… that’s some good stuff and even better ultrasound! These are the moments that make medicine worth it.  

That Feeling When You Walk Out of Your Shift After A Good Save

The Case

Now let’s get into the case. EMS calls over the radio. “This medic 22. We’ve got a 51 yo male coming in with sepsis. Recently discharged from extended admission to  your facility for sepsis from a gluteal wound and skin infection. He was discharged and sent to the SNF for IV antibiotics. Heart rate is 128, BP is 76/45, pulse ox 93%, RR is 22. Patient is awake and talking to us. His only complaint is sweating. See you in five.” Another doc leans over, “Sounds pretty straight forward. It’s just sepsis. Antibiotics and fluids… It’s all yours.”

The patient is sleepy but talking in full sentences with little distress, when he arrives in the resus bay. Nurses get IV access, he is connected to monitors, and I receive medic report. Patient has been getting IV antibiotics via PICC. They don’t know exactly why the SNF called them and neither did anyone at the facility  (business as usual). Patient reports feeling tired and sweaty just before the medics arrived, but has no other complaints. Pressure is now 70/48, HR is 120-130s, oxygen sat in 90%, RR 22, temp 98.9. I examine him. He is obese, oriented x 3, tachycardic with 2/6 systolic murmur, lungs are clear, abdomen is soft without tenderness, pulses present in all 4 extremities, has bilateral lower extremity edema, his gluteal ulcer is well healed with minimal surrounding erythema. I ask the patient several questions. Any history of heart failure, MI, blood clots, COPD, CAD, any lung or heart disease whatsoever? None. Any fever, cough, chest pain, nausea/vomiting, shortness of breath, focal weakness/numbness, abdominal pain, diarrhea, bloody or tarry bowel movements, dysuria or frequency, drainage from previous ulcer site, lower extremity pain? Nope. Nope. Nope. Known heart murmur? Unsure. He just feels sweaty and tired. EKG shows sinus tach without ischemic changes. We hang fluids and I grab the ultrasound.      

 Picking Up the Probe to Find the Diagnosis

The Save

I perform the RUSH (Rapid Ultrasound for Shock and Hypotension) exam that I use for all undifferentiated hypotensive patients. My first two views make the diagnosis clear, PE. The right ventricle is significantly larger than the left ventricle, which is is contracting enthusiastically. The IVC is huge, so are the hepatic veins. It’s not collapsible at all. This is NOT sepsis! This is obstructive shock and without any pulmonary history I doubt another cause of this acute RV dilation. PE is the obvious answer. I move lower and check for DVT to further support my diagnosis. Nothing in the femoral veins, but I strike gold in the left popliteal vein and diagnose a DVT. Ladies and gentlemen, this patient has obstructive shock from a pulmonary embolism.

Apical Four Chamber – Right Ventricle Dilation

Dilated IVC

Popliteal Fossa – DVT

I tell the room its a PE not sepsis and call the scanner to tell them we’ll be there in 2 minutes to confirm the diagnosis. Sadly, I have to do this because the ultrasound penetrance at this community hospital I am working in today is quite poor. If the other EM docs who pop in to see if I need a hand looked at me funny when I proudly announced my findings, I doubt the intensivist/cardiologist/surgeon I am dealing with will buy a beside ultrasound diagnosis. It is unlikely they will trust the new person with an ultrasound over the diagnosis momentum of sepsis already in place. I walk the patient to the scanner myself and pharmacy starts mixing TPA. The tech mutters “daaaamn” as the images come up… it’s a massive saddle embolism, the largest I’ve ever seen in a live person. Less than 15 minutes from arrival we have a diagnosis and definitive treatment plan. Fluids are stopped, TPA is given, light pressors started, the patient goes to the ICU, and I buy myself a little street cred at a new hospital.

I am thankful for my ultrasound training and start to think of how this would have gone down without it. I shudder. I imagine thinking this was sepsis and how this would have likely driven the treatment plan for several hours. The chest xray might have looked like pneumonia as the lung infarcted, further supporting infection and explaining his borderline oxygen sat. The patient would have failed to improve and I doubt I would have taken him to the CT scanner so early or at all as the treatment of sepsis worsened his hemodynamics. Instead he would have been slammed with fluids for his hypotension, driving his RV further off the starling curve onto complete failure and cardiac arrest. A long and painful code later I would have been drained, but told myself and his family I did everything I could. Instead, thanks to point of care ultrasound, just one day after a massive saddle embolism the patient is sitting up in bed talking. Without point of care ultrasound this patient (someone’s son, husband, father) would have likely died. This is a win for point of care ultrasound and especially for this patient, and definitely qualifies as a SonoSave!

Ultrasound for Massive PE

So let’s talk ultrasound for pulmonary embolism. There are three areas to ultrasound that support the diagnosis of massive PE – cardiac, IVC, and DVT. You certainly don’t need to do all of these to make the diagnosis. In this case I completed cardiac and IVC scans to make the diagnosis of obstructive shock and used DVT scan to further support my PE diagnosis. Some people include lung ultrasound in their PE assessment, but I don’t find it gives me much additional information to support the diagnosis and can take time away from patient care when PE is your primary concern. Lung ultrasound IS great to look for other serious pathology in critically ill folks though, so remember it for other sick patients. But for PE ultrasound it’s three quick scans and 2-3 minutes to change the course of patient care and save a life.

The biggest value for bedside ultrasound in pulmonary embolism is in the unstable patient. These patient have significant right ventricular dysfunction and compromised hemodynamics, which in an otherwise healthy person requires occlusion of approximately 50% of the pulmonary vasculature. These are patients that need rapid diagnosis and treatment to prevent the significant morbidity and mortality associated with RV failure in massive PEs. Yet such patients are often too unstable to go to the CT scanner, so how do you diagnose their PE? With ultrasound of course! These patients are also so far down the starling curve of their right ventricle that the common treatment of hypotension with IV fluids will only drive them further down the curve, leading to death. This is because as the preload increases several things happen. First, an already failing right heart gets further stretched by the increased preload and RV output decreases as the cardiac myocytes get further stretched down the wrong side of their starling curve. The increase in right heart pressure also causes encroachment of the right heart into the left ventricle, leading to decreased left heart preload and decreased cardiac output for the left heart. This combination of decreased right and left heart output worsens blood pressure and the resulting shock with each bolus of IV fluids. For these reasons early diagnosis is key in the massive PE to prevent harmful interventions that are used to treat other causes of hypotension. This is why be bedside ultrasound is the safest and most reasonable tool to diagnosis massive PE in the unstable, hypotensive patient.

Heart & IVC Ultrasound: IVC & heart ultrasound are the most useful scans when looking for massive PEs and help paint a picture of obstructive shock. These also happen to be a part of the RUSH exam, which is an ultrasound exam for patients with undifferentiated hypotension. My fastest time for a quality RUSH scan to date is < 2 minutes, so it’s certainly worth knowing and being good at this scan. But I digress…  let’s get back to PE ultrasound.

An apical four chamber view is all you need cardiac wise. This view shows you RV size and LV function in one view. The RV should be on screen left (if you positioned your probe marker correctly). Normally its smaller than the LV and should measure less than 60% of the LV (0.6:1 for RV:LV). This does not need to be directly measured. Just eyeball it and know a > 1:1 ratio is very concerning. Another sign of PE is a thin RV free wall with retained function at the apex. This is known as a McConnell’s sign and looks like a fat man is bouncing on a trampoline at the apex of the RV. This is specific, but not sensitive and does not rule out PE. It is also important to confirm the ventricle you are called a strained RV is in fact the RV (and not the normal appearing LV misplaced on the left screen due to probe marker placement). Luckily there are a few ways to confirm your RV. It is more tapered at the apex, its valve is more apically attached to the septum, it does not have an aortic outflow tract when you fan anteriorly,  it may have a visible moderator band, and you can confirm the correct position of your probe marker. You also happen to get a view of the LV with the apical four chamber, so you can also eyeball LV squeeze and ensure cardiogenic shock of the left heart is not contributing to your clinical picture. If you’re feeling fancy, you can also get a parasternal short view of the heart and see the LV become D-shaped as right heart pressures overcome left heart pressures and the RV encroaches on the LV. But really one view gets you what you need to know, so make the apical four chamber your view of choice.

The IVC view will give you insight into right heart pressures and fluid responsiveness. If pressures build up in the right heart, this will translate to the IVC and its appearance on ultrasound will further confirm you concerns for obstructive shock from PE. A large (> 2cm) IVC that does not collapse with respiration is concerning for high right heart pressures and pulmonary obstruction (or cardiogenic shock with fluid overload, which you ruled out with your left heart assessment in your four chamber view). Large dilated hepatic veins emptying into the IVC just caudal to the diaphragm can further support you assessment of the IVC and conclusion that high right heart pressures are high. If the IVC is large without respiratory variation and the right heart is dilated, their blood pressure is unlikely to respond to fluids. Further fluids will likely worsen cardiac output and a change in management to pressors would be more beneficial. IVC and cardiac views can be quickly acquired at the bedside and will paint a picture of obstructive shock in the unstable PE patient.

DVT Ultrasound: Two region compression ultrasound is a great way to assess for DVT with sensitivities in the mid 90s. Almost 95% of lower extremity DVTs will be located in the vessels scanned by this method. You will scan in two regions, the groin and the popliteal fossa. The idea is to assess compressibility of the veins. If there is a clot proximal to your probe, then the vessel won’t completely collapse with compression. Press with enough pressure until you deform the artery. If the vein does not completely collapsed, then there is clot. If you suspect PE and find a DVT, there is likely a PE.   

Femoral Vein – No DVT

Popliteal Fossa – DVT

PE Mimics: It’s also important to be aware of PE ultrasound mimics. COPD and pulmonary hypertension will cause dilation of the right ventricle over time. However these will generally developed slowly and as a result have associated RV hypertrophy. The RV free wall should be < 5 mm thick in the acute setting, so be aware of this to help distinguish chronic RV dilation from acute. RV infarcts can also cause some RV dilation on ultrasound, so be sure to check for inferior MI pattern on the EKG to assess for this. Basically RV infarct, COPD, and pulmonary hypertension cause RV dilation and increased right heart pressures that can be seen in the IVC; but now you know how to distinguish these mimics from an acute massive PE.     

Quick Nutshell of PE Ultrasound: How about a quick summary after reading all that goodness above? Essentially you are looking for a dilated RV, a large IVC that doesn’t change with respiration, and possibly a DVT. Because of how simple and quick it is to find these with bedside ultrasound, it is incredibly useful in the undifferentiated hemodynamically unstable patient and will help you quickly provide definitive treatment to patients when time matters. That’s it. End of story.

Obtaining the Views 

Skip this section if you’re already comfortable with obtaining the views for IVC, apical four chamber, and DVT ultrasound.

Cardiac: The apical four chamber heart view is obtained by placing you probe at the apex of the heart, usually inferior to the left nipple, and fanning anteriorly towards the base of the heart/the right shoulder. You want the apex of the heart towards the top center of your screen, so that when you fan/rotate to get your image you won’t get off axis cuts through the heart and accidently underestimate the right heart size. You’ll also want to rotation your probe very slowly once you get all four chambers in view to make sure you see the whole RV and not an off axis slice that would underestimate its real size. Now what follows is really important to getting your image correct. If your screen marker is in the conventional position on the screen left, then your probe marker should point to the left (aka patient right). If your screen marker is in the cardiology position on screen right, then your probe marker should point to the right (aka patient left). This way your probe marker and the screen marker match and you won’t get an accidentally flipped view of the heart and mistake the right heart for the left heart. That’s all you need to know to get a good view of the right heart for PE ultrasound. If you want to read more, take a look at this Cardiac Basics Cheat Sheet.

Handsome Model Demonstrating Apical 4 Chamber Positioning

IVC: While some think the IVC can be difficult, it can easily be found with a systematic approach. Start with your probe marker facing patient right just inferior to the xiphoid, flatten your probe, and angle towards the right shoulder to obtain a basic subxiphoid view of the heart. Once you see the heart and have it roughly centered on your screen turn the probe 90 degrees (probe marker towards head) and angle the probe a little under the ribs. Because the the IVC empties into the right atrium you can follow it coming right out of the RA and through the liver. You might also see hepatic veins emptying into the IVC at roughly 90 degrees to further confirm you are looking at the IVC. If this view fails, try a “rescue view” by placing the probe in the right upper quadrant at the mid axillary line. You will see the IVC go through the liver just anterior to the kidney. Remember the aorta can sometimes be seen in this view, so don’t be fooled. Check out One Minute Ultrasound’s IVC video for more info.

Handsome Model Demonstrating IVC Starting Position

DVT: DVT ultrasound is one of my favorite scans. Once you know your anatomy, it’s a pretty simple scan. Does the vessel compress or not? Lower extremity DVT scanning involves assessing compressibility in two regions, the femoral and the popliteal areas. Start at the femoral vein, just inferior to the inguinal crease and medial the femoral artery. Assess compressibility there. Follow the common femoral vein slightly inferior and assess compressibility at the greater saphenous vein (as it branches medially) and the deep femoral vein (as it branches posteriorly). You have now completed the femoral region in just a few sweeps of your probe. Now move to the popliteal fossa behind the knee. The popliteal vein will be more superficial, so the “pop”liteal vein will be “on top” of the screen (“pop on top” to remember this). Assess compressibility here at the proximal popliteal vein. Scan inferior to to its trifurcation (anterior tibial, posterior tibial, peroneal veins) and assess compressibility of the proximal calf veins. That’s it. Two regions, vein compression, and knowing your anatomy makes for a quick, easy DVT scan. Check out this DVT Cheat Sheet for a refresher before your next DVT scan.   

Prove It – The Evidence for PE Ultrasound

EM Physicians Are Pretty Good at Finding RV Dilation

• Prospective study: 3 EM physicians acquired cardiac ultrasound for patients being evaluated for PE & compared their interpretation to fellowship-trained ultrasound expert
• 96% agreement between the EM docs and ultrasound expert on presence of RV dilation
• Basically EM physicians can acquire & interpret ultrasound images to diagnosis RV dilation   
• Read It for Yourself

Sick PE Patients have RV Dilation

• Same prospective study as above with EM physician acquired & interpreted ultrasound images. Correlated ultrasound findings to all patients with CT confirmed PE and for PE patients admitted to ICU.
• 100% of patient admitted to ICU and 100% of saddle embolisms had RV dilation. RV dilation was 98% specificity (100% in patients without COPD) and 50% sensitive for PE.
• Basically, RV dilation is a good rule in test for PE and was present in the sickest PE patients (those requiring ICU admission).  
• Read It for Yourself

If There’s a DVT…

• Prospective study of 524 patients suspected to have PE who had CT PE and DVT ultrasound.
• DVT ultrasound was 99% specific and 39% sensitive. Positive likelihood ratio was 42.
• Presence of DVT on ultrasound in patients suspected to have PE is a good rule in test. 
• Read It for Yourself

Conclusion

We all got into medicine to do good and save lives. If you want to be the doctor that young, hopeful medical student/resident you would be proud of, this is an essential scan set. You will save lives that others miss and that kind of save is the most satisfying, the saved life that someone else might have missed and is alive because you were there. As we all know PEs are sneaky and haven’t read the text books. Many present without profound hypoxia, chest pain or evidence of DVT on exam; even when they are massive. If you mistreat this hypotensive patient population with our most common treatment for hypotension (IV fluids), you will likely cause harm and may kill your patient. Getting the ultrasound views takes 2-3 minutes at most and gives you valuable information. This valuable information will enable you to diagnose the cause of shock in patients too unstable for other advanced imaging modalities and allow you to initiate life saving treatments in patients where every minute counts. Patients like this are why we do what we do and cases like this absolutely qualify as a SonoSave. So next time your patient is hypotensive and sick, question the diagnosis momentum and pick up the probe. You won’t regret it and your patient will thank you!

More Resources

If you want to check out more resources, take a look at these great ones. They’re awesome!

• Five Minute Sono – PE
• Ultrasound Podcast – PE

References

• Alder C, Buttner W, Veh R.   Relations of the ultrasonic image of the inferior vena cava and central venous pressure. Aktuelle Gerontologie. November 1983. https://www.ncbi.nlm.nih.gov/pubmed/6140870
• Adhikari S, Zeger W, Thom C, Fields JM. Isolated Deep Venous Thrombosis: Implications for 2-Point Compression Ultrasonography of the Lower Extremity. Annals of Emergency Medicine. November 2014. https://www.ncbi.nlm.nih.gov/pubmed/25465473.
• Crisp JG, Lovato LM, Jang TB. Compression ultrasonography of the lower extremity with portable vascular ultrasonography can accurately detect deep venous thrombosis in the emergency department.Annals of Emergency Medicine. September 2010. https://www.ncbi.nlm.nih.gov/pubmed/20864215.
• Cowger Matthews J, McLaughlin V. Acute Right Ventricular Failure in the Setting of Acute Pulmonary Embolism or Chronic Pulmonary Hypertension: A Detailed Review of the Pathophysiology, Diagnosis, and Management. Current Cardiology Review. February 2008. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2774585/.
• Dawson M, Mallin M. Introduction to Bedside Ultrasound Volume 1. Chapter 5 “Rush”.
• Dresden S, et al. Right Ventricular Dilatation on Bedside Echocardiography Performed by Emergency Physicians Aids in the Diagnosis of Pulmonary Embolism. Annals of Emergency Medicine. August 2013. http://edus.ucsf.edu/sites/edus.ucsf.edu/files/wysiwyg/Dresden%20RV%20dilation%20PE.pdf.
• Five Minute Sono. “PE”. http://5minsono.com/pe/.
• Kucher N, et al. Novel management strategy for patients with suspected pulmonary embolism. European Heart Journal. February 2003. https://www.ncbi.nlm.nih.gov/pubmed/12581684.
• Le Gal G, et al. A positive compression ultrasonography of the lower limb veins is highly predictive of pulmonary embolism on computed tomography in suspected patients. Thrombosis and Haemostasis. June 2006. https://www.ncbi.nlm.nih.gov/pubmed/16732375.
• Life in the Fast Lane. “PE”. https://lifeinthefastlane.com/cardiovascular-curveball-011/.
  
• Lodato JA, Ward RP, Lang RM. Echocardiographic predictors of pulmonary embolism in patients referred for helical CT. Echocardiography 2008, Jul;25(6):584-90.
  
• Mathis G, Blank W, Reissig A, Lechleitner P, Reuss J, Schuler A, Beckh S. Thoracic ultrasound for diagnosing pulmonary embolism: a prospective multicenter study of 352 patients. Chest. 2005;128:1531–1538.
• Mount Sinai EM Ultrasound. “RUSH”. http://sinaiem.us/tutorials/rush/.
• McIntyre K, Sasahara A. The hemodynamic response to pulmonary embolism in patients without prior cardiopulmonary disease. American Journal of Cardiology. September 1971. http://www.sciencedirect.com/science/article/pii/0002914971901160.
• Nazerian P, Vanni S, Volpicelli G, Gigli C, Zanobetti M, Bartolucci M, Ciavattone A, Lamorte A, Veltri A, Fabbri A, Grifoni S. Accuracy of point-of-care multiorgan ultrasonography for the diagnosis of pulmonary embolism. Chest. 2014;145:950–957. https://www.ncbi.nlm.nih.gov/pubmed/16162754.
• Squizzato A, Galli L, Gerdes V. “Point-of-care ultrasound in the diagnosis of pulmonary embolism”. Critical Ultrasound Journal. May 2015. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4447771/.
• Squizzato A, Rancan E, Dentali F, Bonzini M, Guasti L, Steidl L, Mathis G, Ageno W. Diagnostic accuracy of lung ultrasound for pulmonary embolism: a systematic review and meta-analysis. J Thromb Haemost. 2013;11:1269–1278 https://www.ncbi.nlm.nih.gov/pubmed/23574640.
  
• Ultrasound Podcast. “PE”. http://www.ultrasoundpodcast.com/2014/05/multi-organ-us-pe-castlefest-2015-registration-open-last-year-ever-foamed/.

Who Needs an eFAST Ultrasound:

• Blunt and penetrating abdominal trauma
• Blunt and penetrating chest trauma
• Ectopic pregnancies
• Any patient you suspect has abdominal or thoracic free fluid/bleeding

The Technique: 5 Scans in 1 Exam 

Heart

• Probe position: subxyphoid
• Image: four chambers of the heart and pericardium
• Evaluation for: pericardial effusion and cardiac tamponade

Right Upper Quadrant (Perihepatic)Right Upper Quadrant (Perihepatic)

• Probe position: RUQ
• Image: Morrison’s Pouch (liver and kidney), diaphragm, and costophrenic angle
• Evaluation for: intra-abdominal bleeding or fluid and hemothorax

Left Upper Quadrant (Perisplenic)

• Probe position: LUQ
• Image: Spleen, kidney, diaphragm, and costophrenic angle
• Evaluation for: intra-abdominal bleeding or fluid and hemothorax

Pelvis

• Probe position: over the bladder
• Image: in men- bladder and rectum, in women- bladder, uterus, and rectum
• Evaluation for: intra-abdominal bleeding or fluid

Lungs

• Probe position: anterior chest at the 3rd and 4th intercostal space
• Image: ribs, pleura, and lung
• Evaluation for: pneumothorax, pulmonary contusions

eFAST 1 Minute Ultrasound

Facts, Pearls, and Pitfalls

Advantages of Ultrasound

• Faster than CT or x-ray
• Radiation-free!
• Performed at the bedside simultaneously with other medical care
• A superior test is many cases (hemothorax, pneumothorax, etc.)

Limitations of Ultrasound

• It’s not as reliable for detecting solid organ lesions
  • But these probably aren’t as emergent as a raging hemorrhage into the abdomen and if the patient is stable that can go to CT.
• Too much fat is bad. It’s bad for the patient and bad for ultrasound. Getting good images on an obese patient is hard! So practice on stable chunky patients
  • Personally, I troll the ER for obese trauma patients and re-eFAST them, so I’ll be better at obese patient ultrasound when there’s an emergency and it really counts.
• Subcutaneous air can distort ultrasound images. If you feel subcutaneous rice krispies, ultrasound imaging might be difficult.

Pearls

• Repeat the eFAST if your clinical suspicion remains high. Repeat scanning increases the test’s sensitivity.
  • There may be a slow bleed and there wasn’t enough free fluid for a positive exam initially
  • Lower limit of fluid detection in the abdomen is 200 ml of fluid
• Trendelenburg position can make the upper quadrant views more sensitive
• Reverse Trendelenburg can make the pelvic view more sensitive
• Don’t be afraid to get low on the pelvic view. If it feels awkward, you’re probably doing it right.
• Get your pelvic view before they put in the Foley. A full bladder is a visible bladder.
• If you can can’t get the LUQ view, move superior and posterior. The kidney is higher on the left side. Make sure you’re knuckles touch the bed. If they’re not, you’re not posterior enough.

Pitfalls 

• Don’t get tricked by perirenal fat. Free fluid is darker than fat.
• Don’t get tricked by epicardial fat pads. Same rule as above. Fluid is darker than fat.
• Don’t delay care waiting for an eFAST on patients that obviously need surgical intervention (like an abdominal evisceration).
• Don’t crank your probe to extreme angles to visualize the bladder. Keep your probe perpendicular to the patient to avoid false positives and negatives in the pelvis.
• Don’t miss blood because it’s clotted. Clotted blood has varying echogenicity (shades).

Conclusion

The eFAST is a great ultrasound exam. It’s faster than other imaging and can be done in just a few minutes (a huge plus for the hemodynamically unstable patient). It can be performed at the bedside without interrupting ongoing medical care. There’s no radiation, unlike CT or x-ray. It’s sensitive, specific, and accurate. And it’s a superior diagnostic tool for a number of conditions, like pneumothorax and hemothorax. The scan consists of a RUQ, LUQ, pelvic, cardiac, and lung ultrasound. And to top it all off, it’s not that hard to learn… I promise. This is a foundational ultrasound exam in emergency medicine and should be a part of any physician’s exam skills. Now go practice some eFASTs! And be sure to check out the Part 1 and Part 2 SonoMojo posts if you haven’t read them already!

Other Resources

Here are some extra eFAST resources. I highly recommend the Ultrasound Podcast anytime you want to learn more about ultrasound!

• Ultrasound Podcast: eFAST
• eFAST Cheat Sheet 
• “A Song for A Scan” from the Ultrasound Podcast 

In case you haven’t heard… Ultrasound Cheat Sheets are all the basic info you need to review before performing (or teaching) a specific ultrasound scan. They’re 1-2 pages long and consist of an brief check list of information on the application, image acquisition, and interpretation of a scan.

Be sure check out SonoMojo’s latest addition to the Ultrasound Cheat Sheets Collection, ocular ultrasound!

There are a few cases I could talk about… Ultrasound guided LPs have turned out to be a surprisingly useful skill. Lucky for you, I’ve restrained myself.

The first time I heard about ultrasound guided LPs was during a spectacular yearlong ultrasound elective in medical school. I was sitting in the doctor’s pod with THE ultrasound attending of ultrasound attendings. He casually asked “Have you ever heard of ultrasound guided LPs?” Never. “Do you want to see one?” Obviously. He explained how ultrasound guided LPs follow the principle of “Measure twice. Cut once.” He spent a minute (and I mean literally just one minute) visualizing the spinal landmarks and marking them on a somewhat altered, seriously chunky patient. He proceeded to get the LP in one stick! I remember thinking he was a wizard in that moment, a wizard who uses ultrasound to elevate patient care to another level; and that I want to be the badass attending that gets LPs on obese, altered patients in one stick. I had to learn this skill…One year and a few ultrasound guided LPs later, I found myself on an internal medicine rotation. By then I had earned myself a reputation as “the ultrasound chick”. My first senior resident was also especially interested in bedside ultrasound. On our first day without prompting he said “bedside ultrasound is the future of medicine.” I literally did a small happy dance and told him we were going to have a great month. And we did! Internal medicine had never seen so much ultrasound before our partnership. It was wonderful! Fast forward a couple months. The above senior resident catches me in the hall and asks my team if he can borrow me. “I’ve got a patient for you!” It’s an obese, ICU patient with suspected meningitis, who has failed multiple LP attempts. “Can you do an ultrasound guided LP for me?” We were at a small community hospital without interventional radiology. Fluoroscopy isn’t an option (and moving her seems like a bad plan anyway). We roll in the ultrasound, identify the spinous interspace, mark it, and start the LP. I get the CSF and we do happy dance in the hall… Another patient wins thanks to bedside ultrasound!

Intro to Ultrasound Guided Lumbar Puncture

So how exactly does one use bedside ultrasound to enhance a lumbar puncture? I’m glad you asked. Ultrasound guided LPs use ultrasound to directly visualize spinal structures (spinous processes, ligamentum flavum, etc.) and mark the inter-spinous space prior to LP procedures. This is considered static ultrasound guidance, unlike real-time ultrasound guidance that visualizes a procedure as it happens. By marking the exact midline and the exact inter-spinous space you’ve removed the hardest part of the equation, finding the right spot to put your spinal needle.

Besides making your job easier, ultrasound guidance is just plain better for patients. Here’s where ultrasound guided LPs get really get awesome. It decreases overall time of the procedure. Measure twice, cut once WILL save you time. I’m sure you can remember a case that took forever, was miserable for the patient, and frustrating for you because it just wasn’t happening. Not surprisingly ultrasound guidance also decreases the number of LP attempts, LP failure rates, and complications. And if all that wasn’t enough, it decreases pain. When you actually visualized the inter-spinous space and stick your spinal needle directly into that space (instead of repeatedly jabbing the periosteum or paraspinal muscles), it just makes sense that patients experience less pain. That alone is reason enough for me. The benefits seen in ultrasound guided LPs compared to blind LPs are even greater in obese patients, so reach for the ultrasound on your next obese patient. Actually, reach for your ultrasound on your next few patients…

The Technique

The scan boils down to two quick views, a longitudinal and transverse view of the spine. The longitudinal view visualizes the inter-spinous space between two spinous processes. Once the intervertebral space is identified, mark it and rotate the probe 90 degrees for the transverse view. The transverse view is used to identify the exact location of the midline, directly over the spinous processes. The midline is marked. Now you have two lines on the patient, one for the midline and one for the inter-spinous space… “X” marks the spot. When you get comfortable with the scan, it should only take a minute. We’re talking simple stuff here.

Probe Selection

This really depends on your patient. For non-obese patients a high frequency probe, such as a linear probe, is great. It has the best image resolution, but low depth of penetration. For obese patients grab a curvilinear probe. It has a lower frequency, so it penetrates through tissue better than the linear probe. The image won’t be as clear, but you’ll still be able to see the spinous processes you need.

Patient Position

Upright or in lateral decubitus… depends on your needs. Do you need an opening pressure or are you just trying to get a CSF sample? The only important part of patient position is that they DO NOT move once you scan and make your marks. If the patient moves, the skin overlying your inter-spinous space may move too. Plan for this and mark the space after you’ve position the patient. If you need to reposition mid-procedure, you can always use a sterile probe cover.

Interpreting Images

Bone will be a thin hyperechoic structure with posterior shadowing. The spinous process will appear hyperechoic and curved downward in the nearfield with posterior shadowing. The lamina will also be hyperechoic, but come in pairs on either side of the intervertebral space just inferior or superior to the spinous processes. The sacrum will appear as a long thin hyperechoic structure. The dura is a very thin hyperechoic line between and deep to the lamina. Beneath the dura hypoechoic CSF of the subarachnoid space can sometimes be seen. In the transverse view you will also see two round structures with mildly hyperechoic internal bundles just lateral to the spine; these are paraspinal muscles.

Scanning
Start in the longitudinal view. In this view the probe and resulting image are oriented parallel to the long axis of the spine. Place your probe over the sacrum with the probe marker oriented towards the patient’s head. The sacrum will be think hyperechoic line with posterior shadowing. Slide 1-2 cm lateral of midline and slide upwards. You should see the lamina and the intervertebral spaces between. Slide upward, counting the vertebrae, until you find the desired intervertebral space and mark it.

Once you find and mark the intervertebral space, turn your probe 90 degrees and slide back towards midline for the transverse view. In this view the resulting image are now oriented perpendicular to the long axis of the spine. Your probe marker should be oriented towards patient left. Look for the spinous process, which will appear as a hyperechoic curved dot with posterior shadowing, to find midline. Mark your midline.

Now you will have two marks, midline and the intervertebral space. Extend those lines to form the “X” that marks your target and optimal point of entry into the subarachnoid space.
And for bonus points… you can measure the distance to the dura (found between the spinous processes) in the longitudinal view. The subarachnoid space can be seen between the spinous processes bordered superficially by the thin hyperechoic line of the dura mater with anechoic CSF just below the dura. Once you see dura, you can measure the distance from the skin and know the depth at which you should puncture the dura and get CSF.

X Marks the Spot

Use a surgical marker, needle hub, syringe… whatever you’ve got handy. Firmly pressing a needle hub or syringe tip into the skin for several seconds (like 20 sec) will also create a mark that will not disappear when you prep the site. A surgical marker will also stay after you’ve prepped the site. This seems simple, but there is nothing more frustrating than identifying the site and losing it after you prep.

Relevant Anatomy

You can’t be good at bedside ultrasound without getting good at anatomy. You just can’t. So let’s talk spinal anatomy real quick.

The spinal cord ends around the inferior border of L1-L2. Distal to the spinal cord is the loose bundle of spinal nerves known as the cauda equina. The cauda equina is what a spinal needle passes between instead of damaging the spinal cord. This is why it is important to accurately identify the correct spinal level, which brings us to the bony structures of the spine. The spine is made of vertebrae, which consist of the body, a posteriorly protruding spinous process, and two transverse processes connected to the spinous process via lamina.

Vertebra are connected to one another by ligaments. The supraspinous ligament connects the tips of the spinous process. The interspinous ligaments connect adjacent spinous processes along the length of the spinous process. The ligamentum flavum connects the spinous processes anteriorly to form the posterior wall of the spinal canal. It is the strongest ligament of the spine and contributes to the characteristic “pop” experienced when entering the intervertebral space. Once in the spinal canal, the dura and arachnoid mater surround the cauda equina, providing an additional layer to “pop” through before reaching the CSF filled subarachnoid space. Phew… All done! Now onto more ultrasound goodness.

Show Me the Evidence

It’s Fast and Easy…

• Prospective, observational study of EM docs performing 174 scans on patients with mean BMI of 31.4 (aka obese)
• Average scan time was 57.9 seconds!!
  • And who doesn’t have 1 minute to make an LP faster and more successful, especially on obese patients
• High quality images in < 1 minute in 87.9% of scans, and < 5 minutes in 100% of scans
• Basically, adding ultrasound identification of landmarks takes about a minute to get quality images.

Read the Paper for Yourself

But Does It Actually Help?

• Prospective, randomized trial of 80 subjects comparing ultrasound assisted LP to palpation only LP. Done by emergency physicians with 2 hours of training
• Ultrasound group had less pain (4.4 v 7.4/10), decreased procedure times (3.3 v 6.4 min), and fewer attempts (1 v 2)
  • Pain, procedure time, and number of attempts cut in ½ with ultrasound assistance… which group would you want to be in??
• Obese patients are where things get really cool… they had less pain (4.4 v 9), decreased procedure time (3.9 v 9.1 min), and fewer attempts (1 v 3)
• Basically, ultrasound makes LPs better for providers and patients, especially obese patients. It’s faster, less painful, and increases your chances of success!

Read the Paper for Yourself

Plus, We Suck at Finding Anatomy with Palpation!

• Prospective trial comparing ultrasound identified v palpation identified intervertebral spaces in 50 subjects. Each subject assessed by each method, marked with radiopaque labels, and spine radiographs taken to determine accuracy of space identification.
• Palpation group was only correct 31% of the time (versus 70% in ultrasound group)!
  • Palpation group marked over a spinous process or at wrong level 69% of the time!
• Palpation group was 2 spaces higher or lower than estimated level 24% of the time!
• We’re actually pretty terrible at identifying the intervertebral space and level of that space by palpation alone.
• Basically, ultrasound significantly improves accuracy in finding the correct intervertebral space!

Read the Paper for Yourself

Summary

This is good skill to have, period. It’s fast; it’s easy to learn; and it’s better for your patients. Ultrasound assistance improves LP success rates, decreases pain, decreases procedure length, and reduces the number of attempts needed. It’s especially useful for obese patients, where palpation of landmarks can be difficult and lead to blind (and painful) procedures. The literature reflects this too, making it hard for me to justify not using ultrasound to identify LP landmarks in my obese patients. Basically being good at ultrasound guided LPs boils down to being able to recognize and mark the intervertebral space at midline. That’s it. Less than one minute of scanning will save you time, spare your patients pain, and increase your chances of success! Once you have the hang of it, it will improve your patient care and make you look like a rock star doc. Happy scanning everyone!

Suggested Resources

Ultrasound Podcast: US Guided LP Microcast

References

1. Ferre RM, Sweeney TW. Emergency Physicians Can Easily Obtain Ultrasound Images of Anatomical Landmarks Relevant to Lumbar Puncture. Am J Emerg Med 2007;25(3):291-6.
2. Furness G ea. An evaluation of ultrasound imaging for identification of lumbar intervertebral level. Anesthesia 2002; 57:277-80.
3. Murphy M, Nagdev A. Focus On: Ultrasound-Guided Lumbar Puncture. ACEP News
   September 2007. http://www.acep.org/Clinical—Practice-Management/Focus-On–Ultrasound-Guided-Lumbar-Puncture
4. Nomura JT,Leech SJ, Shenbagamurthi S, Sierzenski PR, O’Connor RE, Bollinger M, Humphrey M, Gukhool JA.A randomized controlled trial of ultrasound-assisted lumbar puncture. J Ultrasound Med. 2007 Oct; 26(10):1341-8.
5. Ferre RM,Sweeney TW, Strout TD. Ultrasound identification of landmarks preceding lumbar puncture: a pilot study. Emerg Med J. 2009 Apr;26(4):276-7.
6. Mofidi M, Mohammadi M, Saidi H, Kianmehr N, Ghasemi A, Hafezimoghadam P, and Mahdi Rezai M. Ultrasound guided lumbar puncture in emergency department: Time saving and less complications. J Res Med Sci. 2013 Apr; 18(4): 303–307.
7. Dawson M, Malin M. “Chapter 9: Procedures”. Introduction to Bedside Ultrasound Volume 2. May 2013
8. Dawson M, Malin M. eBook UNIVERSALLY Available: Inkling.com…and Some Ultrasound Guided LP Talk. Ultrasound Podcast. June 2013.
9. Boon JM, Abrahams PH, Meiring JH, Welch T. Lumbar puncture:Anatomical review of a clinical skill. Clinical Anatomy. Volume 17, Issue 7, pages 544–553, 2004.

In case you haven’t heard of “Ultrasound Cheat Sheets”…  they’re all the basic info you need to review before performing (or teaching) a specific ultrasound scan. They are 1-2 pages long and consist of an brief check list of information on the application, image acquisition, and interpretation of a scan.

So be sure check out SonoMojo’s latest addition to the Ultrasound Cheat Sheets Collection,  soft tissue ultrasound!