The literature for using ultrasound guidance in placing a central venous line is robust. There are many articles espousing the benefits of ultrasound guidance: reduced number of attempts, reduced complication rate, increased first pass success rate. So, it is indeed difficult to narrow down to a finger count of 3 articles. But if one were to spend time reading just 3 articles that define the topic, these 3 should be as good as any. Continue reading
While an uncommon condition, a leaking abdominal aortic aneurysm (AAA) is deadly if not recognized quickly.
How good is the physical examination for excluding AAA? Even if the physical exam is specifically directed to look for AAA, the sensitivity is still not good enough to rule out its presence (Sensitivity of 29% for AAAs of 3.0 to 3.9 cm, to 50% for AAAs of 4.0 to 4.9 cm, and 76% for AAAs of 5.0 cm or greater in diameter). So go pick up that ultrasound probe to look for it.
Can ultrasound define the diameter of a AAA as accurately as a CT scan? Pretty close, though ultrasound will probably underestimate the diameter. Where it matters (at and around the bifurcation with a longitudinal view), ultrasound can come within 1cm of the CT diameter 95% of the time.
Knaut, A. L.et al. Ultrasonographic measurement of aortic diameter by emergency physicians approximates results obtained by computed tomography. The Journal of Emergency Medicine, 2005; 28(2), 119-26.
Finally, how good are emergency physicians in detecting AAAs? Pretty good it seems, with 100% sensitivity (95% CI 1⁄4 89.5 to 100), 98% specificity (95% CI 1⁄4 92.8 to 99.8), 93% positive predictive value (27/29), and 100% negative predictive value (96/96).
Pelvic ultrasound is one of our core US applications. It has been incorporated within many emergency departments and it is a bread and butter skill for the EP. So, how do we fare in our performance?
This early study showed that ED ultrasound was very similar to radiology department findings (or final outcome, or both) in 96% of the study cohort. Also, when ED ultrasound accurately identified IUPs, ectopic pregnancies were effectively ruled out with a NPV of 100%.
1. Durham, B., Lane, B., Burbridge, L., & Balasubramaniam, S. (1997). Pelvic ultrasound performed by emergency physicians for the detection of ectopic pregnancy in complicated first-trimester pregnancies. Annals of Emergency Medicine, 29(3), 338-47.
Also, why do we do it in the first place, and not send all the cases to radiology for ultrasound? The answer lies in the reduction of both ED length of stay as well as cost. Any means to reduce ED overcrowding and decrease spending are welcome!
Lastly, when ectopic pregnancy is suspected, remember to perform a FAST exam as a positive finding (free fluid in Morison’s pouch) can predict the need for operative intervention.
The FAST exam is the prototypical application of emergency ultrasound. However, it is important to know that there are limited randomized controlled trials assessing the utility of the FAST exam. Despite this, let’s look at three good articles that all emergency residents should know.
1. In this Cochrane review, the authors’ conclusion was that there was insufficient evidence for the use of ultrasound-based clinical pathways in the initial diagnostic workup of patients with blunt abdominal trauma. Ultrasound was not sensitive and lacked diagnostic accuracy. However, the use of ultrasound did reduce the use of CT scans. The take-home message is that ultrasound should not be used as a single rule-out test for significant intra-abdominal injury and the ED resident should be aware of ultrasound’s limitations.
Stengel D, Bauwens K, Sehouli J, Rademacher G, Mutze S, Ekkernkamp A, Porzsolt F. Emergency ultrasound-based algorithms for diagnosing blunt abdominal trauma (Review). The Cochrane Collaboration. February 18th, 2008.
2. Interestingly, this review used the same methodology as the Cochrane review and found that an adequately performed FAST exam can predict the need to send a patient to the operating room, with a high degree of sensitivity (98.9%) and specificity (98.1%).
Melniker LA. The value of focused assessment with sonography in trauma examination for the need for operative intervention in blunt torso trauma: a rebuttal to “emergency ultrasound-based algorithms for diagnosing blunt abdominal trauma (review)”, from the Cochrane Collaboration. Critical Ultrasound Journal. 2009;1:73-84.
3. Thoracic ultrasound has become part of the standard assessment of the trauma patient. Ultrasound has been shown to be much more sensitive than CXR in the detection of pneumothorax when compared to CT as the gold standard. There are many studies proving this point and this is a good example.
In this series, we cut to the chase and highlight our choice for the the top three articles on a given topic. Read on for the articles and brief discussion.
Three DVT articles that every emergency physician should know. What are they?
1) If there is any “must know” article for DVT or PE, this is it: commonly known as the Well’s Criteria, it provides a framework for the EP to approach any patient presenting with the the suspicion of DVT or PE. It is the ability to categorize patients into the different risk categories that we’re able to effectively use pre-test and post-test probability of a negative D-dimer to rule out the disease.
2) With the introduction of bedside clinician performed ultrasound, EPs now have a tool to evaluate the proximal lower extremity veins themselves. While there is abundant literature suggesting the feasibility of an EP performed bedside ultrasound, this review article showed that properly trained EPs can accurately diagnose DVTs with a pooled overall sensitivity and specificity of 95% and 96% respectively. However, several limitations were highlighted with regards to the available literature – there is no standardization of the technique used, and the studies involved EPs already highly trained in ultrasound and so the results cannot be generalized to all EPs.
3) This large RCT compares 2 point compression ultrasonography plus D-dimer with formal ultrasonography in symptomatic patients with suspected DVT. The rates of confirmed DVT at 3 months were similar in the 2 groups. This suggests that EPs can manage symptomatic patients suspected of having DVT with just 2-point compression ultrasound and D-dimer.
Bernardi E, Camporese G, Büller HR, et al. Serial 2-point ultrasonography plus D-dimer vs whole-leg color-coded Doppler ultrasonography for diagnosing suspected symptomatic deep vein thrombosis: a randomized controlled trial. JAMA. 2008;300:1653-1659.
Do you have other suggestions for studies? Comment below!