I have to say, I’m a little confused by all the new SonoSite television ads – direct-to-consumer marketing for sports medicine ultrasonography? Or for zero-complication central line placement? Weird.
But, I digress. A little. This is a pediatric study of lightly trained ultrasonographers with varying levels of expertise using ultrasound to diagnose long-bone fractures. They performed 98 ultrasound examinations that were followed up by plain radiography, and they picked up 41 of the 43 fractures present, with 8 false positives: 95% sensitivity and 85% specificity. Six required reduction, all of which were identified as meeting criteria for reduction on ultrasound – as well as one additional false positive from a distal radius fracture.
As a feasibility study, it’s a nice little pilot. As a practice-changing strategy, it needs larger sample sizes and external validity. However, it does seem as though it will soon become reasonable to use bedside ultrasound to quickly rule-out fracture in patients with a low pre-test probability, while plain radiography will continue to play a role in advanced orthopedics management.
“Emergency Ultrasound in the Detection of Pediatric Long-Bone Fractures”
www.ncbi.nlm.nih.gov/pubmed/23114237
Category: Ultrasound
Sometimes, the Dead (by Ultrasound) Rise
This article received a little bit of dissemination, with the assertion that some apparently futile resuscitations may yet be salvaged despite the lack of cardiac activity on ultrasound.
But, this article doesn’t necessarily tell the entire story. It’s a systematic review of several small, poor-quality cardiac arrest cohorts for whom bedside cardiac ultrasonography was performed. In aggregate, there were 378 patients with no cardiac activity visualized during resuscitation – and 9 went on to have return of spontaneous circulation. They calculate this out as an LR of 0.18 for ROSC after finding no cardiac activity.
The problem is, this is the only information we have regarding the context of the ultrasound findings or the performance characteristics of the ultrasonographers at work. The authors also appropriately note that ROSC is not necessarily the ultimate patient-oriented outcome of interest – since we know that most ROSC after cardiac arrest admitted to the hospital still goes on to have a dismal outcome.
I’m not entirely sure what my takeaway should be from this study, and it’s not going to significantly modify my practice. In the appropriate clinical context, a lack of cardiac activity will still lead me to cease resuscitative efforts. It would be extraordinarily helpful to have a larger body of data specifically regarding the patient characteristics of those who did have ROSC despite lack of cardiac activity, to see if there is a usable pattern to this small population of exceptions.
“Bedside Focused Echocardiography as Predictor of Survival in Cardiac Arrest Patients: A Systematic Review”
The “Peripheral” IJ
Some patients just have no IV access – no superficial peripherals, no deep peripherals, no external jugular veins. In a critical emergency, this is the perfect time for an intraosseous line. But, what about the situation where IV access is simply necessary, but not urgent? Placing a central line is the last thing we’re interested in doing – draping, opening a costly central line kit, billing for an expensive procedure, exposing them to risks of over-the-wire techniques in the central circulation.
This technique, described formally here by folks from Highland Hospital, involves placing a standard, peripheral catheter into the internal jugular vein under ultrasound guidance. While I think this is a fantastic idea – much faster and less expensive than a full multi-lumen central line set-up – I wouldn’t characterize it as “risk-free”, either. The nine cases in this year-long review all demonstrated a lack of complications, but more data would help refine the procedural risks.
“The ultrasound-guided ‘peripheral IJ’: internal jugular vein catheterization using a standard intravenous catheter.”
Ultrasound In Undifferentiated Infant Vomiting
Is there anything ultrasound can’t do? Trauma, vascular access, undifferentiated abdominal pain – and another nice case report for vomiting in children.
These authors are using ultrasound in the projectile-vomiting infant looking at the pylorus, and, after finding a normal pylorus, they scan the rest of the abdomen. Lo and behold, they identify intussusception. I am not entirely certain I would be able to well-identify the pylorus, but I can definitely see potentially noting the intussusception. The authors include several nice images as teaching points.
As the barriers to routine ultrasound use in the ER decrease, hopefully we will all become more facile with using it in many more clinical situations.
“Use of Emergency Ultrasound in the Diagnostic Evaluation of an Infant With Vomiting”
www.ncbi.nlm.nih.gov/pubmed/21975504
Endotracheal Tube Verification Via Ultrasound
I think I’ve discovered the new paradigm of research in ultrasound. Every time you do a procedure or make a diagnosis, slap the ultrasound on someone and see if you can reliably identify anatomic changes.
It looks like, with their practiced ultrasonographers, that they can get some preliminary information regarding endotracheal tube placement by performing transtracheal ultrasound. Their “gold standard” was waveform capnography – which is a fair gold standard, but not universally sensitive and specific for tube placement in all clinical situations. Essentially, if the ETT is in the correct place, there is only one “air-mucosal interface” observed with high-frequency linear probe, and, if the ETT is in the esophagus, you have a second, posterior air-mucosal interface.
Seems reasonable.
Experts did it correctly with 99% sensitivity and 94% specificity, and the main advantage was speed.
“Tracheal rapid ultrasound exam (T.R.U.E.) for confirming endotracheal tube
placement during emergency intubation.”
Ultrasound Guided Subclavian Access
Ultrasound guidance and visualization of anatomy and/or the needle tip during jugular venous cannulation is, essentially, the standard of care given the frequency of complications using anatomic landmarks alone – not to mention the “growing” U.S. population that has outgrown their landmarks. It’s also the standard of care because residents finishing their training right now have never done an IJ without the ultrasound.
So, what do we do when we don’t have ultrasound? Then you’re left with the decision to do subclavian or femoral.
Well, ultrasound-guided subclavians are well-described in the literature, and this is an article from our critical care colleagues with 400 subclavian access attempts – half with landmarks and half with ultrasound. Fewer complications, fewer attempts, less time to access. Hard to argue with that. If you aren’t getting familiar with ultrasound, I would start thinking about ways to become more comfortable.