EUS: Pyloric Stenosis, Early Pregnancy, Serratus Plane block

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Brown Ultrasound Tape Review – 11:19:15
At this week’s BUTR, we again reviewed some great ultrasound images that were scanned over the past week.
Resident reviewer: Dr. Mike Hunihan
Faculty reviewers: Drs. Erika Constantine and Otto Liebmann
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PYLORIC STENOSIS
When to suspect pyloric stenosis:
– Onset between 3-5 weeks old, but can occur up to 12 weeks old.
– More commonly affects males.
– Risk factors include family history of pyloric stenosis, maternal smoking, macrolide antibiotics administered to infant, and bottle-feeding.
– Classic presentation is “hungry vomiter”; postprandial forceful non-bilious vomiting.
How to diagnose: 
– “Olive-shaped” mass that can be palpated along the R rectus sheath is pathognomonic, but rarely found.
– Ultrasound is the gold standard test when done by an experienced ultrasonographer.
– Additional studies, when ultrasound and exam are nondiagnostic, include barium swallow and upper endoscopy.
Ultrasound diagnostic criteria: 
Pyloric Muscle Thickness = >3mm
Pyloric Muscle Length = >14mm
Helpful mnemonic to remember this: Pi =3.14 (PYloric stenosis, >3mm thick, >14mm long)
Screen Shot 2015-11-30 at 12.26.58 PM Screen Shot 2015-11-30 at 12.27.12 PM
Abnormal findings: (Upper) Channel length (Lower) Muscle wall thickness
Another component of the US exam is to watch for passage of gastric contents through the pylorus. If you visualize passage of gastric contents, this is reassuring that there is no pyloric stenosis. However, sometimes you can get passage of small volumes of liquid through a tight pylorus and still have pyloric stenosis – it’s called the string sign with barium studies.
The other pertinent signs of pyloric stenosis:
1. Antral Nipple Sign: Redundant pyloric mucosa that protrudes into gastric antrum resembling a nipple.
 image
2. Target Sign: Hypertrophied hypoechoic muscle surrounding echogenic mucosa layer, visualized in short axis.
target sign
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3. Cervix Sign: Indentation of the pylorus into the fluid filled antrum. image (1)
In 2013, there was a prospective observational trial of PEM fellows performing bedside US for diagnosis of pyloric stenosis. They had a convenience sample of patients who were suspected to have pyloric stenosis based on history and physical exam, and who were ordered to have a formal ultrasound in the radiology department. The PEM fellows also performed bedside ultrasound on those same patients and compared their results to the radiology results. They enrolled 67 patients into their study, of which, 10 patients (15%) were found to have pyloric stenosis. The results of their study showed a 100% sensitivity and 100% specificity for PEM fellows performing bedside ultrasound. They had zero false positives or false negatives. This study suggests that bedside ultrasound for evaluation of pyloric stenosis is feasible for our residents, fellows, and attendings in the ED.
Sivitz, Adam B., Cena Tejani, and Stephanie G. Cohen. “Evaluation of hypertrophic pyloric stenosis by pediatric emergency physician sonography.”Academic Emergency Medicine 20.7 (2013): 646-651.
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EARLY PREGNANCY

We also discussed the use of ultrasound in early pregnancy patients. From the ED perspective, our main question should be: IUP or no IUP?  If we cannot visualize a definitive IUP (gestational sac + yolk sac) then we need to be concerned about ectopic pregnancy.
But what about heterotopic pregnancy?
-A heterotopic pregnancy is the presence of both an IUP AND an ectopic pregnancy at the same time!
– In females who become pregnant by natural means, the chance is 1 in 10,000.
– In females who have assisted reproduction (IVF or even just hormone therapy) that chance increases to 1 in 1,000.

Moral of the story: When performing ultrasound in early pregnancy be sure to take a good history of any assisted reproduction techniques used for that pregnancy 
 
In addition to determining the location of an early pregnancy, we discussed the diagnostic criteria for non-viable IUP. A helpful review article in NEJM by Doubilet et al reviews the topic at length. 
 
Important measurements on US that are diagnostic for nonviable pregnancy: 
CRL >7mm with no heartbeat 
GS diameter >25mm with no embryo 
 
image (2)
Doubilet, Peter M., et al. “Diagnostic criteria for nonviable pregnancy early in the first trimester.” New England Journal of Medicine 369.15 (2013): 1443-1451.

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SERRATUS NERVE BLOCK
Finally, we discussed a novel serratus plane nerve block that could be useful for anesthesia for axillary abscesses, rib fractures, or even chest tube placement. The aim is to block the thoracic intercostal nerves and provide anesthesia to the lateral hemithorax. The images below show the two options for serratus nerve plane block; injecting superior or inferior to the serratus anterior.
image (3)
 image (4)
Although this study gave the initial description of a serratus nerve plane block, there is still further studies to be performed. Something to keep an eye out for!
Blanco, R., et al. “Serratus plane block: a novel ultrasound‐guided thoracic wall nerve block.” Anaesthesia 68.11 (2013): 1107-1113.

Orthopedic Review: Distal Radius Fracture Reduction

Case: 64 yo F presents to the Emergency Department after tripping over a curb and suffering a FOOSH (fall on outstretched hand) injury. There is obvious deformity about the wrist with associated swelling and tenderness. X-ray imaging reveals the following:

Her exam and imaging are consistent with a distal radius fracture. How do you treat this?

Page ortho?

Providing adequate analgesia, reduction of fracture, and proper splinting is well within the scope of EM practice, especially in the community setting. This post will review the technique of hematoma block for analgesia as well as the different techniques for reduction of distal radius fractures and application of splint.

Hematoma Block

  • Can be used alone or in combination with other analgesic modalities such as IV narcotics or benzodiazepines
  • Simple technique
  • Very few complications

 

But is hematoma block effective?

  • In 2011, prospective randomized controlled trial comparing hematoma block to conscious sedation with IV Propofol
  • 96 patients underwent randomization and researchers compared patients’ pain using VAS (visual analog scale) during the procedure and after the procedure
  • Patients who received Propofol had pain scores of 0 during the procedure compared to 0.97+/-0.7 in patients who received hematoma block
  • After the procedure, patients who received Propofol had pain scores of 2.72+/-0.7 compared to 2.25+/-0.2 in patients who received hematoma block
  • Patients who received hematoma block had significantly shorter ED stay times (0.9hrs vs 2.6 hrs)

Hematoma blocks result in similar analgesia as conscious sedation with IV Propofol AND leads to shorter ED stay times

Setting up for the procedure:

  • 10cc 1% Lidocaine
  • 10cc syringe with 2 large needles (one for drawing up Lidocaine, one for injecting)
  • Skin cleanser (betadine, Chloraprep, or alcohol wipe)

Procedure Technique:

  1. Identify the fracture site by palpating along the dorsal aspect of the forearm to feel for bony step-off. Cleanse this entire area thoroughly with skin cleanser.
  2. Insert needle attached to syringe filled with 10cc 1% Lidocaine at that site and advance needle along periosteum until needle falls into fracture site.
  3. Draw back on plunger to aspirate blood confirming the needle is in the fracture site.
  4. Inject 10cc Lidocaine into fracture site and remove needle.
  5. Allow 10-15min to pass to ensure full analgesic effect.

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