Archive | September, 2013

pulmonary embolism ECG findings

30 Sep

Interesting article by Marchick et al from a 2010 Annals:

6,049 patients that a doc had enough suspicion for a PE to order testing (d-dimer, CTPA, V/Q scan).

Some tables worth eyeballing:

petable2

TAKEAWAYS:

sensitivity of all the ECG findings suck.  can’t rule out PE if you don’t see these.

specificity isn’t that great either (mostly in the 80s).  Among the better ones:

  • inverted anterior (V1-4) t-waves
  • S1Q3T3 (classically taught)
  • RBBB

petable3

 

TAKEAWAYS:

some context for you: compare the odds ratio of the d-dimer (a notoriously non-specific test that is elevated by many things), vs. the odds ratio of some of the more specific ECG findings.

so seeing these (e.g. anterior TWIs, S1Q3T3) may increase your suspicion for a PE, by no means is it a slam dunk.  Keep an eye out for these ECG findings, but take ’em with a grain of salt, keep your mind open.

 

References: annals article (tables from article).

common bile duct on RUQ ultrasound

27 Sep

This is always the hardest part of the RUQ ultrasound for me (finding the CBD), so I figured since a picture is worth a thousand words, here are a nice set of pictures for reference landmarks and reinforcement.  Enjoy!

Check out the Sonoguide website for a quick tutorial/refresher.

sonoguide

(A = CBD, B = gallbladder)

References: sonoguide and first pic; pic 2; pic 3; pic 4; pic 5; pic 6

laryngoscope flashlight for oral procedure?

26 Sep

June’s ACEP News mag has a quick procedure review for ultrasound-guided peritonsillar abscess (click through for the whole article, with handy pictures), but included a tip I thought was worth adding to the toolbox for tricky oral procedures (e.g. PTA drainage).

 

Use a Macintosh laryngoscope, curved part down resting on their lower lip, as your light source.  Keeps the mouth open, keeps your view relatively clear, and theoretically provides a stabilizing surface if you want to rest your needle on it as you slide it toward the back

oralmac

(don’t forget that needle guard, too).

 

Neat.

 

References: ACEP News article; pic from the same article.

Sgarbossa revisited – MI in LBBB

25 Sep

wanted to revisit this useful tool for looking for MI’s in those hard to interpret EKGs with LBBB (left bundle branch block)

USEFUL BASICS (click through for the breakdown):

–you’re handed an EKG, and there’s a LBBB

–look for >=1mm concordant ST elevation
–look for ST depression in anterior leads (V1, V2, V3)

if you see these things, worry about an MI (>90% specific)

 

MODIFIED CRITERIA:

same as above, but also add this:

–look for discordant ST deviation

–if ST segment change is > 1/4th the amplitude of the R or S-wave, worry about an MI

 

WHAT IF ITS PACED?

–if you see discordant ST elevation >5mm in a paced rhythm, worry about an MI.

 

 

References: basics; modified; paced; picture

quick ER math: bladder volume

24 Sep

If you don’t have a bladder scanner handy (that does the work for you, more or less), and want to calculate bladder volume on bedside ultrasound, here’s the quick formula for estimation:

 

(diameter cubed) /2          [or written another way] diameter^3 * 0.5

OR

length x width x height / 2

if you care about where this comes from, remember that 4/3 * pi * r^3 formula for the volume of a sphere?

pi is ~3, so simplify to 4 * r^3

r (radius) = 1/2 diameter, so 4 * (1/2 diameter)^3 = 4 * 1/8 diameter^3 = 1/2 diameter^3

and that’s enough math for one day

the most reference multiplier is diameter^3 * 0.52, but 0.5 is probably good enough for estimation anyways

there are other formulas, but the one above seems just as accurate, and is probably the quickest to do in the ER setting anyways.

 

 

References: crashingpatient.com; emory for 0.52 reference and picture; article

 

ultrasound IVs: triangle tip

23 Sep

Nice little tip for your ultrasound-guided IV (PIV or central) procedure:

 

Make your needle insertion site the same distance from the probe as the depth (distance from skin) of the vessel.  

Make your angle of approach 45 degrees.  

iv1

iv2

Thanks to Pythagoras, you should be able to get to the vessel this way.

 

QUICK RECAP:

Insertion site distance = depth of vessel from skin

angle of approach = 45 degrees

hurrah, math!

 

References: crashingpatient.com post with the idea; ACEP focus with the pics; procedure pic

blood cultures in complicated cellulitis?

20 Sep

Interesting article in August’s JEM, and the title says it all:

Blood culture results do not affect treatment in complicated cellulitis. (Paolo et al).

 

Click through to the pubmed link for the article.  Some highlights:

retrospective chart review, 639 adult patients (314 “complicated cellulitis”, 325 without comorbidities)

complicated cellulitis defined by

  • diabetes, (N=189)
  • active chemotherapy, (N=28)
  • dialysis, (N=19)
  • HIV/AIDS, (N=22)
  • organ transplantation (N=13)
  • PVD (N=24)
  • Hep B/C/cirrhosis (N=42)
  • other immunosuppression (N=49)

 

positive blood cultures:

  • complicated cellulitis 29/314
  • uncomplicated cellulitis 17/325

 

clinically significant change in management (change in class of antibiotic)

  • complicated cellulitis 6/314
  • uncomplicated cellulitis 4/325

 

THEIR CONCLUSION:

“Within this cohort of patients with complicated cellulitis, blood cultures rarely changed management from empirical coverage.”

 

References: the article; picture