UMEM Educational Pearls

 Myocardial infarctions involving the left circumflex artery are often associated with ECGs that lack any ST-segment changes (38% in one representative study). Oftentimes when there are ST-changes, there may simply be anterior lead ST-segment depression. In these patients, acquisition of a few posterior leads frequently demonstrates STEMI. Some data does exist that failure to diagnose these posterior STEMIs (e.g. simply diagnosing anterior "ischemia" rather than posterior "STEMI") results in increased mortality.

So what's the bottom line?
1. In patients with isolated anterior lead ST-segment depression, always check for posterior STEMI with a couple of posterior leads.
2. In patients with non-significant ECGs but concerning persistent symptoms, always check for posterior STEMI with a couple of posterior leads.

This is always a great time to use that 80-lead ECG if your ED has one.

Amal

MEWDS (Multiple Evanescent White Dot Syndrome)

• A rare, unilateral, self-limiting inflammatory disease
• Afflicts young women more than men in a 4:1 ratio.
• Patients typically present complaining of
  • Sudden, painless, monocular decline in central acuity
  • Photopsias-- def. appearance as of sparks or flashes in retinal irritation
  • Dyschromatopsia-- def> disorder of color vision
  • Central/paracentral scotomas
• Visual acuity usually in the  20/40-20/400
• Fluorescein angiography of active lesions typically demonstrate a "wreath-like" hyperfluorescence of the white dots
• Disease is usually self limited (resolves in weeks to months) with an excellent prognosis.
• There are no known treatment options.

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Global symptoms of elevated intracranial pressure (ICP) include:

• Headache (likely mediated via the pain fibers of cranial nerve V in the dura and blood vessels)
• Depressed consciousness (likely due to either the local effect of mass lesions or pressure on the midbrain reticular formation)
• Vomiting

There is no prospective, randomized study to elucidate propofol’s effect on the critically ill patient. By definition, Propofol Infusion Syndrome (PRIS) has the following characteristics:

• acute bradycardia progressing to asystole
• lipemic plasma
• fatty liver enlargement
• metabolic acidosis with negative base excess > 10
• rhabdomyolysis or myoglobinuria

It has been thought that PRIS was limited to patients with prolonged use, but we now know that this is not necessarily true.

It has been shown that PRIS is more likely with the following risk factors:

• <19 years old
• male
• received a vasopressor
• cardiac manifestations (including Brugada Syndrome)
• metabolic acidosis
• renal failure
• hypotension
• rhabdomyolysis
• dyslipidemia

The treatment for suspected PRIS is:

• Stop infusion
• Hemodynamic stabilization
• Carbohydrate substitution
• Hemodialysis or hemofiltration
• ECMO as necessary

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Well, this monday's pearl is a bit different than prior pearls. I wanted to let you know about a very cool website I came across recently called Clinical Reader. There is a whole lot in the recent medical education literature that discusses "Web 2.0." Web 2.0 involves learning through interactive websites, blogs, podcasts, etc. Medical education is really starting to head out of the classroom, and I wanted to mention a newer website that a lot of folks are talking about. 

Clinical Reader is a new medical RSS aggregator. What, you might ask, does this mean?

An RSS aggregator is a site that puts together information for you, that's right, for you. It actually does the work for you. Did I mention that it does the work for you? On this site, for example, if you are interested in "Emergency Medicine," the site finds all (or almost all) EM journals and brings you all of the latest information and updated articles. If you are into "Medical Education," you simply choose that category from a drop down menu and poof, you have all of the latest publications/reviews from the major medical education journals. Just choose your category and/or specialty and you are off and running. 

Try it out. It isn't 100% perfect, but it is very cool.

http://clinicalreader.com/

During this season of the ever-present viral respiratory illness, we must be on the lookout for the potentially-deadly -entity of myocarditis. A recent study suggests some clues to when the diagnosis should more strongly be considered in patients presenting with viral respiratory symptoms.

1. Most cases of myocarditis were not initially recognized by primary care MDs or emergency health care providers. 84% of patients needed more than one visit within 2 weeks before the diagnosis was made. This highlights the difficulty in Dx and frequent misdiagnosis rate.
2. The most common presenting symptom was dyspnea (69%) and most common sign was tachypnea (60%).
3. Although resting tachycardia is often taught as a common finding, 66% of patients had a normal HR.
4. The most helpful findings in terms of helping distinguish myocarditis from benign common viral URIs was hepatomegaly (present in 50%) and cardiomegaly (present in 60%).
5. An abnormal ECG was present in 100% of cases. The most common abnormalities were tachycardia, ventricular hypertrophy, and ST or T wave changes.
6. 54% of patients had elevated troponin levels.

So what's the bottom line?
1. If your patient has tachypnea or dyspnea, strongly consider getting a CXR. In that case, look carefully for cardiomegaly.
2. Always assess for and document the presence or absence of hepatomegaly.
3. A completely normal ECG is strong evidence against myocarditis.

[Durani Y, Egan M, Baffa J, et al. Pediatric myocarditis: presenting clinical characteristics. Am J Emerg Med 2009;27:942-947.]

Scaphoid Fractures in Children:

1. Rare before the age of 11.
2. Make up less than 0.34% of all pediatric fractures
3. Scaphoid fractures may be missed 12.5% - 37% on the initial presentation.
4. 30% of patients will have an radiographically apparant fracture on repeat films done 2 weeks later.
5. These physical exam findings are more specific for fracture:
   1. Volar tenderness over the scaphoid
   2. Pain with radial deviation
   3. Pain with active wrist range of motion.  
6. Though snuff box tenderness was seen in 100% of patients eventually proven to have a fracture, it was also seen in 92% of the patients that did not have a fracture at follow-up making it non-specific but sensitive.
    

Because of the high (30%) fracture rate seen on followup films it is recommended that all children be placed into a thumb spica splint until followed up.

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The newest antidote for cyanide poisoning, hydroxocobalamin, has several advantages over the older Cyanide Antidote Kit (amyl nitrite, sodium nitrite, sodium thiosulfate).  Hydroxocobalamin works rapidly, does not induce methemoglobinemia, and does not cause vasodilation/hypotension.

• The first is self-limiting hypertension. However, think about the patient population you are treating.  They are most likely hypotensive from the cyanide/carbon monoxide poisoning.  Increased blood pressure is a welcome adverse effect in these cases.
• The second is red discoloration of the skin and urine, secondary to the red color of hydroxocobalamin (see attached picture).  This effect can be quite pronounced, especially if you aren’t prepared for it. There is no harm to the patient although it can last up to 8 days.

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Attachments

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• Guillain-Barre’ syndrome can be associated with marked neuropathic pain which is best described as having “burning” skin.

• Additionally, these patient may develop hemodynamic instability and adynamic ileus, both related to autonomic dysfunction.

• Classically, GB patients present with a foot drop several days after an episode of food poisoning, most commonly from Campylobacter jejuni.

Severe Acute Pancreatitis

• Patients with acute pancreatitis are considered to have severe acute pancreatitis (SAP) if they manifest signs of shock, respiratory failure, renal faliure, or GI bleeding.
• SAP is almost universally associated with pulmonary dysfunction, typically manifested as an S_pO₂ < 90% in the first few hours of illness.
• In fact, ARDS develops in at least one-third of patients with SAP.
• Take Home Point: Pay close attention to the patient with acute pancreatitis and a low pulse oximetry reading, as many will rapidly deteriorate from ARDS. In those who deteriorate, early intubation with implementation of lung protective ventilatory strategies is indicated.

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Slipped Capital Femoral Epiphysis (SCFE)

SCFE can present as hip, thigh or knee pain in the young adolescent. Risk factors include hypogonadism, hypothyroidism, hypopituiratism, and obesity. One way to make the diagnosis is to obtain a AP view of the pelvis and draw a line(Klein's line) along the superior border of the neck of the femur.  This line should intersect the femoral epiphysis. If it does not the diagnosis of SCFE can be made.

However, this is only about 40% sensitivity. Green et al recently published a study that demonstrated that if you measure the distance from Klein's line and the lateral edge of the femoral epiphysis on both sides, and the difference between the two is more than 2mm you can make the diagnosis of SCFE more accurately and sooner.

FIGURE 1. Measurement methods on an anterior-posterior radiograph of a right slipped capital femoral epiphysis. White lines indicate Klein’s line for each hip. A and B, indicate maximum epiphyseal width lateral to Klein’s line. As A is 2mm narrower than B, the right (A) hip qualifies as a slip using our modification but not Klein’s original definition.

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Conjunctivitis in Children:

• Usually a self-limiting process, very common in school-aged children and children in daycare or group home settings
• Crusting/swelling treated with warm compresses
• Antibiotics are not necessary outside of the neonatal period, but they do speed recovery
• Neonates with conjunctivitis - send cultures (gonococcal ophthalmia neonatorum);  all others - no cultures necessary
• Treatment with erythromycin ointment, Polytrim solution, ciprofloxacin solution (usually practicioner preference unless dealing with a recurrent/resistant case)

HOWEVER... remember to consider other common etiologies of a red eye in a child!

• Corneal abrasions
• Acute angle closure glaucoma (sickle cell patients)
• Allergic sources

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• Infections induce activated T cells and antibodies, which within the context of an influenza syndrome, are thought to cross react with axonal antigens and macrophages, resulting in demyelination.  This process likely triggers a subsequent Guillain-Barre’ syndrome (GBS).

• Presumably, influenza vaccine induces a similar response in susceptible individuals.

• Juurlink and colleagues found there to be a 1.45 relative risk, which equals a 1.7-fold adjusted relative risk for contracting GBS, associated with influenza vaccination.

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Hypoxemia in the Intubated Asthmatic

• Intubating and mechanically ventilating the asthmatic patient can be frought with potential complications that markedly increase morbidity and mortality.
• In the ventilated asthmatic who develops persistent or worsening hypoxemia, evaluate the patient for the following complications:
  • right main stem intubation
  • pneumothorax
  • ETT displacement
  • ETT obstruction
  • air leak around the ETT
  • gastric distention (decreases respiratory system compliance)
  • ventilator malfunction
  • progressive bronchospasm

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A varicocele is a collection of venous varicosities in the spermatic veins in the scrotum. This is caused by imcomplete drainage for the pampiniform plexus. This may be seen is up 20% of males and is asymptomatic most of the time. Most are found on the left side.

Why should you care, you might ask? Well, the right spermatic vein drains into the IVC and then into the renal vein, whereas the left spermatic vein drain drains directly into the renal vein.

In the patient with new onset, unilateral varicocele, consider an IVC thrombus/tumor if right sided and a left renal clot if left sided.

A case we had recently was a 30 yo male with nephrotic syndrome (a HUGE risk factor for renal vein thrombosis) who presented with left-sided scrotal swelling. He was found to have a left-sided varicocele. Based on this finding, a renal sono was performed and the diagnosis of left renal vein thrombosis was made.

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Increasing literature has demonstrated that patients post-cardiac arrest benefit from induced hypothermia (IH). In addition, increasing literature has demonstrated that patients with cardiac arrest associated with STEMI are best treated with rapid percutaneous intervention (PCI) after their resuscitation. But what about the combination of IH + PCI in resuscitated cardiac arrest patients with STEMI?

There's now growing support for this concept as well. Wolfrum et al. demonstrated an improved mortality at 6 mos. (35% vs. 25%) in patients that had the combination of IH + PCI vs. patients receiving PCI alone after cardiac arrest and they also had better neurological outcomes.

Next time you have a STEMI patient that has a cardiac arrest who you resuscitate, talk to your cardiologists about the literature demonstrating the improved outcomes with combination IH plus PCI.

[Wolfrum S, Pierau C, Radke PW, et al. Mild therapeutic hypothermia in patients after out-of-hospital cardiac arrest due to acute ST-segment elevation myocardial infarction undergoing immediate percutaneous coronary intervention. Crit Care Med 2008;36:1780-1786.]

Wound Irrigation

A recent article by Thomas et al showed that any concentration of betadiene and hydrogen peroxide used to irrigate a wound was  more toxic to fibroblasts (required for wound healing) then it was to bacteria.  Low concentrations of chlorhexidine remained bactericidial while having minimal affects on fibroblasts. 

WIth the addition of this study the routine practice of soaking a wound in betadiene or hydrogen peroxide should be abandoned.  Good irrigation with normal saline or even tap water is all that is really needed to decontaminiate a wound.  If a bactericidal agent is needed then low concentrations of chlorhexidine should be used.

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• comprehensive history and thorough external genital exam (often without direct visualization of the cervix) will lead to appropriate diagnosis
• estrogen withdrawal following birth or ingestion of oral contraceptives
• vaginal foreign bodies (such as toilet paper, small toys)
• bacterial infections (strep and shigella)
• trauma from sexual abuse or straddle injuries
• vascular lesions such as hemangiomas
• be careful to differentiate urethral bleeding from vaginal bleeding

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 Toxicology Expert: Poisoning Of Harvard University Scientists "No Accident"

• 6 scientists in a Boston area lab drank coffee that was laced with sodium azide
• Presented with hypotension, nausea and vomiting - one had a syncopal episode
• Sodium Azide is a chemical compound (NaN3) that is used as a preservative at very low concentrations but in higher concentrations can be lethal. It is even found in the propellant that is found in automobile airbag mechanisms
• It acts similiar to cyanide where it inhibits cytochrome oxidase and presents like a cyanide poisoning.
• No antidote, cyanide antidote kit will not work

• In 1976, vaccination with the swine flu vaccine was associated with a small risk of developing Guillain Barre Syndrome (GBS), approximately 1 additional case per 100,000 people who received the swine flu vaccine, which was slightly higher than the background rate for GBS.

• Since then, numerous studies have been done to evaluate if other flu vaccines were associated with GBS. In most studies, no association was found, but two studies suggested that approximately 1 additional person out of 1 million vaccinated people may be at risk for GBS associated with the seasonal influenza vaccine.

• It is important to keep in mind that severe illness and possible death can be associated with influenza, and that vaccination is the best way to prevent influenza infection and its complications.

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