UMEM Educational Pearls

The WBC count is not an accurate predictor of bacteremia in the elderly. 20-45% of elderly patients with proven bacteremia have a normal WBC on presentation.

[from Caterino JM, et al. Bacteremic elder emergency department patients: procalcitonin and white count. Acad Emerg Med 2004;11:393-396.]

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Odontoid Fractures:

There are three types of C2 odontoid fractures:

1. Type I is an oblique fracture through the upper part of the odontoid process. This fracture is normailly stable and can be treated with a hard cervical collar.
2. Type II is a fracture occurring at the base of the odontoid as it attaches to the body of C2.  These fractures can be treated surgically, or conservatively with hard collar or a halo brace
3. Type III fractures occurs when the fracture line extends through the body of the axis. These fractures are normally treated surgically with or without a halo brace.

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• autossomal dominant disorder most commonly in Scandinavian and British descent due to deficiency of HMB-synthetase
• most heterozygotes are asymptomatic unless some factor increases the production of pyrogens, usually medications
• common drugs include steroids, alcohol, low calorie diets, and drugs (barbituates, sulfonamide antibiiotics, grisefulvin, and synthetic estrogens (birth-control)
• attacks of abdominal pain lasting several hours is the most common symptom and may be secondary to ileus or distension, but tenderness on exam and fever are absent
• peripheral neuropathy and muscle weakness improves over days, but may take years to return to normal
• diagnose: gold standard test measures RBC HMB-synthetase, screening test of normal PBG (porphobilinogen) level in urine rules out the condition
• treatment: narcotics, IV glucose (300g/day), and IV heme (4g/day)
   

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In the state of Maryland, the most common venomous snake is the copperhead. Though not as dangerous as the rattlesnake, it can still cause loss of function of limb and mortality in the pediatric patient.

Treatment has involved the use of CroFab (Protherics, Atlanta). This ovine derived monovalent immunoglobolin is actually made against the following snakes:

• Eastern diamondback rattlesnake
• Western diamondback rattlesnake
• Mojave rattlsnake
• Cottonmouth (Water moccasin)

Though efficacy has been shown with these snakes, we are hoping for cross-reactivity when we treat copperheads. There are case series and case reports (1) that have shown anectdotal improvement. We are still awaiting a real randomized controlled trial - may never happen.

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• Multiple Sclerosis (MS) is a relapsing condition caused by the destruction of myelin sheaths.
• Ninety percent of MS-related lesions can be detected on T2 MRI images.
• These lesions are typically para-ventricular, sometimes ovoid in shape (referred to as "Dawson's Fingers"), and often located on medullary veins.

Acute renal failure occurs in 1-25% of critically ill patients, with an associated mortality of 28 - 90%. 

The RIFLE Criteria represent the first consensus definition of acute renal failure used to classify critically ill patients as to their kidney function.  Notably, we use the worst possible classification according to the criteria, which measures either serum creatinine, urine output or both. 

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The nitrite test on urine dipstick is commonly used for diagnosis of UTI. However, the test is only reliable in those bacteria that convert nitrates to nitrites, which primarily includes enterobaceriaceae. However, elderly patients often develop UTIs with Staph saprophyticus, pseudomonas, and enterococcus, none of which produce positive nitrites on dipstick testing. The takeaway point here is very simply....don't assume you've excluded UTI (esp. in elderly populations) just because the nitrite test is negative.

reference: Anderson RS, Liang SY. Infections in the elderly. Critical Decisions in Emergency Medicine, April 2010.

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Toxicodendron dermatitis:

This is the contact dermatitis caused by the plant genus Toxicodendronm, better known as Poison Ivy.  Here are some types to prevent the dermatitis and how to treat it:

1. Barrier products like Ivy Block® are on the market that go on like suntan lotion and provides a protective barrier on your skin that prevents the plants urushoil, the toxin responsible for the dermatitis, from making contact with your skin. This can help prevent the dermatitis if you are able to wash the oils off.
2. Most soaps can not remove urushiol and may actually increase its spread. Several products are on the market, one being Zanfel® , that are a little more effective than water in removing the urushiol which can help to minimize the dermatitis and its spread.
3. The mainstay of treatment is systemic steroids.  This condition does not do well with a short (5 day) burst therapy and patients will typically get a rebound dermatitis when the burst is complete.  Patients should be placed on a 14 day steroid taper.

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• Calcium channel blockers, such as nicardipine, play an important role in treating arterial hypertension and cerebral vasospasm, both of which are associated with intracranial hematoma and increased intracranial hypertension.

• Many consider nicardipine to be an excellent choice for treating an acute hypertensive emergency in the setting of intracranial hemorrhage.

• Dosing should start at an infusion of 5 mg/hr.  Titrate by 2.5 mg/hr every 5 to 15 minutes to desired effect, up to a maximum dose of 15 mg/hr. 

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Hypotension after intubation and initiation of mechanical ventilation

• Approximately 25-30% of patients develop hypotension after intubation and initiation of mechanical ventilation (MV).
• Although the literature is not robust, risk factors for hypotension after initiation of MV include:
  • hypotension prior to intubation
  • tachycardia prior to intubation
  • obesity
  • high intrathoracic pressure (COPD)
  • excess catecholamine states (ETOH withdrawal, cocaine intoxication) with rapid relaxation during RSI
• In addition to administering isotonic intravenous fluids (IVFs) while preparing for intubation, consider having a vasopressor medication, such as phenylephrine, available if IVFs alone prove insufficient at maintaining blood pressure.

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Submitted on behalf of Dr. Michael Abraham

Thyrotropin (TSH) 

• Different types of test available:
  • The first tests available were radioimmunoassay. 
  • The next type of test available is the immunometric test.

• As each test is developed there has been a trend to use the term ‘generation’ for a 10 fold increase in sensitivity. ¹

• Indications for ordering in the ED:   Hypothyroidism, Graves Disease, Hashimoto’s Thyroiditis, Thyroid storm.

• Diagnostic Accuracy
  • The original TSH benchmark was the ability to measure euthyroid (0.4 – 4mIU/L) from very low (<0.01 mIU/L) which is suggestive of Graves disease. 
  • Most new tests have a functional sensitivity of <0.02mIU/L. 
  • The clinical sensitivity and specificity have to be determined by each laboratory’s staff. This requires testing of samples over a 6-8 week period as should include a sample of the population that is being tested.²
• Average turnaround time to complete test: 
  • The tests are mainly run on large lab analyzers. There are many commercially available tests the turnaround time is dependent on the manufacturer of the machine.

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Pericardial tamponade is a physiological diagnosis, not an ECG diagnosis. At best, the ECG can suggest the presence of large pericardial effusions--look for the combination of low voltage, tachycardia, and electrical alternans.

Be aware, however, that electrical alternans is only present in < 1/3 of patients with large pericardial effusions. Although it is "classic" and always seems to show up on board exams, in the textbooks, and in lectures, electrical alternans in not a consistent finding in patients with large effusions or tamponade. 

Calcaneus Fractures:

Calcaneus fractures can easily be missed on plain films and the true extent of the injury might not be appreciated until a CT is done.  However, you can increase your change of picking up a calcaneal fracture by evaluating Bohler's Angle. 

Lateral radiographs of the foot are needed to evaluate the Bohler angle.  This is the angle made by drawing a line from anterior process of the calcaneus to the peak of the posterior articular surface and a second one drawn  from the peak of the posterior articular surface to the peak of the posterior tuberosity. (See Picture) The average angle is 25-40°. Angles less than 25' are strongly suggestive of a fracture and the patient should probably get a CT of their foot if there is clinical suspicion.

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Current American Burn Association guidelines state that any child with a greater than 10% total body surface area (TBSA) burn should be admitted to a center capable of caring for pediatric burns, rather than being discharged after wound management.  However, physician use of TBSA% estimation techniques is variable.  An excellent free tool for estimating TBSA is available online, allows for automatic weight based calculation, and allows printing of your diagram.  The diagram is available at http://www.sagediagram.com/.  More to come...

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Physostigmine has been used extensively in the fields of anesthesiology and emergency medicine.  The only use of physostigmine with sound scientific support is for the management of patients with an anticholinergic syndrome, particularly those without cardiovascular compromise who have an agitated delirium.  In this population, physostigmine has an excellent risk-to-benefit profile.

• Try benzodiazepines first.  They last longer and may diminish the need for physostigmine.
• Obtain ECG.  If there are signs of sodium channel blockade (QRS prolongation), do not use physostigmine.
• Administer 1-2 mg via slow IV push/infusion over at least 5 minutes.
• Have atropine available at the bedside.
• Effects last about 1 hour.

Once you've punctured the spinal canal space during lumbar puncture, the following tips can be used to improve the rate of cerebrospinal fluid (CSF) flow, should it be suboptimal:

1. Ask the patient to cough or bear down as in the Valsalva maneuver.
2. Ask an assistant to intermittently press on patient's abdomen.
3. Turn the spinal needle 90 degrees such that the bevel is cephalad.
4. Use a larger diameter spinal needle (increases risk of post-lumbar puncture headache).

Platelet Transfusions in the Critically Ill

• Recommendations for the transfusion of platelets in the critically ill patient is primarily extrapolated from the oncology literature; literature that is predominantly observational and expert opinion.
• Nevertheless, indications for the transfusion of platelets in a critically ill ED patient include:
  • active bleeding with a plt count < 50 x 10⁹/L
  • plt count < 10 x 10⁹/L (high risk of spontaneous bleeding)
  • prior to an invasive procedure when the plt count is < 50 x 10⁹/L
• Importantly, the decision to transfuse platelets should also take into account the clinical setting (ie. a uremic patient with active bleeding)

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Thrombolytic Therapy for Pulmonary Embolism

Current, FDA-approved thrombolytic therapy for PE:

• tPA 100 mg over two hours-infusion
• Heparin drip should be turned off during tPA infusion and turned back on ONLY after PTT has fallen to 2 X normal
• Other drugs are being used-like Tenecteplase (TNKase), but strictly speaking, not FDA approved for thrombolysis of PE
• Most studies to date do not show that catheter-based delivery of lytics is safer than systemically administered lytics
   

Up to 25% of elderly patients with appendicitis are initially sent home from the ED, an indication of the high misdiagnosis rate for appendicitis in the elderly population. Why are elderly patients so often misdiagnosed when they have appendicitis? The answer is simple....they present very atypically.

• The classic migratory pattern (periumbilical pain that migrates to the RLQ) is absent in > 50%
• Nasea, vomiting, and anorexia are each absent in > 50%
• Fever is absent in up to 50%
• Guarding and rebound are absent in 50%
• The WBC is normal in up to 45%
• Up to 15% have pyuria or bacteriuria, leading to misdiagnoses of UTI

Expect the atypical in elderly patients!
 

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Wound Care:

Patients and many providers want to irrigate or wash a wound with an antiseptic solution in order to decrease the risk of infection.  Most studies have shown that irrigation whether with tap water or sterile water is effective enough in reducing bacterial counts in a wound so does adding an antiseptic solution offer any additional benefit.

It turns out that hydrogen peroxide, and iodine based solutions can actually hinder wound healing as they causes delays in the migration and proliferation of fibroblasts at concentrations that are not even bactericidal.  Chlorhexidine, and silver containing antiseptics [i.e.: silver sulfadiazine and silver nitrate] are bactericidal at concentrations that do not affect fibroblasts.

So in the end, if you feel the need to use an antiseptic, use chlorhexidine or a silver containing antiseptic.  The use of hydrogen peroxide and iodine based solutions should be abandoned as they are not even bactericidal at concentrations that have profound affects on the fibroblasts.

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