UMEM Educational Pearls

• Total body calcium consists of about half biologically active (ionized) and half inactive (80% bound to albumin and 20% to other ions)
• hypocalcemia caused by hypoalbuminemia is physiologically insignificant, and correction factors are not accurate or reliable
• The best way to measure true active calcium is to order an ionized calcium level

There are several conditions that alter ionized calcium levels, including:

• alkalosis (increases binding to albumin)
• gas bubbles in the sample (false lowering of calcium)
• anticoagulants (must be collected in a red top tube)
• blood transfusions (binding to citrate)
• cardiopulmonary bypass
• drugs (aminoglycosides, cimetidine, heparin, theophylline)
• fat embolism
• hypomagnesemia (correcting mg levels may preclude need for Ca repletion)
• pancreatitis (several mechanisms, poor prognosis)
• renal insufficiency (impaired phosphate retention)
• sepsis

The bottom line is to measure ionized calcium, and consider all other factors that can be contributing to hypocalcemia in addition to repleting it. 

Altered Mental Status-Does Your Patient Have Non-Convulsive Status Epilepticus?

Ever intubated a patient in status epilepticus and wondered if they were still seizing after sedation and paralysis? Ever taken care of an altered patient and wondered if you should consult neurology and attempt to get an EEG?

NCSE is defined as continuous seizure activity without obvious outward manifestations of a seizure. This is important for emergency physicians to consider because it has to be detected early to prevent morbidity and mortality.

When to consider NCSE:

• Prolonged postictal period
• Unexplained altered mental status in a patient with a history of seizures
• Altered mental status associated with "eye twitching" or blinking
• Stroke patient who clinically looks worse than expected

Scaphoid Fractures:

For suspected scaphoid fractures with negative radiographs it is common practice to put a person in a short arm thumb spica splint until followup up radiographs can be obtained in 10-14 days.

However, there is evidence that a short arm thumb spica splint is not enough for people that have a true scaphoid fracture.  Gellman et al demonstrated that long arm thumb-spica cast immobilization for six weeks followed by short arm thumb-spica cast immobilization decreased time to union by 25% when compared to short arm thumb-spica casting alone.

The theory is that the short arm splint still allows for forearm rotation that can cause shearing motion of the volar radiocarpal ligaments.  A long arm splint prevents this shearing action.  The disadvantage of a long arm splint though is potential elbow joint stiffness and muscle atrophy that can occur during the prolonged period of immobilization.

So for your next patient with a scaphoid fracture seen on radiographs place them in a long arm thumb spica splint.

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CARBAPENENEMS

• Broadest spectrum of activity of all classes
• Imipenem has slightly better gm + activity; lowers seizure threshold
• Meropenem has slightly better gm - activity
• Ertapenem does not cover Pseudomonas
• Doripenem has the most activity against Pseudomonas
• May use in PCN allergic patients (cross reactivity lower than previously thought)

TIGECYCLINE

• Has broad coverage, but does not cover Pseudomonas
• Bacteriostatic; derivative of tetracycline
• Does NOT require renal dosing
• Higher mortality in VAP than other agents; do not use for intra-abdominal infections (poss higher risk of perforation)

AMIKACIN

• Has antipseudomonal activity
• Used in combination with other agents for MDR (multi-drug resistant) bacteria
• Causes nephrotoxicity and ototoxicity

COLISTIN

• Bacteriocidal against many MDR gram - bacteria
• Not active against Proteus, Provincia, Burkholderia, Neisseria, or Serratia
• Nephrotoxicity and ototoxicity reported

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• In states without mandatory physician reporting of patients with seizures, the decision of whether to breach confidentiality and report a poorly controlled epileptic patient who continues to drive an automobile becomes an ethical dilemma.
• In making this decision, one must consider the probability and magnitude of the potential harm.
• If the probability and magnitude are both low, or the probability of harm is high but the associated magnitude is low, there is generally no moral obligation to breach confidentiality and report.
• If the probability of harm is low but the potential magnitude of the harm is high, one should strongly consider reporting the case.
• Each case should be handled on an individual basis, take into consideration the risks and benefits to the patient and society if reporting is ensued, and perhaps elicit the advice of risk management.

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The Rapid Ultrasound in Shock (RUSH) Exam

• Evaluating the ED patient with undifferentiated shock can be challenging.
• Ultrasound can be an invaluable tool in helping to differentiate between hypvolemic, cardiogenic and obstructive shock.
• The RUSH exam essentially focuses on the evaluation of the "pump", the "tank" and the "pipes".
• The pump: exclude pericardial effusion, global estimate of LV EF, and determine if RV strain is present.
• The tank: evaluate the IVC/jugular veins for volume status, look for fluid in the thorax/peritoneum, and exclude pulmonary edema or pneumothorax.
• The pipes: look for a ruptured AAA or aortic dissection and DVT.

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Pulmonary Embolism-Myths and Misconceptions

Just wanted to mention a few myths/misconceptions about acute PE that I have recently heard discussed in the ED.

1. Emergency physicians have to "get help" to give thrombolytic therapy. Sure it makes sense that we consult critical care and perhaps interventional radiology in some cases. But we do not need permission to use this drug by ourselves if indicated. Consider using lytics ESPECIALLY if the patient is unstable or if there is evidence of RV dysfunction (elevated troponin, echo criteria for dysfunction, or CT with large RV and bowing of the septum). What about the patient with RV dysfunction and a normal BP? Evidence is mounting that lytics are indicated to reduce the severity of pulmonary hypertension. 

2. "Just get a d-dimer." Be very careful. Lots of false positives. D-dimer often clouds the picture more often than not. 

3. "The mortality rate of missed PE is high." Often quoted as a 30%+ mortality rate if missed. Recent data suggests that it is < 5%. 

Missed cases of ACS account for 10% of all malpractice cases in emergency medicine, yet account for 30% of all the money emergency physicians pay out in malpractice cases. This misdiagnosis is the biggest cause of monetary payout in the specialty.

Three main themes account for the majority of missed cases of ACS:
1. Failure to recognize atypical presentations (e.g. dyspnea)
2. Failure to recognize high-risk groups (e.g. women, diabetics)
3. Over-reliance on negative tests (e.g. negative troponin or recent stress test)

Temporal Arteritis (TA) is commonly associated with the sudden onset of a unilateral headache centered around the temporal region.  The most devastating consequence of TA is blindness though this is only reported in up to 50% of cases though can be bilateral in up to 33% of patients.

According to the American College of Rheumatology criteria for classification of temporal arteritis this diagnosis can be made in the ED without a biopsy.  You just need at least 3 of the following 5 items to be present (sensitivity 93.5%, specificity 91.2%) to make the diagnosis :

1. Age of onset older than 50 years
2. New-onset headache or localized head pain
3. Temporal artery tenderness to palpation or reduced pulsation
4. Erythrocyte sedimentation rate (ESR) greater than 50 mm/h
5. Abnormal arterial biopsy (necrotizing vasculitis with granulomatous proliferation and infiltration)

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The umbilical site normally heals by 1 month of age. 

Any fluid draining after this period suggests an abnormal connection between the surface of the abdomen and the underlying structures, and requires further investigation.  Clear yellow fluid could represent a persistent connection of the bladder with the umbilicus called a patent urachus. The fluid that leaks is actually urine. The treatment is surgical closure of the connection.

Pus oozing from the umbilical stump would imply infection, especially if there is concomitant redness of the skin around the umbilicus.  An omphalitis can be life-threatening, and requires admission for invtravenous antibiotics.

Umbilical hernias are common in infants, and are usually noted with diastasis of the rectus muscles.  Most umbilical hernias resovle by school age, and do not require surgical intervention.

An umbilical granuloma is a small piece of bright red, moist flesh that remains in the umbilicus after cord separation. It is scar tissue, usually on a stalk, that did not become normally covered with skin cells. It contains no nerves and has no feeling. Most can be simply cauterised with silver nitrate.

Apologies - last few bullets were cutoff - Continuing - Prophylaxis against RCIN has been attempted with the following:

• IV saline infusion
• Sodium Bicarbonate bolus
• IV acetylcysteine infusion

No one therapy has been show to have superior efficacy.

Radiocontrast Induced Nephropathy (RCIN)

• Occurs within 24 hrs of administration followed by oliguric phase
• Usually improves within a week and rarely needs dialysis
• Initial injection is an osmotic load, leads to volume expansion and diuresis. Follwed by intense vasoconstriction suggesting possible ischemic role in pathophysiology.
• There is also a direct toxic effect to the kidneys however
• High Risk patients: HTN, DM,  Chronic Renal Insuff, Bence Jones proteinuria and large injections of IV dye
• Possible prophylaxis: There is almost no data studying this effect in the Emerg Dept patient. One trial look at IV acetylcysteine in the Emergent CT (RAPPID trial) did show benefit but has flaws within the study. IV hydration and sodium bicarbonate

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• Apart from time and rehabilitation, there is currently no effective treatment for reversing brain damage caused by stroke.

• Clinical recovery after a stroke results from neuro-restorative processes such as neurogenesis, angiogenesis, synaptic plasticity, and/or re-modeled and strengthened connections between neurons. 

• Stem cell therapy for stroke is a novel, but progressive area of research which would potentially facilitate the neuro-restorative processes required for recovery. 

• Despite the extremely complex nature of brain function and central nervous system networks, successful stem cell therapy for brain infarct could become the wave of the future for optimal stroke management.

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Patients in the Critical Care setting may develop HIT as a result of chronic pre-existing risk factors (malignancy, obesity, hypertension, diabetes or medications) or acquired factors secondary to their ICU stay (post-operative state, trauma, central lines or medications such as heparin).

Diagnosis of HIT:

• platelet count<150,000 or relative decrease of 50% or more from baseline
• documentation of antibodies binding platelet factor 4 and heparin, as well as a confirmation test
• typically occurs 5-14 days after initiation of heparin therapy
• can have a rapid (usually a result of previous exposure) or delayed onset
• thrombotic complications develop in 20-50 percent of patients

Treatment of HIT:

• Remove all sources of heparin (including heparin-bonded catheters)
• initiate a non-heparin anticoagulant
• Direct thrombin inhibitors:
  • Lepirudin (cleared by kidney)
  • Argatroban (cleared by liver)
  • Bivalirudin (cleared by proteolysis 80% and kidney 20%)
• Other agents used include:
  • Danaparoid (antifactor Xa activity - not available in North America)
  • Fondaparinux (synthetic selective inhibitor of Xa)

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Can you use a serum d-dimer to rule out aortic dissection?

The answer to the question, in 2010, is no.  

There has been a flurry of recent literature about the use of serum d-dimer to rule out aortic dissection. Some studies have shown a sensitivity of nearly 100%, but other studies have shown sensitivities of only 60-70%....pretty abysmal sensitivities. And despite some of the authorities on the subject touting how good the test is, there is not firm literature to support it. Better yet, there are some active medical malpractice cases I am aware of in which the diagnosis of aortic dissection was missed based on a "negative d-dimer."

My suggestion, and the vascular pearl for the day, is to avoid using d-dimer as a aortic dissection rule out strategy until good evidence (if it ever becomes available) exists. I know that people are using this test to rule out the disease, just realize that EVERY time I have ever given a talk on acute aortic disasters, 2-3 people from the audience always share that they had a case of a "d-dimer negative dissection." 

Be careful....

Women are more likely to be misdiagnosed than men when they present with acute coronary syndromes. There are several possible reasons for this:
1. Women are more often older and more often have diabetes, both of which are factors involved in atypical presentations.
2. Women present with chest pain less often than men. On the other hand, women are more likely to present with nausea, vomiting, indigestion, malaise, loss of appetitie, or syncope than men.
3. When women do have chest pain, they are more likely to report pain that has atypical features, such as radation to the right arm or shoulder, front neck, or back; and the pain is more often described as sharp, stabbing, or tansient.

The bottom line is something that I've believed since high school: women are confusing...!

[the references for this ACS information comes from many different sources, but if anyone needs a good review on this topic, just email me: amattu@smail.umaryland.edu]

Uveitis and Iritis Treatment:

• Once the diagnosis is suspected or made ensure that the patient has ophthamology followup.
• Antibiotics are not needed as this is not an infectious process.
• Pain control is the painstay of therapy (no not narcoletics) but cycloplegics like:
  • Cyclopentolate 0.5-2% 1 gtt TID
  • Homatropine 2-5% 1 gtt TID
  • This will relieve pain and photophobia symptoms
• Topical steroid can be initiated to decrease inflammation but should be done in consultation with the ophthamologist
  • Prednisolone 1% 1 gtt every 1-6 hours.

Quinolone Induced Deliurim

Just to give you another reason NOT to give a quinolone - aside from the C. diff. This adverse effect occurs with quinolones unlike many other antibiotics. It can prolong hospital stay, cause falls and further medical work ups. Some risk factors are:

• Elderly
• Renal Insufficiency
• Benzodiazepine dependence (will actually precipitate withdrawal since quinolones displace the BDZ from the receptor - you have probably done this to a patient if you think about it, that may be why they went crazy)
• Epilepsy - can cause seizures especially with NSAIDs

-- While we typically associate seizures within the context of alcoholism with physiologic withdrawal, studies have shown that there is a dose-dependent relationship between the consumed amount of alcohol and the onset of seizure activity, independent of alcohol withdrawal.

-- Specifically, Ng and colleagues found a 3-fold increase in seizure occurance with 50 to 100 grams of ethanol per day, compared to an 8-fold increase with 101 to 200 grams of ethanol per day.

-- This study further found that ex-drinkers (abstention for >= 1 yr.) were not at any increased risk of seizure and that drinkers who had seizures did so well outside of the conventional window of withdrawal.  

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Defining Acute Kidney Injury (AKI)

• In the pearl from 1/5/10, I highlighted the association of AKI with increased morbidity and mortality in the critically ill along with the avoidance of nephrotoxic medications.
• Currently, two sets of criteria (RIFLE and AKIN) can be used to identify patients with AKI
• According to AKIN, the current diagnostic criteria for AKI is:
  • an absolute increase in serum creatinine > 0.3 mg/dL OR
  • a > 50% increase in serum creatinine from patient baseline OR
  • urine output < 0.5 ml/kg/hr for > 6 hours
• For the critically ill ED patient, the most common causes of AKI include sepsis, hypovolemia, medications, trauma, rhabdomyolysis, obstruction and abdominal compartment syndrome

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