UMEM Educational Pearls

The Severely Hypoxemic ED Patient

• Most define hypoxemia as a P_aO₂ < 60 mm Hg.
• Perhaps a better definition of hypoxemia is a P_aO₂ that is associated with continued tissue hypoxia (rising lactate, low S_cvO₂), the need for vasopressor medications, or severe metabolic acidosis.
• For ED patients that remain hypoxemic despite increased F_iO₂ and high levels of PEEP, consider the following rescue therapies:
  • Recruitment maneuvers - brief periods of high PEEP (35-50 cm H₂O) or pressure-controlled breaths to reopen collapsed alveoli
  • High-frequency oscillatory ventilation - employs a high airway pressure to recruit closed alveolar segments
  • Prone positioning - believed to improve oxygenation through a redistribution of ventilation and perfusion
  • Extracorporeal membrane oxygenation

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Adverse drug effects are a major issue in geriatrics.
Elderly patients take, on average, 5 prescription medications + 2 over-the-counter medications.
Adverse drug effects account for approximately 5% of all hospital admissions.
Nearly 20% of patients brought to the ED for psychiatric complaints have symptoms that are primarily caused by medication effects.

Be very wary whenever prescribing ANY new medications for even a short time to elderly patients.

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Sulfamethoxazole (SMX)/trimethoprim (TMP) is the treatment of choice for PCP pneumonia. The IV formulation has been unavailable for almost a year due to shortage. It is contraindicated in patients with sulfa allergy. Here are the alternatives with adverse effects. You'll quickly see why pentamidine should generally be reserved for those with sulfa allergy and G6PD deficiency.

Mild-to-moderate disease:

1. Primaquine 15-30 mg PO PLUS Clindamycin 600 mg IV or 300-450 mg PO
2. Dapsone 100 mg PO PLUS TMP 5 mg/kg PO
3. Atovaquone suspension 750 mg PO

Moderate-to-severe disease:

1. Primaquine 15-30 mg PO PLUS Clindamycin 600 mg IV or 300-450 mg PO
2. Pentamidine 4 mg/kg IV

Adverse Effects:

• Primaquine: Rash, fever, methemoglobinemia, hemolytic anemia (check for G6PD deficiency)
• Clindamycin: Rash, diarrhea, Clostridium difficile colitis, abdominal pain
• Dapsone: Rash, fever, gastrointestinal upset, methemoglobinemia, hemolytic anemia (check for G6PD deficiency)
• TMP: Rash, gastrointestinal distress, transaminase elevation, neutropenia
• Atovaquone: Rash, fever, transaminase elevation
• Pentamidine: Nephrotoxicity, hyperkalemia, hypoglycemia, hypotension, pancreatitis, dysrhythmias, transaminase elevation

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Now that influenza season is in full swing, remember that early antiviral treatment can reduce the risk of complications in high-risk individuals. One of those high-risk groups is children <2 years, with the highest hospitalizations and mortality in infants <6 months.

According to the CDC website:
Recommended antiviral medications (neuraminidase inhibitors) are not FDA-approved for treatment of children aged <1 year (oseltamivir) or those aged <7 years (zanamivir). Oseltamivir was used for treatment of 2009 pandemic influenza A (H1N1) virus infection in children aged <1 year under an Emergency Use Authorization, which expired on June 23, 2010. Nevertheless,

•  3-11 months => Treatment: 3 mg/kg/dose BID, Chemoprophylaxis: 3 mg/kg/dose once daily
•  infants <3 months => Treatment: 3 mg/kg/dose BID, Chemoprophylaxis: not recommended
• newborns <14 days => 3 mg/kg/dose once daily
• treatment doses for children >1 year of age varies by weight:

•  <15 kg: 30 mg BID
• 15-23 kg: 45 mg BID
• 23-40 kg: 60 mg BID
• >40 kg: 75 mg BID

Current CDC guidance on treatment of influenza should be consulted; updated recommendations from CDC are available at http://www.cdc.gov/flu

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Recently a case report was published in which a child was incorrectly diagnosed with MRSA. He actually had systemic loxoscelism from a Brown Recluse spider bite.

A patient who has been bitten by brown recluse spider bite may present with pruritis, pain and swelling. The classic lesion has a bluish-purple central region, surrounded by concentric rings of pale ischemia and erythema. (“red, white and blue”) Bites may progress over days to a bleb with necrosis and eschar formation, followed by ulceration.

Systemic loxoscelism presents with a scarlatiniform rash that spreads dependently. It may have the classic purple lesion surrounded by concentric rings of pale ischemia and erythema. The patient may be uncomfortable but is usually stable. Treatment is supportive care.

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• Phenytoin has a wide volume of distribtuion and is 90% bound to protein. 
• Only the unbound proportion is biologically active, and therefore, FREE levels of phenytoin should be checked to determine whether acute seizure activity is related to suboptimal levels or not. 
• Given these properties, patients with the following conditions are more likely to become phenytoin toxic:  neonates and the elderly (due to poor metabolism and low protein production); uremia, nephrotic syndrome, pregnancy, malignancy, malnutrition (due to low potein levels).

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Question

24 yo woman presents with syncope, abdominal pain, and normal menses 4 days prior. Urine HCG(+) and quantitative beta-HCG is 1300 with the transvaginal ultrasound seen below. Diagnosis?

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The long QT syndrome and causes of acquired long QT interval are well-known to most emergency physicians, but a short QT can be problematic as well. Short QT-syndrome is an inherited ion-channel disease that predisposes to ventricular dysrhythmias and sudden death. The QTc in these patients is generally < 340 msec. This condition is more common in children, and it should be considered in the differential diagnosis and evaluated on ECG in children presenting with syncope.

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Sever's disease ,aka calcaneal apophysitis, is a common overuse injury in the pediatric and adolescent population.

Occurs secondary to traction of the calcaneus that most often occurs in young athletes (8-12 yo)

     -Avg. age of presentation is 11 years 10 months in boys & 8 years 8 months in girls

     -Repetitive traction to the weaker apophysis, induced by the pull of the Achilles on its insertion

Hx: Heel pain that increases with activity (running, jumping).

     -May involve one (40%) or both (60%) feet

PE: Tenderness of the posterior heel at the Achilles tendon insertion and ankle dorsiflexor weakness

Imaging:  Radiography is often normal.  When positive, show fragmentation and sclerosis of the calcaneal apophsis. NOTE:  These findings are nonspecific and also are observed in asymptomatic feet.

http://t0.gstatic.com/images?q=tbn:ANd9GcQ9R-fx1iyhbhNJpNL2W72bWdK72_mRBLNX5DUDtcMfnDli-x7Ong

DDx: Includes osteomyelitis and tarsal coalition.

Tx: Rest from aggravating activities, NSAIDs, ice (both pre and post sport).  When pain free a program of stretching (gastrocnemius-soleus), strengthening (dorsiflexors) and shoe inserts (heel cups, lifts, pads, or orthotics) can provide significant pain relief.

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•  disorder in which the entire left side of the heart is underdeveloped
•  the right side of the heart is dilated and hypertrophied, and supports both the systemic and pulmonary circulations via PDA
•  accounts for nearly 1/4 of all cardiac deaths in the first year of life
•  infants present within the first days or weeks of life acutely ill with signs of CHF
• PE often shows cyanosis and poor pulses but hyperdynamic cardiac impulses
• CXR shows cardiac enlargement and prominent pulmonary vasculature
• EKG shows RA and RV hypertrophy
• echo is diagnostic
• acute treatment is PGE1 to maintain the PDA.

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Continuing with the synthetic/designer drug theme. Last time we were discussing synthetic marijuana.  Another old drug making a resurgence under the designer drug category is mephedrone.This amphetamine-like drug has been purportedly the active substance in "bath salts". It has also been sold as "plant food" - still trying to figure that one out.

Sold in head shops under the name Bliss or Cloud 9 - they have been reported to be available in Baltimore, MD recently. They can also be bought over the internet. Crushed, snorted or ingested, the effect is similiar to cocaine with a largely sympathomimetic toxidrome. Mephedrone has been labeled an entactogen with users behaving similiar to an MDMA ingestion. A Baltimore news station incorrectly called it "synthetic cocaine" - though the effect may be similiar, completely different molecular structure.

Treatment is cooling, check lytes (especially sodium), check for rhabdomyolysis and sedation with benzodiazepines. Below is one link from a Denver News Station. Attached is a picture of a bath salt product.

The latest and greatest on the street - synthetic marijuana and bath salts!

http://www.thedenverchannel.com/news/26567376/detail.html

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• 1102241706_bath-salts.jpg (38 Kb)

• A simple febrile seizure (SFS) is generalized, tonic-clonic in type, and occurs in children between the ages of 6 months and 6 years of age, lasting less than 15 minutes and NON-recurring in a 24 hour period.
• According to the 1996 guidelines of the American Academy of Pediatrics (AAP) and based on the consensus that seizure is a common presenting symptom of bacterial meningitis, the following indications should be used to determine whether lumbar puncture (LP) is performed in patients presenting with SFS:

             --  6 to 12 months  >  "strongly consider" LP

              --  12 to 18 months  >  "consider" LP

              --  18 months and up  >  LP not routinely necessary; may consider after clinical assessment

              --   Any infant/child with recent antibiotic treatment plus SFS  >  "strongly consider" LP

• Despite these relatively outdated guidelines based largely on retrospective data, more recent literature suggests that serious bacterial infections such as meningitis are very rarely associated with simple febrile seizures, such that guidelines and practice paradigms may soon change.   

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Hemodynamic Monitoring in the Ventilated Patient

• Consider pulse pressure variation (PPV) as a method to monitor volume responsiveness in your mechanically ventilated ED patients.
• The theory behind PPV:
  • When a positive pressure breath is delivered via the ventilator, pleural pressure rises and causes a decrease in venous return, right heart filling, and right heart output.
  • Simultaneously, the positive pressure breath causes an increase in left heart filling and a decrease in left heart afterload.  This is reflected clinically as an increase in blood pressure.
  • Within a few beats, the decreased right heart output is transmitted to the left heart resulting in a decrease in blood pressure during expiration.
• Patients who are volume depleted can have significant differences in blood pressure between inspiration and expiration - i.e. a large variation in pulse pressure.
• PPV values > 12% have been shown to identify patients who are volume responsive.
• Importantly, PPV works best in vented patients who have no spontaneous respiratory effort, are in sinus rhythm, and receiving 8 ml/kg tidal volumes.

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Question

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[Here's a nice simple pearl from Jeff Tabas, MD (Prof of EM at UCSF).]

3 causes of bradycardia to consider when the rhythm is not clearly sinus bradycardia:
1. Junctional bradycardia
2. Hyperkalemia
3. Digoxin toxicity

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Distal Radius Fractures

Typically distal radius fractures are treated with closed reduction and splinting in the ED, followed by operative repair. This is done because it is felt that patients will have the best functional outcomes if the bones are restored to their normal anatomic alignment.  However, two studies published in 2010 suggest differently.

The study by Neidenbach showed that after one year there was no difference in functional outcomes between patients that were just splinted in the ED in the position the fracture was found versus those that had closed reduction with splinting. 

The second study by Ego showed that there was no difference in outcomes between those that underwent conservative treatment with closed reduction and splinting versus those that underwent operative repair.

The take home point from these studies for the EM physician is that most distal radius fractures can be splinted in the position found with them following up with an orthopaedist.  There is probably little advantage to performing a closed reduction in the ED knowing that this procedure can use a lot of valuable time and resources.

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Sold under the name of K2, Spice. Patients exposed to this will present with dry mouth, paranoia, tachycardia, hallucinations but will resolved rather quickly over several hours. Observation in the ED and supportive care is usually all that is needed. A little history about synthetic marijuana:

• JWH-018 is a synthetic cannabinoid (SC) that acts at cannabinoid receptors.
• Synthetic cannabinoids were created s in the 1960’s and continued to be developed as appetite stimulants (e.g., dronabinol).
• The JWH series of SCs are named for the chemist who first synthesized them, John W. Huffman, Ph.D. (thus the JWH prefix).
• SCs recently appeared for sale in smoke shops and other outlets (such as gas stations) as herbal incense.
• These products contain plant material that mimics smell and appearance of marijuana but is adulterated with one or more SCs.

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• 1102180659_Spice_drug.jpg (558 Kb)

• Procedural sedation consists of administering sedatives (i.e. midazolam, etomidate, propofol) or dissociative agents (i.e. ketamine) with or without opioid analgesics such as morphine and fentanyl.
• The widespread use of ketamine for procedural sedation may be limited by physician concern about unpleasant, vivid dreaming, hallucinations, and reactions after its administration known as recovery agitation.  This has been found to occur in 12 percent of cases and is seen less often in youth.
• In some instances, ketamine might be considered more ideal than other procedural sedation agents because it provides sedation, analgesia, and an amnestic-like dissociation between mind and body.
• Recent studies have shown that administering ketamine with a benzodiazepine such as midazolam significantly reduces the incidence of recovery agitation following procedural sedation; this alternative might therefore be considered when appropriate.
   

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Question

(Please note the prior version of this pearl was incorrect with respect to the images referenced. This version is corrected.)

Patient s/p blunt chest trauma. CXR (image 1) vs. lung ultrasound (image 2), do you see any inconsistencies?

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