UMEM Educational Pearls

Patellofemoral Syndrome (Chondromalacia Patella)

• Due to degeneration of the cartilage underneath the patella
• Patients often present with:
  • A grinding sensation when the knee is extended
  • Pain in the front of the knee that typically worsens after sitting for a long period of time
  • Knee pain that worsens with using stairs, running or when needing to bend the knee deeply (i.e.: squats)
• Commonly thought to be due to overuse (i.e.: new running program, or marching as in military recruits), but can also be due to anatomic abnormalities like pes planus or a large Q angle.  Ultimate cause is likely to be multifactorial
• 
• Can be treated with NSAIDs, and limiting activity
• Physical Therapy that helps to strengthen the quadriceps can help prevent the patella from grinding on the femoral condyles.

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Slipped capito-femoral epiphysis (SCFE) is a favorite board exam topic, and typically involves a young early or pre-adolescent obese girl with hip pain and the classic "ice cream falling off the cone" appearance on hip radiographs. However, keep these three pearls in mind when thinking about SCFE:

1. Girls > Boys, but boys may be older at presentation - don't forget 15 year old boys and SCFE.
2. An early radiographic finding may only be physis widening, so consider comparison films - the ice cream may only be levitating, but not falling off.
3. 23% of these children present with knee pain - think before diagnosing an obese 15 year old boy with a knee sprain from football. *bonus* Recall that this injury is non weight-bearing.

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Although we may not be able to eat as much shellfish after the oil spill, there are still some left that can cause some interesting toxicity here in the USA. Shellfish act as vectors for the bacteria, virus etc that produces toxin thus not specific to one species of shellfish. There is a map attached that shows where shellfish poisoning occurs most. In the picture CFP=ciguatera, PSP=Paralytic and ASP=AmnesticC. Surprising the distribution and it will be interesting how the oil spill affects the distribution. Treatment for all of these is supportive with no known antidote and incidence increases during Red Tide months:

• Paralytic Shellfish Poisoning
  • Saxitoxin, potent, heat-stable, blocks fast sodium channels
  • Symptoms: Paresthesias, weakness, bulbar symptoms, blindness and paralysis (30m-2hrs after meal)
• Amnestic Shellfish Poisoning (my favorite excuse for why I forget my anniversary)
  • Domoic acid build up created from Nitzchia spp (a marine diatom). This causes release of gluatamate thus causing excitotoxic nerve damage.
  • 1987 outbreak in Canada saw GI Sx in 24 hrs followed by HA, SZ, memory loss - has been fatal

Attachments

1009302022_US-toxinmap-circles-2009-web_86265.jpg (86 Kb)

Chlorhexidine (CHG) has rapidly become the antiseptic of choice for most skin preparation prior to any percutaneous procedures including:

• venipuncture
• laceration repair,
• joint aspiration
• lumbar puncture???

The Chlorprep^(R) label notes: "DO NOT USE FOR LUMBAR PUNCTURE OR IN CONTACT WITH THE MENINGES" (attached)

Authors of the British Royal College of Anaesthetists 3rd National Audit Project provided some guidance for the use of chlorhexidine for spinal procedures

• Clinicians must take care to prevent CHG from reaching the CSF
  • Keep CHG away from other drugs and equipment being used
  • Allow solution to dry prior to beginning procedure
  • Avoid using solutions > 0.5% chlorhexidine
• Further comments
  • Chlorhexidine 0.5% in alcohol 70% is the optimal skin preparation for neuroaxial procedures
  • Risk of vertebral canal sepsis is greater than the very rare risk of neurotoxicity and arachnoidits from chlorhexidine
  • This is OFF-LABEL use and should be instituted formally at a departmental level with an audit process for complications

Further: Correspondance from the Journal of  Regional Anesthesia and Pain Medicine

"Dr. David Hepner published a correspondence in the April 2007 issue of Anesthesiology that stated the expert panel for Regional Anesthesia and Pain Medicine “felt strongly that although the US Food and Drug Administration has not approved chlorhexidine before lumbar puncture, it has a significant advantage over povidone iodine because of its onset, efficacy, and potency” and commented that “interestingly, povidone iodine is also not approved for lumbar puncture."

Chlorhexidine off-label use is supported in academic literature.  Due to specific labeling prohibiting use, a formal institutional policy to support such use may be indicated.

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Attachments

1008270020_chlorprep_instructions.pdf (293 Kb)

While you should always involve ID consultants when managing critically-ill HIV/AIDS patients on HAART, consider this; sub-therapeutic levels of anti-retrovirals may promote HIV resistance, potentially invalidating a class of drug for future use. Therefore, it may be advantageous to discontinue the drug(s) during critical-illness to avoid resistance. 

Two examples leading to sub-therapeutic HAART levels in critical-illness:

1. Reduced absorption of PO medications from bowel wall edema and/or decreased splanchnic perfusion.
2. Interactions with HAART medications and the multitude of other drugs administered in the ICU.

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Approximately 4% of acute MIs will present as an isolated posterior MI (AKA "true posterior MI"). These are easily misdiagnosed as simply anterior ischemia because of the ECG findings. However, the distinction is critically important because posterior STEMI is now considered an indication for immediate reperfusion (PCI or lytics), whereas anterior ischemia is not.

The diagnosis of posterior STEMI is made by looking for:
1. ST segment depression, typically in leads V1-V3
2. upright T-waves in leads V1-V3
3. development of tall R-waves (R > S in amplitude) in V1-V3 over the course of a few hours (this is analogous to Q-waves forming in the posterior portion of the ventricle)

Early on, you may not be able to rely on the presence of tall R-waves to help you. Therefore, it's best to simply do the following: whenever you find ST-segment depression in leads V1-V3, always repeat the ECG using posterior leads (simply place a couple of the V leads on the left mid-back area). These leads will "look" directly at the posterior heart. If those leads show ST elevation, the diagnosis is posterior STEMI. If those leads don't show ST elevation, you can then make the diagnosis of simply anterior ischemia and hold off on immediate PCI or lytics.

The first ECG below shows ST depression in the anteroseptal leads, suspicious for posterior STEMI. The ECG was then repeated, second ECG, with leads V3-V6 placed wrapping around to the left mid-back area. The ST elevation in these leads confirmed the presence of a posterior STEMI and justified immediate reperfusion therapy.

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Injury was originally described as an occupational hazard in Scottish gamekeepers (from breaking the necks of rabbits against the ground). Today, skiing is now the most common cause and injury is now the second most common orthopedic injury in skiers (MCL injury #1).

Injury to the ulnar collateral ligament (UCL) results from a sudden forced abduction (radial deviation) stress at the MCP joint of the thumb, commonly due to a fall against a ski pole or the ground.

http://blog.fitter1.com/wp-content/uploads/2010/04/b_14_1_2a.jpg

The most frequent site of rupture is the insertion into the proximal phalanx. The UCL may even avulse a small portion of the proximal phalanx at its insertion site.

http://img.medscape.com/pi/emed/ckb/sports_medicine/84611-97564-98460-1652013.jpg

Consider imaging before stress testing (to avoid further displacing a fracture)

http://img.medscape.com/pi/emed/ckb/sports_medicine/84611-97564-98460-1652060.jpg

Stabilize in a thumb spica splint and refer to hand surgery.

Calling this entity a “simple sprain” may result in chronic disability (chronic pain, instability, loss of pinch strength)

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• When examining the hand, it is always important to document assessment of the ulnar, median, and radial nerves.
• The motor function of the hand can quickly and simply be assessed with the following examination techniques:
• Ulnar motor function >> Ask patient to first turn hand prone and spread fingers apart to a maximal distance.  Then, ask the patient to resist your attempts to squeeze the fingers together.
• Median motor function >> Ask patient to touch the distal tip of the thumb to the distal tip of the fifth finger and hold it.  Then, attempt to pull the two fingers apart and ask patient to resist.
• Radial motor function >> Ask patient to extend the wrist (i.e. as if trying to stop traffic) and push back against you attempting to push the hand into the flexed position.

Life-threatening Bleeding in Hemophilia A Patients

• Although an infrequent occurrence, patients with Hemophilia A can present with life-threatening hemorrhage (e.g. ICH).
• Recall that normal clotting factor levels range from 50-150 IU/dL - reported by the lab as 50-150%.
• Life-threatening bleeding requires Factor VIII levels between 80-100%.  In general, each unit of FVIII/kg raises plasma levels by 2%.
• Recombinant Factor VIII products are preferred over plasma derived concentrates or blood products and are dosed as:
  • FVIII - 50 IU/kg loading dose followed by infusion of 3 IU/kg/hr
• In the event you don't have access to recombinant or plasma derived FVIII concentrates, cryoprecipitate (contains FVIII) can be used.

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Pulmonary Embolism and IVC Filters

Inferior vena cava filters are placed in patients with massive DVT and /or in patients who cannot receive systemic anticoagulation.

The question is, can patients develop pulmonary embolism if a filter is already in place? The answer: yes

How does this happen?:

• Clot burden at the site of cava-filter insertion (below the filter). Clots can dislodge at this site and slip through the filter.
• Embolization around the IVC filter via retroperitoneal collaterals.

There is a correction factor for erythrocyte sedimentation rate in the elderly. The top normal ESR in the elderly is (age + 10)/2. For example, an 80 yo patients would have a top normal ESR of (80+10)/2 = 45. Most laboratories do not, however, report this correction factor, but simply list < 20 (or thereabouts) as normal.

Be certain to take this correction factor into account when using ESRs for workups for temporal arteritis or other similar conditions.
 

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Pain Control in the Elderly

• Narcotic pain relievers are often avoided in the elderly due to the concern of sedation, risk of falls and the concern of them causing delirium.
• Delirium can cause significant morbidity and mortality and can be difficult to differentiate between the sedation and mild confusion that often occurs with opioid dose escalation.
• However, delirium has been shown to occur more commonly as a result of the under treatment of pain rather than as an opioid adverse effect.

So the take home lesson for this pearl is that the elderly have a lower risk of delirium if their pain is treated appropriately.

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A fentanyl patch contains 100-fold more fentanyl in the reservoir than what is posted on the patch. For instance, 100mcg/hr patch will have over 10mg - thats milligrams - of fentanyl. This provides a rather large source for potential abuse. Overdose and deaths have occurred by patients in the following ways:

1. Ingesting
2. Placing in a cigarette and inhaling
3. Inadvertent overdose by sleeping with an electric heating blanket and increasing absorption through the skin
4. Steeping the patch in hot water
5. Actually stealing the patches off of dead bodies in the morgue

It is the many

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• The largest and most commonly injured peripheral nerve of the upper extremity is the radial nerve.
• Radial nerve palsy presents with decreased dorsal sensation, poor extensor motor strength, and a deficit in the abduction of the arm and/or hand. The degree of disability depends on where the injury takes place along the course of the nerve and its extent.
• Patients presenting with radial nerve palsy often erroneously think that they have suffered a stroke, given the severe degree of flaccidity and functional loss that typically results.
• Emergency department management of radial nerve palsy consists of splinting the wrist in a slightly extended position, along with physical and occupational therapy, and Orthopedic/Hand follow up as needed.

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(Sorry for the previously mislabeled pearl...)

Necrotizing soft tissue infections (NSTI) are on the rise and, despite improved surgical and critical care, over the years there has only been a mild reduction in mortality. Survival is associated with early diagnosis and treatment. Unfortunately, NSTI are not always obvious because deeper tissues made be involved first. Despite a validated scoring system and better radiology, our clinical suspicion still rules and relies on a meticulous history and physical exam. 

Here are some subtle signs of NSTI:

Pain out of proportion to exam

Edema beyond region of erythema

Skin anesthesia

Skin erythema and/or hyperthermia

Epidemolysis

Skin bronzing

If NSTI is suspected, be vigilant! Start broad-spectrum antibiotics, begin appropriate resuscitation and involve your surgeons early.

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17-18% of cases of syncope are attributable to arrhythmias

The greatest predictors of arrhythmias as the cause of syncope are:

a.            Abnormal ECG (odds ratio 8.1)

b.            History of CHF (odds ratio 5.3)

c.            Age older than 65 (odds ratio 5.4)

[Sarasin, et al. Academic Emergency Medicine 2003]

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Supraspinatus: “Empty can” test. Have the patient abduct the shoulders to 90 degrees in forward flexion with the thumbs pointing downward. The patient attempts to lift the arms against the examiner’s resistance.

http://bjsportmed.com/content/42/8/628/F2.large.jpg

Infraspinatus and teres minor: These muscles are responsible for external rotation of the shoulder. Have the patient flex both elbows to 90 degrees while the examiner provides resistance against external rotation.

http://www.physio-pedia.com/images/4/4b/Infraspinatus_test.jpg

Subscapularis: “Lift-off” test. The patient rests the dorsum of the hand on the lower back (palm out) and then attempts to move the arm and hand off the back.  Patients with tears may be unable to complete test due to pain.

http://www.aafp.org/afp/2008/0215/afp20080215p453-f4.jpg

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As RSV season approaches, remember these key points in managing bronchiolitis:

• Diagnosis is clinical - labs and XRays will not help you, unless you want to rule out a specific alternate diagnosis.  It's all about the H&P.
• Supportive care, including bulb suction of secretions, placing the child in a position of comfort, and possibly providing humidified air, is the mainstay of treatment.
  • Ribavirin, corticosteroids, and antibiotics are not indicated.  Don't use them.
  • Bronchodilators have no benefit in bronchiolitis alone, and non-response to bronchodilators supports the diagnosis of bronchiolitis.  If a trial does work, know what you are treating - some children with bronchiolitis may have an underlying component of reactive airway disease, and should be treated accordingly.
• Before disposition be sure that the child can tolerate PO.  A fussy, tachypneic child may require admission for IV hydration if they are unable to tolerate feeds - recall that infants are obligate nose breathers.
• Finally, beware the RSV bronchiolitis bounceback - the peak incidence of respiratory failure in RSV bronchiolitis is after 3-4 days of illness, when most children should be improving.

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In the setting of acute cyanide poisoning, it is virtually impossible to obtain a timely cyanide level to help assess toxicity.  However, there are two diagnostic tests that can help confirm your diagnosis.

1. Anion gap metabolic acidosis with elevated lactate
2. Narrowing of the venous-arterial PO₂ gradient

Remember cyanide halts cellular respiration meaning the cells cannot utilize oxygen.  Therefore, the venous PO₂ should be about the same as the arterial PO₂.  The cells then switch to anaerobic metabolism, thereby producing lactate.

How to Perform a Median Nerve Block

• The most common emergency department indication for performing median nerve blocks is to anesthetize its hand distribution (i.e. volar surface of hand) for pain control and/or to perform procedures such as laceration repair and dislocation reductions.
• The median nerve is located at the proximal flexor crease of the wrist, between the palmaris longus (PL) and flexor carpi radialis (FCR) tendons.  The FCR lies radial to the PL tendon.
• Use a 25 or 27 gauge needle, inserted to a depth of 1 cm, to inject 3-5 mL of plain lidocaine proximal to the distal wrist flexor crease, just ulnar to the PL tendon.
• If the PL tendon is absent, as is the case in 25% of people, direct the needle in line with the ring finger.
• If distal paresthesias result, withdraw and reposition the needle as this suggests that the median nerve was directly struck, which should be avoided.

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