UMEM Educational Pearls

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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Pulmonary Contusion and Ventilator Management

• Pulmonary contusion is the most common injury in blunt thoracic trauma.
• Patients with pulmonary contusion often present with hypoxia, hypercarbia and increased work of breathing.
• Importantly, patients with pulmonary contusion have a low cardiopulmonary reserve.  Maintain a low threshold for initiating mechanical ventilation is these patients.
• When starting mechanical ventilation, think about the following:
  • Patients are at high risk for developing ARDS
  • Most centers use a low tidal volume ventilatory strategy
  • Higher levels of PEEP may be necessary to recruit collapsed alveoli
  • High frequency oscillatory ventilation (HFOV) and airway pressure release ventilation (APRV) are modes of ventilation that are gaining in popularity for ventilating patients with pulmonary contusions.

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Acute use of cocaine increases risk of acute MI due to tachydysrhythmias, vasospasm, and increased platelet aggregation. There is a 24-fold increased risk of MI in the first hour after use of cocaine. 6% of patients presenting with cocaine-chest pain rule in for acute MI.

[Weber, Acad Emerg Med 2000]

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Radiologic evaluation of the elbow (Part 2)

Helpful clues in the evaluation of elbow trauma:

• The Anterior humeral line and the Radiocapitellar line
  • The anterior humeral line: On a true lateral film, this line is drawn along the anterior aspect of the humeral shaft on the lateral radiograph This line passes through the middle one third of the capitellum in bones that are not injured. It is very useful for detecting subtle fractures.
    • http://www.radiologyassistant.nl/images/thmb_4214e859138b1anthumlinebest.jpg
  • Fractures (i.e. supracondylar) usually result in displacement of the capitellum posteriorly.
  • Thus, the anterior humeral line passes through the anterior one third or entirely anterior to the capitellum.
    • http://www.imageinterpretation.co.uk/images/elbow/RAISED FAT PADS, SUPRACONDYLAR graphic.jpg
• The Radiocapitellar line: Since the radius articulates with the capitellum, a line is drawn through the middle of the radius shaft and extended proximally through the joint should bisect the capitellum on all views (AP & lateral).
  • http://img.medscape.com/pi/emed/ckb/radiology/336139-415822-5412.jpg
  • http://nypemergency.org/images/v2c18n.jpg
  • Improper alignment indicates a radial head dislocation (which may be very subtle)
    • http://nypemergency.org/images/mont.jpg
    • http://www.radiologyassistant.nl/images/49304bf192d7e12.jpg

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A recent study examined the effects of accidental digital epinephrine injection from auto-injectors. 127 cases with complete follow-up had the following effects:

• no effects were reported in 10%
• minor effects in 77%
• moderate effects in 13%
• major effects in 1 case

Pharmacologic vasodilators were used in 23%. Four patients had possible digital ischemia. All patients had complete resolution of symptoms, most within 2 hours. No patient was admitted, received hand surgery consultation, or had surgical care. 

Although this speaks for the safety of digital anesthesia using epinephrine, it underscores the importance of providing education to patients who are prescribed epinephrine auto-injectors.

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• Ulnar nerve blocks are relatively easy to perform and excellent for anesthetizing the ulnar nerve distribution, particularly of the hand.

• Ulnar nerve blocks can be performed at the level of the wrist (dorsal or volar side) or at the elbow.  Volar side blocks at the wrist tend to be easier to perform and associated with less risk. 

• Using a 27 gauge needle, infiltrate 2 to 3 mL's of lidocaine between the flexor carpi ulnaris tendon and the distal-most aspect of the ulnar bone.  The needle should be inserted 1 to 2 cm's at about a 40 degree angle, at the proximal-most wrist crease.

• Do not puncture the actual ulnar nerve or the ulnar artery.  Should needle insertion cause distal hand paresthesias or blood withdrawal, do not inject and immediately remove the needle, as this suggests that the ulnar nerve or artery was struck, respectively.  The objective is to allow the lidocaine to infiltrate into the nerve, not to inject it directly into the nerve.

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Hyponatremia plagues many neurosurgical patients due to the syndrome of inappropriate secretion of ADH (SIADH) or the cerebral salt wasting syndrome (CSW). Both diseases may appear similar (hyponatremia, increased urine osmolarity, increased urine sodium, normal adrenal, renal and thyroid function), but there is one BIG difference. Patients with SIADH are euvolemic or hypervolemic (excess ADH causes fluid retention) whereas patients with CSW are fluid depleted (impaired renal handling of sodium and water). To differentiate, look for signs of hypovolemia: orthostatics, dry mucus membranes, hemoconcentration, pre-renal azotemia, and/or hemodynamics (IVC collapse anyone?).

Bottom line: Distinguish SIADH from CSW because the treatments are exact opposites:

SIADH: Fluid restrict

CSW: Give water and salt (i.e., 0.9% saline)

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Hypertensive Encephalopathy (HE) is a clinical diagnosis and can look like many other disease entities.

HE refers to a relatively rapidly evolving syndrome of severe hypertension in association with severe headache, nausea, and vomiting, visual disturbances, convulsions, altered mental status and, in advanced cases, stupor and coma.

The key is the presence of severe hypertension. Remember, though, that 160/105 mm Hg may be high for an individual patient. Most patients with the syndrome will have diastolic pressures well in excess of 120-130 mm Hg. The only way you will know if the diagnosis is correct is to treat the BP (carefully control), work up other etiologies, and see of symptoms improve with BP control.

Beware the patient with severe HTN and seizure. Seizure may be the first, and only, symptom of hypertensive encephalopathy. 

Some confusion exists regarding proper distinction and treatment between the different tachydysrhythmias associated with WPW. Here's the scoop:
1. orthodromic SVT: narrow regular tachycardia, looks just like a routine SVT, treat just like any other SVT (AV nodal blockers work fine)
2. antidromic SVT: wide regular tachycardia, looks just like VTach, treat like VTach (amiodarone, procainamide, shock; lidocaine won't work, though won't harm either)
3. atrial fibrillation: very different!! irregularly irregular, morphologies of the QRS complexes vary between narrow and wide, some areas may have rates as high as 250-300/min, MUST avoid all AV nodal blockers (which includes adenosine, CCBs, BBs, digoxin, amiodarone); treat with procainamide or sedation+cardioversion

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Adhesive Capsulitis -- Frozen Shoulder

1. Characterized by pain and loss of motion or stiffness in the shoulder.Normally not seen below the age of 40, affects ~2% of the population and diabetics are at increased risk.
2. Due to thickening and contracture of the capsule surrounding the shoulder joint.
3. Can occur after trauma to the shoulder if the shoulder is not moved early enough, but is also know to occur idiopathically.
4. X-rays are only helpful to rule out other causes of the shoulder pain and are typically normal in Adhesive capsulitis.
5. Typically will get better on its own over 2-3 years.
   1. Physical Therapy and home exercises aimed at restoring ROM can shorten the duration of pain and stiffness.
   2. Surgery can be done if there is no improvement with medical management and physical therapy.
6. Prevention strategies include early ROM exercises in those with shoulder injuries especially in the elderly diabetic.

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