UMEM Educational Pearls

So, how good is a screening CXR for aortic dissection?

• Classic CXR finding is a wide mediastinum
• Pooled literature shows that the overall sensitivity of a CXR is about 67-70% for aortic dissection (even if upright, or PA and Lateral)
• Most authorities agree that a screening CXR alone is not sufficient to r/o aortic dissection

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17-18% of cases of syncope are attributable to dysrhythmias.
The best predictors of dysrhythmias in these patients are:
1. abnormal ECG (odds ratio 8.1)
2. history of CHF (odds ratio  5.3)
3. age > 65 (odds ratio 5.4)

[reference: Sarasin FP, et al. A risk score to predict arrhythmias in patients with unexplained syncope. Acad Emerg Med 2003.]

Paracentesis:

Since we have covered so many other procedures I though I would include paracentesis for completion.

A diagnostic paracentesis (typically 30-60 ml)  is indicated to:

• Determine etiology of new ascites (transudate vs exudate, cancer, infection)
• Rule out spontaneous bacterial peritionitis...(suspect this in any patient with a history of ascites that has fever, mental status changes, or diffuse abdominal pain)

A therapeutic paracentesis (large volume >1L) is indicated in the emergency department for:

• Respiratory distress from abdominal distension
• Abdominal compartment syndrome.  See Dr. Winters Pearl

Remember large volume paracentesis can result in profound fluid shifts and subsequent hypotension.

Absolute Contraindications to paracentesis include:  Acute abdomen requiring surgery

Relative contraindications are:

• Platelets <20,000
• INR > 2
• Pregnancy
• h/o adhesions
• abdominal wall cellulitis (just don't stick the needle through the cellulitis)
• Distended bowel or bladder

To view a video on how to do a paracentesis please visit the New England Journal of Medicine http://content.nejm.org/cgi/content/short/355/19/e21

Next I will address how to interpret the paracentesis fluid results.

Oxycodone v. Codeine for Fracture Pain Management in Children

• When choosing an oral narcotic to give a child for fracture analgesia oxycodone is a better choice than codeine. 
• In this study children were randomized to recieve equianalgesic oral doses of either oxycodone (0.2 mg/kg, max 15 mg) or codeine (2mg/kg, max 120 mg) for forearm fractures
• Children given oxycodone reported a pain score significantly lower than children given codeine
• And children given oxycodone had less itching than those given codeine

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 Cheese Heroin: a slang term for the combination of heroin with an over-the-counter antihistamine

• The two are combined and forms a cheesy like powder that is different from pure heroin
• A string of deaths were reported between 2005-2007 in Texas, many adolscents
• This concoction is more often insufflated than smoked or injected
• Combines opioid effect with the anticholinergic confusion and hallucinations
• Scorpion was a heroin that was combined with scopolamine that had similiar effect

Treatment

• Find the anticholinergic toxidrome, place the foley and supportive care are mainstays
• Consider administration of physostigmine 1mg IV slowly over 2-5 minutes (call toxicologist)
• The anticholinergic effects will linger much longer than the heroin effects ( <1hr)

tPA should NOT be used to treat ischemic stroke in the following instances:

• Platelet count < 100,000
• INR > 1.7 or PT > 15
• Heparin administration within past 48 hours with subsequent PTT above upper limits of normal

Health care-associated pneumonia

• Health care-associated pneumonia (HCAP) is a distinct entity
• HCAP includes any patient with pneumonia and 1 or more of the following:
  • hospitalization for 2 or more days in an acute care facility within the preceeding 90 days
  • nursing home patients
  • patients of long-term care facilities
  • patients who attend a hospital or hemodialysis clinic
  • patients who received IV antibiotics, chemotherapy, or wound care within 30 days of infection
• Data indicate that the mortality for HCAP is higher than CAP
• The most common organisms in HCAP include S.aureus, P.aeruginosa, Klebsiella species, Haemophilus species, and Escherichia species
• An initial recommended antibiotic regimen includes a combination of an antipseudomonal cephalosporin plus a fluoroquinolone plus an agent active against MRSA

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Key Cardiovascular complications of cocaine:

• Myocardial ischemia and infarction
• Myocarditis and cardiomyopathy
• Aortic dissection
• Vessel thrombosis
• Stroke (usually hemorrhagic) 
• Visceral ischemia

Pearls:

• Cocaine and abdominal pain=mesenteric ischemia, hemoperitoneum (described)
• Cocaine and chest pain=MI, aortic dissection
• Cocaine and extremity pain=arterial thrombosis, aortic dissection
• ~ 6% of cocaine chest pain patients rule in for MI

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 HIV positive patients are at increased risk of premature atherosclerosis for at least a few reasons:
1. HIV disease causes increased activation of platelets.
2. HIV produces arterial endothelial dysfunction [which promotes thrombosis formation].
3. Protease inhibitors produce dyslipidemias and insulin resistance.

HIV-associated CAD is also unusual in that the vessel involvement is frequently diffuse and circumferential along the whole artery.

HIV positive patients are known to have their first MI at an earlier age than non-HIV controls, and the effect is not related to CD4 count (not related to severity of disease).

The takeaway point here is to always strongly consider ACS in the differential diagnosis of patients with HIV that are presenting with cardiopulmonary complaints, even in relatively younger patients.

Amal

[reference: Khunnawat C, Mukerji S, Havlichek D, et al. Cardiovascular Manifestations in Human Immunodeficiency Virus-Infected Patients. Am J Cardiol 2008;102:635-642.]

Dental Pain and Blocks:

I am sure that most of us have felt like we should  have attended dental school when we see the fifth toothache of the day, but for those with true dental pain it can be severe and debilitating.  For these patients the only way to truly get their paint under control is to perform a dental block.  This will provide the patient with several hours of excellent pain relief, and may be all they need before seeing a dentist the next day.

For those that are not familiar with dental blocks, a great web page that I found that covers the advantages and disadvantages of the more common blocks is http://www.septodont.ca/Septodont/english/other/cea_di01.html

So for your next dental pain consider performing a dental block instead of just sending them home with a P&P pack (percocet and penicillin)

 Latrodectus sp (Black Widow Spider)

• The only indigenous neurotoxic insect  in the state of Maryland and found through many states in the US
• The "bite" often not visible and does not cause a necrotic lesion like the brown recluse
• Causes Acetycholine release from post-synaptic motor and sensory nerves
• This leads to intense muscle contraction and pain. There have been reports of a black widow spider on the leg and the patient undergoes ex lap surgery for suspected acute abdomen only to find out the abdominal muscles were fasciculating due to envenomation
• Treat with aggresive analgesia and benzodiazepines.
• Not often lethal with approximately 60-70 deaths in the US over 30 years

Take a look at a picture of the black widow on the following attachment

Attachments

• 0809112343_black-widow-spider-1.jpg (14 Kb)

• Arteriovenous malformation (AVM) is a congenital defect of the circulatory system, comprised of a nest of blood vessels.
• AVM is typically detected incidentally during CT or MRI studies.
  
• Symptoms vary depending on the location of the AVM and the amount of hemorrhage, but can be as general as a seizure or headache.
• The following clinical symptoms commonly occur with AVM bleeds:
  

 Management of acute limb ischemia

Just a few pearls regarding acute limb ischemia

• Presents with an acutely painful extremity (may be pale and cool as well)
• Common etiologies include atrial fibrillation, embolism from aortic plaques, and thrombosis of extremity vessels
• Most patients need to be anticoagulated (heparin) 
• Vascular surgery should be consulted immediately or the patient needs transfer to a facility that can handle acute vascular emergencies
• Use caution when performing the physical examination, because there may be a pulse present
• Perform bedside ABI to the best of your ability and document
• Diabetics with stiff vasculature may have ABIs of 1 or greater so may be less reliable

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Intraabdominal Hypertension and the Critically Ill

• Intraabdominal hypertension (IAH) is increasingly recognized in a wide variety of critically ill patients and is associated with significant morbidity and mortality
• Normal intraabdominal pressure (IAP) is 5 - 7 mm Hg
• IAH is defined as the sustained elevation in IAP of at least 12 mm Hg
• Physical exam is inaccurate in detecting IAP with sensitivities of 40-60%
• The most common method of measuring IAP is intravesicular (bladder)
• Importantly, IAP should be measured at end-expiration after ensuring that abdominal muscle contractions are absent, with the patient in the supine position, and with the transducer zeroed in the midaxillary line at the level of the iliac crest

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 Troponin levels are often elevated in patients with sepsis. This doesn't necessarily mean that the patient has suffered an acute Mi or ACS, but rather it seems to correlate with myocardial dysfunction that is caused by sepsis. Much like with true MI, troponin elevations predict a greater risk of in-hospital mortality in these patients.

When the Sting REALLY hurts!!

• Anaphylaxis is an acute, potentially life-threatening problem, with multisystemic manifestations.(Remember 2 or more organ systems are required by definition!)
• In Children, foods (Milk, Eggs, Wheat, and Soy (MEWS) are the most common allergens
• But...peanuts and fish are among the most potent!!
• Also children can develop anaphylaxis from the fumes of cooking fish or residual peanut in a candy bar.
• Other common causes are preservatives, medications (antibiotics), insect venom (bee stings!!!!!!)

Remember the dose of Epinephrine is : 

0.01 mg/kg or 0.01 mL/kg of 1:1,000 IM or

0.01 mg/kg IV or 0.1 mL/kg/dose 1:10,000 IV

to the adult dose or 0.3 mg 

Also

Epipen Jr = 0.15 mg (use for < 30 Kg)

Epipen = 0.3 mg (use for > 30 Kg)

To show patients an instructional video click on the referenced link.

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To echo Dr. Rogers' fantastic airway tips:

When considering an intubation or managing an emergent respiratory concern, keep the "P"s of intubation in mind:

1. P osition:  No intubating on the floor!  Don't get sucked into the patient's oropharynx! Maintain an appropriate distance. Align the airway axes. Sniffing position is utilized for non traumatic adult airways; this involves flexion of the lower c-spine and a bit of extension at the upper cervical levels. Take off cervical collars. Use pillows / blankets to align the external auditory canal (EAC) with the sternal notch to help w/visualization. Cricoid pressure is NOT designed to facilitate passage of the ETT- it MAY help prevent excessive gastric insufflation.

2. P reparation: Two tubes. Two blades. Two intubators. Plan B(ougie) or Plan C(cric). Though your emergency airway plans may differ, think of ALL airways as potentially difficult ones. Respect the epiglottis. 

3. P reoxygenation: 100% via NRBM when possible to ensure oxygenation and nitrogen washout. In patinets with at least some reserve, this will help to avoid pulse ox pitfalls. True RSI does NOT involve positive pressure ventilation.

4. P remedication: Know your sedatives in advance. Etomidate ? Ketamine ? Diprivan ? Whatever your agent of choice, know indications and drug dosages. Emergent RSI is a less than ideal time to access Epocrates.

5. P aralysis:  This is pretty much the point of no return. Administration of paralytics commits you to securing a patient's airway. Both rocuronium and succynylcholine can be dosed at 1 mg/kg IV.

6. P ass the tube: What Dr. Rogers said.

7. P osition confirmation: Direct visualization of the tube through the glottic opening coupled with end tidal Co2 is ideal.

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Topical Lidocaine for local anesthesia

Disclosure: I have no financial or invested interest in the product or the company.

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• Asterixis is a tremor of the wrist that occurs when the wrist is extended (dorsiflexed).
• It is also often referred to as a "flapping tremor" or "liver flap."
• Asterixis results from arrhythmic, interrruptions of voluntary muscle contraction resulting in brief lapses in posture.
• It is most often associated with hepatic encephalopathy that results from abnormal metabolism of ammonia to urea, causing brain cell damage.  The subsequent elevated levels of ammonia are due to liver failure.
• In addition to hepatic enephalopathy, asterixis can also be associated with the following conditions:

               -- azotemia

               -- cardon dioxide toxicity

              -- metabolic encephalopathies

              -- Wilson's Disease

Bicarbonate for severe lactic acidosis from shock?

• In critically ill patients, one of the most common causes of acidosis is hypoperfusion induced lactic acidosis
• Importantly, the source of lactic acid during hypoperfusion/shock is intracellular, and the intracellular compartment is not readily accessible to extracellular bicarb
• Exogenous bicarbonate will certainly raise extracellular pH but does not readily correct intracellular acidosis
• This increase in pH is transient and typically lasts approximately 30 minutes
• In studies to date, exogenous bicarbonate did raise pH, serum bicarbonate concentrations, and P_aCO₂ but importantly did not improve cardiac output, mean arterial pressure, or sensitization to catecholamines
• Take Home Point: Based on available literature, there is no utility to giving bicarbonate in hypoperfusion induced lactic acidosis when the pH is > 7.0

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