UMEM Educational Pearls

• Remember that lithium overdoses should not be treated with oral activated charcoal, as these charged particles are not adequately absorbed by this method.
• Instead, whole bowel irrigation using 500 mL to 2 liters of polyethylene glycol should be administered within the first 2-3 hours of presumed large ingestions (ie. at least 10 to 15 pills), with a goal of having the patient pass stool to the point of clear rectal effluent.
• Hemodialysis (HD) should be reserved to treat severe lithium toxicity, which is somewhat loosely defined as a serum level greater than 3.5 to 4 meq/L (mmol/L). 
• For levels > 4 meq/L, most experts agree that HD should be performed regardless of whether associated symptoms are present.  For levels > 2.5 meq/L with associated clinical signs/symptoms (i.e. tremulousness, dizziness, lethargy, seizure), conditions that would limit lithium excretion (i.e. renal insufficiency), or conditions that would limit ability to aggressively hydrate (i.e. CHF), HD should be performed.   

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Positive-pressure ventilation (e.g., mechanical ventilation) increases intrathoracic pressure potentially reducing venous return, right-ventricular filling, and cardiac output.

Pericardial tamponade similarly causes hemodynamic compromise through increased pericardial pressure which reduces right-ventricular filling and cardiac output.

When mechanically ventilating a patient with known or suspected pericardial tamponade the mechanisms above may be additive, causing cardiovascular collapse and possibly PEA arrest.

For the patient with known or suspected pericardial tamponade consider draining the pericardial effusion prior to intubation or delaying intubation until absolutely necessary.

If intubation is unavoidable, consider maintaining the intrathoracic pressure as low as possible (by keeping the PEEP and tidal volumes to a minimum) to ensure adequate cardiac filling and cardiac output.

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Blood pressure cuffs tend to OVERESTIMATE true blood pressure in obese patients. Even larger cuffs tend to do this as well. While low blood pressures are often reliable in diagnosing shock, be wary of  assuming a "normal" blood pressure (e.g. SBP 100-120s) rules out shock in an obese patient who is sick. A-lines might be necessary to accurately assess the blood pressure.

[adapted from ACEP talk by Dr. Tiffany Osborn]

A recent randomized trial compared nicardipine as a continuous infusion to labetalol boluses to determine which one was more effective at lowering blood pressure to a target range within 30 minutes.

Median initial SBP for the 226 patients was 212 mm Hg. Within 30 minutes, nicardipine patients more often reached target range than labetalol (91.7 vs. 82.5%, P = 0.039). Of 6 BP measures (taken every 5 minutes) during the study period, nicardipine patients had higher rates of five and six instances within target range than labetalol (47.3% vs. 32.8%, P = 0.026).

What this means: Nicardipine is a reasonable choice for patients needing acute lowering of blood pressure (e.g., ischemic stroke with tPa).  Nicardipine seems to achieve faster and smoother lowering of blood pressure than labetalol therapy with less blood pressure readings outside the target range.

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Salicylates:

• stimulate the respiratory center in the brainstem, causing respiratory alkalosis
• interfere with the Krebs cycle, limiting ATP production, leading to an anaerobic metabolism
• uncouple oxidative phosphorylation, causing accumulation of pyruvic and lactic acid and heat production, resulting in acidosis and hyperthermia
• increase fatty acid metabolism, generating ketone bodies

Overall, this results in a mixed respiratory alkalosis and metabolic acidosis. 

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• A huge limitation to effectively managing acute ischemic stroke in rural areas is the frequent lack of access to local experts in vascular neurology.  While most guidelines encourage the use of telemedicine to overcome such barriers, the start up costs of such programs are sometimes prohibitive, particularly for small, rural practices. 
• A recent, small study showed that providers may be able to use the iPhone as a primary or adjunctive tool with telemedicine, to properly diagnose and manage acute stroke.
• The study compared a face-to-face provider's NIH Stroke Scale (NIHSS) interpretation to that of a remote provider using an iPhone with FaceTime software that allows real-time streaming of audio and video.
• Agreement between providers was excellent (intraclass correlation coefficient 0.98); the NIHSS score of the providers did not differ by more than 1 point in 17 of the 20 cases; in only one category - ataxia - was agreement poor.
• TAKE HOME POINT:  Streaming real-time video technology may offer an effective and economically feasible alternative to suboptimal acute stroke care in rural areas or an alternative/adjunct to pure telemedicine programs.  (This is not an advertisement or endorsement for the iPhone.)

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Mechanical Ventilation in Patients with Pulmonary HTN 

• In the critically ill patient with pulmonary HTN and respiratory failure, improper mechanical ventilator settings can be disastrous.
• Large lung volumes and high levels of PEEP can result in acute cardiovascular collapse.
• When setting the ventilator is these patients, select low tidal volumes and relatively low levels of PEEP (3-5 cm H₂O).
• In addition, small studies suggest avoiding permissive hypercapnia, as this may increase pulmonary vascular resistance and mean pulmonary arterial pressure.

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Question

72 year-old man, one-week post right fem-pop bypass presents with painful blue and black toe. Diagnosis?

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Today's cardiology pearl provided by EMS guru Dr. Ben Lawner. Consider this one if you are caring for a patient with what appears to be shock-resistant VFib.

An intervention that has its roots in the electrophysiology lab has now gained traction on the front lines of resuscitation: double sequential defibrillation. Prospective studies are currently underway to examine the feasibility of this technique. New Orleans (LA) EMS boasts several anectodal accounts of survival, with neurologically intact recovery, from refractory ventricular fibrillation. The next time you can’t stop the fibbing, consider this:

·       Apply TWO sets of defibrillator pads to the patient; one in traditional sternum/apex configuration and the other in anterior/posterior configuration

·       If ventricular fibrillation persists despite several shocks, coordinate the simultaneous firing of BOTH defibrillators

Some caveats:
This treatment is based upon EP lab data; each MONOPHASIC defibrillator was set at 360J. EMS services in New Orleans and Wake County (NC) have used two biphasic defibrillators, each set a 200J. There is not sufficient data to make any widespread recommendation, but the idea of double sequential defibrillation may be another tool in a limited ACLS bag of tricks for patients who simply cannot come out of V-fib. New Orleans EMS has initiated the double-defib protocol after four shocks, and Wake County’s protocol recommends initiation after five. Wake's protocol also recommends firing the defirbillators "as synchronously as possible."

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Methotrexate is a chemotherapeutic that is utilized in non-Hodgkin lymphoma and breast CA. It is also used as an immunosuppressant for rheumatoid arthritis and psoriasis. Finally, we see it used in the ED for the treatment of ectopic pregnancy. Overdose, often unintentional, can have a lethal outcome.

Toxicity: LFTs rise, N/V, stomatitis, mucositis, leukopenia, thrombocytopenia, renal failure

Antidote: Leukovorin (Folinic Acid)

Other Tx: Carboxypeptidase G2, Charcoal Hemoperfusion, HD (possible)

• Myasthenia Graves (MG) is often associated with several, distinct clinical findings which patients may have during their crisis in the emergency department. These findings may include the following:

              -  Mask-like face

              -  Eyelid weakness 

                    --  leads to ptosis

                    --  exacerbated by sustained upward gaze

                    --  improved by closing the eyes for a short while

                -   Extraocular motion abnormality

                     --  usually affects more than one extraocular muscle

                     --  may be assymetrical

                     --  may result in mild proptosis

                 -   Weak palatal muscles

                      --  nasal-sounding voice

                      --  nasal regurgitation of food

                  -  Weak jaw muscles

                  -  Absent gag reflex

                  -  Pupils normal

• On October 25, 2011, Eli Lilly announced a voluntary-recall of activated drotrecogin alfa (Xigris) following a recent trial (PROWESS-SHOCK), which demonstrated no survival benefit when using the drug when compared to placebo.

• Activated drotrecogin alfa is a recombinant form of human activated protein C previously recommended for adults with severe sepsis and a high-risk of death (APACHE II > 25 or multi-organ failure); it is included in the 2008 International Sepsis Guidelines (Grade 2b recommendation).

• The PROWESS-SHOCK trial reported an all-cause mortality rate of 26.4% in the drotrecogin alfa group compared with 24.2% in the placebo group; this difference was not statistically significant.

• Interestingly, the study also found that severe bleeding (the drug's main side-effect) was found to be 1.2% in the activated drotrecogin alfa group compared to 1.0% for the placebo group (also non-significant) suggesting it does not increase the risk of bleeding as it had previously been reported.

• Hospitals should revise their sepsis guidelines based on this recent news.

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Weird and Unusual Symptoms

Bet you didn't know that severe and intense pruritus of the nostrils, known as Wartenberg's symptom, is an uncommon but characteristic symptom of a brain tumor.

Etiologies include astrocytoma, glioblastoma, oligodendroglioma, medulloblastoma, and metastatic tumors.

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"Women experience higher mortality rates and more adverse outcomes after acute MI than men, despite less obstructive CAD and plaque burden."(1)

How can this be explained? It turns out that women have more frequent coronary remodeling of vessels. "Remodeling" refers to the concept that as plaques grow, they tend grow into the vessel wall causing outward bulging of the wall, rather than growing into the vessel lumen. That means that standard coronary angiography and even stress testing often miss significant lesions because they only evaluate lumen obstruction....which is not directly reflective of plaque size/burden.

The net effect of the above is that women are more likely to have false negative stress tests and angiograms that appear to show non-significant occlusions. Until we have reliable tests that evaluate true plaque burden rather than just vessel occlusion, we can't completely rely on stress testing and angiography to rule out the the presence of significant plaques.

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The TFCC (triangular fibrocartilage complex)  is a ligamentous/cartilage like complex similar to the meniscus of the knee located on the ulnar side of the wrist.

http://yanyanxu.com/wp-content/uploads/2008/01/trifibcc.gif

Hx: ulnar sided wrist pain following trauma and associated with activity related mechanical symptoms such as clicking.

PE:  tenderness to palpation distal to ulnar head or at ulnar styloid . Tenderness against resisted radial deviation.

Plain film may show ulnar styloid avulsion or injury to carpal structures.

Refer to hand/wrist surgeon

Splint in ulnar gutter of long arm spica

MRI or arthrogram are studies of choice.

http://www.cobalthealth.co.uk/MImageGen.ashx?image=%2Fmedia%2F12951%2Fwrist-tfcc-tear-big.jpg&width=170&crop=true

Carbon Monoxide Toxicity and Hyperbaric Oxygen Treatment

CO disrupts cellular function by several mechanisms at a
cellular/mitochondrial level.  Ultimately, these disruptions are
manifested as tissue hypoxia and hypoperfusion.
Initial symptoms may be subtle and nonspecific.  Be sure to ask about
CO exposure when evaluating “viral syndrome” or patients that present
with non-specific neurological complaints especially during fall and
winter months, when people first start using their heating, or after
power outages and generator use. Dysrhythmias, cardiomopathy, MI and
sudden cardiac arrest are reported in severe CO poisoning.

Lab studies- COHb, base excess, lactate and any other studies based on
presentation.

Supplemental oxygen is the cornerstone of treatment.   Oxygen
delivered at hyperbaric pressure (as opposed to sea-level) will
increase the rate of CO dissociation from hemoglobin, and mitigate
damage to cellular and mitochondrial function.

Definite Indications for HBOT:  Current evidence supports the use for
HBOT to reduce cognitive sequelae in CO poisoned patients who have:
LOC , seizure, exposure >23 hours, COHb of 25% or more, and age >36.
Relative Indications:  persistent symptoms after 100% O2 or change in
mental status, pregnancy, persistent cardiac ischemia, increased COHb
levels.

 Disposition:  Clinical judgment should guide your decision.  Most
patients with mild symptoms can be discharged after treatment. If
patient has a more concerning presentation with several risk factors
(extremes of age, CAD, unconscious at arrival in the ED, etc…)
consider admission.

Differentiating Central Retinal Artery vs. Vein Occlusion Fundoscopically

• While there are several historical and clinical features that differentiate central retinal artery (CRA) occlusion from central retinal vein (CRV) occlusion, the fundoscopic examination can also be used to distinguish between the two.
• In CRA occlusion, the retina appears grossly swollen and pale, with a prominent fovea that would otherwise be obscured by a normal, pinkish-red background (see attached - Image 1).
• In CRV occlusion, the disc is massively swollen with splotches of hemorrhage and cotton wool spots diffusely (see attached - Image 2).

Attachments

1110191840_Fundoscopic_Images_of_Central_Retinal_Artery_and_Vein_Occlusion.pdf (103 Kb)

SAH and Electrolyte Disorders

• Hyponatremia can be seen in up to 40% of patients with a SAH.
• Most often, hyponatremia in patients with an SAH is due to SIADH or the cerebral salt wasting syndrome.
• To date, hyponatremia has not been associated with poor outcome.
• Treatment should focus on the underlying cause and often includes volume replacement with isotonic crystalloids (0.9% NaCl).

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Question

5 year-old male with developmental delay presents with intractable non-bloody and non-bilious vomiting over 10 days; bowel movements are normal. Four weeks ago he was placed in a hip-spica cast following a motor vehicle crash. Abdominal x-ray is below. Diagnosis?

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