UMEM Educational Pearls

Neuromuscular Blocking Agents in the Critically Ill

  • NMBAs are used in critically ill patients for RSI, patient-ventilator asynchrony, reducing intra-abdominal pressure, reducing intracranial pressure, and preventing shivering during therapeutic hypothermia.
  • There are a number of alterations in critical illness that affect the action of NMBAs
    • Electrolyte abnormalities
      • Hypercalcemia: decreases duration of blockade
      • Hypermagnesemia: prolongs duration of blockade
    • Acidosis: can enhance effect of nondepolarizing agents
    • Hepatic dysfunction: prolongs effects of vecuronium and rocuronium
  • In addition, there are a number of medications that may interact with NMBAs
    • Increased resistance: phenytoin and carbamazepine
    • Prolongs effect: clindamycin and vancomycin
  • Key complications of NMBAs in the critically ill include:
    • ICU-aquired weakness (controversial)
    • DVT: NMBAs are one of the strongest predictors for ICU-related DVT
    • Corneal abrasions: prevalence up to 60%

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Question

57 year old male presents with a cough. The CXR is shown below. What's the diagnosis?

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  • B-type natriuretic peptide (BNP) is a useful prognostic biomarker in patients with reduced LVEF, but data in heart failure (HF) with preserved ejection fraction (HFPEF) is minimal
  • A recent study sought to determine the prognostic value of BNP in patients with HFPEF in comparison to data in HF patients with reduced left ventricular EF <40%
  • 615 patients with mild to moderate HF were followed for 18 months and BNP was measured at baseline and related to the primary outcomes (mortality and HF hospitalization)
  • BNP levels were significantly higher in patients with reduced LVEF than in those with HFPEF (p < 0.001), however the risk of adverse outcomes and prognosis in patients with HFPEF is as poor as in those with reduced LVEF  

 

 

 

 

 

 

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Category: Orthopedics

Title: What should I MRI

Keywords: MRI, spinal cord compression (PubMed Search)

Posted: 4/27/2013 by Brian Corwell, MD
Click here to contact Brian Corwell, MD

You have a patient with a spinal cord syndrome and you order the MRI. Have you ever had that conversation with radiology where you have to "choose" what part of the spine you want imaged?

The entire spine needs to be imaged!

The reason: False localizing sensory levels.

For example: The patient has a thoracic sensory level that is caused by a cervical lesion.

 

A study of 324 episodes of malignant spinal cord compression (MSCC) found that clinical signs were very unreliable indicators of the level of compression. Only 53 patients (16%) had a sensory level that was within 3 vertebral levels of the level of compression demonstrated on MRI.

Further, pain (both midline back pain and radicular pain) was also a poor predictor of the level of compression.

Finally, of the 187 patients who had plain radiographs at the level of compression at referral, 60 showed vertebral collapse suggesting cord compression, but only 39 of these predicted the correct level of compression (i.e. only 20% of all radiographs correctly identified the level of compression).

The authors note that frequently only the lumbar spine was XR at the time of clinical presentation (usually at the referring hospital), presumably due to false localizing signs and a low awareness on the part of clinicians that most MSCC occurs in the thoracic spine (68% in this series).

 

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An overweight 5 year old male presents with acute onset abdominal pain that localizes to the right lower quadrant. What are some causes of a limited or nondiagnostic ultrasound study in children?

Acute appendicitis is a time sensitive diagnosis. Ultrasound is frequently used as the initial diagnostic imaging in children. There are several reasons why the appendix may not be visualized, including retro-cecal location, normal appendix, perforation, and inflammation around the distal tip. An additional clinical predictor associated with poor or inconclusive ultrasound results in appendicitis is increased BMI (body mass index).

A study examining 263 pediatric patients found when BMI > 85th percentile and clinical probability of appendicitis was <50%, 58% of ultrasounds were nondiagnostic. Children with a BMI <85th percentile and clinical probability of appendicitis was <50%, had nondiagonstic scans 42% of the time. These trends were also mimicked in the patients with a higher clinical probability of appendicitis. In the child with a nondiagnostic ultrasound, options include observation and repeat ultrasound scan or CT scan, both of which have associated risks.

 

Reference:
Schuh S, et al. Predictors of non-diagnostic ultrasound scanning in children with suspected appendicitis. J Pediatr. 2011 Jan;158(1):112-8.


Category: Toxicology

Title: Acetaminophen Toxicity - When Should I Consider Liver Transplant?

Keywords: Kings College, apap, acetaminophen (PubMed Search)

Posted: 4/25/2013 by Fermin Barrueto (Updated: 11/10/2024)
Click here to contact Fermin Barrueto

If you are working in a community hospital and have an acetaminophen overdose, one of the criteria to transfer the patient to a tertiary care center is presence of the King's College Criteria.

The below is taken from mdcalc.com -  http://www.mdcalc.com/kings-college-criteria-for-acetaminophen-toxicity/

Each one is assigned points and can be prognostic for severe toxicity and need for transplant. The lactate and phosphorus are new ones and have modified the criteria. Phosphorus is utilized to create glycogen. If the liver is injured and trying to heal, your phosphorus will be low (good). If the liver is injured and unable to repair itself the phosphorus will be high (bad). This single test has an excellent prognostic ability.

 

Lactate > 3.5 mg/dL (0.39 mmol/L) 4 hrs after early fluid resuscitation?
pH < 7.30 or lactate > 3 mg/dL (0.33 mmol/L) after full fluid resuscitation at 12 hours
INR > 6.5 (PTT > 100s)
Creatinine > 3.4 mg/dL (300 µmol/L)
Grade 3 or 4 Hepatic Encephalopathy?
Phosphorus > 3.75 mg/dL (1.2 mmol/L) at 48 hours

 



Category: International EM

Title: Wait--the creatinine is what?!?!?

Keywords: international, laboratory, lab values, SI, conventional (PubMed Search)

Posted: 4/24/2013 by Andrea Tenner, MD
Click here to contact Andrea Tenner, MD

General Information:

The two main units used by medical laboratories are "conventional (used in the US) and SI (used by most other countries).

Pearls to know:

  • For monovalent ions (i.e. Na+, Cl-) -- mEq/L=mmol/L (135 mEq = 135 mmol/L)
  • For divalent ions (i.e. ionized Ca2+, Mg2+) -- mEq/2=mmol (Mg2+ of 2 mEq/L = 1 mmol/L)
  • Creatinine -- Multiply conventional untis by 88 (1 mg/dL = 88 mmol/L)
  • Glucose -- Multiply SI units by 18 (4 mmol/L = 72 mg/dL)
  • Hemoglobin--Multiply conventional units by 10 (14 g/dL = 140 g/L)

Relevance to the EM Physician:

These tips will help you convert labs to familiar values when reading medical literature, when working in another country, or when working with international colleagues.

University of Maryland Section of Global Emergency Health

Author: Andi Tenner, MD, MPH

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Necrotizing fasciitis (NF) is a rapidly progressive bacterial infection of the fascia with secondary necrosis of the subcutaneous tissue. In severe cases, the underlying muscle (i.e., myositis) may be affected.

Risk factors for NF include immunosuppression (e.g., transplant patients), HIV/AIDS, diabetes, etc.

There are three categories of NF:

  • Type I (poly-microbial infections)
  • Type II (Group A streptococcus; sometimes referred to as the “flesh-eating bacteria)
  • Type III (Clostridial myonecrosis; known as gas gangrene)

In the early stage of disease, diagnosis may be difficult; the physical exam sometimes does not reflect the severity of disease. Labs may be non-specific, but CT or MRI is important to diagnose and define the extent of the disease when planning surgical debridement.

Treatment should be aggressive and started as soon as the disease is suspected; this includes:

  • Aggressive fluid and/or vasopressor therapy
  • Broad spectrum antibiotics covering for gram-positive, gram-negative, and anaerobic bacteria; clindamycin should be added initially as it suppresses certain bacterial toxin formation
  • Emergent surgical consult for debridement
  • Once the patient is stable, other treatments may include intravenous immunoglobulin and hyperbaric oxygen therapy

 

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Category: Pediatrics

Title: Otitis Media (submitted by Ari Kestler, MD)

Keywords: antibiotics, wait and see (PubMed Search)

Posted: 4/19/2013 by Mimi Lu, MD
Click here to contact Mimi Lu, MD

2013 AAP AOM Guidelines UPDATE

 
-AAP released a new clinical practice guideline for diagnosis and management of acute otitis media (AOM).
 
Key Action Statements:
 
Diagnosis if presence of middle ear effusion and
(1) moderate to severe bulging of tympanic membrane (TM) or new otorrhea or
(2) mild bulging of TM and recent ear pain or intense erythema of TM
 
Treatment options:
  • Severe unilateral or bilateral AOM (>6mo): give antibiotics.  Severe AOM is defined as fever >102.2 (39 C), moderate/severe otalgia, or symptoms >48h.
  • Nonsevere unilateral AOM (6-23 months): Advise the parents to consider a period of close observation and follow up (24-72h).  If the childs clinical status deteriorates give antibiotics.
  • Nonsevere bilateral AOM (6-23 months): give antibiotics.
  • Nonsevere unilateral or bilateral AOM (>24 months): Advise the parents to consider a period of close observation and follow up (24-72h).  If the childs clinical status deteriorates, give antibiotics.
 
 
Reference: Pediatrics Vol. 131 No. 3 March 1, 2013


Category: Toxicology

Title: Ricin - of course

Keywords: Ricin (PubMed Search)

Posted: 4/18/2013 by Fermin Barrueto (Updated: 11/10/2024)
Click here to contact Fermin Barrueto

With recent events, a few notes about ricin seems appropriate:

  1. Easy to make from castor bean though heat labile
  2. No antidote, though Fab like digibind is in development
  3. Granule size of the grain of sand can kill
  4. Inhalation, IM, IV all effective
  5. After immediate exposure likely no symptoms
  6. Vomiting and diarrhea initially, acute lung injury and death in 3-5 days

CDC website: http://www.bt.cdc.gov/agent/ricin/



 

General Information:

A parasitic infection caused by the tissue-dwelling filarial nematode worm Wuchereria bancrofti; a wide range of mosquitoes transmit the infection. When the worm is mature, it inhabits lymph nodes and produces sheathed microfilarial larvae that circulate in the peripheral blood.

Clinical Presentation:

- Infection with the adult worms produces painless subcutaneous nodules that are usually less than 2 cm in diameter, typically over bony prominences.

- Symptoms depend on where the microfilariae migrate to, and vary accordingly. They include: pruritus, papular dermatitis, dermal atrophy and depigmentation or hyperreactive skin disease (Sowda), keratitis, iritis, chorioretinitis, optic atrophy and eventually blindness, orchitis, hydrocele, chyluria, elephantiasis, pulmonary eosinophilia, cough, wheezing, and splenomegaly.

Diagnosis:

- Peripheral blood smear taken between 11pm and 1am or after provocation using diethylcarbamazine (DEC).

- Filarial antigen test.

- Eosinophilia, and specific antiflarial IgG and IgE antibodies.

Treatment:

- DEC which must be obtained directly from the CDC.

- Alternatively Doxycycline. Both drugs are effective against both macro and micro-filaria.

Bottom Line:

One billion people globally are at risk for infection with filaria. 120 million already have the infection. Suspect the infection in patients that have been to Africa, Asia, especially India, Western pacific, Haiti, the Dominican Republic, Guyana and Brazil.

 

University of Maryland Section of Global Emergency Health

Author: Walid Hammad, MD

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Massive Transfusion Pearls

  • As discussed in previous pearls, massive transfusion (MT) is defined as the transfusion of at least 10 U of packed red blood cells (PRBCs) within 24 hours.
  • While the optimal ratio of PRBCs, FFP, and platelets is not known, most use a 1:1:1 ratio.
  • Though scoring systems have been published to identify patients who may benefit from MT (ABC, TASH, McLaughlin), they have not been shown to be superior to clinical judgment.
  • A few pearls when implementing massive transfusion for the patient with traumatic shock:
    • Monitor temperature and aggressively treat hypothermia.
    • Monitor fibrinogen levels and replace with cryoprecipitate if needed.
    • Monitor calcium and potassium.  MT can induce hypocalcemia and hyperkalemia.

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Category: Visual Diagnosis

Title: What's the Diagnosis?

Posted: 4/15/2013 by Haney Mallemat, MD (Emailed: 4/17/2013)
Click here to contact Haney Mallemat, MD

Question

35 year-old female presents with fever and hypotension. Bedside ultrasound is performed and is shown here. What's the diagnosis? 

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  • Persistent junctional reciprocating tachycardia (PJRT) occurs in children and is characterized by an incessant & sometimes even permanent narrow complex tachycardia 
  • PJRT also occurs in adults but in about half these patients it is paroxysmal rather than incessant/permanent
  • PJRT is a form of orthodromic AVRT and is caused by a concealed slowly conducting decremental accessory pathway
  • Unlike accessory pathways of Wolff Parkinson White syndrome in children that are associated with a structural heart defect in about 1/3 of patients accessory pathways of PJRT are generally isolated
  • PJRT can be a serious arrhythmia, particularly in children because of tachycardia-induced cardiomyopathy (TIC) - deterioration of ventricular contractile function caused by very prolonged periods in tachycardia
  • LV dysfunction generally resolves following successful ablation of the tachycardia and is indicated even in the very young when the rate is not controlled and especially in patients with persistent left ventricular dysfunction.

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Category: Orthopedics

Title: What should I MRI?

Keywords: MRI, spinal cord compression (PubMed Search)

Posted: 4/13/2013 by Brian Corwell, MD
Click here to contact Brian Corwell, MD

You have a patient with a spinal cord syndrome and you order the MRI. Have you ever had that conversation with radiology where you have to "choose" what part of the spine you want imaged?

The entire spine needs to be imaged!

The reason: False localizing sensory levels.

For example: The patient has a thoracic sensory level that is caused by a cervical lesion.

 

A study of 324 episodes of malignant spinal cord compression (MSCC) found that clinical signs were very unreliable indicators of the level of compression. Only 53 patients (16%) had a sensory level that was within 3 vertebral levels of the level of compression demonstrated on MRI.

Further, pain (both midline back pain and radicular pain) was also a poor predictor of the level of compression.

Finally, of the 187 patients who had plain radiographs at the level of compression at referral, 60 showed vertebral collapse suggesting cord compression, but only 39 of these predicted the correct level of compression (i.e. only 20% of all radiographs correctly identified the level of compression).

The authors note that frequently only the lumbar spine was XR at the time of clinical presentation (usually at the referring hospital), presumably due to false localizing signs and a low awareness on the part of clinicians that most MSCC occurs in the thoracic spine (68% in this series).

 

Show References



Question

64 year-old female presents with chest pain following an argument with her husband. Her echocardiogram (apical four-chamber view) and ECG are shown. Her initial troponin is 10. What's the diagnosis?

 

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  • Takayasu arteritis (TA) is a granulomatous vasculitis that affects the aorta and its major branches
  • Involvement of the aortic arch is associated w/CNS symptoms, claudication, absent peripheral pulses, and cardiac manifestations
  • The EULAR/PReS consensus criteria for Dx of childhood TA requires characteristic angiographic abnormalities of the aorta plus 1 of the following:
  1. Absent peripheral pulses or claudication
  2. Blood pressure discrepancy in any limb
  3. Bruits
  4. Hypertension
  5. Elevated acute phase reactants
  • Gold standard for Dx is angiography; however, CT and MR angiograms are less invasive and can detect inflammation & luminal diameter changes 
  • Tx is challenging, steroids may induce remission in up to 60%
 

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Category: Critical Care

Title: Keeping the Beat: Strategies in Shock Refractory VF

Keywords: Resuscitation, ventricular fibrillation, cardiac arrest, emergency, cardiology (PubMed Search)

Posted: 4/6/2013 by Ben Lawner, MS, DO (Updated: 11/10/2024)
Click here to contact Ben Lawner, MS, DO

Recent advances in resuscitation science have enabled emergency physicians to identify factors associated with good neurologic and survival outcomes. Cases of persistent ventricular dysrhythmia (VF or VT) present a particular challenge to the critical care provider. The evidence base for interventions in shock refractory ventricular VF mainly consists of case reports and retrospective trials, but such interventions may be worth considering in these difficult resuscitation situations:

1. Double sequential defibrillation
-For shock-refractory VF, 2 sets of pads are placed (anterior/posterior and on the anterior chest wall). Shocks are delivered as "closely as possible."1,2

2. Sympathetic blockade in prolonged VF arrest
-"Eletrical storm," or incessant v-fib, can complicate some arrests in the setting of VF. An esmolol bolus and infusion may be associated with improved survival.3  Left stellate ganglion blockade has been identified as a potential treatment for medication resistant VF.4

3. Don't forget about magnesium! 
-May terminate VF due to a prolonged QT interval 

4. Invasive strategies
-Though resource intensive, there is limited experience with intra-arrest PCI and extracorporeal membrane oxygenation. Preestablished protocols are key to selecting patients who may benefit from intra-arrest PCI and/or ECMO. 5

5. Utilization of mechanical CPR devices 
-Though mechanical CPR devices were not officially endorsed by the AHA/ECC 2010 guidelines, there's little question that mechanical compression devices address the complication of provider fatigue during ongoing resuscitation. 

 

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Category: Pharmacology & Therapeutics

Title: tPA Use in Patients on New Oral Anticoagulants: Recommendations from the 2013 Ischemic Stroke Guidelines

Keywords: alteplase, tPA, dabigatran, anticoagulant, apixaban, rivaroxaban (PubMed Search)

Posted: 4/3/2013 by Bryan Hayes, PharmD (Emailed: 4/6/2013) (Updated: 4/5/2013)
Click here to contact Bryan Hayes, PharmD

A new recommendation in the 2013 Ischemic Stroke Guidelines provides guidance on what to do in patients taking new oral anticoagulants who are deemed eligible for IV fibrinolysis. Here is what the guidelines say:

"The use of IV rtPA in patients taking direct thrombin inhibitors (dabigatran) or direct factor Xa inhibitors (rivaroxaban, apixaban) may be harmful and is not recommended unless sensitive laboratory tests such as aPTT, INR, platelet count, and ECT, TT, or appropriate direct factor Xa activity assays are normal, or the patient has not received a dose of these agents for >2 days (assuming normal renal metabolizing function)." (Class III; Level of Evidence C)
 
Additional points:
  • The most helpful lab tests are not widely available.
  • A detailed history is important, but not always obtainable.

Until further data are available, a history consistent with recent use of new oral anticoagulants generally precludes use of IV tPA.

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Category: Pediatrics

Title: Conjunctivitis

Keywords: Conjunctivitis (PubMed Search)

Posted: 4/5/2013 by Jenny Guyther, MD
Click here to contact Jenny Guyther, MD

Children frequently present with "pink eye" to the ED.  When they do, parents often expect antibiotics.  How many of these kids actually need them?  Previous studies have shown approximately 54% of acute conjunctivitis was bacterial, but antibiotics were prescribed in 80-95% of cases.

A prospective study in a suburban children's hospital published in 2007, showed that 87% of the cases during the study period were bacterial.  The most common type of bacteria was nontypeable H. influenza followed by S. pneumoniae.

Topical antibiotic treatment has been shown to improve remission rates by 6-10 days.

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