UMEM Educational Pearls

Title: Vent Management: Finding the AutoPEEP!

Category: Critical Care

Keywords: Mechanical Ventilation, autoPEEP, PEEP, obstructive lung disease, critical care (PubMed Search)

Posted: 12/2/2013 by John Greenwood, MD (Updated: 12/3/2013)
Click here to contact John Greenwood, MD

 

Vent Management: Finding the AutoPEEP!

OK, so we all know not to, "...Fall asleep on Auto-PEEP" thanks to Dr. Mallemat's pearl that can be seen here.  But now the question is, how do you know if your patient is air-trapping?

There are 3 ways you can look for evidence of Auto-PEEP on the ventilator:

  1. Do an end-expiratory hold:  If the measured PEEP is more than the PEEP set on the vent after a 2-3 second hold, the difference is your Auto-PEEP.

  2. Look at the expiratory flow waveform:  If the waveform does not return to baseline (still expiring when inspiratory ventilation occurs), there's Auto-PEEP!

  3. Compare the inspiratory vs. expiratory volumes.  If the inspiratory volumes are much higher then the expiratory volumes, consider Auto-PEEP.

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Question

Which view of the heart is this and can you name the structures from A-G?

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Title: ECG Following Cardiac Transplant

Category: Cardiology

Keywords: Cardiac Transplant (PubMed Search)

Posted: 12/1/2013 by Semhar Tewelde, MD (Updated: 8/28/2014)
Click here to contact Semhar Tewelde, MD

ECG Following Cardiac Transplant

  • Suturing of donor atria to the corresponding structures of a recipient’s residual atria produces two sets of P-waves:
    • A small native P-wave (often so small it may not been visualized)
    • Followed by a donor P-wave of normal size associated w/ a QRS complex
  • A complete or incomplete right bundle branch develops in >80% transplant recipients
  • ~7–25% of recipients also demonstrate a left anterior fascicular block (LAFB)
  • The transplanted heart contracts faster than the atrial remnant secondary to autonomic denervation frequently resulting in an increased resting heart rate 

 

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Title: Posterior Shoulder Dislocation

Category: Orthopedics

Keywords: Posterior, Dislocation, Shoulder (PubMed Search)

Posted: 11/30/2013 by Michael Bond, MD (Updated: 11/24/2024)
Click here to contact Michael Bond, MD

Posterior Shoulder Dislocations

  • A rare type of shoulder dislocation
  • Accounts for 2-4% of all shoulder dislocations
  • Classic mechanism of injury is a seizure or electrocution
  • Reported to occur bilaterally in 15% of cases
  • Often missed on the initial visit.
  • Patient will complain of pain with movement of the shoulder and the arm is held in internal rotation.
  • Can be missed on the AP, lateral and Y-views of the shoulder.
  • Axillary or modified Axillary views are the best view to visualize a posterior shoulder dislocation. Shown below:

Axillary View of Shoulder

(A posterior shoulder dislocation will show the humeral head displayed superiorly in the image away from the clavicle which is the inferior most bone)

Some things to look for on the AP view that will suggest a posterior shoulder dislocation:

  • Lightbulb sign – The head of the humerus in the same axis as the shaft producing a lightbulb shape
  • The ‘rim sign’ – Widening of the glenohumeral space
  • The vacant glenoid sign – the anterior glenoid fossa appears empty

Life in the Fast Lane as a great discussion of posterior shoulder dislocations at http://lifeinthefastlane.com/posterior-shoulder-dislocation/

 Best way to make the diagnosis --- suspect it and get an axillary view.



Title: Clinically Ambiguous Pediatric Abdominal Trauma: Go beyond the FAST!

Category: International EM

Keywords: Pediatric, Trauma, Ultrasound, Abdomen, International (PubMed Search)

Posted: 11/27/2013 by Andrea Tenner, MD
Click here to contact Andrea Tenner, MD

General Information:
Abdominal injuries account for 10% of trauma deaths in patients aged 5–14 years.  The burden of injury is greatest in low- and middle-income countries, where 95% of all childhood injury deaths occur.

Relevance to the EM Physician:
  • In children with abdominal trauma, the clinical picture does not always distinguish who can be managed conservatively versus aggressively.  
  • Also, unlike in adults, 30% of solid organ injury in children presents without free fluid on ultrasound. (In a 107-patient study, ultrasound had a sensitivity of 55% as compared to CT).
  • A study of 497 stable peds patients found that the combination of FAST and LFT results were 88% sensitive and 98% specific (positive predictive value=93.7%, negative predictive value=96.1%) for intra-abdominal injury in pediatrics.

Bottom Line:  In a stable pediatric abdominal trauma victim, combined FAST and LFT results are an effective screening tool to evaluate for intra-abdominal injury.

University of Maryland Section of Global Emergency Health
Author: Tristan Meador, MD

 

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The management of alcohol withdrawal syndrome (AWS) includes supportive care focusing on the ABC’s and administration of benzodiazepines (BDZ). 

While BDZ are effective in the treatment of AWS, some patients may require very high doses of BDZ to control symptoms (tachycardia, hypertension, diaphoresis, etc.); unfortunately, high-doses of BDZ may lead to suppression of the respiratory drive and endotracheal intubation.

Dexmedetomidine (DEX) is a sedative agent that is an intravenous alpha2-agonist (it's like clonidine); it reduces sympathetic outflow from the central nervous system and it may help treat withdrawal syndromes. The major benefit of DEX is that it does not suppress the respiratory drive, thus intubation is not required.

Smaller trials and case series have shown that patients with AWS who were treated with BDZ in addition to DEX had better symptom control, lower overall BDZ doses, and less respiratory depression/intubation.

Bottom-line: While more trials are needed, consider adding DEX for patients with AWS who require high-doses of BDZ.

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Question

What view of the heart is this and can you name everything from A-G?

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Title: Too early to give hypothermia the cold shoulder

Category: Cardiology

Keywords: Therapeutic Hypothermia, ROSC, Cardiac Arrest, Resuscitation (PubMed Search)

Posted: 11/23/2013 by Ali Farzad, MD (Updated: 3/10/2014)
Click here to contact Ali Farzad, MD

Hyperthermia after resuscitation from cardiac arrest is associated with poor outcomes and death. Induced mild hypothermia gained widespread use after two RCT's from 2002 (n=352) showed improved survival & neurological outcomes for select patients with OHCA. 
 
In a new RCT (n=939), patients with ROSC after arrest were assigned to targeted temperature management at either 33°C or 36°C. Survival (51%) and a good neurologic outcome (47 to 48%) did not differ significantly between groups. However, cooling to 36°C is not the same as not regulating temperature and allowing hyperthermia. 
 
In contrast to a decade ago, one half instead of one third of these patients can expect to survive hospitalization. Paying attention to temperature makes survival more likely than death when a patient is hospitalized after cardiac arrest. 
 

Want more emergency cardiology pearls? Follow me @alifarzadmd

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Title: Exercise-induced laryngeal obstruction (EILO)

Category: Orthopedics

Keywords: bronchospasm, asthma, exercise-induced laryngeal obstruction (PubMed Search)

Posted: 11/23/2013 by Brian Corwell, MD
Click here to contact Brian Corwell, MD

Unexplained respiratory symptoms during exercise are often incorrectly considered secondary to exercise induced asthma/bronchospasm.

An important diagnosis on the differential should be exercise-induced laryngeal obstruction (EILO).

Of 91 athletes referred for asthma workup, 35% had EILO.

The presence of inspiratory symptoms did not differentiate athletes with and without EILO.

61% of athletes with EILO used regular asthma medication at referral.

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Title: Can kids survive traumatic cardiac arrest? (submitted by Nikki Alworth, MD)

Category: Pediatrics

Keywords: trauma, cardiac arrest, return of spontaneous circulation (PubMed Search)

Posted: 11/22/2013 by Mimi Lu, MD
Click here to contact Mimi Lu, MD

Pediatric traumatic arrest victims have a very low survival rate. Previous studies have shown that 21% achieve initial ROSC but only 0.3% survive hospital discharge with an intact neurologic status.

A recent retrospective study examined predictors of survival for pediatric traumatic out-of-hospital cardiac arrest. Of the 362 patients included in the study, none had spontaneous circulation upon arrival in ED. BLS was initiated by EMS in the field with a mean response time of 5.4 minutes and mean transport time of 10.2 minutes. The study compared MAP, cardiac rhythm, urine output, skin color of face/trunk, initial GCS and body temperature.

In this study, 9% of kids made it to discharge, 11 of which had good neurologic outcome and 23 with poor neurologic outcome. Predictors of survival were:
  • High or normal BP
  • Normal heart rate after ROSC
  • Sinus rhythm after ROSC
  • Urine output >1 ml/kg/hr
  • Noncyanotic skin color
  • GCS >7 on arrival
Limitations of study: Very few kids survive with good neurologic outcome, making it difficult to identify accurate predictors for this group as the sample size is too small. Further, this study didn't look at hypothermia or ECMO as a means to achieve improved outcome.

Reference: Predictors of survival and neurologic outcomes in children with traumatic out-of-hospital cardiac arrest during the early postresuscitative period. Lin YR, Wu HP, Chen WL, et al. Journal Trauma Acute Care Surg. Sept 2013:75(3);439-447.


Title: aPCC for rivaroxaban and dabigatran

Category: Toxicology

Keywords: rivaroxaban, dabigatran (PubMed Search)

Posted: 11/21/2013 by Fermin Barrueto (Updated: 11/24/2024)
Click here to contact Fermin Barrueto

Reversal of the new anticoagulants rivaroxaban (Xarelto) and dabigatran (Pradaxa) has been challenging particularly in the ED setting with no definitive reversal agent. Intracerebral hemorrhage or critical GI bleed management becomes challenging and worsens mortality.

There is growing literature that states activated prothrombin complex concentrate or non-activated PCC may reverse these new anticoagulants. A volunteer study (1) showed its efficacy and concensus workgroups are now recommending aPCC as first line therapy(2).  The search goes on for a reliable reversal agent for these new anticoagulants which were suppose to solve more problems instead of create new ones.

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Title: Meningococcal Outbreaks and Vaccine Coverage

Category: International EM

Keywords: meningoccocus, Neisseria meningitidis, global, infectious disease (PubMed Search)

Posted: 11/20/2013 by Andrea Tenner, MD (Updated: 11/24/2024)
Click here to contact Andrea Tenner, MD

General Information:

Nisseria meningitidis is the common culprit in epidemic meningitis.  Serogroup B is currently causing an outbreak on the Princeton campus.  So what are the serogroups and why are they important?

Six main serogroups cause disease:  A, B, C, Y, X, W-135.

  • A: most common cause of meningitis in the Meningitis Belt in Sub-Saharan Africa, caused pandemics in the 1960s-1980s in Asia as well
  • B, C, Y: Cause the large majority of cases in Europe and the Americas
  • A, W-135: most common culprits in outbreaks of meningitis associated with the Hajj
  • X: causes disease in some countries in Sub-Saharan Africa

Two quadrivalent vaccines are currently licensed in the US that cover Serogroups A, C, Y, and W-135.

Relevance to the EM Physician: The currently available vaccines in the US cover the majority of serogroups of meningococcus, however, Serogroup B (currently causing an outbreak at Princeton) is not covered, nor is Serogroup X (for travelers to Sub-Saharan Africa).

Bottom Line: Serogroups B and X are not covered by the currently available vaccines in the US and at risk populations (and physicians treating those patients) should be made aware of the gap in coverage.  Investigations for a vaccine for Serogroup B (licensed in Europe and Australia, but not in the US) are currently underway.

University of Maryland Section of Global Emergency Health

Author: Andi Tenner, MD, MPH, FACEP

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Title: Ottawa Rules for Subarachnoid Hemmorhage (SAH)

Category: Critical Care

Keywords: subarachnoid hemmorhage, sah (PubMed Search)

Posted: 11/19/2013 by Feras Khan, MD (Updated: 11/24/2024)
Click here to contact Feras Khan, MD

Ottawa Rules for Subarachnoid Hemmorhage (SAH)

Background

  • Headache is a common reason for ER visits
  • 1-3% of headaches are SAH
  • Misdiagnosis of SAH can be fatal
  • Lumbar puncture can be a painful/time-consuming procedure
  • Goal is to design a decision rule to help guide the clinician

Design

  • Multi-center study at ten Canadian emergency departments.
  • 2131 adults with a headache peaking within 1 hour and no neurologic deficits
  • Non-traumatic headaches only; GCS of 15 required
  • SAH defined as: 1. CT evidence of SAH; 2. Xanthochromia in CSF; or 3. RBCs in the final tube of CSF, WITH positive angiography findings.

Results

132 (6.2%) had SAH

Decision rule including any:

  1. age 40 years or older
  2. neck pain or stiffness
  3. witnessed LOC
  4. onset during exertion

Had 98.5% sensitivity (95% CI, 94.6%-99.6%) and 27.5% specificity (95% CI, 25.6%-29.5%)

Adding “thunder-clap” headache and “limited neck flexion on examination” (inability to touch chin to chest or raise the head 8cm off the bed if supine) resulted in 100% (95% CI, 97.2%-100%) sensitivity.

The rule was then evaluated using a bootstrap analysis on old cohort data to validate the rule.

Conclusion/Limitations

  • Exciting new rule for SAH that needs to be validated in a new, independent cohort
  • The rule may not decrease the rate of investigation (CT, LP, or both)
  • It may decrease the amount of SAH that are missed on first visit to the ER
  • Limited by narrow criteria for inclusion in the rule/not meant for other causes of headache
  • See the JAMA editorial with the article for a nice discussion of the difficulties with decision making rules.
  • The rule:
    The Ottawa SAH Rule
    • For alert patients older than 15 y with new severe nontraumatic headache reaching maximum intensity within 1 h

    • Not for patients with new neurologic deficits, previous aneurysms, SAH, brain tumors, or history of recurrent headaches (≥3 episodes over the course of ≥6 mo)

    • Investigate if ≥1 high-risk variables present:

    1. Age ≥40 y

    2. Neck pain or stiffness

    3. Witnessed loss of consciousness

    4. Onset during exertion

    5. Thunderclap headache (instantly peaking pain)

    6. Limited neck flexion on examination

     

 

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Question

48 year-old presents after falling 15 feet following a “misunderstanding” with police. What's the diagnosis? ...and for a bonus question, why is this called a “Lover’s Fracture”? 

 

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Title: Utility of Intra-Aortic Balloon Pump

Category: Cardiology

Keywords: Intra-Aortic Balloon Pump, Cardiogenic Shock (PubMed Search)

Posted: 11/15/2013 by Semhar Tewelde, MD (Updated: 11/17/2013)
Click here to contact Semhar Tewelde, MD

Utility of Intra-Aortic Balloon Pump (IABP)

  • IABP therapy has not been proven to reduce mortality in all-comers with cardiogenic shock complicating acute myocardial infarction (IABP-SHOCK II)
  • A recent retrospective review of IABP therapy in patients with mechanical complications (ventricular septal rupture [VSR] or mitral regurgitation [MR]) following acute myocardial infarction has proven efficacious in this subset
    • IABP reduced mortality in patient with shock (61% vs 100%, p = 0.04)
    • IABP reduced preoperative mortality (11% vs 88%, p <0.001)
  • Post infarction VSR or MR with signs of cardiogenic shock should be considered for an IABP as a bridge to emergent surgical repair
  • Patients with mechanical complications without shock were not shown to benefit from an IABP and should undergo cardiac surgery after medical stabilization

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Title: Compartment Syndrome

Category: Orthopedics

Keywords: Compartment Syndrome (PubMed Search)

Posted: 11/16/2013 by Michael Bond, MD (Updated: 11/24/2024)
Click here to contact Michael Bond, MD

Compartment Syndrome

Compartment syndrome is classically described as having the 6 Ps:

  • Pain out of proportion to what is expected
  • Pulselessness [Late finding that you hope to never see]
  • Paresthesia
  • Paralysis
  • Pallor
  • Pressure


The diagnosis of compartment syndrome can be difficult but ultimately it comes down to measuring the pressures in the area of concern.  Various recommendations of the allowed pressure can be found, but in general a fasciotomy is not needed if the compartment pressure is 30 mmHg less then the diastolic pressure (The Delta 30).  So if the patients diastolic pressure is 70, a fasciotomy is not need if the compartment pressure is less then 40.  

Finally, if you are suspecting compartment pressure do NOT elevate the limb.  Leave it in a dependent position to help improve blood flow into the limb.



Title: Abdominal pain and fever

Category: Pediatrics

Keywords: Intussusception, abdominal pain, fever (PubMed Search)

Posted: 11/10/2013 by Jenny Guyther, MD (Updated: 11/16/2013)
Click here to contact Jenny Guyther, MD

Question

Case: A 3 year 9 month female presents with fever to 39.4 C and intermittent abdominal pain worsening over 2 days.  The patient had been tolerating food and had no change in her bowel habits.  Based on the imaging below, what is your diagnosis and treatment?

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Title: All Benzodiazepines are Metabolized by the Liver

Category: Toxicology

Keywords: benzodiazepine, lorazepam, liver (PubMed Search)

Posted: 11/11/2013 by Bryan Hayes, PharmD (Updated: 11/14/2013)
Click here to contact Bryan Hayes, PharmD

All benzodiazepines are metabolized by the liver. Some are just metabolized by pathways that are less dependent on global liver function.

The ‘LOT’ drugs are metabolized by conjugation, have no active metabolites, and have minimially affected half-lives even in the setting of liver disease.

  • L – Lorazepam

  • O – Oxazepam

  • T – Temazepam

The rest of the benzodiazepines are primarily metabolized via hepatic CYP-mediated oxidation and may have prolonged duration of effect in patients with marked liver impairment.

For a bit more detail and commentary by Dr. David Juurlink, please read my recent post on the Academic Life in Emergency Medicine blog: http://academiclifeinem.com/all-benzodiazepines-are-metabolized-by-the-liver/

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Helicopter EMS (HEMS) has rapidly grown over the past 30 years.  HEMS is frequently used to transport trauma patients from the scene of a crash. The question is: for which trauma patients is HEMS most useful?

A recent article published in the Journal of the American Medical Association, based upon data from the National Trauma Data Bank (NTDB), looked at injured patients transported to a trauma center by helicopter versus ground ambulance.  It showed that, after controlling for multiple known confounders, more severely injured patients had better outcomes when transported by helicopter than when transported by ground ambulances.  Another recent article in the Journal of Trauma and Acute Care Surgery, again based upon the NTDB further showed that HEMS survival benefit seems to limited to individuals with physiologic instability.

Bottom Line:

Transport of severely injured trauma patients by helicopter versus ground from the scene of injury to a trauma center improved patient outcomes and decreased mortality.  Transportation of stable, less injured patients by helicopter may actually worsen outcomes.

University of Maryland Section of Global Emergency Health

Author: Jon Mark Hirshon

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Acalculous Cholecystitis in the Critically Ill

  • Acute acalculous cholecystitis (AAC) accounts for almost 50% of cases of acute cholecystitis in the critically ill ICU patient.
  • Importantly, the mortality rate for AAC can be as high as 50%.
  • Risk factors for AAC include:
    • CHF
    • Cardiac arrest
    • DM
    • ESRD on hemodialysis
    • Postoperative
    • Burns
  • Unfortunately, the physical exam is unreliable, especially in intubated and sedated patients.
  • Furthermore, less than half of patients with AAC are febrile or have a leukocytosis.  LFTs can also be normal in up to 20% of patients.
  • Ultrasound remains the most common imaging modality for diagnosis.
  • Take Home Point: Consider AAC in the septic critically ill patient without a source.

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