UMEM Educational Pearls

Hematoma blocks for distal radius fractures

Hematoma blocks provide safe, effective analgesia without an increased risk of post procedural infections when compared with other regional blocks

Provide equal reduction quality AND pain control as procedural sedation with Propofol.

However, mean time to reduction (0.9 vs. 2.6 hours) and time to discharge post procedure (0.74 vs. 1.17 hours) were reduced with hematoma blocks.

Consider this option next time the department is busy or the patient is not an ideal procedural sedation candidate.

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• General information
  • Organism: 5 Plasmodium species (P. falciparum, P. vivax, P. ovale, P. malariae, P. knowlesi)
    • P. falciparum is responsible for most severe disease.
    • P. vivax and P. ovale are responsible for recrudescent disease.
  • Transmission via the female Anopheles mosquito, which bites at night or in the early morning.
  • Endemic in Asia, Africa, Central America, and South America

• Clinical presentation
  • Initially, the patient presents with an acute febrile illness: fever, chills, headache, nausea, lethargy, and upper respiratory symptoms.
  • Infection with P. falciparum can further progress to severe organ dysfunction.
  • The disease course is unpredictable in the non-immune individual.

• Diagnosis
  • Thick and thin peripheral blood smears demonstrating organism
    • Thick smear – confirms Plasmodium parasites
    • Thin smear – allows speciation of Plasmodium parasites
  • Hyperparasitemia is associated with increased mortality

• Treatment
  • P. falciparum or species unidentified
    • For severe malaria, IV quinine (quinidine if quinine not available)
    • IV artusenate is available from the CDC as a quinidine/quinine alternative.
    • DO NOT USE Chloroquine for severe malaria
  • Patients with evidence of complicated malaria (>3% parasitemia, signs of organ dysfunction, alterations in mental status) should be admitted to an ICU.

University of Maryland Section for Global Emergency Health

Author: Emilie J.B. Calvello, MD, MPH

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A low-tidal volume (or protective) strategy of mechanical ventilation (i.e., tidal volume of 6-8cc/kg of ideal body weight) has previously been demonstrated to be beneficial in patients with acute respiratory distress syndrome (ARDS).

A meta-analysis was recently performed to determine whether this strategy of mechanical ventilation is also beneficial for patients without lung injury prior to initiation of mechanical ventilation.

Dr. Neto, et al. performed a meta-analysis of 20 studies (total of 2,822 mechanically ventilated patients) comparing a conventional ventilation strategy (average tidal volume was 10.6 cc/kg) to a protective ventilation strategy (average tidal volume was 6.4 cc/kg) of mechanical ventilation.

The authors concluded that patients ventilated with a protective lung-strategy had reductions in:

• Mortality
• Lung injury and ARDS
• Atelectasis
• Pulmonary infections          
• Length of hospital stay

Bottom-line: This meta-analysis supports the notion that a strategy of low-tidal volume ventilation may have benefits for patients without ARDS, however prospective studies are needed.

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Do you like placing ultrasound-guided IV catheters? Check out this trick for covering the probe during the procedure.

http://ultrarounds.com/Ultrarounds/The_Vascular_Probe_Protector.html

or

https://www.youtube.com/watch?v=ZuOq6Ea_FbA&feature=plcp

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Tarsal Tunnel Syndrome (TTS)

Prior pearls have addressed Carpal Tunnel Syndrome and Cubital Tunnel Syndrome, which affect the median and ulnar nerves, respectively.  Tarsal tunnel syndrome, is a similar compression neuropathy of the tibial nerve as it transverses through the tarsal tunnel of the foot.

The tarsal tunnel is located behind the medial malleolus, and is where the posterior tibial artery, tibial nerve and several tendons transverse.  Patients will present complaining of numbness of the foot radiating into  Digits 1-4, pain, burning , and tingling of the base of the foot and heel.  TTS has many causes and is more common in athletes.

Consider the diagnosis in patients with foot pain and numbness.  If interested in more information about TTS please consider reading this eMedicine article, http://emedicine.medscape.com/article/1236852-overview

Question

A 1 year old gets sent from their pediatrician’s office for rule out meningitis. They presented with fever for 2 days and neck rigidity. Your LP results are normal. What additional test should you consider?
 

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·      Explosions can cause a complex series of injuries, which may include subtle or delayed findings.  Repeated evaluations, such as serial abdominal exams, may be required.

·      Blast injuries are divided into 4 categories:

o   Primary blast injuries: Injury from blast wave over-pressure. Found in gas filled structures (ear, lung, hollow organs)

o   Secondary blast injuries: Injury from thrown objects (primarily penetrating trauma, but may blunt)

o   Tertiary blast injuries: Injuries from patient being thrown by blast wave (blunt trauma)

o   Miscellaneous (quaternary) blast injuries: Injuries from other causes, such as burns, crush injuries, rhabdomyolysis, and toxic chemicals.

·      The most common primary blast injury is tympanic membrane rupture.

University of Maryland Section for Global Emergency Health

Author: Jon Mark Hirshon

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Burn Patients and Antibiotic Dosing

• Burn patients have a number of abnormalities in the early postinjury phase that can significantly impact the efficacy of antimicrobial therapy.  These include hypovolemia, hypoalbuminemia, and increasing GFR.
• A few pearls when dosing select antibiotics in burn patients:
  • Aminoglycosides: in the absence of renal impairment, consider more frequent dosing to achieve adequate concentrations.
  • Beta-lactams: typical doses often don't reach effective concentrations; increase the dose, frequency of administration, or duration of infusion.
  • Vancomycin: the typical dose of 1 gm is usually ineffective; use a larger loading dose (15-20 mg/kg).
  • Linezolid: standard doses are usually ineffective; use a higher initial dose.

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Question

33 year-old male found unconscious by EMS and complains of right shoulder pain upon waking up in the ED. Diagnosis? 

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Bazett's Formula QTc = QT/RR^1/2 

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Injury is often caused by sudden dorsiflexion on a plantar flexed foot w/ the knee in extension or similarly sudden knee extension with the ankle in a dorsiflexed position.

Injury has a predilection for the poorly conditioned middle-aged athlete, with "thick calves" who are engaged in strenuous activity

Strains are treated with ice, analgesics, and compression (decreases hematoma size and facilitates healing)

Also, consider casting/splinting as dictated by injury severity, such as with a night splint or a CAM boot.

Severe strains and ruptures can be splinted in plantar flexion for 3 weeks.

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Background

• Patients who are intoxicated with, or emerging from, phencyclidine (PCP) highs present with acute agitation that can be challenging to treat

• Risks of physical restraints for combative patients include injury, hyperthermia, rhabdomyolysis, and increased agitation or excited delirium

• Haloperidol is an option for chemical restraint that is typically safe and rapid acting

• Some concerns related to haloperidol use in PCP-intoxicated patients include worsened PCP-induced hyperthermia, dystonic or anticholinergic reactions, lower seizure threshold, and hypotension

 Data

• A recent retrospective case series assessed the frequency of adverse effects from the combination of PCP and haloperidol

• Of 59 cases, only two patients experienced an adverse reaction, and neither could be conclusively linked to haloperidol administration

• This analysis had several major limitations including retrospective design for identifying adverse reactions, potential for false positive PCP screens, and possible haloperidol administration more than 24 hours after PCP intoxication

​Bottom Line

While haloperidol may be safe for agitated PCP-intoxicated patients, this paper adds nothing to refute or support its use. Benzodiazepines and calm environment are still first-line therapy.

It should be noted that no data exist showing poor outcomes in PCP-intoxicated patients administered haloperidol, which begs the question "Is there even an issue?" Dr. Leon Gussow, author of The Poison Review, provides a nice answer and summary of the article here.

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• General Information
  • Organism: Bunyaviridae virus
  • Transmission: inhalation of aerosols contaminated with rodent urine or feces.
  • Seen in the southwestern United States, South and Central America
  • Death occurs from decreased cardiac output and circulatory failure.
• Clinical Presentation
  • Initial symptoms are nonspecific and occur 1-5 weeks after exposure: fever, malaise, myalgia, and GI upset
    • Can progress to fulminant ARDS-like picture in previously health young patients.
  • Signs NOT consistent with HPS: rash, hemorrhage, petechiae, peripheral or periorbital edema.
• Diagnosis
  • The diagnosis must initially be made clinically.
  • Lab tests may reveal nonspecific findings of thrombocytopenia, atypical lympthocytes with bandemia, hemoconcentration, and renal failure.
  • Chest film will demonstrate bilateral interstitial infiltrates.
  • Serology (ELISA) available through the CDC.
• Treatment
  • There is no specific therapy for hantavirus infection; Treatment is primarily supportive, with attention to respiratory status and oxygenation.

University of Maryland Section for Global Emergency Health

Author: Andi Tenner

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Previous pearls have described the increasing evidence against colloid (e.g., hydroxyethyl starch) use during resuscitation. Now it appears that the crystalloid 0.9% normal saline (NS) may be under fire. 

The use of large volumes of NS has been associated with hyperchloremic metabolic acidosis and harm in animal studies. The risk of harm in humans, however, has been less clear. 

Bellomo et al. conducted a prospective observational study in which patients being resuscitated in the control group received NS at the clinicians' discretion; i.e., chloride-liberal strategy. The use of NS was restricted in the intervention group, where other less chloride containing fluids were used for resuscitation (e.g., Ringer's Lactate); i.e., a chloride-restrictive strategy. 

The authors found that when compared to patients in the chloride-liberal group, the chloride-restrictive group had significantly less rise in baseline creatinine, less overall AKI, and a reduced need for renal replacement therapy.

Bottom line: Although this was only an observational study, the liberal use of normal saline during resuscitation may increase the risk of AKI and renal replacement therapy. 

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Question

11 year-old male is tackled and falls on his outstretched hand while playing football. X-rays are shown below. What's the diagnosis?

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An ECG pattern that signifies occlusion of the proximal left anterior descending coronary artery (LAD) without ST-segment elevation

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It seems we've finally put to bed the myth that 10% of penicillin-allergic patients will also react to cephalosporins. Dr. Campagna, et al. recently published a review article concluding that the true cross-reactivity is negligible except when side-chains are similar [PMID 21742459]. 

This topic was also the subject of a recent post on the Academic Life in EM blog (http://academiclifeinem.blogspot.com/2012/08/busting-myth-10-cephalosporin.html).

But what about the reverse question? Can I give a penicillin to a cephalosporin-allergic patient?

Dr. Romano's group tested 98 patients with skin-test postitive cepahlosprin allergy (mostly IgE -mediated anaphylaxis). Patients were then skin tested for penicillin allergy. Those testing negative were challenged with a penicillin.

• 25% of patients reacted to the penicillin

• Similar side-chain was a strong predictor of cross-reactivity

​A Letter to the Editor response to this study pointed out that the authors used a smaller-than-standard size threshold for a positive response to the penicllin AND used a higher-than-standard dose of amoxicillin for testing. In light of this, the rate of subjects with cephalosporin allergy who do not have a history of penicillin allergy but with true IgE-mediated allergy to penicillin might be much closer to 5%.

Bottom line: The cross-reactivity of penicillins in cephalosporin-allergic patients is somewhere between 5-25%.

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Conventional pediatric nasal cannula can safely deliver up to 4 lpm but are limited by cooling and drying of the airway. This leads to decreased airway patency, nasal mucosal injury, bleeding and possibly increase in coagulase negative staph infections.

HFNC delivers flow up to 40 lpm with 95-100% relative humidity at a controlled temperature. In infants, the initial flow rate is set between 2-4 lpm and can be increased to 8 lpm. Older children and can be started at 10 lpm and increased as high as 40 lpm. Oxygen is also adjustable.

Studies have shown improved comfort, respiratory rate and oxygenation compared to nasal CPAP.

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