UMEM Educational Pearls

Methemoglobin (MetHb) is produce when Fe+2 in heme is oxidized to Fe+3 under oxidative stress (caused by mediation and chemicals). MetHb does not bind to oxygen and thus decrease RBC’s O2 carrying capacity.

Among medication, overdose of local anesthesia - benzocaine, dapsone, and phenazopyridine are often implicated. (Table 1)

Think about methemoglobinemia in presence of low pulse oximetry (~85%) with lack of response to supplemental oxygen, cyanosis, dyspnea, etc. (see Table 2 – signs and symptoms of MetHb) in patients who are taking or overdosed on medication listed in Table 1.

Diagnosis: CO-oximetry detects toxin-induced hemoglobinopathies, including COHb and MetHb.

Treatment: Methylene blue (1 mg/kg over 5 min) in symptomatic patients or MetHb level > 25%. Resolution of methemoglobinemia should be noted in 30 – 60 min.

G6PD deficiency: Prevalence in the U.S. is 4-7% with highest prevalence in African American population (11%). Methylene blue causes hemolytic anemia in patients with G6PD deficiency within 24 hours of administration. However, G6PD status is often unknown in ED patients.  When caring for patients with known G6PD deficiency and methemoglobinemia, providers must carefully consider the risk and benefit of treating MetHb (including severity of poisoning/MetHb) with methylene blue.

Table 1. Causes of MetHb

Table 2. Signs and symptoms

Background:

While diarrhea in adults can be inconvenient and briefly debilitating, in children it can be fatal.  Globally, diarrheal diseases are the second leading cause of death for children under five.

• Approximately 760,000 children under five die each year from diarrhea
  • Kills 2,200 children daily- more than AIDS, malaria and measles combined
• Most of the diarrhea can be prevented
  • Safe drinking water
  • Adequate sanitation and hygiene
• Diarrhea is also a leading cause of malnutrition

Clinical types of Diarrhea (with common infectious causes):

• Acute watery diarrhea lasting hours or days (e.g. rotavirus, norovirus, Vibrio cholerae)
• Acute bloody diarrhea, a.k.a. dysentery (e.g. Entamoeba histolytica, Shigella, Salmonella, Campylobacter, E. coli)
• Persistent diarrhea lasting longer than 14 days (e.g. parasites, C. difficile)

Clinical assessment:

• Early dehydration- no signs or symptoms
• Moderate dehydration
  • Thirst
  • Irritability/tiredness/lightheadedness
  • Dry mucous membranes/decreased tears
  • Decreased urine output/dark (concentrated) urine
  • Sunken eyes
  • Decreased capillary refill (2-4 sec)*
  • Decreased skin turgor*
  • Increased respiratory rate*
• Severe dehydration
  • Decreased mental status
  • Shock (rapid heart rate, low blood pressure)
  • Minimal or no urine output
  • Very sunken eyes/no tears
  • Parched/cracked mucous membranes
  • Marked decreased capillary refill (> 4 sec)*
  • Skin tenting*
  • Markedly increased respiratory rate*

*Best indicators of hydration status

Next week: Prevention and Treatment

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Advances in Catheter-Directed Therapy for Acute PE - The PERFECT Registry

Earlier this month, initial results from the multicenter PERFECT registry (Pulmonary Embolism Response to Fragmentation, Embolectomy, and Catheter Thrombolysis) were released. In this study, 101 consecutive patients with massive or submassive PE were prospectively enrolled to receive early catheter-directed therapy.

Inclusion criteria:

• Massive or submassive PE
• Presented within 14 days of symptoms
• Had CT evidence of proximal filling defect (main or lobar pulmonary artery)
• Age > 18 years old
• Had no contraindications to therapeutic anticoagulation
• PE not related to tumor thrombus

Therapy provided:

• Submassive PE: Low-dose (0.5 - 1.0 mg/hr of urokinase) infusion directly into clot
• Massive PE: catheter-directed mechanical or pharmacomechanical thrombectomy followed by low-dose thrombolytic therapy used for submassive PE patients.

Outcomes: Clinical success (stabilization of hemodynamics, improvement in pulmonary hypertension and/or right heart strain, and survival to discharge) was achieved in 86% of patients with massive PE and 97% of patients with submassive PE. There were no major procedure-related complications or major bleeding events.

Bottom Line: In patients with massive or submassive pulmonary embolism, there is growing evidence that early catheter-directed therapy may become first-line therapy for selected patients.

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Question

5 year-old with no past medical history, complains of a limp and mild left knee pain. No history of trauma. Physical exam is significant for a low-grade fever and is otherwise normal. What’s the diagnosis?

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Tensor Fascia Latae (Iliotibial Band) Pain Syndrome:

Some patients will complain of hip and back pain and can have multiple visits before somebody considers Tensor Fascia Latae Pain Syndrome AKA Iliotibial Band Syndrome.

The tensor fascia latae helps with thigh flexion at the hip, abduction, and medial rotation; and stabilizes the knee laterally

When this muscle/fascia gets tight and overcontracted it will lead to dysfunction of the gluteus and rectus femoralis muscles leading to increased hip pain due to abnormal movement of the joint.

Patients often complain of increased pain with running, especially downhill and exam is notable for local tenderness (approx. 2cm above lateral joint line) & occasional swelling over the distal lateral thigh.

Most patients respond to conservative treatment involving NSAIDs, stretching of the iliotibial band, physical therapy, strengthening of the gluteus medius, and altering their running regimens.

Lice are spread through direct contact as they crawl. Indirect contact (through brushes or hats) is less likely. One study showed that live lice were found in only 4% of infested volunteers pillowcases.

During an initial infestation, lice can reside on the head for up to 4 to 6 weeks before becoming symptomatic. Therefore, when lice are detected at school, there is no need to send the child home (or to the ED). Children also do not need to be kept out of school while receiving treatment.

Bonus: First line treatment is 1% Permethrin applied on day 0 and 9. The patient should wash their hair first with a non conditioned shampoo, apply Permethrin for 10 minutes and then rinse.

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Dabigatran is an orally administered, potent, direct thrombin inhibitor approved for the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation, and for the treatment and secondary prevention of venous thromboembolism.

Several pharmacokinectic studies have suggested that dabigatran possesses a number of ideal properties for expedited removal via extracorporeal methods.  Dabigatran has low oral bioavailability (3-7%) and is predominantly cleared (80%) by the kidneys.  It is not significantly protein bound, low-to-moderate steady state volume of distribution, and has a low molecular weight.  All of these attributes make it a candidate for extracorporeal removal.  Low protein binding may suggest redistribution into the plasma post extracorporeal removal.  

Dabigatran is a substrate for the multidrug efflux transporter P-glycoprotein.  Administration of the drug with potent P-glycoprotein inhibitors (ketoconazole, verapamil, amiodarone, quinidine) may significantly increase risk of toxicity, i.e. bleeding.

Most of the current evidence is based on case reports/case series where HD was the primary mode of removal.  

Caution: Redistribution effect in plasma dabigatran concentration was also observed in several cases within 20 min to 12 hours post cessation of renal replacement therapy.   Other limitations include:

1) Hemodynamic instability such as hypotension that may make initiation of extracoporeal removal difficult

2) Availability of indicators demonstrating effectiveness of extracorporeal removal 

3) Amount of time needed to prepare patient to receive extracorporeal therapy

4) Use of extracorporeal removal as a treatment modality has not been prospectively evaluated

Bottom line: Extracorporeal removal may be an option for patients in the setting of life-threatening bleeding but with consideration of several limitations and should not preclude or delay use of other supplemental hemostatic therapies.

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Are We Using the Glasgow Coma Scale Reliably?

• The Glasgow Coma Scale (GCS), first described in 1974, has been a tool used worldwide to assess and communicate the consciousness of patients with traumatic brain injury (TBI).
• There have been reports of variations in which GCS is assessed, such as differences in technique used to elicit pain and how confounding factors such as intubation are reported.
• Reith et al. conducted an international survey of 613 health care practitioners on their methodology of GCS assessment, reporting of GCS, and attitudes toward its current use in daily practice.
  • Participants included nurses, intensivists, anesthesiologists, emergency physicians, and neurosurgeons
• Some variations in applications, methodology, and reporting from the survey include:

• This survey suggests that there is a lack of standardization of GCS assessment and reporting which affects its reliability as an assessment and communication tool
• A free educational tool has been developed (http://www.glasgowcomascale.org) to provide a standardized approach to the use of GCS

Bottom line: There are variations in the application, assessment, and reporting of the GCS.  A standardized approach is needed for it to be a reliable assessment and communication tool.

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There is little debate that ultrasound-guided central lines are safer, faster, and more reliable compared to a landmark technique; there is some debate, however, as to whether the short axis (SA) or long axis (LA) approach is the best (see clips below).

The referenced study compared the SA and the LA technique for both the internal jugular (IJ) and subclavian (SC) venous approach. The authors measured number of skin breaks, number of needle redirections, and time to cannulation for each method.

This study demonstrated that the LA technique for subclavian placement had fewer redirections, decreased cannulation time, and fewer posterior wall punctures as compared to the SA. With respect to the IJ approach, the LA was also associated with fewer redirections than the SA view.

Bottom line: Consider the long-axis technique the next time you place an ultrasound guided central line.

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Ischemic ECG Findings: Significance of the U-wave

The U-wave is a small deflection immediately following the T-wave, commonly with the same polarity as the T-wave and most prominently seen in precordial leads V2–V3.

Prominent U-waves are most often seen with bradycardia and hypokalemia, but can also be secondary to other electrolyte imbalances and medications.

Typically, T- and U-wave polarities are concordant; discordant U-waves have been identified several hours prior to other ECG changes in acute myocardial infarction.

Some studies note that exercise induced U-wave inversion is highly predictive of CAD; negative U -waves in the precordial leads during exercise had a higher specificity (88% vs. 70%) & positive predictive value (77% vs. 61%) for ischemia than ST-depression.

Reinig et al. 2005 showed that negative concordance of T- and U-waves have poor prognosis & is quite specific for ischemia.

·      ECG’s were divided into 3 groups:

o   Type 1 T-U discordance (negative T waves + positive U waves)

o   Type 2 T-U discordance (positive T waves + negative U waves)

o   Negative T-U concordance (both T & U waves negative)

* Significantly higher rate of CAD (88% vs. 58%) (P-value <. 0001) in the negative T-U concordance group 

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Posterior Shoulder Dislocations are uncommon (strong supporting structures vs. anterior)

But commonly missed by physicians

Mechanism: Direct blow anterior shoulder/FOOSH with shoulder internally rotated and ADDucted)

May also see with seizure/electric shock (tetanic contraction)

Clinical findings subtle

Shoulder held in ADDuction and internal rotation. Patient unable to externally rotate arm from this position. If habitus allows, anterior shoulder depression/posterior fullness.

Radiology: Decreased overlap between humeral head and glenoid fossa. Proximal humerus fixed in internal rotation looks like a light bulb on a stick.

Y view will show subtle posterior displacement of humeral head (not as dramatic as is in anterior dislocations!)

http://cdn.lifeinthefastlane.com/wp-content/uploads/2009/06/posterior_shoulder_dislocation_005.jpg

http://eorif.com/Shoulderarm/Images/Shoulder-dislocationP1.jpg

Background

In addition to the down regulation of GABA receptors in chronic ethanol users, there is an upregulation in NMDA receptor subtypes. Although the pathophysiology is much more complex, when ethanol abstinence occurs, there is a shortage of GABA-mediated CNS inhibition and a surplus of glutamate-mediated CNS excitation. If GABA agonists are the mainstay of treatment, why not also target the NMDA receptor? Enter ketamine.

The Data

Only one study exists and was published recently.

• Retrospective review of 23 adult patients administered ketamine specifically for management of AWS.
• Mean time to initiation of ketamine from first treatment of AWS, and total duration of therapy were 33.6 and 55.8 hours, respectively.
• Mean initial infusion dose and median total infusion rate were 0.21 and 0.20 mg/kg/h, respectively.
• No change in sedation or alcohol withdrawal scores within 6 hours of ketamine initiation.
• Median change in benzodiazepine requirements at 12 and 24 hours post-ketamine initiation were -40.0 and -13.3 mg, respectively.
• One documented adverse reaction of oversedation, requiring dose reduction.
• Authors concluded that ketamine appears to reduce benzodiazepine requirements and is well tolerated at low doses.

Application to Clinical Practice

While the dexmedetomidine studies should not be using reduction in benzodiazepine requirements as an endpoint, it may be acceptable for ketamine since it actually works on the underlying pathophysiology. More studies are needed but it's good to see we’re starting to look at it.

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Introduction:

There were approximately 56 million deaths worldwide in 2012. The causes of death vary significantly based upon the income level of the country.

High-income Countries:

• 7 out of 10 deaths were among individuals 70 years or older
• Only 1 in 100 deaths were in children under 15 years
• Most deaths were due to chronic diseases, such as cardiovascular diseases, cancer, dementia, COPD or diabetes

Low-income Countries:

• Only 2 of every 10 deaths were among individuals 70 years or older

• Almost 4 of every 10 deaths were among children under 15 years
• People frequently die of infectious diseases, such as lower respiratory infections, HIV/AIDS, diarrheal diseases, malaria and tuberculosis.
• Complications of childbirth are also among the leading causes of death

Bottom Line:

Acute care services in the US and high-income countries need to acknowledge the growing number of individuals with chronic diseases and the rapidly growing elderly population. In low-income countries, acute care services still need to primarily address maternal/child infections and problems as well as infectious diseases.

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Safety of Thoracentesis

• Thoracentesis is routinely performed in both acute and non-acute patients while patients are admitted to the hospital for respiratory distress
• A recent 12 year cohort study of 9320 thoracenteses was published from Cedars-Sinai Hospital
• The clinicians that perform these procedures are well experienced
• The most common complications include pneumothorax, re-expansion pulmonary edema, and bleeding

Results after 24 hours of followup post-procedure

• 0.61% of iatrogenic pneumothoraces
• 0.01% rate of re-expansion pulmonary edema
• 0.18% of bleeding episodes

Other interesting points:

• Pneumothorax was associated with removing >1500 mL of fluid and more than one needle pass
• Ultrasound was routinely used
• A safety-tipped needle/catheter was used
• Fluid was removed by manual hand pumping (not vacuum bottles)
• CXR only done post-procedure if patients were symptomatic
• No blood products were given for low platelets or thrombocytopenia

Bottom line: Use your ultrasound to direct your tap and dont take out more than 1500 mL routinely

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Aside from sodium chloride and sodium bicarbonate, several commonly used emergency department medications (namely IV antibiotics) contain a significant amount of sodium. In patients with heart failure or other conditions requiring sodium restriction, judicious use should be considered.

Notes:

• Available references all quote slightly differing sodum contents. Therefore, the daily totals are approximate, but within 100 mg of the various references.
• To convert mg to mEq or mmoL, divide by 23.

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There are some studies that have shown that NSTEMI patients have done worse when administered opioids. Most studies were not well controled and the exact mechanism was not clear. This study adds a biological mechanism to these fidnings.

Hobl et al. showed clopidogre concentrations delayt peak yhours, have overall decrease AUC and actually decrease active metabolites when morphine is administered IV. Morphine may not be the right choice in any ACS that receives clopidogrel.

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A Lancet Commission on Global Surgery has just published a 56 page article about the need to improve access to surgery and anesthesia care.  Its five key messages are:

• 5 billion people lack access to safe, affordable surgical and anaesthesia care when needed
• 143 million additional surgical procedures are needed each year to save lives and prevent disability
• 33 million individuals face catastrophic health expenditure due to payment for surgery and anaesthesia each year
• Investment in surgical and anaesthesia services is affordable, saves lives, and promotes economic growth
• Surgery is an indivisible, indispensable part of health care

The need for high quality acute care, both for urgencies and emergencies, is clearly an important component of providing “universal access to safe, affordable surgical and anaesthesia care”- the vision of the Commission.

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SIRS and Severe Sepsis Screening

• Sepsis remains one of the most common critical illnesses managed by emergency medicine and critical care physicians.
• Many EDs and ICUs have screening protocols for early detection of the patient with sepsis. Most protocols use the systemic inflammatory response syndrome (SIRS) as a central component of early identification.
• A recent study stresses caution when simply using the SIRS criteria to screen for severe sepsis:
  • Retrospective review of the ANZICS Adult Database
  • Divided patients into SIRS-positive ( 2 SIRS criteria with at least 1 organ failure) and SIRS-negative ( < 2 SIRS criteria with at least 1 organ failure)
  • 109,663 patients
  • 12% of patients diagnosed with severe sepsis or at least 1 organ failure had < 2 SIRS criteria at admission.
  • Mortality for the SIRS-negative cohort remained relatively high at 16.1%
• Take Home Point
  • Using the SIRS criteria to screen patients for severe sepsis will miss 1 out of every 8 patients with infection and organ dysfunction.

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