UMEM Educational Pearls

Carbamazepine

• Anticonvulsant that can be monitored (you can draw a level)
• Toxicity resembles a TCA with seizures and cardiac conduction delays
• > 40 mcg/mL assoc with coma, seizures, respiratory failure and cardiac toxicity
• Treat widened QRS comples with sodium bicarbonate
• Adsorbs very well to activated charcoal, multi-dose may be required

• Xanthochromia is the result of metabolized hemoglobin in cerebrospinal fluid (CSF), which suggests intracranial bleed.
• It helps differentiate traumatic lumbar puncture results from true intracranial bleeding.
• It causes the CSF to have a yellowish color which can be detected with the naked eye or analyzed with a machine (done visually at UMMS).
• It typically takes at least 6 hours for xanthochromia to manifest itself. 

Degree of D-Dimer elevation and Mortality Rates

Evidence now exists that links the degree of D-Dimer elevation with mortality rate. The higher the D-Dimer, the higher the PE mortality rate.

Consider this when risk stratifying patients with PE. This adds to our use of biomarkers for risk stratification. Elevation of BNP, D-Dimer, and Troponins have been shown to predict mortality.

Critical Care Pearls for Traumatic Brain Injury

• Avoid hypotension and hypoxia - SBP < 90 and/or PaO2 < 60 are associated with significant increases in morbidity and mortality
• Hypertonic saline remains controversial - a recent large, controlled trial did not show any early or long-term benefit
• ICP monitoring routinely recommended in patients with GCS < 8 - they have a 60% chance of increased ICP
• Maintain ICP < 20 mmHg and CPP > 60
• Supportive care
  • Elevate the head of bed > 30 degrees, if possible
  • Control fever
  • Provide analgesia and sedation
• Ventilator management - keep PaCO2 between 30-35 mmHg
• Surgery - last resort to controlling increased ICP
  • Decompressive craniotomy
  • Decompressive laparotomy

The T-wave in lead V1 is usually inverted or flat. When the T-wave is upright, especially if it is tall (taller than the T-wave in lead V6), be worried about cardiac ischemia...especially if the large upright T-wave is a new finding compared to prior ECGs.

LVH, LBBB, and misplaced precordial leads are the other causes of tall upright T-waves in lead V1. In the absence of any of these three conditions, worry about ischemia.

Marriott described this finding many years ago and refers to it as "loss of precordial T-wave balance."

Seat Belt Sign:

• Patients with a seat belt sign have a high risk of hollow viscus injury
• Often have a negative CT scan
• Admit for serial exams and observation, at an absolute minimum patient should be watched 6 hours.
• Look for associated Lumbar Chance Fractures.

Severe Asthma in Pediatrics (Using “the kitchen sink” when all else fails)

Every effort should be made to avoid intubating an asthmatic pt.  Here are some possible options to consider:

• Atrovent - Multiple doses should be preferred to single doses of anticholinergics. The available evidence only supports their use in school-aged children with severe asthma exacerbation. (reference #1)
• Magnesium - Magnesium sulfate appears to be safe and beneficial in patients who present with severe acute asthma (based on 5 adult and 2 pediatric studies)
• Noninvasive ventilation - The application of NPPV in patients suffering from status asthmaticus, despite some interesting and very promising preliminary results, still remains controversial. (only one trial met criteria.  No pediatric studies)
• Heliox – No good evidence to support its use, but it is relatively safe to use, provided the patient doesn’t need more than 30% FiO2 (70%Helium)
• Ketamine – Cases suggest that for children experiencing severe asthma exacerbations, intravenous ketamine may be an effective temporizing measure to avoid exposing children to the risks associated with mechanical ventilation.
• Singulair - Intravenously administered montelukast, in addition to standard therapy, provided rapid benefits and was well tolerated among patients with acute asthma. (Study population 15yrs – 54yrs).
   

• References:

1. Plotnick LH, Ducharme FM. Combined inhaled anticholinergics and beta2-agonists for initial treatment of acute asthma in children. Cochrane Database of Systematic Reviews 1997, Issue 2. Art. No.: CD000060.
2. Rowe BH, Bretzlaff JA, Bourdon C, Bota GW, Camargo CA Jr. Magnesium sulfate for treating exacerbations of acute asthma in the emergency department. Cochrane Database of Systematic Reviews 1999, Issue 2. Art. No.: CD001490.
3. Ram FSF, Wellington SR, Rowe B, Wedzicha JA. Non-invasive positive pressure ventilation for treatment of respiratory failure due to severe acute exacerbations of asthma. Cochrane Database of Systematic Reviews 2005, Issue 1. Art. No.: CD004360.
4. Rodrigo, GJ. et al. Use of Helium-Oxygen Mixtures in the Treatment of Acute Asthma. Chest. 2003;123:891-896. 2003
5. T. Kent Denmark, Heather A. Crane, Lance Brown. Ketamine to avoid mechanical ventilation in severe pediatric asthma. Journal of Emergency Medicine. Volume 30, Issue 2. pages 163-166
6. James, JM. et al. A RANDOMIZED, CONTROLLED TRIAL OF INTRAVENOUS MONTELUKAST IN ACUTE ASTHMA. PEDIATRICS Vol. 114 No. 2 August 2004, pp. 547

SSRI Toxicity

Things to watch for in patients that are taking SSRI:

• Therapeutic administration usually safe
• Hyponatremia is a common adverse effect (ADH secretion regulated by serotonin)
• Serotonin Syndrome is a possibilty in combination with other serotnergic drugs
• One SSRI is more problematic than the rest => Citalopram and Escitalopram
  • The only SSRI that can cause QT prolongation (even 24hrs after OD) and can cause seizures
  • This is the only SSRI with significant toxicity and unfortunately is the most commonly Rx by psych

Don't forget to do  thorough assessment of deep tendon reflexes on physical examination when appropriate.  DTR assessment can help localize a lesion and determine a diagnosis (i.e. thyroid disease, Guillain Barre, spinal cord and peripheral nerve lesions).

DTR Assessment Scale:

• 4+ - very brisk, hyperactive with clonus<
• 3+ - brisker than normal
• 2+ - average, normal
• 1+ - somewhat diminished, low normal
• 0 - no response

Major DTR Assessment Locations:

• Triceps (C6, C7)
• Supinator or Brachioradialis (C5, C6)
• Knee (L2, L3, L4)
• Ankle (mainly S1)
• Plantar (L5, S1)

• Binding of vasopressor agents to their receptors is influenced by pH (and temperature and concentration)
• Acidic conditions have been shown to alter receptor numbers on cell surfaces as well as alter binding affinity
• Overall, pH values > 7.15 do not have an appreciable clinical effects on vasopressors
• At pH values < 7.1 reductions in effectiveness become apparent
• Routine administration of bicarbonate remains controversial
• Aggressively search for and treat the underlying cause of the acidosis

Blue Toe Syndrome

This syndrome refers to acute digital ischemia caused by athero-microembolism and is associated with cool, painful, cyanotic toes in the presence of palpable distal pulses.

Presence of this syndrome should prompt the Emergency Physician to search for the proximal source. Failure to identify the source and aggressively treat may lead to limb loss.

Common etiologies include:

• AAA
• Iliac artery aneurysm
• Popliteal artery aneurysm

Recent  studies have identified that a significant cause of morbidity and mortality in women, elderly, and patients with renal failure is the failure to consider renal insufficiency in dosing certain anticoagulants and anti-platelet medications, resulting in bleeding complications. Medications should be based on creatinine clearance, NOT SERUM CREATININE. When the creatinine clearance is < 30 mL/min, the dose of any renally-excreted medications should be decreased.

For example, an 85 yo woman that is 110 lbs and has a serum creatinine of 1.2 (sounds normal!) actually has a creatinine clearance < 30, which means that she has relative renal insufficiency. Her dosages of medications (e.g. enoxaparin) should be adjusted for this.

 Creatinine clearance can easily be calculated via computer programs that you can "google" (e.g. just google "creatinine clearance calculation"). If you enter the patient's gender, age, weight, and serum creatinine, the programs will calculate the value for you.

Placental Abruption

• Leading cause of fetal death (1-80 pregnancy)
• Evaluation
  • Ultrasound has very poor sensitivity
• Can check D-Dimer, Coags, Fibrinogen and Fibrin Split Products
• For a stable patient MRI can make diagnosis.
• Fetal monitoring (minimum four hours) where fetal distress and uterine contractions are seen.
• Risk factors for Placental Abruption
  • Hypertension
  • Pre-eclampsia
  • Diabetes
  • Trauma
  • Smoking
  • Cocaine
  • Advanced maternal age
• Treatment
  • C-Section

Pediatric Septic Shock

• Sepsis is the most common cause of pediatric deaths worldwide.
• Recognition is paramount!  Delayed Dx = Higher Mortality
  • Hypotension is a late finding. 
  • Look for other signs of End Organ Hypoperfusion
    • Prolonged Cap Refill, Change in MS
    • Tachycardia, Tachypnea
    • Elevated Lactate / unexplained metabolic acidosis
• Management strategy is similar to that of adults
  • Get access (Don’t forget your I/O’s if necessary)!
  • Fluid Resuscitation is the most important aspect of the management
    • Get 20-60ml/kg infused within the first 15 minutes
    • Children with septic shock who get >40ml/kg before the first hour have increased survival compared to those who do not.
      • They may require 60-200ml/kg over the first few hours.
  • Get your Abx on board quickly
  • Currently there are Protocols that are based on the Adult Surviving Sepsis Campaign.

Goldstein B, Giroir B, Randolph A. International pediatric sepsis consensus conference: definitions for sepsis and organ dysfunction in pediatrics.  Pediatr Crit Care Med. 2005 Jan;6(1):2-8.

GHB

• Sedating and amnestic, has become notorious in chemical submission (date rape)
• Very fast onset and rapid resolution though respiratory depression can occur 
• Difficult to test for with few labs and quickly eliminated through urine 
• Best chance to catch it is if the patient's first urine void is collected and tested

According to ACEP's clinical policy, a non-contrast head CT is only indicated in mild traumatic brain injury under the following circumstances:  

1)  headache
2)  vomiting
3)  age over 60
4)  drug or alcohol intoxication
5)  short-term memory deficits
6)  physical evidence of injury above the clavicle
7)  seizure

A recent study came out which confirms what we already knew... that MRSA infections are no longer confined to ICUs but are spreading to the community. What the new study does show, is that it affects particular populations disproportionately and Baltimore City, more than any other study population. The full article is attached below, or can be obtained for free from the JAMA website.

Attachments

0710170948_jama_mrsa.pdf (129 Kb)

Hyperammonemia in the Critically Ill

• Patients with acute hyperammonemia have significant morbidity and mortality 
• Fulminant hepatic failure is the most common cause of acute hyperammonemia in adult ICUs
• Other causes include TPN, GI hemorrhage, steroid use, trauma, multiple myeloma, infection with urease-splitting organisms, and drugs (salicylates, valproate) 
• Cerebral edema, intracranial hypertension, seizures, and herniation are the most significant effects
• Initial management should focus on treating intracranial hypertension - mannitol, hypothermia, N-acetylcysteine have been used
• Lactulose has not been shown to reduce mortality in acute hyperammonemia but is unlikely to be harmful

Clay AS, Hainline BE. Hyperammonemia in the ICU. Chest 2007;132:1368-1378.

There is no good evidence for what type of workup an asymptomatic hypertensive patient should get in the ED.  An ECG is likely to show LVH, a cxr will be normal in most cases, and many patients will have some degree of proteinuria.

So, what is a safe and reasonable strategy to workup these patients?

• Consider checking a serum creatinine. I say consider because even this recommendation isn't terribly evidence-based. Elevated creatinine may NOT indicate that a hypertensive emergency is present, but if the creatinine is elevated it might persuade you to choose a different antihypertensive agent (HCTZ won't lower BP effectively if the creatinine near 2.0, and many of us would be a little hesitant to start an ACE-I if the creatinine is elevated). Although there is one study that showed absence of proteinuria and hematuria was correlated with a normal serum creatinine, many patients with asymptomatic HTN will have proteinuria.
• Repeat the BP several times. One study has shown that as many as 1/3 of patients with high BP in the ED do not have elevated BP when followed up as an outpatient. Many patients' BPs will spontaneously decline (regression to the mean).
• In the asymptomatic patient a CXR and ECG will likely not help you manage a patient, so don't waste your time and the patient's money getting it.

American College of Emergency Physicians 2006 Guidelines on the evaluation of asymptomatic HTN.

New onset atrial fibrillation is rarely the sole manifestation of myocardial infarction. In other words, in the absence of accompanying chest pressure, dyspnea, diaphoresis, or other anginal equivalents, a rule-out ACS workup in not supported by the literature and is not cost-effective.

The two exceptions to the statement above are elderly and diabetic patients, in whom subtle presentations of ACS are common with or without atrial fibrillation.