Maple Syrup Urine Disease: clear the cobwebs

19 Sep

Maple syrup urine disease (MSUD)

an autosomal recessive metabolic disorder due to deficiency of the mitochondrial branched-chain alpha-keto acid dehydrogenase (BCKD)

 

Say what??? 

TRANSLATION:

The body is unable to break down certain branched chain amino acids (BCAA) causing elevated blood levels of BCKD and increased urinary excretion of  BCAA -> sweet smelling urine

 

 

Typically diagnosed on newborn screening, however initial presentation in a newborn would be irritability, poor feeding, vomiting, lethargy, and ketonuria within 48 hours of birth.

Eventually leading to neurologic manifestations of dystonia, seizures, and cerebral edema.

 

 

So, I work in the emergency department… why do I care?

 

Episodes of acute exacerbation can occur in children who are usually controlled by nutritional management

 

Induced by intercurrent illness, exercise, injury, surgery, or fasting

 

 

Clinical manifestations of epigastric pain, vomiting, anorexia, muscle fatigue

 

Neurologic signs of hyperactivity, sleep disturbance, stupor, decreased cognitive function, dystonia, ataxia (in a child think about loss of previously mastered motor and speech function)

 

When in doubt, look for the acute onset of sweet smelling urine and send for qualitative urine organic acids to confirm

 

 

Aggressive treatment involves lowering concentrations of plasma branched chain amino acids (inhibiting protein catabolism and enhancing protein synthesis)

-IV fluid resuscitation

-treating the inciting cause (for example gastroenteritis, upper respiratory infection, etc.)

-hospital admission for serial neurological exams and monitoring for clearance of amino acids from the urine

 

 

K Estes

 

Source: Kleopa, K. A., Raizen, D. M., Friedrich, C. A., Brown, M. J. and Bird, S. J. (2001), Acute axonal neuropathy in maple syrup urine disease. Muscle Nerve, 24: 284–287.; picture

brain jog of the day: lactic acidosis

15 Sep

Something light to start off the week and jog your memory:

Check out this chart via Medscape, refresh your mind on the various potential reasons for LACTIC ACIDOSIS:

 

Most of the time we focus on the possibility of ischemia/hypoperfusion as the reason for lactic acidosis, but this chart is a quick reminder to consider other options as well.  Some highlighted alternatives:

  • hypoxia
  • hepatic/renal dysfunction (impaired lactate clearance)
  • salicylates (e.g. uncoupling)
  • anti-retrovirals
  • valproic acid
  • biguanides (e.g. metformin)
  • seizures 

 

Remember, you can’t diagnose it if it never crosses your mind.  

 

References: medscape article (includes chart)

valproic acid toxicity and ammonia

12 Sep

(repost, but came up again recently, so worth a review)

RAGING HYPOTHETICAL:

–wacky/altered patient, happens to be on valproate, what could be going on?

psych?

seizure?

or maybe….

VALPROIC ACID TOXICITY
–if you’re worried about this, your differential for secondary problems/causes can include:

  • cerebral edema,
  • electrolyte abnormalities,
  • hepatotoxicity,
  • hyperammonemia/encephalopathy

HYPERAMMONEMIA w/VALPROIC ACID:

can occur after acute toxicity or chronic use

not always associated with elevated liver function tests

happens ’cause a metabolite of valproic acid inhibits an enzyme needed for ammonia elimination by the urea cycle (you can look up the names if you really want to)

valproate may also mess with carnitine, elevate ammonia that way too


BOTTOM LINE
:

wacky patient with valproate on their med list, consider sending an ammonia level and/or checking for asterixis

 

Reference(s): uptodate.com: valproic acid poisoning, picture

great visual: hematoma block

11 Sep

if you have 10 seconds only, check out this great picture for those visual learners from an old EP Monthly article:

 

if you have more than 10 seconds to spare…

 

HEMATOMA BLOCK (check out this previous post for another nice review):

  • draw up 10 cc or so of 1-2% lidocaine
  • clean site
  • insert needle into fracture spot, confirmation by
    • ultrasound
    • needle “falls” into the fracture with loss of resistance
    • flash of blood
  • infiltrate 8-12 cc lidocaine
  • wait 5-10 minutes
  • reduce away

 

References: EP monthly article; picture

Dextromethorphan intoxication

8 Sep

Dextromethorphan (DXM):

Metabolism:

Hepatic P450 enzymes into active metabolite dextrorphan.  10% of patients are poor metabolizers.

Time of peak serum concentration is 2-2.5 hours

Half-life for DXM is 1.5-4 hrs.  Half-life for dextrorphan is 3-6 hrs


Receptor activity

  • DXM is an opioid agonist at the brain stem cough center. Can cause respiratory depression, particularly in children
  • Dextrorphan
    1. serotonergic agonist: can cause serotonin syndrome
    2. adrenergic reuptake inhibitor: tachycardia, mydriasis, HTN, diaphoresis
    3. NMDA and glutamate antagonist: behavioral effects ranging from euphoria to complete dissociation. Gait ataxia.

 

Clinical effects are at plateaus of DXM doses.

  • Mild stimulation at 1.5 mg/kg or 100-200 mg
  • Euphoria and hallucination at 2.5-7.5 mg/kg or 200-400 mg
  • Partial dissociation at 7.5 mg-15 mg/kg or 300-600 mg
  • Complete dissociation at 15 mg/kg or >600 mg

 

Formulations are often combination medications with:  

  • diphenhydramine,
  • acetaminophen,
  • salicylates,
  • phenylephrine,
  • and pseudoephedrine.

robo

Workup should include labs looking for coingestants like acetaminophen and salicylates. DXM levels are available only at dedicated toxicology laboratories and not helpful.

Treatment of respiratory depression is naloxone IV 0.1mg/kg.  Other than that, treatment is supportive and specific to coingestants.

 

Submitted by Matthew Kongkatong MD.

 

References:

Dextromethorphan. DrugPoints summary. Micromedex 2.0. Truven Health Analytics, Inc. Greenwood Village, CO. Available at: http://www.micromedexsolutions.com. Accessed September 4, 2014.

Rosenbaum Chris and Edward Boyer. Dextromethorphan abuse and poisoning: clinical features and diagnosis. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA.

Rosenbaum Chris and Edward Boyer. Dextromethorphan poisoning: treatment. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA.

loop drainage with glove cuff

5 Sep

Neat idea from a recent JEM article:loop

THE PROCEDURE: Loop Drain for Abscess I&D:

Basics:

  • 1 cm incision on perimeter of the abscess
  • put clamp/forceps in to explore, break up loculations
  • push forceps to opposite end of abscess, cut another 1-cm incision down to the forceps
  • grab the loop drain, pull through to first incision
  • tie it off

(check out this previous post for a nice video & review)

 

THE SUGGESTION FROM THE ARTICLE:

since its hard to find a sterile loop drain in the ED…

cut the cuff off of the bottom of a sterile glove, use that as your “loop”

 

OTHER, less sterile options for loops:

non-sterile glove/cuff

trim a tourniquet

 

There you go.  Other trick up your sleeve, if you need it.

 

References: JEM article, picture 1picture

ultrasound for AAA

4 Sep

QUICK PEARLS:

Bedside ultrasound is the initial imaging modality of choice for identifying the size of the abdominal aorta.

 

It does not show leak, although if significant blood is present in the abdomen, that may be seen (e.g. positive FAST)

 

Ultrasound by a trained operator is 90-100% sensitive.

 

may identify a dissection flap.

 

 

abdominal aorta > 3cm define AAA.  Measurement is from outside wall to outside wall. 

 

Ultrasound may be more difficult in some due to obesity, bowel gas, or tenderness.

Common pitfall: ID-ing the IVC instead of the aorta

 

Submitted by J. Stone.

 

References: (Tintinalli’s Emergency Medicine, Chapter 63 – Symptomatic Abdominal Aortic Aneurysms; Emergency ultrasound imaging criteria compendium. Annals of Emergency Medicine 48: 487, 2006.; http://www.sonoguide.com); picture; picture 2

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