January 24, 2010

Traumatic rhabdomyolysis

In recent news, a survivor of the 7.0 earthquake in Haiti have been found after 10 days -- including a 22 year old, Jean-Pierre.  In the rubble of the collapsed hotel he fed on cola, beer and cookies to stave off dehydration and malnutrition until his timely rescue.

He was lucky enough to dive underneath a desk as the earthquake hit, avoiding major trauma.  What if his legs were pinned under tons of rock and timber?  What if he were held immobile for the better part of a week?

Jean-Pierre was spared the fate of acute renal failure/acute tubular necrosis by traumatic rhabdomyolysis.  It would start as dark red urine, that eventually lessens until there is no urine being produced at all.



Myoglobin is a heme-binding molecule present in skeletal and cardiac muscle. It makes our muscles red, especially the slow-twitch (Type I) muscles. It is similar to hemoglobin but greedier -- it's affinity for oxygen is much stronger.  Underwater mammals like seals and whales are able to hold their breath much longer than us due to their higher concentration of myoglobin in muscle.

For reasons that are not entirely clear to us, when muscle tissue breaks down from trauma and immobility, myoglobin is released into the bloodstream and subsequently filtered by the kidneys where it can cause major damage -- nephrotoxicity by iron-dependent and -independent mechanisms.
1) Ferrous oxide (Fe2+) is oxidized into Ferric oxide (Fe3+) and leads to free radical damage in the kidneys.
2) Tubule obstruction and direct toxic effects are thought to occur as well.

Aggressive saline infusions with possible addition of sodium bicarbonate to alkalinize the urine (and prevent conversion of myoglobin into its more toxic metabolites) are the sole treatment of this kidney condition.  This makes sense, since you're clogging up the filtration system with this muscular gunk, you vigorously flush the whole system out!

We're talking about boluses of 20cc/kg (or ~1.5 L of NS for the typical person) initially, with maintenance IVF of 200-300cc/hr thereafter!

This is expected to go on until the urine output hits 2-3cc/kg/hr (or 150-200cc/hr for the typical person) and the urine clears up.


Hopefully you find this topical and interesting as well.



Photo by simminch via flickr

BurnDoc ICU Rounds:
-Traumatic rhabdomyolysis/Crush Syndrome
-Acute Renal Failure

Myoglobinuria - Medscape

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