Crush syndrome and rhabdomyolysis after limb injury

What it is

Crush syndrome, also called rhabdomyolysis, occurs when skeletal muscle is rapidly broken-down, releasing myoglobin, K+ and P into the circulation, and this leads to acute renal failure.

That one line carries the whole topic. The myoglobin released is what the dark urine points to, the K+ released from the muscle is what U&E shows as hyperkalemia, and acute renal failure is the end the treatment is given to prevent.

Under the wider heads of muscle necrosis and myoglobinuria, the causes given are crush syndrome and ischaemia, with others that are medical or due to drugs.

How it presents

The clinical features are given in two places, the limb and the renal:

• Limb: pulseless, red, swollen
• Renal: low output, acidosis

Beside that there is a second list, of what should make muscle necrosis and myoglobinuria be suspected at all: compartment syndrome, severe muscle crushing, dark urine, fever, delirium, myalgia, and a Ca2+ decrease.

So the Ca2+ goes down while the K+ goes up, and dark urine after a crush injury is on the suspect list rather than on the list that settles it.