Compartment syndrome
Definition
Injury to compartments of the limbs cause rise in pressure of one compartment leading to rises in surrounding compartment, causing positive feedback and dangerously high pressures.
Pathophysiology
Every limb is split into "compartments" i.e. fascia splits the limb connective tissue into separate areas (see diagram). The forearm has 2 compartments, the thigh, 3 and the the lower leg, 4.
An insult to a compartment (such as a fracture) can cause a rise in pressure of that compartment. This can compromise venous outflow (the veins in the compartment are being squashed). Capillary blood flow is reduced (the blood can't get out of the capillaries as quickly) meaning that tissues in that compartment can become ischaemic - not enough oxygenated blood is getting to them. This ischaemia results in increased blood flow to the area but this compounds the problem further as this results in a further rise in pressure Thus, a vicious cycle of increasing pressure and reducing blood flow takes place.
Untreated, this can lead to severe ischaemia, gangrene and may result in the need for limb amputation.
Risk Factors
Anything that results in an increase in pressure within a compartment:
Clinical Features
- Occur within 48 hours of injury
- Pain despite fracture immobilisation
- Altered sensation (in distrubtion compatible with nerves passing through affected compartment)
- Muscle tenderness
- Excessive pain on passive movement
- Peripheral pulses may NOT be affected
Management
The basic idea is to reduce pressure. First things first - remove anything that may be increasing the pressure (casts, splints, spandex Wolverine outfit). If this doesn't work you, or somebody good at it, needs to perform a fasciotomy. This involves cutting the affected compartment open and leaving the wound open until the situation resolves. Obviously, this means the sking and tissue will heal less quickly but that's better than losing your leg.