Compartment syndrome Flashcards
What are the compartments of the lower limb?
- Anterior
- Lateral
- Superficial posterior
- Deep posterior
What is the definition of compartment syndrome?
Elevated interstitial pressure within a closed fascial compartment resulting in microvascular compromise
What are the causes of compartment syndrome?
- Increased internal pressure e.g. bleeding, swelling, iatrogenic infiltration
- Increased external compression e.g. casts/bandages, full thickness burns
- Combination of the two
Explain the process following increased compartment content within an expansile compartment
- Compartment content rises
- Temporary rise in pressure
- Comaprtment expands and pressure stabilises, blood flow is maintained
Explain the process following external compression of an expansive compartment
- Swelling e.g. after an injury
- External compression removed
- Pressure increases
- Venous flow is restored and circulation improves
- Pressure normalises
Describe the process leading to compartment syndrome when there is bleeding into a compartment
- Bleeding into the compartment increases the compartment content
- Pressure increases
- Venous flow reduced but arterial inflow increases
- Pressure increases, ishcaemia and permanent damage result
What is the pathophysiology of compartment syndrome?
- Pressure within the compartment exceeds pressure within the capillaries -> reduced blood flow
- Muscles become ischaemic and develop oedema through increased endothelial permeability
- Auto-regulatory mechanisms become overwhelmed
- Necrosis begins in the ischaemic muscles after 4 hours. The damaged muscles release myoglobin
- Ischaemic nerves become neuropraxic. This may recover if received early but permanent damage may result after as little as 4 hours
- Irreversible damage: loss of the function, limb, or life
- late: compromise of the arterial supply
What are the effects to the limb compartment after one hour of ischaemia
Nerve conduction normal, muscle viable
What are the effects to the limb compartment of 4 hours of ischaemia?
- Neuropraxia in nerves (reversible)
* Reversible muscle ischaemia
What are the effects to the limb compartments after 8 hours of ischaemia?
- Nerve axonotmesis and irreversible change
* Irreversible muscle ischaemia and necrosis
What are the end stage limb changes in compartment syndrome?
- Stiff fibrotic muscle compartments
- Impaired nerve function
- Clawing of limbs
- Loss of function
What are the internal pressure causes of compartment syndrome?
- Trauma: fractures, entrapment
- Muscle oedema/myositis
- Intracompartmental administration of fluids/drugs
- Re-perfusion - vascular surgery
What are the external compression causes of compartment syndrome?
- Impaired consciousness/protective reflexes: drug/alcohol misuse, iatrogenic
- Positioning in theatre - lithotomy
- Bandaging/casts
- Full thickness burns
What are the clinical features of compartment syndrome?
- Pain out of proportion to that expected from the injury (main symptom)
- Pain on passive stretching of the compartment
- Pallor
- Parasthesia
- Paralysis
- Pulselessness
- Swelling
- Shiny skin
- Autonomic responses: sweating, tachycardia
Explain the diagnosis of compartment syndrome relating to pressure measurement
- Normal pressure of compartment is 0-4mmHg or up to 10mmHg with exercise
- The difference between diastolic BP and the compartment should be less than 30mmHg
- CP>30mmHg
