Compartment Syndrome Flashcards
Describe the definition of compartment syndrome
elevated interstitial pressure within a closed fascial compartment resulting in microvascular compromise
Describe the causes of compartment syndrome
Internal pressure increase:
- trauma (fracture, entrapment)
- bleeding
- muscle oedema/myositis
- intracompartmental fluid/drug administration
- re-perfusion (vascular surgery eg. stent/bypass)
External compression:
- impaired consciousness/loss of protective reflexes (drug/alcohol/iatrogenic)
- positioning in theatre (esp lithotomy)
- bandaging/casts
- full thickness burns
What are the clinical features of compartment syndrome?
- pain (out of proportion to that expected of the injury)
- pain on passive stretching of compartment
- pallor
- parathesia (later)
- paralysis (later)
- pulselessness (later)
What would you see at the site of compartment syndrome?
- swelling
- shiny skin (due to swelling/changes in autonomic function)
- autonomic response (sweating, tachycardia)
How is a diagnosis of compartment syndrome carried out?
- majority of cases is clinical diagnosis
But if patient has decreased consciousness:
- compartment pressure measurement
- normal = 0-4mmHg, 10mmHg with exercise
- diagnosis: CP>30mmHg/ DBP-CP <30mmHg
What is the management of compartment syndrome?
- open any dressings/bandages urgently
- reassess patient
- if symptoms settle then that is fine
- if no improvement/deterioration then patient needs surgical release of fascial compartment
- delayed wound closure (>48hrs), skin grafting
Describe the pathophysiology of compartment syndrome
- in a non-expansile compartment increases in internal pressure/external compression results in increase in pressure of the compartment
- results in reduction in venous outflow (collapse of capillaries once compartmental pressure exceeds capillary pressure) but continuation of arterial inflow which perpetuates pressure increase
- oedema (endothelial permeability increased) and autoregulatory mechanisms overwhelmed
- results in ischaemia (+ release of myoglobin) and permanent damage (4hrs)
- ischaemic nerves can become neuropraxic 4hrs (irreversible if left too long)
- compromise of arterial supply late
Describe the cycle of events in compartment syndrome which lead to progressive pressure increases
- increased compartment pressure
- reduced venous outflow
- reduced blood flow and tissue perfusion
- ischaemia and muscle swelling
- increased membrane permeability and leaking of fluid
When is considered a late presentation for compartment syndrome and what has occurred at this stage?
- 8 hrs
- nerve axonotmesis and irreversible change
- irreversible muscle ischaemia and necrosis
What are the end stage limb changes that occur due to compartment syndrome?
- stiff fibrotic muscle compartments (muscle dying, nerves cannot contract)
- impaired nerve function (loss of sensation)
- clawing of limbs
- loss of function
Describe a fasciotomy
- release of pressure (full length decompression) + dead muscle excised with wounds left open
- outflow restored, debridement repeated every 48hrs until pressures normalise
- circulation restored and tissues preserved
What are the perioperative aims of a fasciotomy?
- release pressure of muscular compartment and debridement of dead tissue
- adequate hydration and correction of fluid loss
- monitor and regulation of electrolytes
- correction of acidosis
- monitor renal function
- address myoglobinuria
In what circumstances would we not carry out a fasciotomy on a patient with compartment syndrome?
- if the patient presents too late
- irreversible damage is already present (and therefore the outcome won’t change)
- fasciotomy may just predispose to infection
- non-operative treatment opted for
- splint limb in position of function (eg. Fingers extended or plantar extension)
