Acute Compartment Syndrome is one of the few orthopaedic emergencies. If missed, it can lead to severe and life-changing consequences for the patient. This article will focus on acute compartment syndrome of the limbs.
What is compartment syndrome?
Let’s start by understanding a couple key principles and definitions.
- A compartment is a group of muscles and its associated neurovascular structures surrounded by fascia. A primary function of fascia is to provide structural support, therefore does not easily expand or stretch.
- Blood flow is dictated by a pressure gradient and flows from an area of high pressure (arterial) to an area of low pressure (venous).
If there is an increase in pressure within a compartment, due to whatever reason, it can affect the blood flow within that compartment. With enough increased pressure, it can cause excessive fluid leak from the capillaries into the extracellular space and reduced absorption by the venous system. This will further increase the intra-compartmental pressure, perpetuating the cycle. With enough swelling combined with the non-compliance of the surrounding fascia, this can lead to compression or obstruction of blood supply to the compartment. This will cause reduced oxygen supply (hypoxia) to the muscles and nerves leading to tissue ischaemia and eventually necrosis. Understanding this pathophysiology will help you understand the signs and symptoms patients experience.
How does compartment syndrome present?
There are typically five signs and symptoms (5 P’s) of compartment syndrome; which are: pain, pain, pain, pain and pain. The first sign patient’s experience is pain out of proportion to the injury. This type of pain is unique, it will not ease with pain relief and is exaggerated by passive stretching of the muscles in the affected compartment.
For example, in lower leg anterior compartment syndrome, passive flexion of the big toe (extensor hallucis longus) will cause severe pain. Other, potentially late signs and symptoms of compartment syndrome include:
These late signs and symptoms indicate potential nerve damage or vascular occlusion and could lead to irreversible consequences.
What causes compartment syndrome?
Acute compartment syndrome is usually secondary to trauma. A fracture or crush injury to an extremity are the common areas affected. A fractured tibia is the most common cause of compartment syndrome. It is therefore more common in males under 35 years of age probably due to their relatively larger muscle mass & likelihood of being involved in trauma.
Other causes include prolonged compression of a limb, application of a cast following a fracture, ischaemic-reperfusion injury or formation of eschar following a burn. Eschar following a full-thickness, circumferential burn can form non-compliant, tough, inelastic tissue anywhere in the body. The associated swelling from tissue breakdown leads to increased pressure leading to compartment syndrome.
What should you do?
If there is any clinical indication for compartment syndrome, prompt steps should be taken. To aid diagnosis a few things need to be checked on the initial assessment:
- Is the affected limb swollen?
- Has the limb been elevated appropriately?
- Has any analgesia been offered to the patient?
- Are any external compressive factors i.e., casts/bandaging been removed?
If after your initial A-to-E assessment and the appropriate steps have been taken (affected limb has been elevated, compressive materials removed and pain relief offered) and the patient is still in severe pain; compartment syndrome should be your top differential. Your seniors should be informed immediately. Following this and your seniors agree with your diagnosis, the patient should be stabilised if necessary and prepped for immediate theatre.
There are diagnostic instruments available to measure intra-compartmental pressures which can help aid your diagnosis, however, they may not be readily available and require correct placement and interpretation of results.
The definitive management of compartment syndrome is via fasciotomies. This will release the pressure within the compartment and restore circulation. Following the fasciotomy, the underlying pathology may need to be appropriately managed simultaneously or at a later date. The incision wounds are usually left open to prevent a further rise in compartment pressure and are usually difficult to close due to swelling. Further input may be necessary from plastic surgeons.
If diagnosed early, a fasciotomy may reverse any temporary damage. However, if the diagnosis is delayed, the risk of necrosis increases and could lead to the need for amputation.
Whilst reviewing any unwell patient, a uniformed approach should be taken following ALS/ATLS protocol. In traumatic patients, an underlying pathology can be missed when distracted by the primary complaint. An A-to-E approach will help reduce the incidence of missed pathologies.
For further advice on how to observe, diagnose and manage compartment syndrome, here are some useful links:
- Royal College of Nursing: Acute Limb Compartment Syndrome Observation Chart
- British Orthopaedic Association – Diagnosis & Management of Compartment Syndrome
- Patient.info – Compartment Syndrome
Written by Dr Sanjeevan Yoganathan (T&O SHO)
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