Compartment syndrome (CS) is a potentially limb or even life-threatening orthopaedic emergency. Its management is time-critical, and rapid and effective decision making is vital. The orthopaedic SHO overnight will often be the first responder to a suspected case. As with any emergency situation, the key is thorough examination and quick escalation. Consider the diagnosis in any patient with pain out of proportion to their injury, particularly in the lower leg, although compartment syndrome also occurs in the thigh, foot, forearm, hand, arm and even deltoid.
What is compartment syndrome?
The muscular compartments of the limbs are constrained by fascia, which is relatively inelastic and constrain expansion of the contents. Acute CS occurs when pressure within a fascial compartment builds to a level that compromises tissue perfusion. If the compartment pressure is not reduced, this eventually leads to ischaemia and tissue necrosis. The effect can be an unsalvageable limb, and even death, due to the subsequent burden of rhabdomyolysis on the kidneys, and consequences of amputation. Milder cases may lead to a Volkmann’s ischaemic contracture, with significant disability.
Acute CS is generally seen after a major insult to a limb, such as in trauma or surgery. Causes of acute CS include:
- Long-bone fracture (including open fractures)
- Significant soft tissue injury, including crush injuries
- Surgery, in particular intramedullary nailing
- Constriction from dressings or cast
- Ischaemia, and reperfusion injury following ischaemia
Initial assessment and management
Compartment syndrome and major trauma go hand in hand – assess for compartment syndrome in any patient with a high energy injury, and assess any patient with suspected compartment syndrome with an ATLS approach to make sure no other life-threatening injury has been missed.
The ‘6 Ps’ and the real 6 Ps
Most people know the ‘6 Ps’ as signs and symptoms of compartment syndrome (pain, pallor, pulselessness, paraesthesia, paralysis and perishingly cold), but the latter five are all very late signs – by the time they develop, the limb is probably unsalvageable. The real six Ps are: pain, pain, pain, pain, pain and pain!. Specifically:
- Pain (out of proportion to injury)
- Pain (despite fracture reduction and immobilisation)
- Pain (with increasing analgesic requirements or despite adequate analgesia)
- Pain (that’s getting worse)
- Pain (on passive stretch)
- Pain (on palpation of the compartments)
Ask about the following:
- Time and mechanism of injury
- Any treatment thus far (e.g. manipulation, plaster casting, surgery)
- Where the pain is (fracture site vs. muscular)
- What is happening to the pain – getting worse, staying the same, improving
- What analgesia have they had, and does it help?
- Is the patient anticoagulated? Relatively minor trauma may cause significant contusion and even frank haematoma, leading to CS in these patients
- Any distal paraesthesia, which may follow a nerve distribution (acute carpal tunnel due to a haematoma is well recognised, with median nerve pain and paraesthesia)
Note of caution: patients who have had an intra-operative or ED nerve block, or are obtunded for any reason, may have blunted pain sensation. They may present with unexplained tachycardia. Have a low threshold for compartment pressure checking and liaise with a senior if you are concerned.
Assuming an ATLS primary survey has been performed, document the following:
- Look: any obvious swelling or bruising? Any open wounds (in which case treat as an open fracture if there is a bony injury)?
- Feel: are the compartments soft or tense? Are they tender ++ to palpate? Check neurovascular status.
- Move: is there pain on passive stretch of the affected compartment(s)? Be selective: a patient with an ankle or distal tibial fracture will have pain on ankle movements, so move the toes instead
As soon as you suspect the diagnosis, initiate the following (which can be instructed over the ‘phone as you’re on the way to see the patient):
- Split all dressings/casts/backslabs down to the skin (i.e. including all layers of wool etc.)
- Elevate the limb to the level of the heart
- Maintain a normal blood pressure, with IV fluids if required
- Keep nil-by-mouth
Following instigation of these measures, you must review the patient within 30 minutes and assess their effect.
If you have any suspicion of compartment syndrome, the signs and symptoms are not resolved by the above measures, and you have not already done so: call a senior urgently. They may require surgical decompression (fasciotomies) within an hour.
Compartment pressure monitoring
Compartment pressure monitoring (CPM) is not a routine part of the assessment of compartment syndrome. If the diagnosis is clear, then the patient must undergo urgent fasciotomies. CPM is mainly of use in the following situations:
- Diagnosis not clear
- Obtunded patient (e.g. intubated) with a high-risk injury
CPM may be performed as a one-off measurement, or with indwelling pressure monitoring. Its use varies by centre: some perform it almost routinely, whilst others use it very sparingly. Normal compartment pressures do not rule out the diagnosis.
Find out how to measure compartment pressures in your trust. There may be a specific compartment pressure monitoring device, or you may have to use an arterial pressure monitoring set (speak to ITU/anaesthetics for help with this). As with all invasive procedures, do not attempt to perform these unless you have been trained and are confident to do so.
To correctly interpret compartment pressures, you must also know the diastolic blood pressure. CS is typically defined as either of:
- Absolute compartment pressure >40mmHg
- ΔP (diastolic BP – compartment pressure) <30mmHg
- Initial assessment documented (including time and nature of injury, level of consciousness, analgesia and response to analgesia, level and nature of pain and examination findings)
- All circumferential dressings split to skin, limb elevated to level of the heart and blood pressure maintained
- Response to initial management steps documented
- Senior informed if ongoing concerns
- Patient nil-by-mouth
Admission, discharge and calling a senior
When to call a senior
Call a senior about any patient in whom you are concerned about compartment syndrome. If you are worried, call early, even if just for advice about how to assess them correctly
Who to admit
Admit everyone if you are worried. Even if they don’t have compartment syndrome at the time of admission, they will benefit from a period of elevation and observation
There is no role for imaging in diagnosing compartment syndrome. Ensure you have plain XRs of the offending area – if there is a fracture it will be stabilised at the time of surgery. Compartment syndrome can (and does) occur without bony injury, however. Do not delay seeking help and initiating management to obtain imaging.
Whilst management is being initiated, obtain routine bloods including a creatine kinase (CK) and U&E. This is often elevated, but a normal CK does not rule out the diagnosis. A raised CK may indicate rhabdomyolysis, with potential for renal impairment and hyperkalaemia.
The definitive management of most compartment syndromes is urgent (within 1hr) fasciotomies. This involves splitting the fascia constricting the compartments, and thus relieving the pressure. It is important to perform fasciotomies in all compartments of the affected limb region, as forgetting to relieve the deep compartment of the lower leg, for instance, can still result in morbidity. The most common location for compartment syndrome is in the lower leg, and the BOAST for open fractures (here) has a guide to performing these.
Possible exceptions to mandatory urgent fasciotomy include:
- Compartment syndrome of the foot
- Delayed presentation/missed diagnosis (>12 hours after symptom onset)
Do not be tempted to sit on these patients however: let a senior surgeon make these controversial decisions.
Following faciotomies, the wounds will be left open and dressed appropriately. The patient will require a wound review after about 48hrs (usually in theatre). They may well require plastic surgical input to achieve skin coverage.
The BOAST for compartment syndrome is here.
The BOAST for open fractures is here.
Author: Paul Foster
Editor: Hamish Macdonald
Last updated: 06/04/2020