Acute Compartment Syndrome: Limb-Saving Diagnosis in the ED

Authors: Kishan Indrakumar, Thomas Moore, Abdirahman Yassin Mohamed, Sana Arif / Editor: Charlotte Davies / Codes: / Published: 28/07/2026

A 28-year-old male arrives in your ED following a low-speed football tackle. Hes otherwise healthy, but hes pale, diaphoretic, and clutching his lower leg in agony.

X-ray shows a closed midshaft tibial fracture. Straightforward until he winces violently as you gently flex his ankle.

Despite IV morphine, he rates his pain 10 /10. Its worse than when it broke, he gasps. The leg is swollen, firm, and becoming increasingly tense.

You consider giving more analgesia but something about this pain feels disproportionate.

Could it be Acute Compartment Syndrome (aCS)?

aCS is a limb-threatening emergency caused by rising pressure in a closed muscle compartment. Left untreated, it leads to nerve damage, muscle necrosis, and irreversible loss of function or limb.

While most common in the leg and forearm, dont forget: any closed fascial space from the hand to the buttock can be affected.

Why Does Compartment Syndrome Occur?

Compartment syndrome happens when pressure builds up inside a closed muscle compartment, usually after trauma, fractures, crush injuries, tight casts, or after blood flow is restored (reperfusion).

  • Muscle compartments are surrounded by tight fascia that cannot stretch.
  • Bleeding or swelling inside the compartment increases the pressure.
  • Veins get compressed first, reducing drainage. This causes fluid to leak into the tissues, making the pressure worse.
  • Nerves become compressed, leading to tingling (paraesthesia) and possible weakness.
  • As compartment pressure rises and approaches (or exceeds) diastolic blood pressure, arterial inflow is compromised, leading to ischaemia
  • If untreated, this results in ischaemia and permanent muscle and nerve damage.
Fig.1 Image via Shutterstock

Key Compartments at Risk

There are 46 fascial compartments in the human body – 38 of which are in the limbs.

Lower Limb (Leg)

4 compartments:

  • Anterior Deep peroneal nerve, anterior tibial vessels
  • Lateral Superficial peroneal nerve
  • Superficial posterior Sural nerve
  • Deep posterior Tibial nerve, posterior tibial artery
Upper Limb (Forearm)

3 compartments:

  • Volar (flexor) Median & ulnar nerves
  • Dorsal (extensor) Radial nerve
  • Mobile wad Brachioradialis, ECRL/B
When Should You Suspect aCS?

Ask yourself:

  • Is there pain out of proportion?
  • Does passive movement make it worse?
  • Are they at risk?
Fig.2 - Image created by the author using ChatGPT-4 (OpenAI), 2025. For illustration purposes only

Were taught the “6 Ps”:

Pain, Pallor, Paraesthesia, Pulselessness, Paralysis, Perishingly cold.

But heres the reality:

  • Pain out of proportion = earliest, most reliable sign
  • Pain on passive stretch = critical red flag
  • Pulselessness and cap refill are late signs. If absent, think vascular injury or hypotension, not early aCS.
High-Risk Scenarios:
  • Crush injuries
  • Tibial or forearm fractures
  • Anticoagulant use ( bleeding risk)
  • Tight casts or splints
  • Burns with eschar formation
  • Post-reperfusion injuries (e.g. vascular repair)
open-tibia-and-fibula-fracture
Fig.3 - Tibia and fibula fractures. Courtesy of Shailaja Muniraj, Radiopaedia.org, rID: 49420

Investigations

When to Measure Pressure?

aCS is a clinical diagnosis. Never delay for imaging or labs.

  • Normal compartment pressure is typically 1012 mmHg.
  • A perfusion pressure (P = Diastolic BP Compartment Pressure) of <30 mmHg indicates high risk of ACS. (2)
  • An absolute pressure >40 mmHg with symptoms is considered diagnostic of aCS. (2)
  • In unconscious or intubated patients, consider intra-compartment pressure monitoring when clinical assessment is limited. [3]
Techniques for Pressure Monitoring

Invasive:

  • Slit catheter technique (standard method)

Emerging non-invasive methods:

  • Near-infrared spectroscopy (NIRS)
  • Laser Doppler flowmetry
Pressure Measurement Points (Lower Leg)

Compartment

Site for Measurement

Anterior

1 cm lateral to anterior tibial border insert needle perpendicular

Deep posterior

Just posterior to medial tibial border aim toward fibula

Lateral

Just anterior to posterior fibular border

Superficial posterior

Middle of calf

Compartment pressure using stryker Device

Fig. 4 - Compartment pressure measurement using Stryker device. Adapted from EM:RAP YouTube educational video

Measure pressure as close to the fracture site as possible for accuracy. Before checking the pressure, check your departments policy as in some, it will be an orthopaedic procedure.

When suspected, what should you do in the ED?

Initial actions:

  • Escalate to orthopaedics.
  • Remove all constrictive dressings to skin do not delay
  • Do not elevate the limb this reduces arterial perfusion pressure and may worsen ischaemia. Keep the limb at heart level.
  • High-flow O + IV fluids improve perfusion
  • Reassess within 30 minutes
  • No improvement? Escalate again! Dont watch and wait
  • Escalate early involve orthopaedics at the first clinical suspicion.

Surgical Management

If aCS is suspected fasciotomy now, not later.

  • Late presenters (>12 hours) have a high risk of complications
  • Extensive fasciotomy can lead to significant fluid loss. Prepare for fluid resuscitation and possible blood transfusion.
Fasciotomy,Swollen,Foot,Acute,Pain,Crush,Limb,Ischemia,Deep,Vein
Fig.5 - Fasciotomy for compartment syndrome. Image via Shutterstock

There is a risk of infection from this procedure, and it should ideally be performed in theatre.

Clinical Pearls
  • Suspect early, intervene early don’t delay for imaging
  • Pain out of proportion + passive stretch pain = Red Flags
  • Pulses can be present dont be reassured
  • Avoid nerve blocks they mask pain
Essential Documentation
  • Time of injury and exam
  • Pain score + analgesia response
  • Neurovascular findings
  • Actions taken (e.g., cast removal, repositioning)
  • Regional anaesthesia use
  • Consultant/senior review

Summary

  • Most commonly affects the lower limbs, especially after trauma or fractures.
  • Diagnosis is clinical look for pain out of proportion to the injury or pain that worsens despite treatment.
  • Emergency fasciotomy is the definitive treatment delay can cost the limb.
  • Monitor closely for complications such as rhabdomyolysis and reperfusion syndrome.

References

  1. Williams C, Nickson A, editors. The RCEM Lecture Notes: Emergency Medicine. 5th ed. Hoboken (NJ): Wiley-Blackwell; 2023. p. 112
  2. British Orthopaedic Association (BOA). BOA Standard (BOAST): Diagnosis and Management of Compartment Syndrome of the Extremities [Internet]. London: BOA; 2025 [cited Jun 3 2026].
  3. Stehr W. The Mont Reid Surgical Handbook, sixth edition. 2008.

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