Compartment syndrome and fat embolism: catching them early

What it is

In acute compartment syndrome, swelling inside a closed muscle compartment raises the pressure until blood flow to muscle and nerves fails. It follows fractures (above all of the tibia), crush injuries, tight casts or dressings and surgery; it is treated by urgent surgical decompression (fasciotomy), and delay can leave permanent damage. Fat embolism syndrome appears usually one to three days after a long-bone or pelvic fracture, with breathing problems, confusion and a petechial rash. For both, the nurse's job is to recognise the early signs, act at once and call.

Reference values

• Normal compartment pressure at rest is a few mmHg; a pressure of about 30 mmHg or more is treated as critical.
• Permanent nerve damage can follow less than 12 to 24 hours of high pressure, and muscle damage sooner.
• Fat embolism usually appears 24 to 72 hours after the injury.
• Patients at higher risk: tibial and forearm fractures, crush injuries, anticoagulants or bleeding disorders, tight casts, and young men for compartment syndrome; long-bone, pelvic and multiple fractures for fat embolism.

What you need

• Neurovascular observation chart and the service's pain scale.
• The other limb for comparison.
• Pulse oximeter, preferably continuous in patients at high risk of fat embolism.
• A torch to look for petechiae in the conjunctivae and armpits.

How to measure it (and why)

1. Ask about pain at every check and compare it with the injury — pain out of proportion is the earliest sign of compartment syndrome.
2. Gently stretch the fingers or toes of the limb and watch the response — pain on passive stretch points to raised compartment pressure.
3. Feel the compartment: tense, hard swelling is a warning — the closed fascia does not stretch.
4. Check sensation, movement, colour, temperature and pulses against the other side — numbness and weakness come before loss of pulse.
5. If suspected, loosen bandages, report the cast for splitting per protocol and keep the limb at heart level — raising it higher lowers perfusion.
6. Avoid flexing the knee or pulling the foot up in a suspected leg compartment syndrome — these postures raise the pressure.
7. In long-bone or pelvic fractures, monitor breathing rate and saturation, continuously if ordered — low oxygen can appear before breathlessness.
8. Check the level of consciousness and look for petechiae on the chest, armpits, neck and conjunctivae — confusion and rash complete the picture of fat embolism.
9. Record the time of each finding and of each call — in both conditions delay changes the outcome.

How to read it

• Compartment syndrome is a clinical diagnosis: no single sign is reliable, so the trend of pain and nerve signs matters.
• Not all the classic signs appear; a pink limb with a pulse can still be in compartment syndrome.
• Fat embolism is also a clinical diagnosis: breathing problems and low oxygen often come first, and the rash may be missing.
• Tachycardia and fever are non-specific but add to the picture.
• After compartment syndrome, muscle breakdown can damage the kidneys: watch urine output.

Next step: when to call for help

• Call the doctor at once for pain out of proportion or pain on passive stretch; do not just give more pain relief.
• Call at once for numbness, weakness, a tense compartment, or a pale, cold or pulseless limb.
• Call urgently for a fall in oxygen saturation, rising respiratory rate, new confusion or petechiae after a fracture; give oxygen as ordered.
• Escalate with SBAR and the times of the findings: both conditions are surgical or medical emergencies.
• After a fasciotomy, report falling urine output.

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Elsewhere in DurgiPedia

• Compartment syndrome: the early signs

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Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.

Sources: Pechar J, Lyons MM. Acute compartment syndrome of the lower leg: a review. J Nurse Pract 12(4):265-270 (The Journal for Nurse Practitioners (PubMed Central, open access), 2016); Compartment syndrome, MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); Shaikh N. Emergency management of fat embolism syndrome. J Emerg Trauma Shock 2(1):29-33 (Journal of Emergencies, Trauma, and Shock (PubMed Central, open access), 2009); Shaikh N et al. Fat embolism syndrome: evolving perspectives on diagnosis and care. Cureus 17(11):e96136 (Cureus (PubMed Central, open access), 2025).

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