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⚠️ Reduction of Risk · Lesson 4 of 6 · 7 min

Compartment Syndrome and Fat Embolism: Pain and Petechiae

🦴 A casted leg hurts more every hour and the pain medication stops working. The textbook student elevates it higher. The exam, and the surgeon, want the opposite.

💡 Key idea

Compartment syndrome: unrelenting pain and pain on passive stretch come first; loosen the cast, keep the limb at heart level, call. Fat embolism: dyspnea, confusion and chest petechiae 1 to 3 days after a long-bone fracture.

🧠 Why it matters

COMPARTMENT SYNDROME is rising pressure inside a muscle compartment, within a cast or after a crush injury or burn, that cuts off perfusion. The earliest and most reliable signs are PAIN out of proportion to the injury that is not relieved by opioids and PAIN WITH PASSIVE STRETCH of the fingers or toes, followed by paresthesia and tense swelling; pallor, paralysis and loss of pulses are LATE and mean tissue is already dying. Act within hours: loosen or bivalve the cast or dressing, keep the limb at HEART LEVEL (elevating above the heart lowers arterial pressure into the compartment), do not apply ice, and notify the provider immediately; the treatment is a fasciotomy. FAT EMBOLISM syndrome follows long-bone and pelvic fractures, usually within 24 to 72 hours: sudden dyspnea, hypoxemia, confusion or restlessness, tachycardia, fever and a PETECHIAL rash over the chest, axilla and conjunctiva; treat with oxygen, support, and early immobilization of fractures to prevent it. Routine NEUROVASCULAR checks (the 6 Ps: pain, pressure, paresthesia, pallor, paralysis, pulselessness) are compared with the opposite limb every 1 to 2 hours after casting or surgery. For SKELETAL TRACTION, weights hang freely and are never removed, pin sites are cleaned per policy, and the client is kept in alignment.

🏥 In the real world

🚨 Six hours after a tibial fracture is casted, a client rates the pain 10/10 despite two doses of morphine and screams when the nurse gently moves his toes. The nurse does not give a third dose and does not elevate the leg higher. She loosens the cast per protocol, keeps the leg at heart level and calls the orthopedic team. Fasciotomy saves the leg. Pain that medication cannot touch is a diagnosis, not a dosing problem.

📌 Takeaways

  • Unrelieved pain and pain on passive stretch are early; pulselessness is late
  • Limb at heart level, cast loosened, provider notified; fasciotomy treats it
  • Fat embolism: 24 to 72 hours after long-bone fractures, petechiae on the chest

📖 Terms in this lesson

Compartment syndrome: Rising pressure inside a muscle compartment that cuts off blood flow; the first signs are pain out of proportion and pain on passive stretch.

Fat embolism syndrome: Fat from a long-bone fracture reaching the lungs and brain within 24 to 72 hours, with dyspnea, confusion and chest petechiae.

✅ Test yourself

A client with a fresh forearm cast reports severe, increasing pain unrelieved by analgesics and pain when the nurse passively extends the fingers. What is the nurse's priority action?
  1. Administer an additional dose of opioid
  2. Notify the provider immediately
  3. Elevate the arm above the heart and apply ice
  4. Document and reassess in 2 hours

Answer: B · Notify the provider immediately

These are early signs of compartment syndrome. Pressure must be relieved within hours; elevation above the heart and ice worsen perfusion.

Two days after a femur fracture, a client becomes confused and short of breath, and the nurse notes petechiae across the chest. What complication should the nurse suspect?
  1. Fat embolism syndrome
  2. Compartment syndrome
  3. Wound infection
  4. Osteomyelitis

Answer: A · Fat embolism syndrome

Dyspnea, altered mental status and chest petechiae 24 to 72 hours after a long-bone fracture are classic for fat embolism.

Which finding is a LATE sign of compartment syndrome?
  1. Paresthesia
  2. Pain out of proportion to the injury
  3. Pain with passive stretching
  4. Absence of the distal pulse

Answer: D · Absence of the distal pulse

Pulselessness appears only after prolonged ischemia, when muscle and nerve damage may be irreversible.

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