Escalating Pain in a Casted Tibial Shaft Fracture
Mr. A, 34, is admitted with a closed tibial shaft fracture after a soccer collision. He has a long leg cast and a morphine PCA. At 06:00, 10 hours after cast application, he rates pain 10/10 and says it is "the worst pain of my life," worse when the nurse passively dorsiflexes his toes. The anterior compartment is tense and shiny; there is numbness in the first web space; dorsalis pedis pulse is 2+, capillary refill 2 seconds, and the toes are pink. A resident measures a compartment pressure of 36 mmHg; his diastolic blood pressure is 64 mmHg. He has received 8 mg morphine in the last hour and is becoming agitated. He has no allergies and received ketorolac 30 mg IV 6 hours ago.
1. Calculate the delta pressure and interpret it. Why does a palpable pulse not exclude compartment syndrome?
Read the worked answer
Delta pressure = diastolic pressure − compartment pressure = 64 − 36 = 28 mmHg.
A delta pressure below 30 mmHg is considered abnormal and consistent with compartment syndrome; many services use less than 30 mmHg as the threshold for fasciotomy. This patient also has the clinical picture: pain out of proportion to the injury, pain with passive stretch, a tense compartment, and a sensory deficit in the first web space (deep peroneal nerve).
A palpable dorsalis pedis pulse is not reassuring. Compartment syndrome is a problem of microvascular perfusion: tissue pressure rises above capillary perfusion pressure, so muscle and nerve die while the larger arteries still transmit a pulse. Pulselessness is a late and unreliable sign - if you wait for it, you have waited too long. The earliest and most dependable findings are escalating pain, pain on passive stretch, and paresthesia.
2. What are your immediate nursing actions?
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This is an emergency; fasciotomy within hours preserves muscle and nerve.
- Remove the constriction - bivalve the cast and cut through all padding and bandages down to skin if the surgeon is not immediately available. This is a nursing action that buys time.
- Keep the limb at heart level - do not elevate above the heart, because that lowers arterial pressure and worsens perfusion. Do not apply ice or compression.
- Notify the surgeon now and state the delta pressure and the findings, not just "he has pain."
- Treat pain and maintain perfusion - give ordered analgesia, keep the patient normotensive; hypotension worsens compartment perfusion. Avoid ketorolac if it increases bleeding risk near fasciotomy, per orders.
- Prepare for the operating room - NPO, consent, IV access, type and screen.
- Monitor - q1-hour neurovascular checks, urine output and color (myoglobinuria), creatine kinase, and watch for rhabdomyolysis.
3. The resident says he is busy and will recheck the compartment pressure in 2 hours. What do you do?
Read the worked answer
Do not accept a 2-hour delay for a patient with a delta pressure of 28 mmHg and a new sensory deficit. Muscle necrosis can begin within a few hours, and the consequence of waiting is permanent disability.
- Escalate up the chain of command: page the orthopaedic attending on call, the charge nurse, and the rapid response team if needed. Use a structured message: patient, fracture, cast, pain 10/10, passive stretch pain, first web space numbness, pressure 36 with diastolic 64, delta 28, and time of measurement.
- Keep acting in your scope: bivalve the cast, position at heart level, continue q1-hour checks, and document that you escalated and when.
- Document the disagreement factually - the findings, the call times, the names, and the response - and use an incident or safety report if the delay continues.
- Continue monitoring for deterioration: increasing pain, worsening sensation or motor function, and tense swelling. Reassess and re-escalate with new data.
Advocacy here is not insubordination; it is the standard of care.