A 27-year-old soldier stationed in Libya sustains a shrapnel injury during an attack, causing a traumatic above-elbow amputation. The resulting arterial bleed is managed with a tourniquet prior to transport to the military treatment facility. On arrival, he is alert and oriented to person, place, and time. His armor and clothing are removed. His pulse is 145/min, respirations are 28/min, and blood pressure is 95/52 mm Hg. Pulmonary examination shows symmetric chest rise. The lungs are clear to auscultation. Abdominal examination shows no abnormalities. There are multiple shrapnel wounds over the upper and lower extremities. A tourniquet is in place around the right upper extremity; the right proximal forearm has been amputated. One large-bore intravenous catheter is placed in the left antecubital fossa. Despite multiple attempts, medical staff is unable to establish additional intravenous access. Which of the following is the most appropriate next step in management?

Perform endotracheal intubation

Establish central venous access

Replace the tourniquet with a pressure dressing

A 38-year-old man is brought to the emergency department 35 minutes after he sustained a gunshot wound to the right thigh. He has type 1 diabetes mellitus. On arrival, his pulse is 112/min, respirations are 20/min, and blood pressure is 115/69 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 98%. There is an entrance wound on the anteromedial surface of the right thigh 2 cm below the inguinal ligament. There is no bruit or thrill. There is no exit wound. The pedal pulse is diminished on the right side compared to the left. The abdomen is soft and nontender. The remainder of the examination shows no abnormalities. Laboratory studies show: Hematocrit 46% Serum Urea nitrogen 24 mg/dL Glucose 160 mg/dL Creatinine 3.1 mg/dL Which of the following is the most appropriate next step in management?

Digital subtraction angiography

Wound cleaning and tetanus toxoid

A 35-year-old man is brought to the emergency department from a kitchen fire. The patient was cooking when boiling oil splashed on his exposed skin. His temperature is 99.7°F (37.6°C), blood pressure is 127/82 mmHg, pulse is 120/min, respirations are 12/min, and oxygen saturation is 98% on room air. He has dry, nontender, and circumferential burns over his arms bilaterally, burns over the anterior portion of his chest and abdomen, and tender spot burns with blisters on his shins. A 1L bolus of normal saline is administered and the patient is given morphine and his pulse is subsequently 80/min. A Foley catheter is placed which drains 10 mL of urine. What is the best next step in management?

Additional fluids and escharotomy

Additional fluids and admission to the ICU

A patient presents to the emergency department with arm pain. The patient recently experienced an open fracture of his radius when he fell from a ladder while cleaning his house. Surgical reduction took place and the patient's forearm was put in a cast. Since then, the patient has experienced worsening pain in his arm. The patient has a past medical history of hypertension and asthma. His current medications include albuterol, fluticasone, loratadine, and lisinopril. His temperature is 99.5°F (37.5°C), blood pressure is 150/95 mmHg, pulse is 90/min, respirations are 19/min, and oxygen saturation is 99% on room air. The patient's cast is removed. On physical exam, the patient's left arm is tender to palpation. Passive motion of the patient's wrist and fingers elicits severe pain. The patient's left radial and ulnar pulse are both palpable and regular. The forearm is soft and does not demonstrate any bruising but is tender to palpation. Which of the following is the next best step in management?

Measurement of compartment pressure

Three hours later, the patient is reassessed. Her right arm is put in an elevated position and physical examination of the extremity is performed. The examination reveals reduced capillary return and peripheral pallor. Pulse oximetry of her right index finger on room air shows an oxygen saturation of 84%. Which of the following is the most appropriate next step in management?

Obtain split-thickness skin graft

Perform right upper extremity amputation

A 36-year-old man comes to the emergency department 4 hours after a bike accident for severe pain and swelling in his right leg. He has not had a headache, nausea, vomiting, abdominal pain, or blood in his urine. He has a history of gastroesophageal reflux disease and allergic rhinitis. He has smoked one pack of cigarettes daily for 17 years and drinks an average of one alcoholic beverage daily. His medications include levocetirizine and pantoprazole. He is in moderate distress. His temperature is 37°C (98.6°F), pulse is 112/min, and blood pressure is 140/80 mm Hg. Examination shows multiple bruises over both lower extremities and the face. There is swelling surrounding a 2 cm laceration 13 cm below the right knee. The lower two-thirds of the tibia is tender to palpation and the skin is pale and cool to the touch. The anterior tibial, posterior tibial, and dorsalis pedis pulses are weak. Capillary refill time of the right big toe is 4 seconds. Dorsiflexion of his right foot causes severe pain in his calf. Cardiopulmonary examination is normal. An x-ray is ordered, which is shown below. Which of the following is the most appropriate next step in management?

Open reduction and internal fixation

Compartment syndrome diagnosis and fasciotomy for USMLE Step 2 CK: High-Yield Surgery Lessons

🦵 Pathophysiology - Pressure Cooker Leg

A vicious cycle where swelling within a fixed fascial compartment increases pressure ($P_{ic}$).
Common causes: Fractures (esp. tibia), crush injuries, burns, tight casts, reperfusion injury.
When $P_{ic}$ exceeds capillary perfusion pressure ($P_{cp}$), blood flow is compromised.
This leads to ischemia, capillary leak, and further edema, perpetuating the cycle.

⭐ Irreversible muscle damage begins after 4-6 hours of ischemia. Nerve damage becomes permanent after 8 hours, making immediate intervention critical to prevent permanent disability.

🦵 Clinical Manifestations: The Painful Six Ps

📌 Mnemonic: The 6 Ps

Pain: Severe, out of proportion to injury. Worsens with passive stretch of muscles in the affected compartment.
Paresthesia: Numbness, tingling (pins & needles).
Pallor: Pale, dusky skin from decreased perfusion.
Paralysis/Paresis: Muscle weakness; a late sign.
Pulselessness: Loss of distal pulse; a very late, ominous sign.
Poikilothermia (Polar): Coolness of the extremity.

⭐ Pain out of proportion to injury and pain on passive stretch are the earliest and most reliable findings. Paresthesia is also an early sign. Late signs imply irreversible damage.

🩺 Diagnosis - Measuring the Squeeze

While diagnosis is often clinical, objective measurement is vital in equivocal cases (e.g., unconscious patients).

Intracompartmental Pressure (ICP) Monitoring:
- The definitive diagnostic tool, often using a Stryker needle.
- Fasciotomy is indicated for an absolute pressure > 30 mmHg.
Delta Pressure ($ \Delta P $):
- More specific, as it accounts for systemic blood pressure.
- Formula: $ \Delta P = \text{Diastolic BP} - \text{ICP} $.
- Fasciotomy is strongly considered if $ \Delta P < \textbf{20-30 mmHg}$.

⭐ In an obtunded or polytrauma patient where the clinical exam is unreliable, objective pressure measurement is the gold standard for diagnosis.

Stryker method for intracompartmental pressure measurement

🔪 Management - Slice to Save

Initial Steps:
- Immediately remove all constricting casts, splints, and dressings.
- Position limb at heart level (⚠️ avoid elevation, as it ↓ perfusion).
Definitive Treatment: Emergent Fasciotomy.
- Leg: A 2-incision approach is standard to release all 4 compartments.
- Forearm: A single volar (Henry) approach is common.
Post-Fasciotomy Care:
- Wounds are left open, covered with sterile dressings.
- Delayed primary closure or skin grafting is performed in 3-5 days.

⭐ Fasciotomy is a limb-saving emergency. Irreversible muscle and nerve damage can occur within 4-8 hours of ischemia onset.

Lower leg compartments, neurovasculature, and fasciotomy

💥 Complications - When Pressure Wins

Volkmann’s ischemic contracture of the hand

Local Tissue: Irreversible muscle necrosis (after 4-8 hrs) and permanent nerve damage.
Deformity: Volkmann's ischemic contracture (claw-like hand/foot) from muscle fibrosis.
Systemic: Rhabdomyolysis from muscle breakdown leads to myoglobinuria and Acute Kidney Injury (AKI).
Limb Loss: Amputation if treatment is delayed or ineffective.

⭐ Volkmann's contracture is a classic, late complication of untreated compartment syndrome, particularly following supracondylar humerus fractures in children.

⚡ Biggest Takeaways

Pain out of proportion to the injury is the earliest and most sensitive sign.

The 6 P's are classic, but pulselessness and paralysis are very late, ominous findings.

Common causes: tibial fractures in adults, supracondylar humerus fractures in children.

Diagnosis is primarily clinical; confirm with compartment pressure measurement if uncertain.

A delta pressure < 30 mmHg (Diastolic BP - Compartment Pressure) is diagnostic.

Treatment is emergent surgical fasciotomy to relieve pressure and restore perfusion.

Delay risks irreversible damage and Volkmann's ischemic contracture.

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