A 24-year-old woman is admitted to the hospital after a motor vehicle accident resulted in a right humerus fracture, multiple rib fractures, and a contusion over her right leg. The patient receives multiple packed red blood cell transfusions. Chest and abdominal evaluation show a right-sided hemothorax. A chest tube is inserted. Pain is controlled with intravenous morphine. The next morning, she has a crawling and burning sensation and worsening pain in her right leg despite repeated doses of morphine. Temperature is 37.2 C (99 F), blood pressure is 140/82 mm Hg, heart rate is 96/min, and respirations are 18/min. The right leg is swollen and tense. Pulses are palpable in both lower extremities.
Which of the following complications is most commonly associated with the condition affecting this patient's right leg?

Question

A 24-year-old woman is admitted to the hospital after a motor vehicle accident resulted in a right humerus fracture, multiple rib fractures, and a contusion over her right leg.  The patient receives multiple packed red blood cell transfusions.  Chest and abdominal evaluation show a right-sided hemothorax.  A chest tube is inserted.  Pain is controlled with intravenous morphine.  The next morning, she has a crawling and burning sensation and worsening pain in her right leg despite repeated doses of morphine.  Temperature is 37.2 C (99 F), blood pressure is 140/82 mm Hg, heart rate is 96/min, and respirations are 18/min.  The right leg is swollen and tense.  Pulses are palpable in both lower extremities. 
Which of the following complications is most commonly associated with the condition affecting this patient's right leg?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c113_986f_8f63_d7fed36bfea2_MD0005_00 Increased edema in an enclosed compartment leads to compression of neurovascular bundles. Arterial and venous occlusion in the extremity results in anoxic muscle necrosis (rhabdomyolysis). The released myoglobin is filtered and degraded in the kidney. Heme pigment from myoglobin degradation: Is directly toxic to proximal tubular cells Combines with Tamm-Horsfall protein to form tubular casts Induces vasoconstriction, reducing medullary blood flow These mechanisms lead to acute renal failure (ARF), particularly in volume-depleted states (eg, hemorrhage), which worsens vasoconstriction and cast formation. (Choice B) Compartment syndrome (CS) of the leg in this patient can cause occlusion of the anterior and posterior tibial arteries and the fibular artery but not the iliac artery due to location. Arterial shearing resulting in intimal tear is a complication of blunt trauma, and the arterial lumen can be partially or completely occluded by the intimal flap; this complication is very rare. (Choice C) Microangiopathic hemolytic anemia in both trauma and CS may be caused by disseminated intravascular coagulation. However, ARF is a more common complication of CS. (Choice D) Compression of nerves in CS causes sensory and motor loss below the compression site in the affected limb. Paraparesis would be expected with spinal cord injury. (Choice E) Extremity immobilization does increase this patient's risk for deep venous thrombosis and pulmonary embolism. However, ARF is more commonly associated with CS. Educational objective: Patients with compartment syndrome may develop rhabdomyolysis and release of myoglobin. Heme pigment from myoglobin is nephrotoxic; patients may develop acute renal failure, especially if they are volume depleted. References: Acute lower-leg compartment syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/23937740)

A 24-Year-Old Woman Is Admitted to the Hospital After a Motor