Compartment syndrome: Clinical sciences

Acute compartment syndrome is a surgical emergency that occurs when muscle compartments, which are bounded by noncompliant fascial membranes, have an increase in pressure, causing tissue ischemia. Although it’s usually associated with extremity trauma, any condition that increases intracompartmental pressure can lead to compartment syndrome.

Acute compartment syndrome is typically a clinical diagnosis, but you can confirm the diagnosis of unclear cases with a direct measurement of compartment pressures. Compartment syndrome can lead to irreversible tissue damage requiring amputation, without rapid diagnosis and surgical decompression by fasciotomy.

When assessing a patient with signs and symptoms suggestive of acute compartment syndrome, first perform an ABCDE assessment to determine if the patient is unstable or stable. If the patient is unstable, start acute management immediately to stabilize their airway, breathing, and circulation. This means that you might need to intubate the patient, obtain IV access, begin fluid resuscitation, and monitor their vitals before continuing with your assessment. Once this important step is complete, obtain a focused history and physical exam, as well as labs like CBC, CMP, CPK and lactate.

Now, let's first look at history. The patient might present with ongoing severe extremity pain, swelling, and rapid progression of symptoms over a few hours. You can also suspect some causes of acute compartment syndrome based on history. The patient may have a known history of extremity trauma, such as a fracture, burn, or crush injury. They might have a history of prolonged ischemia with reperfusion, such as a recent surgical revascularization procedure. Other causes include extended immobility or extreme exercise, which can lead to rhabdomyolysis, and even massive DVT, like phlegmasia cerulea dolens.

Okay, the exam may reveal tachycardia and hypotension, as well as a tense “wood-like” muscle compartment on palpation, motor paralysis, and sensory loss. Physical exam findings can also include skin changes like pallor or mottling; as well as poikilothermia, or skin that is cold to the touch; and as a late sign, weak or absent extremity pulses. Additionally, a key sign that’s considered compartment syndrome until proven otherwise is pain in the leg with passive stretching of the muscles, such as pain in the leg with passive dorsiflexion of the foot. It is important to always perform a thorough neurovascular examination of the affected extremity because, after more than six hours of ischemia, tissue damage can become irreversible.

Signs of severe ischemia include foot drop from peroneal nerve injury, or Volkmann’s contracture in the arm, which results in a claw-like deformity of the hand. If tissue necrosis has already occurred, a secondary soft tissue infection may also be present. Here is a clinical pearl! The lower leg consists of four muscle compartments: anterior, lateral, superficial posterior, and deep posterior. However, the deep posterior compartment cannot be palpated on physical examination! Finally, labs might reveal leukocytosis, electrolyte abnormalities such as hyperkalemia, and in some cases even evidence of acute kidney injury, such as an elevated BUN to creatinine ratio, as well as an elevated CPK. Lactate can also be elevated since it’s released by damaged cells. If you see these signs and symptoms, you can diagnose acute compartment syndrome.

Now that the diagnosis is made, let’s talk about treatment. Compartment syndrome is an emergency, so the first thing to do is call the surgical team for consultation. Then, immediately start with supportive care, which includes IV fluid resuscitation, correction of electrolyte abnormalities, broad-spectrum antibiotics, supplemental oxygen, and pain management as needed. Once ready, the surgical team will perform emergent fasciotomy. Finally, treat the underlying cause, if found.

Okay, now that the unstable patients are taken care of, let’s return to the ABCDE assessment and talk about stable patients. Your first step here is to obtain a focused history and physical exam, as well as labs like CBC, CMP, CPK, and lactate. Now, history and labs are usually similar in all patients with compartment syndrome. The history might reveal pain, paresthesias such as pins and needles sensations or numbness, and rapid progression of symptoms over a few hours. As before, patients might report traumatic injuries such as fractures, burns, crush injuries, or even a new constrictive cast or bandage.

You should also look out for other causes, such as animal bites and stings, prolonged ischemia and reperfusion, spontaneous hemorrhage or hematoma, and even extravasation of IV fluid, medication, or drugs. On the flip side, labs typically reveal leukocytosis, electrolyte abnormalities such as hyperkalemia, and elevated CPK, and lactate.

Now, the real difference in presentation is the physical exam. Some patients might present with clear findings of compartment syndrome. In this case, the physical exam reveals pain out of proportion to physical findings, extremity swelling, a tense “wood-like” muscle compartment on palpation, and pain to passive stretch. They may even have motor or sensory deficits, depending on the duration and severity of limb ischemia. If you see these clear findings, you can make a clinical diagnosis of acute compartment syndrome.