Markedly deficient expression of membrane-activated complex 1 (Mac-1; CD11b/CD18) by polymorphonuclear neutrophils (PMN) of human neonates compared with adults is well documented. To define postnatal maturation of Mac-1 expression of PMN, lysates of PMN from 21 infants, aged 1-14 months, and concurrent adult controls were assayed by ELISA for total cell content of Mac-1 and LFA-1 (CD11a/CD18), and LFA-1 content was within the normal adult range at all ages tested. Mac-1 content was approximately 50% of adult levels for infants 1-2 months of age and steadily increased to reach normal adult levels by 11-12 months of age. For a separate group of 25 infants, aged 0.5-11 months, measurement of surface expression of Mac-1 and LFA-1 on activated PMN by immunofluorescence flow cytometry yielded results that were similar to those obtained by ELISA.

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Introduction. Acute compartment syndrome (ACS) occurs secondary to increasing pressure within a fascial compartment that exceeds perfusion pressure. This can be caused by spontaneous hematomas, which can be secondary to prolonged anticoagulation therapy. Eliquis® has not been associated with ACS of the thigh in any of the currently published literature. Identifying ACS early is important because it can reduce the risk of permanent structural damage, limb amputations, and mortality rates. Case Report. A 43-year-old male with past medical history of unprovoked Deep Vein Thrombosis (DVT) eight months prior to presentation on Eliquis® presented to the emergency department for significant right thigh pain after riding a roller coaster. There was increased tone/firmness of the anterior compartment and tenderness on palpation of the proximal two-thirds of the anterior thigh. Imaging, clinical findings, and Stryker needle measurements confirmed ACS secondary to hematoma, which required fasciotomy and evacuation of the hematoma. The patient was temporarily switched to aspirin for DVT prophylaxis postoperatively to prevent new hematoma formation. Six weeks later, the patient arrived at the ED with a DVT that was treated with Eliquis®. Eight months later, the same patient presented with acute right thigh pain that started while lying in bed. A diagnosis of recurrent ACS in the right anterior thigh was made, requiring a fasciotomy. Surgery was successful without any complications. Discussion. Eliquis® is associated with an increased risk of hematoma formation, which can lead to ACS. This is a rare adverse effect that providers should be aware of because it requires early management to prevent ACS-associated complications. This is significant because no currently published literature has identified an association of Eliquis® with ACS in the thigh. In cases of atraumatic ACS, we were unable to find any protocols advocating for or against the use of DVT prophylaxis postfasciotomy in the literature.