4 Postoperative Events: Fat Embolism and Compartment Syndrome Abstract This chapter will provide an overview of common life- and limb-threatening events fat embolus and compartment syndrome. The reader will be able to diagnose these conditions through their hallmark presentations, and demonstrate application of algorithms for treatment. Keywords: fat embolus, compartment syndrome, compartment pressures Six Key Points • Fat embolism presents as hypoxemia, petechial rash, and mental status changes. • Fat embolism is a clinical diagnosis. • Treatment for fat embolism is supportive. • Compartment syndrome presents with the five ‘Ps.” • Compartment syndrome is a clinical diagnosis, although compartment pressures of > 30mmHg are an indication to perform a fasciotomy • Treatment of compartment syndrome is surgical, and post-operative care includes frequent neurovascular assessments A woman calls 4 days after an abdominoplasty and liposuction and reports that she has shortness of breath. 1. What do you do? She should be evaluated in clinic, and it should include vital signs, examination of the surgical site, evaluation of the lower extremities, and cardiac and pulmonary evaluation, and general skin assessment. Leg swelling must be evaluated to rule out a deep venous thrombosis (DVT), and if leg swelling is the only symptom, imaging should include a duplex ultrasound to rule out a DVT. If a patient has pulmonary symptoms, such as shortness of breath, or has a low-grade fever, a spiral CT/pulmonary embolism (PE) protocol should be considered. RATIONALE: A study using national databases to evaluate postoperative complications found that DVT/PE occurred at a rate of 0.1 or 0.3% (depending on the database) when performed alone, and 0.4 or 0.27% when combined with another procedure.1 2. The patient comes to the clinic, and has a rash. What do you do? A petechial rash is concerning for fat embolism syndrome, which can occur after liposuction. Initial diagnostic imaging should include chest imaging with a chest X-ray and a CT. RATIONALE: The signs and symptoms of the syndrome usually present between 24 and 72 hours after the inciting event (surgery), and are most commonly seen on the neck and axillae. There are three features of fat embolism: hypoxemia, petechial rash, and mental status changes. Pulmonary symptoms usually occur early in the time course of the syndrome. The petechial rash is typically the last symptom to present, and present in approximately one-third of cases.2 While there are characteristic features of fat embolism syndrome, it is a clinical diagnosis. It is considered a diagnosis of exclusion as the features of the syndrome are nonspecific. The differential diagnosis should exclude other etiologies of emboli, such as thrombus. Of the conditions included in the differential diagnosis, the one that bears the most similarity to fat embolism syndrome is silicone embolism syndrome, which occurs after silicone has been injected. While treatment for silicone embolism syndrome is supportive as well, the prognosis in patients who have neurological symptoms with silicone embolism syndrome is worse. 3. You have diagnosed fat embolism syndrome. What do you do now? Treatment is supportive. The patient should be admitted to the hospital, and given supplemental oxygen and fluid resuscitation as needed. If escalated respiratory support is needed, such as mechanical ventilation, it should be instituted. RATIONALE: There is no single therapeutic intervention for fat embolism syndrome. In most cases, patients with fat embolism syndrome recover with supportive care, and recovery can occur as quickly as several days. You are managing a 68-year-old male patient in-house for a scalp rotation flap after resection of a scalp squamous cell carcinoma; he is on warfarin and his most recent international normalized ratio (INR) was 2.8. Nursing calls to inform you that he has fallen, and his forearm appears swollen. 1. What do you do? The primary differential diagnoses are hematoma, generalized swelling, orthopaedic trauma/broken bones, or compartment syndrome. Initial assessment includes thorough history of the events surrounding the fall, and whether it was associated with a loss of consciousness, to rule out underlying cerebral or cardiac events. Assuming there is no reason to suspect cerebral events such as stroke as a causative factor or brain injury as a resultant factor, or cardiac events, the time course of the swelling is assessed. A full physical examination is conducted and includes examination and assessment for a localized fluid collection, assessment of movement (flexion and extension), a full nerve examination, and pulse assessment. 2. What else do you do? A radiograph should be taken to rule out underlying fracture, but a concern in a swollen, tense arm after a fall in an anticoagulated patient is compartment syndrome. RATIONALE: The clinical signs of compartment syndrome are pain, pallor, paresthesias, pulselessness, and poikilothermia. Pulselessness is often a late finding (Fig. 4.1). Compartment pressures should be measured, and there are multiple ways to measure compartment pressure. RATIONALE: • Warfarin Available Kits (e.g., Stryker): The Stryker monitor is a handheld device that uses readily available equipment. It allows for continuous monitoring and requires minimal setup. • Whitesides’ Method: Whitesides and Heckman3 described a method of measuring tissue pressures that utilizes a 20-mL syringe, IV extension tubing, a hypodermic needle, and a manometer (Fig. 4.2). While this requires setup, it uses equipment that is readily available in a hospital setup. • Matsen’s Continuous Infusion: Matsen described a technique of measuring compartment pressures with a pressure transducer and monitor, and an infusion pump (Fig. 4.3).4 Though equipment is not always readily available, continuous monitoring of tissue pressure can occur for 3 days. While advocated for equivocal cases, the authors of the original study noted that individuals varied in their tolerance of increased compartmental pressures, and emphasized the clinical nature of the diagnosis.
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