Lutheran Medical Center Department of Surgery

Transcription

1 Lutheran Medical Center Department of Surgery Morbidity & Mortality Conference Case & Topic Presentation Baiju C. Gohil, M.D. April 9, 2004

2 FAT EMBOLISM SYNDROME

3 INTRODUCTION Fat emboli were first noted by F.A. Zenker in 1861 in a railroad worker with a thoraco-lumbar crush injury Fat Embolism Syndrome (FES) was first described by Von Bergman in 1873 in a diagnosis confirmed by post mortem examination In the US, frequency of FES is unknown; clinical diagnosis; dx missed because of subclinical illness or confounding injury or illness Fat embolism develops in nearly all pts with fractured bones or during ortho procedures and is asymptomatic In minority of pts s&s develop as a result of organ dysfunction, notably lungs, brain, and skin; FES Mortality rate 10-20% Chest Volume 123 Number 4 April 2003

4 PATHOPHYSIOLOGY Two theories exist about FES: Mechanical theory states that large fat droplets are released into venous system, deposit into pulmonary capillary beds, and through a-v shunts to the brain; microvascular lodging of droplets causes local ischemia and inflammation Biochemical theory states that hormonal changes caused by trauma and/or sepsis induce systemic release of free fatty acids and chylomicrons; acute phase reactants cause chylomicrons to coalesce and create ischemia Chest Volume 123 Number 4 April 2003

5 CLINICAL SIGNS OF FES Cardiopulmonary Early persistent tachycardia Tachypnea, dyspnea, and hypoxia due to V-Q abnormalities hrs after insult High temperature spikes Dermatological Reddish-brown nonpalpable petechiae over upper body, esp axillae, hrs after insult; occur in 20-50% of pts and resolve quickly Subconjunctival and oral hemorrhages/petechiae Neurologic CNS dysfunction initially manifests as agitated delirium; may progress to stupor, seizures, or coma; frequently unresponsive to correction of hypoxia Retinal hemorrhages with intra-arterial fat globules are visible upon fundoscopic examination Arch Surg 1997; 132:

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11 CAUSES OF FES Blunt trauma; multiple long bone and pelvic fxs (assoc w/ 90% of FES cases) Acute pancreatitis DM Burns Joint reconstruction Liposuction Cardiopulmonary bypass Parenteral lipid infusion Sickle cell crisis

12 WORKUP Laboratory ABG Thrombocytopenia, anemia, and hypofibrinogenemia are indicative of FES, but nonspecific Urine, blood, sputum examination with Sudan or oil red O staining detect fat globules Imaging CXR-diffuse b/l pulmonary infiltrates Head CT-nl or diffuse white matter petechial hemorrhages Chest CT-parenchymal changes c/w lung contusion, acute lung injury, or ARDS V/Q scan-nl or subsegmental perfusion defects Procedures BAL-staining of alveolar macrophages for fat

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15 FES: CRITERIA FOR DIAGNOSIS Dx of FES requires at least one sign from major criteria and at least four signs from the minor criteria category Gurd's Major Criteria: axillary or subconjuctival petechia; occurs transiently (4-6 hours) in % of the cases hypoxemia (PaO2, <60 mmhg) central nervous system (CNS) depression disproportionate to hypoxemia, and pulmonary edema Gurd's Minor Criteria: tachycardia (more than 110 beats per minute) pyrexia (temperature higher than 38.5 degrees) emboli present in retina on funduscopic examination fat present in urine sudden unexplainable drop in hematocrit or platelet values increasing sed rate fat globules present in sputum Misc: occurs w/in 72 hours of skeletal trauma shortness of breath altered mental status occasional long tract signs and posturing urinary incontinence J Arthroplasty Sep;15(6):

16 TREATMENT Medical care Supportive in nature Maintain oxygenation and ventilation Stabilize hemodynamics Blood products as needed Hydration DVT & stress related GI bleed prophylaxis Nutrition Surgical care Early stabilization of long bone fractures to minimize bone marrow embolization into venous system Arch Surg 1997; 132:

17 CONTROVERSIES Surg Gynecol Obstet Sep;147(3): Corticosteroids in patients with a high risk of fat embolism syndrome Alho A, Saikku K, Eerola P, Koskinen M, Hamalainen M. Effects of methylprednisolone on clinical FES were studied in series of 60 pts. who had at least two fractures of the pelvis, femur and tibia and who did not have any other significant injuries 31 controls; 29 pts. given 10 mg/kg methylprednisolone 3 times, once at admission and, at 8 and 16 hrs post-trauma FES defined as combination of hypoxemia, bilateral "snow storm" infiltrations of the lungs, petechial rash, mental disturbances, pyrexia, anemia and thrombocytopenia Varying degrees of FES observed in 2 steroid pts. And in 15 controls Methylprednisolone in an early pharmacologic dosage is effective in fulminant instances of fat embolism that occur in spite of adequate respiratory care and the proper treatment of fractures

18 CONTROVERSIES J Trauma Oct;27(10): 'Low-dose' corticosteroid prophylaxis against fat embolism. Kallenbach J, Lewis M, Zaltzman M, Feldman C, Orford A, Zwi S. 82 skeletal trauma pts. Identified as high risk for FES 42 control subjects given placebo and 40 steroid-treated subjects (9 mg/kg methylprednisolone) Fat embolism occurred in ten controls (23.8%) and one steroidtreated subject (2.5%) Hypoxemia was severe (PaO2 less than 50 mm Hg) in 12 controls (28.6%) and two (5%) of the steroid-treated subjects Although methylprednisolone in a relatively low dose provides protection against fat embolism and pulmonary dysfunction after skeletal trauma, the safety of this therapy requires further evaluation

19 CONTROVERSIES Corticosteroids as prophylaxis for FES: Several studies have demonstrated varying results using corticosteroids in patients identified as high-risk for developing FES; while the data appear compelling, the optimal timing, duration, and dose of steroids are undetermined

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