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Lutheran Medical Center

Department of Surgery

Morbidity & Mortality Conference

Case & Topic Presentation

Baiju C. Gohil, M.D.April 9, 2004

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FAT EMBOLISM

SYNDROME

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INTRODUCTION

Fat emboli were first noted by F.A. Zenker in 1861 in arailroad worker with a thoraco-lumbar crush injury

Fat Embolism Syndrome (FES) was first described by

Von Bergman in 1873 in a diagnosis confirmed by postmortem examination

In the US, frequency of FES is unknown; clinicaldiagnosis; dx missed because of subclinical illness or

confounding injury or illness Fat embolism develops in nearly all pts with fracturedbones or during ortho procedures and is asymptomatic

In minority of pts s&s develop as a result of organdysfunction, notably lungs, brain, and skin; FES

Mortality rate 10-20%

Chest Volume 123 Number 4 April 2003

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PATHOPHYSIOLOGY

Two theories exist about FES: Mechanical theory states that large fat

droplets are released into venous system,deposit into pulmonary capillary beds, andthrough 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 sepsisinduce systemic release of free fatty acids

and chylomicrons; acute phase reactantscause chylomicrons to coalesce and createischemia

Chest Volume 123 Number 4 April 2003

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CLINICAL SIGNS OF FES

Cardiopulmonary

Early persistent tachycardia

Tachypnea, dyspnea, and hypoxia due to V-Q abnormalities

12-72 hrs after insult High temperature spikes

Dermatological

Reddish-brown nonpalpable petechiae over upper body, esp

axillae, 24-36 hrs after insult; occur in 20-50% of pts andresolve quickly

Subconjunctival and oral hemorrhages/petechiae

Neurologic

CNS dysfunction initially manifests as agitated delirium; mayprogress to stupor, seizures, or coma; frequently unresponsiveto correction of hypoxia

Retinal hemorrhages with intra-arterial fat globules are visibleupon fundoscopic examination

Arch Surg 1997; 132:435439

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CAUSES OF FES

Blunt trauma; multiple long bone andpelvic fxs (assoc w/ 90% of FES cases)

Acute pancreatitis DM

Burns

Joint reconstruction Liposuction

Cardiopulmonary bypass

Parenteral lipid infusion

Sickle cell crisis

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WORKUP

Laboratory ABG

Thrombocytopenia, anemia, andhypofibrinogenemia are indicative of FES, butnonspecific

Urine, blood, sputum examination with Sudan or oilred O staining detect fat globules

Imaging CXR-diffuse b/l pulmonary infiltrates

Head CT-nl or diffuse white matter petechialhemorrhages

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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FES: CRITERIA FOR DIAGNOSIS

Dx of FES requires at least one sign from major criteria and at least four signsfrom the minor criteria category

Gurd's Major Criteria: axillary or subconjuctival petechia; occurs transiently (4-6 hours) in 50-60 % of the cases

hypoxemia (PaO2,

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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 tominimize bone marrow embolization intovenous system

Arch Surg 1997; 132:435439

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CONTROVERSIES

Surg Gynecol Obstet. 1978 Sep;147(3):358-62

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

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CONTROVERSIES

J Trauma. 1987 Oct;27(10):1173-6.

'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 steroid-treated 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 providesprotection against fat embolism and pulmonary dysfunction after

skeletal trauma, the safety of this therapy requires further

evaluation

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CONTROVERSIES

Corticosteroids as prophylaxis for FES:Several studies have demonstrated

varying results using corticosteroids inpatients identified as high-risk fordeveloping FES; while the data appearcompelling, the optimal timing, duration,

and dose of steroids are undetermined

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