acute respiratory distress syndrome after...

Acute Respiratory Distress Acute Respiratory Distress Syndrome after Trauma: Syndrome after Trauma: Fat Embolism SyndromeFat Embolism Syndrome

Jessica O’BrienJessica O’BrienMSIII Radiology Core ClerkshipMSIII Radiology Core ClerkshipBeth Israel Deaconess Medical CenterBeth Israel Deaconess Medical CenterHarvard Medical SchoolHarvard Medical SchoolMarch 19, 2010March 19, 2010

AgendaAgenda

Index CaseIndex CaseGround Glass OpacitiesGround Glass OpacitiesARDS: Diagnosis and ARDS: Diagnosis and PathophysiologyPathophysiologyCauses of ARDSCauses of ARDSFat Embolism SyndromeFat Embolism SyndromeCorrelated RadiologyCorrelated Radiology

Index Patient: Index Patient: Initial PresentationInitial Presentation

Our patient is a 20 Our patient is a 20 yoyo female, who female, who sustained a massive right lower extremity sustained a massive right lower extremity injury after a motor vehicle accidentinjury after a motor vehicle accident–– AirAir--flightedflighted from outside hospital due to from outside hospital due to

extensive soft tissue deextensive soft tissue de--gloving with exposed gloving with exposed tibiatibia

–– Patient reported brief loss of consciousness Patient reported brief loss of consciousness during event during event

In the ER, she was stabilized and In the ER, she was stabilized and evaluated…evaluated…

Index Patient: Fractures on Lower Index Patient: Fractures on Lower Extremity Plain FilmExtremity Plain Film

PACS, BIDMC

Findings:

Compound Comminuted Mid-diaphyseal Tibia and Fibula Fractures

Frontal Right Tib/Fib XR

Index Patient: Frontal CXR Index Patient: Frontal CXR

PACS, BIDMC

Findings:

Low lung volumes

No pleural effusion

No pneumothorax

Portable A/P CXR

Index Patient: Chest CTIndex Patient: Chest CT

PACS, BIDMCAxial C+ Chest CT

Findings:

Normal lung parenchyma

Low lung volumes

No pleural effusion

No pneumothorax

Index Patient: Summary of Index Patient: Summary of Radiographic Findings of Initial Radiographic Findings of Initial PresentationPresentation

R R TibTib/Fib XR: /Fib XR: TibTib--fib fracturesfib fracturesNo other acute process on:No other acute process on:–– CXRCXR–– CT CCT C--SpineSpine–– CT HeadCT Head–– CT Trauma Torso series, including Chest, Abdomen, PelvisCT Trauma Torso series, including Chest, Abdomen, Pelvis

Patient underwent emergent surgery:Patient underwent emergent surgery:–– Irrigation and debridement of lacerationIrrigation and debridement of laceration–– IntramedullaryIntramedullary nailing of right open tibianailing of right open tibia--fibula fracturefibula fracture–– VAC applicationVAC application

Index Patient: Interim HistoryIndex Patient: Interim History 24 hours after admission24 hours after admission

Patient developed Patient developed dyspneadyspnea and nonand non--productive cough productive cough –– Febrile to 102.8Febrile to 102.8–– TachycardicTachycardic to 150to 150–– O2 O2 satssats 80% on RA 80% on RA →→

95% with face95% with face--maskmask

Physical exam was notable for Physical exam was notable for inspiratoryinspiratorycrackles at basescrackles at bases

Patient was evaluated with CTAPatient was evaluated with CTA

Index Patient: Chest CTAIndex Patient: Chest CTA

PACS, BIDMCAxial C+ Chest CTA

Please evaluate and proceed to next slide.

Index Patient: Ground Glass Index Patient: Ground Glass Opacities on Chest CTOpacities on Chest CT

PACS, BIDMCAxial C+ Chest CTA

Bilateral multifocal ground glass opacities, mostly at peripheryConsolidative areas at basesNo pulmonary embolism

Index Patient: Comparison of Index Patient: Comparison of Chest Chest CTsCTs

Admission 33 hours later

PACS, BIDMCPACS, BIDMC

Rapid development of multifocal ground glass opacities within 33 hours

Axial C+ Chest CTAAxial C+ Chest CT

PACS, BIDMC

Index Patient:Index Patient: Ground Glass Opacities on Ground Glass Opacities on SagittalSagittal

CTCT

Development of multifocal ground glass opacities in all lobes within 33 hours

Sagittal C+ Chest CT Sagittal C+ Chest CT

Right Major Fissure

Minor Fissure

PACS, BIDMC

Left Major Fissure

Let’s move on to discuss ground Let’s move on to discuss ground glass opacities.glass opacities.

Ground Glass Opacities: Ground Glass Opacities: Definition and DifferentialDefinition and Differential

Definition: semiDefinition: semi--transparent opacities that allow transparent opacities that allow pulmonary vasculature to be visualizedpulmonary vasculature to be visualized–– When describing lung findings, this terminology is When describing lung findings, this terminology is

reserved for Chest CTreserved for Chest CT

NonspecificNonspecific–– InterstitialInterstitial–– AlveolarAlveolar–– MixedMixed

DDxDDx is broadis broad–– Fluid: pulmonary edemaFluid: pulmonary edema–– Blood: contusion, hemorrhageBlood: contusion, hemorrhage–– Pus: infectious pneumonia, Pus: infectious pneumonia, pneumonitispneumonitis–– Cells: malignancyCells: malignancy–– Other: fibrosisOther: fibrosis

Ground Glass Opacities: Narrowed Ground Glass Opacities: Narrowed Differential Diagnosis Differential Diagnosis s/ps/p

TraumaTrauma

Pulmonary Hemorrhage/ContusionPulmonary Hemorrhage/ContusionAspiration Aspiration pneumonitispneumonitisPulmonary edemaPulmonary edema–– CardiogenicCardiogenic–– NoncardiogenicNoncardiogenic

Fat embolismFat embolismPneumonia (later onset)Pneumonia (later onset)

SuperSuper--infectioninfectionHospitalHospital--acquiredacquiredVentilatorVentilator--associatedassociated

Let’s return to our patient, 48 Let’s return to our patient, 48 hours after admission. hours after admission.

Index Patient: Interim History Index Patient: Interim History 48 hours after admission48 hours after admission

Patient’s respiratory status worsensPatient’s respiratory status worsens–– Episodes of Episodes of dyspneadyspnea and tachycardiaand tachycardia–– Continues to spike fevers despite broad antibiotic coverageContinues to spike fevers despite broad antibiotic coverage

New onset headacheNew onset headache

Acute confusion and hypoxiaAcute confusion and hypoxia–– Emergent intubationEmergent intubation–– ABG: paO2 = 50ABG: paO2 = 50

Index Patient: Index Patient: Development of ARDSDevelopment of ARDS

Our patient continued to require mechanical Our patient continued to require mechanical ventilationventilation

PaO2 remained low despite ventilation and PEEPPaO2 remained low despite ventilation and PEEP–– Indicated significant intraIndicated significant intra--pulmonary shuntpulmonary shunt

Ratio of PaO2 to FiO2 ranged from 97Ratio of PaO2 to FiO2 ranged from 97--158158

Our patient was diagnosed with Acute Respiratory Our patient was diagnosed with Acute Respiratory Distress SyndromeDistress Syndrome

Index Patient: Frontal CXR at 48 Index Patient: Frontal CXR at 48 hours after Admissionhours after Admission

PACS, BIDMC


A/P CXR

Index Patient: Alveolar Opacities on Index Patient: Alveolar Opacities on Frontal CXRFrontal CXR

PACS, BIDMC

Findings:

Widespread patchy pulmonary opacities → alveolar

Left >Right

Endotracheal tube tip at orifice of right main bronchus

No cardiomegaly

Appropriately placed NG tube A/P CXR

Index Patient: Chest CT at 76 hours Index Patient: Chest CT at 76 hours after Admissionafter Admission


Axial C+ Chest CT PACS, BIDMC

Index Patient: Consolidation on Index Patient: Consolidation on Chest CTChest CT

Ground glass opacities

Increased areas of consolidation

Axial C+ Chest CT PACS, BIDMC

Let’s discuss Acute Respiratory Let’s discuss Acute Respiratory Distress Syndrome.Distress Syndrome.

Acute Respiratory Distress Syndrome: Acute Respiratory Distress Syndrome: Definition and DiagnosisDefinition and Diagnosis

ARDS: syndrome of acute and persistent lung ARDS: syndrome of acute and persistent lung inflammation with increased pulmonary vascular inflammation with increased pulmonary vascular permeability, resulting in severe hypoxemia permeability, resulting in severe hypoxemia

4 Diagnostic Features:4 Diagnostic Features:1.1.

Acute onsetAcute onset–– Develops over 4 to 48 hours, persists for days to weeksDevelops over 4 to 48 hours, persists for days to weeks

2.2.

Radiograph appearance of bilateral infiltrates Radiograph appearance of bilateral infiltrates consistent with pulmonary edemaconsistent with pulmonary edema

3.3.

PaO2/FiO2 PaO2/FiO2 ≤ 200 mmHg≤ 200 mmHg–– Regardless of level of PEEPRegardless of level of PEEP

4.4.

NoncardiogenicNoncardiogenic–– No evidence of elevated L No evidence of elevated L atrialatrial pressure or pulmonary capillary pressure or pulmonary capillary

wedge pressure < 18 mmHgwedge pressure < 18 mmHg

Acute Respiratory Distress Syndrome: Acute Respiratory Distress Syndrome: PathophysiologyPathophysiology

Injury to alveolar epithelial cells Injury to alveolar epithelial cells ± capillary endothelial cells± capillary endothelial cells

⇓⇓Inflammation with Inflammation with neutrophilsneutrophils

⇓⇓Expression of leukocyte adhesion moleculesExpression of leukocyte adhesion molecules

Release of multiple cytokine mediators, Release of multiple cytokine mediators, proteases, oxidantsproteases, oxidants

⇓⇓Contribute to increased vascular and alveolar Contribute to increased vascular and alveolar

permeabilitypermeability⇓⇓

Increased fluid movement from capillaries to Increased fluid movement from capillaries to interstitiuminterstitium in excess of lymphatic in excess of lymphatic

reabsorptionreabsorption⇓⇓

Alveolar edemaAlveolar edemaUpToDate

Acute Respiratory Distress Syndrome: Acute Respiratory Distress Syndrome:

CausesCauses

AspirationAspiration–– GastricGastric–– Near drowningNear drowning–– HydrocarbonsHydrocarbons

Toxic gas inhalationToxic gas inhalation–– SmokeSmoke

Bilateral PNABilateral PNA–– ViralViral–– BacterialBacterial–– PneumocystisPneumocystis jirovecijiroveci

SepsisSepsisTraumaTraumaDICDICEmbolismEmbolism–– FatFat–– Amniotic fluidAmniotic fluid

TransfusionTransfusionDrugsDrugsPancreatitisPancreatitisNeurogenicNeurogenic

Acute Respiratory Distress Syndrome:Acute Respiratory Distress Syndrome: Causes After TraumaCauses After Trauma

Bilateral lung contusion/pulmonary Bilateral lung contusion/pulmonary hemorrhagehemorrhageExtensive aspirationExtensive aspirationFat embolismFat embolismSepsis Sepsis Massive traumatic tissue injuryMassive traumatic tissue injuryIatrogenicIatrogenic–– Drugs, transfusionDrugs, transfusion--relatedrelated

Acute Respiratory Distress Syndrome:Acute Respiratory Distress Syndrome: Radiographic AppearanceRadiographic Appearance

Chest XChest X--RayRay–– Bilateral alveolar infiltratesBilateral alveolar infiltrates–– If not present initially, must develop within 24 hoursIf not present initially, must develop within 24 hours–– Normal heart size, unless prior heart disease and Normal heart size, unless prior heart disease and cardiomegalycardiomegaly

unrelated to present problemunrelated to present problem

CTCT–– MultiMulti--focal ground glass opacitiesfocal ground glass opacities–– Progresses to consolidationProgresses to consolidation–– Usually begins in dependentUsually begins in dependent--regions and periphery before regions and periphery before

becoming diffusebecoming diffuse–– Pleural effusions common, usually smallPleural effusions common, usually small

Acute developmentAcute development

Companion Patient #1: Acute Respiratory Companion Patient #1: Acute Respiratory Distress Syndrome on CXRDistress Syndrome on CXR

Findings:

Bilateral alveolar opacities

No cardiomegaly

UpToDateA/P CXR

Companion Patient #2: Acute Respiratory Companion Patient #2: Acute Respiratory Distress Syndrome on CTDistress Syndrome on CT

Findings:

Multi-focal ground glass opacities

Consolidations

Greater in dependent areas

UpToDateThis companion patient developed ARDS from sepsis after pneumoccal pneumonia

Axial C- Chest CT

Our patient was felt to have Our patient was felt to have developed ARDS from Fat Embolism developed ARDS from Fat Embolism Syndrome.Syndrome.

Let’s move on to discuss Fat Embolism Let’s move on to discuss Fat Embolism Syndrome.Syndrome.

Fat Embolism Syndrome: Fat Embolism Syndrome: DefinitionsDefinitionsFat emboli: Presence of fat droplets within the systemic and Fat emboli: Presence of fat droplets within the systemic and pulmonary circulation with or without clinical pulmonary circulation with or without clinical sequelaesequelae

Fat embolism syndrome: Clinical Fat embolism syndrome: Clinical sequelaesequelae that manifests 24that manifests 24--72 72 hours after initial insulthours after initial insult

1.1. Respiratory distressRespiratory distress2.2. Mental status changesMental status changes3.3. PetechialPetechial rashrash

Causes of Fat Embolism Syndrome:Causes of Fat Embolism Syndrome:–– TraumaTrauma--relatedrelated

Long bone and pelvic fracturesLong bone and pelvic fracturesOrthopedic proceduresOrthopedic proceduresLiposuctionLiposuction

–– NontraumaNontrauma--related very rarerelated very rarePancreatitis, bone tumor Pancreatitis, bone tumor lysislysis, lipid infusion, lipid infusion

Fat Embolism Syndrome:Fat Embolism Syndrome: PathogenesisPathogenesis

Two Hypotheses:Two Hypotheses:

1.) Mechanical Obstruction:1.) Mechanical Obstruction:--Fat emboli obstruct pulmonary Fat emboli obstruct pulmonary and systemic vasculatureand systemic vasculature--Does not explain symptomDoes not explain symptom-- free interval following acute free interval following acute insultinsult

2.) Toxic Intermediates:2.) Toxic Intermediates:--Fat emboli are degraded into Fat emboli are degraded into free fatty acidsfree fatty acids→→FFAsFFAs are very toxic to lungs are very toxic to lungs --Explains symptomExplains symptom--free free intervalinterval--Supported by animal studies Supported by animal studies of of FFAsFFAs initiating ARDS in miceinitiating ARDS in mice

Akhtar. Anesthesiology Clin 2009; 27: 533-550

Fat Embolism Syndrome:Fat Embolism Syndrome: DiagnosisDiagnosis

Diagnosis remains elusiveDiagnosis remains elusive–– Incidence is unknown, ranges from 0.25% to 35% in postIncidence is unknown, ranges from 0.25% to 35% in post--

trauma patientstrauma patients–– Complicated by authors’ use of different diagnostic criteriaComplicated by authors’ use of different diagnostic criteria

3 Sets of Diagnostic Criteria3 Sets of Diagnostic Criteria

Often indistinguishable from Acute Respiratory Often indistinguishable from Acute Respiratory Distress SyndromeDistress Syndrome

Fat Embolism Syndrome:Fat Embolism Syndrome: Original Diagnostic CriteriaOriginal Diagnostic Criteria

GurdGurd and Wilson (FES = 1 major + 4 minor + fat and Wilson (FES = 1 major + 4 minor + fat microglobulinemiamicroglobulinemia))–– Major criteria:Major criteria:

Respiratory insufficiencyRespiratory insufficiencyCerebral involvementCerebral involvementPetechialPetechial rashrash

–– Minor criteria Minor criteria PyrexiaPyrexiaTachycardiaTachycardiaRetinal changesRetinal changesJaundiceJaundiceRenal changes (Renal changes (anuriaanuria or or oliguriaoliguria))Thrombocytopenia (a drop of >50% of the admission Thrombocytopenia (a drop of >50% of the admission thrombocytethrombocyte value)value)High erythrocyte sedimentation rateHigh erythrocyte sedimentation rateFat Fat microglobulinemiamicroglobulinemia

PetechialPetechial rash considered rash considered pathognomonicpathognomonic in appropriate clinical setting but in appropriate clinical setting but only present in 20only present in 20--50% of cases50% of cases

Presence of fat globules in sputum, urine, or wedged PA catheterPresence of fat globules in sputum, urine, or wedged PA catheter is now not is now not considered to be necessary to confirm diagnosisconsidered to be necessary to confirm diagnosis


Fat Embolism Syndrome:Fat Embolism Syndrome: New Diagnostic CriteriaNew Diagnostic Criteria

Fat embolism index (FES = 5 or more points) in appropriate cliniFat embolism index (FES = 5 or more points) in appropriate clinical cal settingsetting–– Diffuse Diffuse petechiaepetechiae (5 points)(5 points)

Alveolar infiltrates (4 points)Alveolar infiltrates (4 points) Hypoxemia (<70 mm Hg) (3 points)Hypoxemia (<70 mm Hg) (3 points) Confusion (1 point)Confusion (1 point) Fever 38°CFever 38°C Heart rate >120/minHeart rate >120/min Respiratory rate >30/minRespiratory rate >30/min

LindequeLindeque criteria (FES = femur fracture ± tibia fracture + 1 feature)criteria (FES = femur fracture ± tibia fracture + 1 feature)–– A sustained PaO2 <60 mm HgA sustained PaO2 <60 mm Hg

A sustained PaCO2 >55 mm Hg) or pH <7.3A sustained PaCO2 >55 mm Hg) or pH <7.3 A sustained respiratory rate >35/min even after adequate sedatioA sustained respiratory rate >35/min even after adequate sedationn Increased work of breathing judged by Increased work of breathing judged by dyspneadyspnea, use of accessory , use of accessory muscles, tachycardia, and anxietymuscles, tachycardia, and anxiety

All sets of diagnostic criteria have unknown specificity and senAll sets of diagnostic criteria have unknown specificity and sensitivitysitivity


Let’s evaluate our patient for Fat Let’s evaluate our patient for Fat Embolism Syndrome.Embolism Syndrome.

Index Patient: Diagnosis of Fat Index Patient: Diagnosis of Fat Embolism SyndromeEmbolism Syndrome

Our patient was evaluated with the Fat Embolism Index Our patient was evaluated with the Fat Embolism Index Criteria :Criteria :–– No diffuse No diffuse petechiaepetechiae = = 0 points0 points–– Alveolar infiltrates Alveolar infiltrates = = 5 points5 points–– Hypoxemia < 70 mm Hg Hypoxemia < 70 mm Hg = = 3 points3 points–– Confusion Confusion = = 1 point1 point–– Fever > 38°C Fever > 38°C = = 1 point1 point–– Tachycardia > 120/min Tachycardia > 120/min = = 1 point1 point–– TachypneaTachypnea > 30/min > 30/min = = 1 point1 point

Total points on Fat Embolism Index = 12 pointsTotal points on Fat Embolism Index = 12 points

She satisfied the Fat Embolism Index (> 5 points) for the She satisfied the Fat Embolism Index (> 5 points) for the diagnosis of Fat Embolism Syndromediagnosis of Fat Embolism Syndrome

Let’s continue to examine the Let’s continue to examine the radiographic findings of Fat Embolism radiographic findings of Fat Embolism Syndrome. Syndrome.

Fat Embolism Syndrome:Fat Embolism Syndrome: Radiographic Appearance of Pulmonary Radiographic Appearance of Pulmonary

FindingsFindings

Nonspecific Nonspecific –– Indistinguishable from ARDSIndistinguishable from ARDS–– Also can progress to ARDSAlso can progress to ARDS

Chest XChest X--RayRay–– Bilateral alveolar infiltratesBilateral alveolar infiltrates

CTCT–– MultiMulti--focal ground glass opacitiesfocal ground glass opacities–– May progress to consolidationsMay progress to consolidations–– Pleural effusions uncommon, usually smallPleural effusions uncommon, usually small–– Evidence of obstructive fat emboli in vasculature is extremely Evidence of obstructive fat emboli in vasculature is extremely

rare and not recently reportedrare and not recently reported

Companion Patient #3: Fat Embolism Companion Patient #3: Fat Embolism Syndrome on CXRSyndrome on CXR

Constantino M et al. Semin Roentgenol 2006 Jul;41(3):209-25

A/P CXR

Findings:

Bilateral alveolar infiltrates

Companion Patient #4: Fat Embolism Companion Patient #4: Fat Embolism Syndrome on Chest CTSyndrome on Chest CT

Malagari K et al. Chest 2003;123:1196-1201

Axial C+ Chest CT

Multi-focal ground glass opacities

Let’s conclude by returning to our Let’s conclude by returning to our patient.patient.

Index Patient: ConclusionIndex Patient: Conclusion

At the time of this publication, our patient was felt At the time of this publication, our patient was felt to have Acute Respiratory Distress Syndrome to have Acute Respiratory Distress Syndrome secondary to Fat Embolism Syndromesecondary to Fat Embolism Syndrome–– Satisfied ARDS Diagnostic CriteriaSatisfied ARDS Diagnostic Criteria–– Satisfied Fat Embolism Index CriteriaSatisfied Fat Embolism Index Criteria–– Further workFurther work--up for Fat Embolism up for Fat Embolism SyndomeSyndome, such as the , such as the

presence of fat presence of fat microglobinemiamicroglobinemia, was not pursued, was not pursued–– Multiple infectious workMultiple infectious work--ups were negativeups were negative

Our patient received supportive management Our patient received supportive management –– Mechanical Ventilation with PEEPMechanical Ventilation with PEEP

She made a full recovery 15 days laterShe made a full recovery 15 days later

Many Thanks To:Many Thanks To:

Adam JeffersAdam JeffersPaul Paul SpirnSpirnGillian LiebermanGillian LiebermanMaria Maria LevantakisLevantakis

ReferencesReferencesAkhtar S. Fat embolism. Anesthesiol Clin 2009 Sep;27(3):533-50

Costantino M, Gosselin MV, Primack SL. The ABC’s of thoracic trauma imaging. Semin Roentgenol 2006 Jul;41(3):209-25

Gotway MB, Reddy GP, Webb WR, Elicker BM, Leung JW. High-resolution CT of the lung: patterns of disease and differential diagnoses. Radiol Clin North Am 2005 May;43

Hansen-Flaschen J, Siegel MD. Acute respiratory distress syndrome: Definition; epidemiology; diagnosis; and etiology. UpToDate 2009.

Malagari K, Economopoulos N, Stoupis C, Daniil Z, Papiris S, Muller N, Kelekis D. High- Resolution CT findings in Mild Pulmonary Fat Embolism. Chest 2003; 123; 1196-1201

Seigel MD. Acute respiratory distress syndrome: Pathophysiology; clinical manifestations; prognosis; and outcome. UpToDate 2009

Weinberger SE, Cockrill BA, Mandel J. Acute Respiratory Distress Syndrome. Principles of Pulmonary Medicine, Fifth Edition. Saunders Elsevier 2008; 344-355

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