Acute Respiratory Distress Syndrome, Fat Embolism, &

Thromboembolic Disease in the Orthopaedic Trauma Patient

Steve Morgan, MD

Objectives

• Define– ARDS– FES

– Thromboembolic Disease

• Understand Etiology & Physiology of each Condition

• Understand– Prevention– Diagnosis

– Treatment – Outcomes

ARDS

• Acute respiratory failure in the post traumatic period characterized by a decreased PaO2 and a diffuse and often massive extravasation of fluid from the pulmonary vasculature to the interstitial space of the lungs.

ARDSCommon Causes

• Trauma• Massive Transfusion

• Embolism• Sepsis• Aspiration

• Abdominal Distension

• Pulmonary Edema• Prolonged LOC

• Cardiopulmonary Bypass

• Pancreatitis• Major Burns

MULTIFACTORAL

ARDS Etiology

• ARDS related to MSOF

• Release of inflammatory mediators results in organ dysfunction

Trauma InflammatoryMediators

OrganInjury

ARDS PATHOPHYSIOLOGY

• Systemic Inflammatory Mediators

• Damage to Endothelial Lining

• Increased Capillary Permeability

• Fluid Extravasation

• Alveolar Collapse • Decreased Pulmonary

Compliance

• Ventilation Perfusion Abnormalities

• Arteriolar Hypoxemia

ARDS Chest Radiograph

ARDS Chest CT Scan

ARDSPrevention

• Limiting Blood Loss

• Decreasing Transfusion Requirements

• Early Fixation Of Unstable Fractures

• Early Prophylactic Mechanical Ventilation

ARDS Treatment

• Ventilator Support

• Goals– Acceptable ABG’s– Prevent alveolar damage– Facilitate healing

– Non-toxic FIO2 (< .60)

• Research– Optimal ventilator settings

ARDSOutcome

• Significant Cause of Mortality

• Major Cause of Death in Patients with the Lowest ISS scores

• 40% - 50% Mortality Rate– Mortality Rate Slowly Decreasing with

Changing & Improving Therapy

Fat Embolism Syndrome(FES)

• A Causative Factor In ARDS

• Occurs Following A Long Bone Fracture

• Characterized by:– Hypoxia– Mental Confusion– Petechial Rash

FES

• Unanticipated Respiratory Distress

• Diagnosis of Exclusion

• Often Placed in The Category of ARDS

• R/O other Causes of Hypoxia– Pulmonary Contusion– ARDS– Pneumonia

Etiology

• Mechanical

• Biochemical

• No simple etiology

Mechanical Etiology

• Fracture Liberates Fat

• Intravasation - Fat Enters Venous System

• Fat Causes Mechanical Obstruction

Mechanical Etiology

• Systemic Fat Embolization

– Patent Foramen Ovale

– Pulmonary Pre-Capillary Shunts

FES To Brain On MRI

Biochemical Etiology

• Chemical Mediators Released @ time of Fracture

• Fat Released at Time of Fracture

• Fat Metabolism by Lipase releases Free Fatty Acids

• Free Fatty Acids Result in Endothelial Lung Damage

Gurd et al

FES Diagnosis

• Major Criteria– Hypoxemia– CNS Depression

– Petechial Rash– Pulmonary Edema

• Minor Criteria– Tachycardia– Pyrexia

– Retinal Emboli– Fat in Urine– Fat in Sputum– Thrombocytopenia– Decreased Hematocrit

Gurd et al

FES Diagnosis

• 1 Major Criteria

• 4 Minor Criteria

FES Treatment

• Supportive

• Oxygen Therapy to maintain PaO2

• Mechanical Ventilation

FES Treatment• Steroids

– Decrease endothelial damage– 30mg/kg initial dose repeated @ 4 Hours, 1gm

dose repeated @ 8 Hours: Total 3 Doses

• Complications - Frequent– Infection

– GI

• Steroid Therapy Avoided Secondary To Poor Risk Benefit Ratio

FES Prevention

• Therapies– Fluid Loading

– Hypertonic Fluid– Alcohol– Heparin– Dextran– Aspirin

• Not Shown to be Effective

FES Prevention

• Appropriate Splinting

• Early Fracture Stabilization

• Oxygen Therapy

Timing of Fracture Fixation

• Early Fracture Fixation Optimal

• Decreases Pulmonary Complications

• Delayed Fracture Fixation– Increased Pulmonary Dysfunction

Type of Fracture Fixation-Controversial-

• IM Nail - Reamed vs Un-Reamed – Increased Pulmonary Dysfunction With Reamed

technique– Decreased with Unreamed Technique

– Pape et al

• IM Nail Reamed vs Plate Osteosynthesis– No Difference In Pulmonary Dysfunction

• Bosse et al

Effect of IM Nailing

• Canal Opening

• Reaming

• Nail Insertion

• Unreamed Nail Insertion

• All Cause Increased IM Pressure

• All Cause Embolic Showers On Echocardiograms

Systemic Effects of Trauma

Injury

12 hours 24 hours

PostinjuryInflammatoryResponse

Second Insult

MOF

IM Nailing As A cause of Secondary Systemic Injury

DVT Incidence

• DVT occurance 60% if ISS >9.

• 35%-60% DVT in pelvic fracture

• PE-Most common preventable cause of death in trauma.

Virchow Triad

Hypercoaguability

• Tissue Thromboplastin

• Activated Procoagulants

• Decreased Fibrinolytic Activity

• Ineffective Heparin Clearance of Activated Clotting Factors

• Catecholamine Release

Endothelial Injury

• Direct Trauma to Vein @ time of Injury

• Compression of the Vein Secondary to Fracture Position

• Vein Manipulation @ Time of Fracture Fixation

Venous Stasis

• Immobilization

• Hypotension

• Venous Occlusion – Edema– Fracture Position

DVT Prevention

Goals

• Clinically significant events– PE– Post Thrombotic syndrome

• Low Complication Rate• High Compliance Rate• Cost Effective

DVT Prevention

Prophylaxis

• Elastic Stockings

• Mechanical Compression Devices

• Inferior Vena Cava Filter (IVC)

• Heparin

• Warfarin

• Low Molecular Weight Heparin

• Aspirin

Mechanical Methods

• Activity• Compression

Stockings• Sequential

Compression Device• Pedal PumpsMechanism of Action• Decrease Stasis∀ ↑ Fibrinolytic Activity

IVC Filter Indications

• Anticoagulation Prohibited

• High Risk Patients

• DVT Prior to Necessary Surgery

• PE Despite Anticoagulation

IVC Filter

• Prevents Major PE

• Low Morbidity – 96% Patent

– 8% Migration

– 4% PE

• Filter insertion in the ICU

• Expensive

• Invasive

• Does not treat DVT

• Venous Insufficiency

• Filter Occlusion

• Permanent

Advantages Disadvantage

Heparin

• Heparin Potentiates Anti-Thrombin III Activity

• Complex Inhibits

– Thrombin (IIa), IXa, Xa

• Heparin effect relative short duration

– Reversed with Protamine Sulfate

• Significant hemorrhage risk

SQ Heparin

• Low Cost

• No Monitoring

• Convenient

• Relatively Low Incidence of Bleeding

• Insufficient Efficacy in High Risk Patients

• Unpredictable Responses

• Heparin Induced Thrombocytopenia

Advantages Disadvantage

Low Molecular Weight Heparin(LMWH)

• Potentiates Antithrombin III

• Specific for Factor Xa

• Minimal effects on other Factors

LMWH

• No Monitoring

• Increased Efficacy

• Longer 1/2 life

• Predictable Response

• Lower risk of thrombocytopenia

• Parenteral Administration

• Cost

Advantages Disadvantage

Aspirin

• Inhibits cyclooxygenase

• Decreases Platelet Adherence

• ? Effectiveness in Musculoskeletal Trauma– Venous clots not typically found to have

Platelet aggregates

Aspirin

• Oral Administration• Tolerated well

• In-expensive• No Monitoring

• ? Efficacy when used alone

• GI Intolerance

• Prolonged anti-platelet effect

Advantages Disadvantage

Warfarin

• Blocks Vit K conversion in Liver

• Effects Vit K Dependent Factors

• Effects the Extrinsic Clotting System

• Factor VII Effected first, Short Half Life

• Monitored with Pro-Time– INR 2.0-2.5

• Reversed With Vitamin K or FFP

Warfarin

• Effective• Oral Administration

• Inexpensive

• Requires Monitoring• Difficult to Reverse

• Increased Bleeding Complications in Elderly

Advantages Disadvantage

DVT screening

• Physical Exam

• Ascending venography

• Duplex Ultrasonography

• Magnetic Resonance Venography

Physical Examination

• Calf Swelling

• Palpable Venous Cords

• Calf Pain

• Homan’s Sign

• All Unreliable

Ascending Contrast Venography

• Sensitive for detection• Invasive• Dye Problems

(allergies, renal)• Injection Site Irritation• Poor Pelvic Vein

Evaluation

• Gold Standard

*Invasiveness,expense make ACV a poor screening tool

Doppler/Duplex Ultrasound

• Comparable to Venogram• Non Invasive

• No Morbidity• Poor Axial (i.e Pelvic)

Vein Evaluation• Operator Dependent• Good Screening Tool

– Noninvasive, reproducible

Magnetic Resonance Venography

• Non Invasive• Good Visualization of

Pelvic Veins• Difficult in Polytrauma

Patient• Excellent specificity and

sensitivity for suspected DVT

• Controversial for screening

Pulmonary Embolism

Clinical

Shortness of breath, agitation, confusion

Laboratory

↓ PaO2, ↑ A-a gradient

Diagnostic studies

V/Q scans

Pulmonary Angiogram

Ventilation Perfusion Scan

• Ventilation Perfusion mismatch• Results

– Low probabiltity• 15% False Negative

– Medium• Need Angiogram

– High probability• 15% False Positive

• Screening Tool

Pulmonary Angiogram

• Angiographic Evaluation of pulmonary vascular tree

• Allows Placement of IVC Filter in same setting if indicated

• Sensitive - Standard in PE Detection. Diagnostic

Treatment PE

• Anticoagulation

• Filter for recurrent event despite anticoagulation

• Thrombectomy– Serious Acute PE– Patient in extremous– Large identifiable PE

Treatment DVT/PE

• Heparin– Bolus 10-15K units– Continuous Infusion

• 1000Units/Hr– Goal → PTT 2x Control

• Prevent Clot propagation and recurrent PE

– Discontinue when Therapeutic on Wafarin

• Warfarin– INR 2.0-3.0– 3-6 Month Duration– Contraindicated in:

• Pregnancy

• Liver insufficieny

• Poor Compliance

– Prolonged Therapy may decrease recurrence rates (6 mos)

DVT/PE Outcome

• No Diagnosis and Treatment – 30% Mortality

• Correct Diagnosis and Therapy– 11% Mortality in First Hour

– 8% Mortality After First Hour

DVT/PE Outcome

• Post Thrombotic Syndrome– Valvular Incompetence– Venous Stasis– Edema– Cutaneous Atrophy

• Recurrent DVT– 20% of Patients

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