g05 ards, fes, dvt, pe
TRANSCRIPT
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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