Pulmonary Thromboembolism (PTE) Jamil A. Alarafi, D.O. An Elusive Diagnosis
Goals • Understand the historical context of pulmonary emboli • Comprehend the pathophysiology and know some common risk factors • Be aware of the clinical features of PE and have a basic understanding of various diagnostic test • Gain a therapeutic approach to the treatment of PE and discuss a simplified method in the work-up of PE • Attempt to dispel a few “myths”about pulmonary emboli
Perspective • A Common disorder and potentially deadly • 650,000 cases occurring annually • Highest incidence in hospitalized patients • Autopsy reports suggest it is commonly “missed” diagnosed
Perspective • Presentation is often “atypical” • Signs and symptoms are frequently vague and nonspecific and rarely “classic” • Untreated mortality rate of 20% - 30%, plummets to 5% with timely intervention
Historical Context • Pre-1930’s • Heparin • Eugine Robin article
Historical Context • PIOPED (Prospective Investigation of Pulmonary Embolism Diagnosis) • The Electronic Era, 2000 and Beyond…
So What Do We Do ??? • Confusing for Emergency Physician Do we under diagnose/over diagnose? Why don’t we have a standardized method of work up after all these years?
Pathophysiology Rudolph Virchow, 1858 Triad: • Hypercoagulability • Stasis to flow • Vessel injury
Risk Factors Hypercoagulability Malignancy Nonmalignant thrombophilia Pregnancy Postpartum status (<4wk) Estrogen/ OCP’s Genetic mutations (Factor V Leiden, Protein C & S deficiency, Factor VIII, Prothrombin mutations, anti-thrombin III deficiency) Venous Statis Bedrest > 24 hr Recent cast or external fixator Long-distance travel or prolong automobile travel Venous Injury Recent surgery requiring endotracheal intubation Recent trauma (especially the lower extremities and pelvis)
Clinical Presentation • The Classic Triad: (Hemoptysis, Dyspnea, Pleuritic Pain) • Not very common! • Occurs in less than 20% of patients with documented PE • Three Clinical Presentations • Pulmonary Infarction • Submassive Embolism • Massive Embolism
Mythology of PE • Myth • “Patients with pulmonary embolism are short of breath and have chest pain!” • Reality: You can forget about making the diagnosis on clinical grounds, but wait…don’t plan on completely ruling it out either!
Clinical Features Symptoms in Patients with Angio Proven PTE Symptom Percent Dyspnea 84 Chest Pain, pleuritic 74 Anxiety 59 Cough 53 Hemoptysis 30 Sweating 27 Chest Pain, nonpleuritic 14 Syncope 13
Clinical Features Signs with Angiographically Proven PE Sign Percent Tachypnea > 20/min 92 Rales 58 Accentuated S2 53 Tachycardia >100/min 44 Fever > 37.8 43 Diaphoresis 36 S3 or S4 gallop 34 Thrombophebitis 32 Lower extremity edema 24
Who do we work up? - Pretest Probability • Definition: “The probability of the target disorder (PE) before a diagnostic test result is known”. • Used to decide how to proceed with diagnostic testing and final disposition • “Gestalt” • This is really what it boils down to!
Diagnostic Test • Imaging Studies • CXR • V/Q Scans • Spiral Chest CT • Pulmonary Angiography • Echocardiograpy • Laboratory Analysis • CBC, ESR, Hgb/Hct, • D-Dimer • ABG’s • Ancillary Testing • EKG • Pulse Oximetry
Diagnostic Testing- CXR’s Chest X-Ray Myth: “You have to do a chest x-ray so you can find Hampton’s hump or a Westermark sign.” Reality: Most chest x-rays in patients with PE are nonspecific and insensitive
Diagnostic Testing - CXR’s Chest radiograph findings in patient with pulmonary embolism ResultPercent Cardiomegaly 27% Normal study 24% Atelectasis 23% Elevated Hemidiaphragm 20% Pulmonary Artery Enlargement 19% Pleural Effusion 18% Parenchymal Pulmonary Infiltrate 17%
Chest X-ray Eponyms of PE • Westermark's sign • A dilation of the pulmonary vessels proximal to the embolism along with collapse of distal vessels, sometimes with a sharp cutoff. • Hampton’s Hump • A triangular or rounded pleural-based infiltrate with the apex toward the hilum, usually located adjacent to the hilum.
Radiographic Eponyms - Hampton’s Hump, Westermark’s Sign Westermark’s Sign Hampton’s Hump
Diagnostic Testing– EKG’s • EKG • Most Common Findings: • Tachycardia or nonspecific ST/T-wave changes • Acute cor pulmonale or right strain patterns • Tall peaked T-waves in lead II (P pulmonale) • Right axis deviation • RBBB • S1-Q3-T3 (occurs in only 20% of PE patients)
Diagnostic Testing - Pulse Oximetry • The Pulse Oximetry Myth: • “ You must do a pulse oximetry reading, since patients with pulmonary embolism are hypoxemic!” • Reality: • Most patients with a PE have a normal pulse oximetry, and most patients with an abnormal pulse oximetry will not have a PE.
Diagnostic Testing - ABG’s • The ABG/ A-a Gradient myth: • “You must do an arterial blood gas and calculate the alveolar-arterial gradient. Normal A-a gradient virtually rules out PE”. • Reality: • The A-a gradient is a better measure of gas exchange than the pO2, but it is nonspecific and insensitive in ruling out PE.
Diagnostic Testing • Echocardiography • Consider in every patient with a documented pulmonary embolism • EKG maybe helpful in demonstrating right heart strain • Early fibrinolysis can reduce mortality 50%!
Ancillary Test • WBC • Poor sensitivity and nonspecific • Can be as high as 20,000 in some patients • Hgb/Hct • PTE does not alter count but if extreme, consider polycythemia, a known risk factor • ESR • Don’t get one, terrible test in regard to any predictive value
D-dimer Test • Fibrin split product • Circulating half-life of 4-6 hours • Quantitative test have 80-85% sensitivity, and 93-100% negative predictive value • False Positives: Pregnant Patients Post-partum < 1 week Malignancy Surgery within 1 week Advanced age > 80 years Sepsis Hemmorrhage CVA AMI Collagen Vascular Diseases Hepatic Impairment
Diagnostic Testing • D-dimer • Qualitative • Bed side RBC agglutination test • “SimpliRED D-dimer” • Quantitative • Enzyme linked immunosorbent asssay “Dimertest” • Positive assay is > 500ng/ml • VIDAS D-dimer, 2nd generation ELISA test
Ventilation/Perfusion Scan - “V/Q Scan” • A common modality to image the lung and its use still stems from the PIOPED study. • Relatively noninvasive and sadly most often nondiagnostic • In many centers remains the initial test of choice • Preferred test in pregnant patients • 50 mrem vs 800mrem (with spiral CT)
V/Q Scan • Technique • Interpretation • Normal • Low probability/”nondiagnostic” (most common) • High Probability • Simplified approached to the interpretation of results: High probability Treat for PE Normal Scan If low pre-test, your done Everything else Purse another study (CT, Angio)
Spiral (Helical) Chest CT • Advantages • Noninvasive and Rapid • Alternative Diagnosis • Disadvantages • Costly ($600 - 900/scan) • Risk to patients with borderline renal function • Hard to detect subsegmental pulmonary emboli
Pulmonary Angiography • “Gold Standard” • Performed in an Interventional Cath Lab • Positive result is a “cutoff” of flow or intraluminal filling defect • “Court of Last Resort”
Dr. Batizy explaining the CT results Treatment: Patient replies: “Uh-huh, when do I get to eat!” Goals: • Prevent death from a current embolic event • Reduce the likelihood of recurrent embolic events • Minimize the long-term morbidity of the event
Treatment • Anticoagulants • Heparin • Provides immediate thrombin inhibition, which prevents thrombus extension • Does not dissolve existing clot • Will not work in patients with antithrombin III def. • In this case use hirudins • Few absolute contraindications
Treatment • Anticoagulants • Heparin • Available as Unfractionated or LMW Heparin • FDA approved dosing: • Unfractionated: 80 units/kg bolus, 18 units/kg/hr • LMWH: 1 mg/kg Q 12 or 1.5mg/kg Q D • LMWH (Lovenox) prefered in pregnant patients
Treatment • Anticoagulants • Warfarin (Coumadin) • Interferes with the action of Vit-K dependent factors: II, VII, IX, and X, as well as protein C & S • Causes temporary hypercoagulable state in first 5 days of treatment • Important a patient is anticoagulated with heparin before initiating warfarin therapy • Target INR is 2.5 – 3.0
Treatment • Fibrinolytic Therapy (Alteplase) • Indications: • Documented PE with: • Persistent hypotension • Syncope with persistent hemodynamic compromise • Significant hypoxemia • +/- patient with acute right heart strain • Approved Altivase regimen is 100mg as a continuous IV infusion.
Treatment • Embolectomy • Prefininolytic therapy this was only therapy for massive PE • Carries a 40% operative mortality • Alternative is Transvenous Catheter Embolectomy
A Simplified Algorithm • Pre-test probability • D-dimer (VIDAS-DD) • CT angiography Low Pre-test, D-dimer (-), patient had < 1.7% 90 day PE occurrence in a Mayo Clinic Study
Special Circumstances • Morbid Obesity • Pregnancy • V/Q has considerable less radiation • 50 mrem vs. 800 mrem • Almost all will have positive D-Dimer • Heparin safe in pregnancy • Witnessed Cardiac Arrest • Standard ACLS, if known PE, the lytics.
ConclusionSummary Points • Pulmonary Emboli remain a potentially deadly and common event which may present in various ways • Don't’ be fooled if your patient lacks the “classic” signs and symptoms! • Consider PE in any patient with an unexplainable cause of dyspnea, pleuritic chest pain, or findings of tachycardia, tachpnea, or hypoxemia • 2nd Generation Qualitative D-Dimers have NPV of 93-99% • Heparin remains the mainstay of therapy with the initiation of Warfarin to follow • Simplified Algorithm: ( Pretest probability, D-Dimer, +/- CT angio), then disposition)
The End! Questions????
1. Which of the following is not a part of virchows triad? • Hypercoagulability • Stasis to flow • Vessel injury • History of previous DVT
Which of the following is the propper treatment of fat emboli? • Platelets • High dose steroids • Heparin • cryoprecipitate
The Classic Triad of patients presenting to the ED with PE includes all of the following except: • Hemoptysis • Dyspnea • + Homans’ sign • Pleuritic Pain
What is the most common symptom in a patient with Angio Proven PTE? • Dyspnea • Chest Pain, pleuritic • Anxiety • Cough
What is the most common ecg finding in patients with PE? • Right axis deviation • RBBB • S1-Q3-T3 • Tall peaked T-waves in lead II (P pulmonale) • Sinus tachycardia
Answers • D • B • C • A • E