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5aa1Acute Pulmonary embolism

VIEWS: 4 PAGES: 91

									Pulmonary Embolism
           EPIDEMIOLOGY
• 65 000 cases per year in Canada1
• Estimated incidence of acute PE in
  community/teaching general hospitals is 0.27% -
  0.40% (95/34567)3
• Mortality of treated PE is 5% (stable) to 20%
  (hypotensive)4
• Mortality from unrecognized PE is up to 30% 1
• PE was not suspected in 70% of those
  diagnosed with PE at autopsy! 2
        PATHOPHYSIOLOGY
Pulmonary embolus exists in the spectrum of venous
  thromboembolism (VTE) which includes deep
  venous thrombosis (DVT).


DVT is found in 70% of those with PE.4
  In the remaining 30%, embolization is assumed to
  have already occurred.
  Other sources of emboli include iliac, renal and
  upper extremity veins, right heart. Emboli do not
  come from the calf, nor do they occur in situ.

Up to 50% of those with popliteal or proximal DVT will
  have PE, usually asymptomatic.4
          PATHOPHYSIOLOGY: Risk
                 Factors
  PREEXISTING DISEASE AND RISK FACTORS IN 500 PATIENTS WITH CLINICALLY SUSPECTED PULMONARY
                                          EMBOLISM (PE) 5

                                      PE Present (n = 202) PE Absent (n = 298)     p Value
                                     n        (%)          n          (%)

Preexisting disease
 Cardiovascular                    53            (26)       96           (32)       0.18
 Pulmonary                         14             (7)       72           (24)      < 0.00001
 Neoplastic*                       36            (18)       43           (14)       0.37
 Endocrine                         21            (10)       32           (11)       0.98
Risk factors
 Immobilization > 3 d              119          (59)       138          (46)       0.007
 Surgery*                          81            (40)      116          (39)        0.72
 Thrombophlebitis (ever)           69            (34)      57           (19)       0.0002
 Bone fractures (lower limb)       46            (23)      36           (12)       0.002
 Estrogen use                      1           (0.5)        1          (0.3)        1.0
 Pregnancy/postpartum              1           (0.5)        4            (1)        0.34

* Clinically active malignancy with pathologic diagnosis within 3 mo of study entry.
* Within 4 wk of study entry.
            VIRCHOW’S
             IMMOBILITY




TRAUMA               CANCER
ORTHO                ATIII, PROTEIN C,S DEF.
SURGERY              POLYCYTHEMIA
CV                   PERIPARTUM
CATHETERS
      PATHOPHYSIOLOGY
• Most PE are multiple.
• Humoral mediators -- thromboxane and
  serotonin from activated platelets may
  increase the pulmonary hypertension and
  severity of disease
• The burden of clot obstructing the
  pulmonary arterial bed and the duration of
  obstruction dictate symptoms:
Presentation      DYSPNEA          ALTERED            RIGHT
                                   HEMO-              HEART
                                   DYNAMICS           FAILURE

Clot Burden       < 50%,           >50%, acute        >50%,
                  acute            (massive)          subacute

Reason            V/Q mismatch +/- RV overload with   Over several
                  shunting         decr. CO           weeks the RV can
                                                      partially
                                                      compensate


Up to 1/3 of patients will have infarction with pleuritic pain +/- fever
CHALLENGES TO DIAGNOSIS
• PE can mimic many other conditions
• PE may coexist in those with diseases that
  present similarily
• History and physical exam are of limited
  utility
• We have multiple tests which have varying
  availability and utility in combination
             UTILITY OF HISTORY
                    SYMPTOMS IN 500 PATIENTS WITH
               CLINICALLY SUSPECTED PULMONARY EMBOLISM (PE) 5

                           PE Present (n = 202) PE Absent (n = 298) p Value
                           n          (%)       n         (%)

Symptoms
 Dyspnea (sudden onset)    158       (78)      87        (29)      < 0.00001
 Dyspnea (gradual onset)   12         (6)      59        (20)      0.00002
 Orthopnea                 2          (1)      27         (9)      0.00004
 Chest pain (pleuritic)    89        (44)      89        (30)      0.002
 Chest pain (substernal)   33        (16)      29        (10)       0.04
 Fainting                  53        (26)      38        (13)       0.0002
 Hemoptysis                19         (9)      16         (5)       0.12
 Cough                     22        (11)      45        (15)       0.22
 Palpitations              36        (18)      46        (15)       0.56
  UTILITY OF PHYSICAL EXAM
                      SIGNS IN 500 PATIENTS WITH
             CLINICALLY SUSPECTED PULMONARY EMBOLISM (PE)5

                             PE Present (n = 202) PE Absent (n = 298) p Value
                             n          (%)       n         (%)

Signs
 Tachycardia > 100/min       48        (24)      69        (23)        0.96
 Cyanosis                    33        (16)      44        (15)        0.73
 Hypotension < 90 mm Hg      6          (3)      5          (2)        0.15
 Neck vein distention        25        (12)      28         (9)        0.36
 Leg swelling (unilateral)   35        (17)      27         (9)        0.009
 Fever > 38° C               14         (7)      63        (21)        0.00003
 Crackles                    37        (18)      76        (26)        0.08
 Wheezes                     8          (4)      39        (13)        0.001
 Pleural friction rub        8          (4)      11         (4)        0.93
     PE: Differential Diagnosis
• Myocardial infarction
• Pneumonia
• Congestive heart
  failure ("left-sided")
• Cardiomyopathy
  (global)
• Primary pulmonary
  hypertension
• Asthma
•   Pericarditis
•   Intrathoracic cancer
•   Rib fracture
•   Pneumothorax
•   Costochondritis
•   "Musculoskeletal pain"
•   Anxiety
         ‘PRETEST’ TESTS
• What diagnostic tests do we use prior to
  our V/Q, spiral CT, or pulmonary
  angiogram?
  – ABG
  – CXR
  – D-dimer
  – EKG
  – Leg imaging (duplex ultrasound, impedence
    plethysmography (IPG), contrast venography)
           ECG FINDINGS
•   Sinus Tachycardia       43%
•   “T” wave inversion      40%
•   ST segment depression   33%
•   Low voltage             16%
•   L axis                  12%
•   S1 Q3 T3                11%
•   ST elevation             11%
•   R Bundle Branch Block    11%
                          ABG
• A-aDO2 is usually elevated in PE… and in many other
  conditions so it is NOT SPECIFIC ENOUGH

• 30% of those <40 years with PE have a PaO2 >80mmHg
  so it is NOT SENSITIVE ENOUGH
(This falls to 3% of those over 40… but many are still in the
  70-79mmHg range)

A-aDO2 gradient has a sensitivity of 84%, specificity of
  27%, PPV of 27% and NPV of 84%8
                    D-Dimer
1. Latex Agglutination: not reliable!
2. SimpliRED (“whole blood”) 9,10
      Anti-D-dimer antibodies, faster than ELIZA
      Good sensitivity with 95% NPV
3. ELIZA Sensitivity: >95% negative predictive
   value for a low reading (<500ng/mL)… but only
   25% of normal subjects have a value that low
   ie. Specificity is poor!
• Different manufacturers have different assays
   with different S&S. Few outcome studies yet.
                 D-Dimer
• May be useful in the settings of low clinical
  suspicion and non-diagnostic lung scan to
  rule out PE9,11
                        PIOPED
 (Prospective Investigation of Pulmonary Embolism Diagnosis, 1990)6

    PERCENT OF PATIENTS WITH PROVEN
          PULMONARY EMBOLISM

V/Q Scan Probability Clinical Suspicion for PE

                       High Intermediate              Low
High                   96        88                   56
Intermediate           66        28                   16
Low                    40        16                   4
Normal                 0          6                   2
  .
                    CXR
• With PE we may see
  – atalectasis
  – pleural effusion
  – pulmonary infiltrates
  – pulmonary consolidation (Hampton’s Hump is
    a peripheral consolidation on infarcted lung)
  – elevated hemidiaphragm
  – oligemia (Westermark’s sign)
                  CXR
• A normal Xray in the setting of marked
  dyspnea (with no evidence of
  bronchospasm or cardiac shunt) is
  strongly suggestive of PE.11
Hampton’s
Pulmonary infarct
Oligemia?
Westermark Sign
PE appears like a mass
pulmonary PE with hemorrhage or
          pul edema
   PE with effusion
and elevated diaphragm
                                             CXR
                     CHEST RADIOGRAPHIC FINDINGS IN 500 PATIENTS WITH
                       CLINICALLY SUSPECTED PULMONARY EMBOLISM (PE)5

                                    PE Present (n = 202)   PE Absent (n = 298)   p Value
                                    n           (%)        n           (%)

•   Finding
•    Right heart enlargement         77           (38)     43         (14)       < 0.00001
•    Left heart enlargement          10            (5)     30         (10)        0.06
•    Cardiomegaly                    36           (18)     65         (22)        0.33
•    Amputation of hilar artery      72           (36)      3          (1)       < 0.00001
•    Oligemia                        91           (45)      3          (1)       < 0.00001
•    Consolidation (infarction)      31           (15)      2          (1)       < 0.00001
•    Consolidation (no infarction) 12              (6)     54         (18)        0.0001
•    Platelike atelectasis           65           (32)     70         (23)        0.04
•    Interstitial edema              1          (0.5)      27          (9)       < 0.00001
•    Elevated diaphragm (unilateral) 86           (43)     89         (30)       0.005
•    Elevated diaphragm (bilateral) 39            (19)     57         (19)        0.95
•    Pleural effusion                91           (45)     104        (35)        0.02
Echo
   Diagnosis of Pulmonary Embolism

           Suspected PE


               V/Q Scan
               (CT, MRI)

NORMAL (14%)               HIGH PROB. (13%)
   No Rx                         Treat


       NONDIAGNOSTIC (73%)
   Diagnosis of PE ~ Ventilation –
      perfusion scintigraphy 1
• Most commonly used non-invasive
  technique with clinical suspicion
• Perfusion lung scan : not specific enough
  for diagnosis of PE
• Ventilation imaging : differentiate vascular
  occlusion from disorder of ventilation
  Diagnosis of PE ~ Ventilation –
      perfusion scintigraphy
Segmental defect
• Occlusion of a branch of a branch of the
  pulmonary artery
• Wedge shape and pleural based
• Conforms to segmental anatomy of the lung
• Large (>75%), moderate(25~75%), small(<25%)
Nonsegmental defect
  Diagnosis of PE ~ Ventilation –
     perfusion scintigraphy 3
V / Q match
• Both scintigrams are abnormal in the
  same area, defects of equal size
V / Q mismatch
• Abnormal perfusion in the area of normal
  ventilation or much larger perfusion
  abnormality than ventilation defect
  Diagnosis of PE ~ Ventilation –
     perfusion scintigraphy 4
High probability
• Segmental or lobar perfusion defect with
  normal ventilation
Low probability of PE
• Perfusion defect with matched ventilation
  abnormality
   Diagnosis of PE ~ Ventilation –
      perfusion scintigraphy 5
Modified PIOPED Criteria

High probability (>80%)
• 2 large mismatched segmental defects without
  radiographic abnormality
• Any combination of mismatched defects
  equivalent to the above
• (2 moderate = 1 large)
Intermediate probability (20~80%)
Low probability (<20%)
• Nonsegmental perfusion defect
• Any perfusion defect with a substantially larger
   radiographic abnormality
• Matched ventilation and perfusion defects with
   normal chest radiograph
• Small subsegmental perfusion defects
Normal
 ( No perfusion defect )
Condition associated with V/Q mismatch
• Acute or chronic PE
• Other cause of embolism : drug abuse,
  iatrogenic
• Bronchogenic carcinoma
• Hypoplasia or aplasia of pulmonary artery
• Vasculitis
• Post radiation therapy
• Mediastinal or hilar adenopathy with obstruction
  of pulmonary artery or veins
Determinining Clinical Likelihood of PE
• Assessment of risk factor for venous
  thromboembolism (leg paralysis, bed rest,
  malignancy, CHF, presence of central
  venous catheter …)
• Evaluation of symptoms and signs
• Interpretation of preliminary investigation
  (eg. chest radiograph and
  electrocardiogram)
                VQ Scan
V/Q Scan       Clinical Suspicion for PE
               High Intermediate        Low
High           96         88             56
Intermediate   66         28             16
Low            40         16              4
 Normal        0           6              2
Positive V/Q Scan
    Spiral tomographic scan 1
• capable of imaging nearly the entire thorax
  during a single breath-hold intravenous
  contrast can be timed to arrive pulmonary
  vasculature
•    Sensitivity : 64 ~ 93 %
     Specificity : 89~100 %
  Especially when PE is involved the main,
  lobar, or segmental pulmonary arteries
Advantage
• High sensitivity and specificity
• Visualize the clot
• Indentify other disease states that can
  mimic PE (lung tumor, pleyral disease,
  pericardial disease)  provide alternative
  diagnosis
• Cost : 1/6 ~ 1/8 angiography
Limitation
• Inability of spiral scanning to detect PE in
  subsegmental pulmonary arteries
  (sensitivity : 29%)
Clinical guidelines
• It should be used as a ”rule-in” modality,
  rather than a ”rule-out” procedure
• if an alternative diagnosis is being
  considered in addition to pulmonary
  embolism, spiral CT scanning can provide
  new information that a ventilation-
  perfusion scan cannot.
               SPIRAL CT
         Segmental Subsegmental

Sensitivity   94%      63%
Specificity   94%      89%

Only 6% of all PE are subsegmental
CT and Spiral CT
                    Diagnosis of Pulmonary Embolism

                                Suspected PE


                                  V/Q Scan
                                  (CT, MRI)

          NORMAL (14%)                         HIGH PROB. (13%)
             No Rx                                   Treat


                          NONDIAGNOSTIC (73%)


          Clinically Stable              Hypotensive/Severely Hypoxemic


Bilateral lower extremity evaluation               Angiogram
         (US, IPG, CV, MRI)
      Pulmonary Angiogram
• Most specific test available for diagnosis of
  PE
• Can detect emboli as small as 1-2 mm
• Most useful when the clinical likelihood of
  PE differs substantially from the lung scan
  result or when the lung scan is
  intermediate probability
Pulmonary Angiogram
Emboli on Angiogram
              LEG STUDIES
• Contrast Venography
  – Gold standard, nearly 100% sensitive and specific
  – Invasive, expensive, requires a dye load



• Impedence plethysmography
  – Detects increased venous outflow resistance using
    electrical current
  – Does not distinguish non-thrombotic obstruction
  – Sensitivity and specificity up to 98%
            LEG STUDIES
• Duplex Ultrasound
  – Doppler blood flow +compression imaging
  = 2-D cross sectional view of leg veins

  – Sensitivity 89-100%     Specificity 95-100%
  – PPV 92-100%             NPV 75%-100%

  - operator dependent, not always available,
    hard to see pelvic DVT
                      Diagnosis of Pulmonary Embolism

                                    Suspected PE


                                         V/Q Scan
                                         (CT, MRI)

              NORMAL (14%)                            HIGH PROB. (13%)
                 No Rx                                      Treat


                                NONDIAGNOSTIC (73%)


            Clinically Stable                   Hypotensive/Severely Hypoxemic


  Bilateral lower extremity evaluation                    Angiogram
           (US, IPG, CV, MRI)

   DVT absent             DVT present
or nondiagnostic            Treat


Serial leg studies
 or angiogram
     SERIAL LEG IMAGING
Remember… >70% of pts with PE will have
 DVT and half of pts with DVT will have PE.

Less than 2% of patients with a non-
  diagnostic VQ had any thromboembolism
  after negative serial US or IPG.
BEYOND THE AMERICAN THORACIC SOCIETY
             GUIDELINES

• Better studies on available D-dimer testing
  (ie. The SimpliRED test)

• Validated combinations of clinical
  prediction rules and lab testing
 EXCLUDING PE AT THE BEDSIDE WITHOUT
         DIAGNOSTIC IMAGING
           WELLS et al. 2001
• “Managing patients on the basis of pretest
  probability and D-dimer result is safe and
  decreases the need for diagnostic
  imaging.”
          Wells et al. 2001
• Clinical scoring system derived and
  validated from 40 clinical variables on
  1239 patients investigated for suspected
  PE
• 930 consecutive ED patients evaluated by
  ED physicians using the clinical score and
  SimpliRED whole blood D-dimer testing.
           The Wells PE Score
Clinical signs of DVT (swelling and pain)   3
HR > 100                                    1.5
Immobilization (>3d) or surgery (<4wks)     1.5
Prior DVT/PE                                1.5
Hemoptysis                                  1
Malignancy                                  1
PE as likely or more likely as other Dx     3

                     Low Risk      <2
                     Mod Risk      2-6
                     High Risk     >6
   Wells’ PE Algorithm
                       Pretest Probability


                        Low               Moderate or High


                       D-dimer                D-dimer


                -                     +

PE EXCLUDED
                                     VQ


              Normal           Indeterminate                 High
                            (Low or moderate)


        PE EXCLUDED                                     Treat for PE
          Wells’ PE Algorithm
                                          VQ


                      Normal            Indeterminate                High
                                     (Low or moderate)


                   PE EXCLUDED             Doppler US         Treat for PE


                                  No DVT           DVT---> Treat


Low Pretest Risk       Moderate                                    High
 PE EXCLUDED


               - Dd                + Dd                 -Dd                 +Dd


          PE EXCLUDED                          SERIAL US              ANGIOGRAPHY
      Diagnosis of PE ~ MRI 1
• Helpful for the diagnosis of pelvic and thigh deep
  venous thrombosis
• Acute, symptomatic, proximal deep vein
  thromboses : sensitivity approaching 100%
• Less sensitive for detecting calf deep venous
  thrombosis
• PE : can demonstrate an embolus directly as an
  intrvascular filling defect
   (sensitivity : < pulmonary angiography)
Diagnosis of PE ~ MRI 2
Treatment
    Anticoagulation for PE #1
• Obtain baseline CBC with platelets, PT,
  PTT
• Check for contraindications to heparin
• Start LMWH (preferred) or unfractionated
  heparin (if severe renal failure)
    • Enoxaparin 1mg/kg sc q 12h
    • Unfractionated heparin weight-based nomogram
          • Chest 2004;126:401S
Recheck aPTT every 6 hours until in therapeutic range, then daily.
    Anticoagulation for PE #2
• Platelet count day 3 and 5 (HIT)
• Start warfarin 5mg on first treatment day
  and use INR to adjust daily doses
• Stop LMWH/heparin after at least 5 days
  and INR >2 for at least 2 days
• For massive PE or severe iliofemoral
  thrombosis, continue heparin for 10 days
          • Chest 2004;126:413S
    Anticoagulation for PE #3:
         Early discharge
• Minimal elements for early discharge
  – Patient stable with normal vital signs
  – Low bleeding risk
  – Absence of severe renal failure
  – Practical system for administration of LMWH
    and warfarin and appropriate monitoring
  – Availability of evaluation/treatment of
    recurrent VTE and bleeding complications
          • Chest 2001;119:176S
    Anticoagulation for PE #4:
       Duration of therapy
• 3-6 months:
    • First event with reversible or time-limited risk factor
• 6 to 12 months:
    •   Antithrombin deficiency
    •   Protein C/S deficiency
    •   Factor V Leiden
    •   Prothrombin 20210 gene mutation
    •   High factor VIII levels
    •   Homocysteinemia
            • Chest 2004;126:401S
    Anticoagulation for PE #4:
    Duration of therapy (cont.)
• Indefinitely or until cancer resolved:
     • Patients with cancer
• Indefinite (high value placed on preventing
  recurrent PE):
     •   First idiopathic episode
     •   Antiphospholipid Ab
     •   Two or more thrombophilic conditions
     •   Two or more episodes of documented PE
             • Chest 2004;126:401S
     Stabilizing the PE patient:
• Hypoxia
  – Supplemental oxygen
  – Intubate if necessary
• Hypotension
  – 500-1000cc fluid resuscitation
  – Norepinephrine or dopamine
• Persistent hypotension
  – Unfractionated heparin rather than LMWH
  – Consider thrombolysis or surgical embolectomy
         Thrombolyic therapy
• Outcomes
     • 24 hours: superior to heparin alone in resolution of
       radiologic and hemodynamic abnormalities
     • Seven days: no difference in echocardiograms
     • No differences in mortality or resolution of
       symptoms
• Use is “highly individualized”;
Thrombolytic therapy in venous thromboembolism;
UpToDate, 2005
Thrombolytic therapy in venous thromboembolism; UpToDate 2005
Thrombolytic therapy in venous thromboembolism;
UpToDate, 2005
      Pulmonary Embolectomy
• Unnecessary for most patients
• Consider in selected highly compromised,
  hemodynamically unstable patients
  – Who are unable to receive thrombolytic
    therapy
  – Whose critical status does not allow sufficient
    time to infuse thrombolytic therapy
           • Chest 2004;126:401S
      IVC Filters: Indications
• Contraindication to anticoagulation
• Complication of anticoagulation
• Recurrent PE despite adequate
  anticoagulation
• Chronic recurrent PE with pulmonary
  hypertension
• Concurrent with surgical pulmonary
  embolectomy
           “Optional” Filters
• “Option” to leave in permanently or to
  remove, usually in two to four weeks
• Three types at UVA
     • Tulip
     • Opease
     • Recovery
• Recovery rate at UVA about 95%
                 Conclusion
• PE is a common complication seen in hospitalized
  pts.
• Clinical presentation of PE is nonspecific and
  difficult to interpret.
• There are many diagnostic tools that complement
  clinical assessments.
• To better improve early diagnosis of PE, preventive
  measures should be in place that counter the risk
  factors, and clinicians should have a greater
  awareness for early signs/symptoms of PE.
Thank U

								
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