Diagnosis of Acute PE

1
Diagnosis of Acute PE

• Risk Factors
• --immobilization
• --Trauma, surgery
• --Active Cancer
• --Prior history of clot
• --Reduced cardiac output
• --Obesity
• --Advanced age
• --Pregnancy, puerperium, OCPs with high
  estrogen content
• --Hypercoagulable states

2
Pathophysiology of Acute PE

• Presentations acute minor (dyspnea, pleuritic
  pain, hemoptysis normal PAP and RAP)
• Acute massive right heart strain with or without
  hemodynamic compromise
• Subacute massive progressive dyspnea and right
  heart strain
• Mechanism(s) of hypoxemia VQ mismatch
  (unembolised areas are relatively overperfused
  with insufficient ventilation to match), Shunting
  (areas of atelectasis or infarction), low mixed
  venous oxygen saturation (if CO reduced), loss of
  surfactant

3
Estimating the pretest probability

• High (85 likely) otherwise unexplained sudden
  onset of dyspnea, tachypnea, or chest pain and at
  least TWO of the following
• --significant risk factor present, syncope with
  signs RV strain, signs of possible leg DVT,
  radiographic signs of infarction, plump hilum, or
  oligemia
• Low (dyspnea and tachypnea and chest pain, OR these
  are present but can be explained by another
  condition (pneumonia, bronchitis), radiography
  explained by another process, anticoagulated
• Intermediate (15-85 likely) neither low nor
  high

4
Diagnostic Strategies

• D-dimer only useful in ruling out PE in the
  outpatient setting with low clinical likelihood.
• V/Q scan most useful when chest radiograph is
  normal. A normal scan virtually rules out PE. A
  nondiagnostic scan, when combined with clinical
  likelihood
• Pre-test Prob
• Result low intermediate high
• Low 4 16 56
• Intermediate 16 28 88
• High 40 66 96
• (percentage probability of existing PE)

5
Diagnostic Strategies

• Spiral CT sensitivity and specificity overall
  are in the low 90 range. Drops off for
  peripheral PE. Good for revealing other cause
  for dyspnea, etc. (mass, pneumonia, COPD, etc)
• If CT is negative and clinical suspicion still
  high, need to pursue other tests dopplers,
  pulmonary angiography, MRI, etc

6
Treatment of Acute PE

• Suspect PE and no strong contraindication for
  heparin begin Heparin
• Pain control
• Supplemental 02
• Hypotension in RV failure the CO is highly
  dependent on preload. Infuse volume. Norepi is
  catecholamine of choice if needed
• Avoid vasodilators as this will drop preload and
  worsen the problem

7
Heparin

• Efficacy depends on achieving a critical
  therapeutic concentration within the first 3
  hours of treatment (aPTT 1.5-2.5x)
• Use weight based nomograms
• Does not lyse clot, but prevents new fibrin
  deposition on the existing thrombus
• Prompt anticoagulation with heparin followed by
  at least 3 mo. Oral anticoagualtion results in
  80-90 risk reduction for recurrent PE

8
Heparin

• When the workup is positive the correct duration
  of heparin treatment in the literature is at
  least a week
• Can switch to LMWH which allows subQ
  administration (outpatient) monitoring only
  needed in renal failure or extreme obesity (Anti
  factor Xa assay).
• Overlap with oral 5days
• Hemorrhagic complications up to 15, serious
  
• Risk factors bleeding diathesis, uremia, age,
  recent surgery/trauma, hypertension, GI bleed,
  antiplatelet drugs
• If contraindication to heparin lepirudin

9
Thrombolytics

• Initial study Goldhaber et al 1993 looked at
  patients with RV dysfunction and hemodynamic
  compromise and showed a mortality benefit
• Later, one small study looked at pts with RV
  dysfunction on an echo and no hemodynamic
  compromise.
• This study showed significant benefit in
  resolution of echo findings (RV strain, etc) but
  did not show any benefit in mortality.

10
Thrombolytics

• One large nonrandomized registry of 719 pts
  showed that in the group that got lytics the
  mortality at 30 days was significantly lower
  (4.7 v 11.1)
• Recurrent PE also less frequent (7.7 vs. 18.7)
• Inclusion criteria clinical, echocardiographic,
  or right heart cath findings of hypotension,
  shock, RV dysfunction, pulm HTN, together with
  () lung scan OR
• Positive lung scan with three of the following
  syncope, tachycardia, tachypnea, hypoxemia, EKG
  findings of RV strain

11
Thrombolytics

• What about catheter directed lytics? No data,
  studies to date indicate central or peripheral
  admin is the same
• Unlike MI, the window for lytics in PE is longer,
  with benefit up to 10-14 d after onset of
  symptoms

12
Pulmonary embolectomy

• Emergency situations (i.e. to prevent death)
• Mortality in the range of 33 without arrest,
  43-84 in those resuscitated
• Catheter techniques still developing, mortality
  during extraction 30, rotational devices for
  mechanical thrombolysis are experimental

13
Oral Anticoagulation

• No preexisting risk factor 6 months
• Active tumors, thrombophilic d/o, recurrent
  thromboembolism, pulm HTN lifelong
• Other risk factors that may be modified (estrogen
  use, immobilization) duration may be shortened
• Filters failed adequate anticoagulation, or
  cannot anticoagulate