What do all of these things have in common

1
What do all of these things have in common?
CXR
VQ Scan
They all are PEs
Pulmonary artery Angiogram
CT
2
Why do we care about this?

• The dreaded saddle embolus
• PE has a mortality rate of 30 without treatment1
• An accurate diagnosis w/ anticoagulant therapy
  decreases this rate to 2-8

Pulmonary embolism mortality in the United
States, 1979-1998 an analysis using
multiple-cause mortality data. AUHorlander KT
Mannino DM Leeper KV SOArch Intern Med 2003 Jul
28163(14)1711-7.
3
Symptoms and signs of acute pulmonary embolism
4
PIOPED

• BEAT (OR FLOG) A DEAD HORSE
• British politician John Bright thought the
  Reform Bill of 1867, which called for more
  democratic representation, would never be passed
  by Parliament.
• Trying to rouse Parliament from its apathy on the
  issue, he said in a speech, would be like trying
  to 'flog a dead horse' to make it pull a load.
• This is the first recorded use of the expression,
  which is still common for 'trying to revive
  interest in an exhausted issue

Encyclopedia of Word and Phrase Origins" by
Robert Hendrickson (Fact on File, New York, 1997)
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PIOPED in brief
Angiography
VQ scan
vs

• The challenger
• Non-invasive
• Good for patients with dye allergy
• Good for patients with renal disease
• Low risk

• Gold standard
• Invasive
• Patients must not be allergic to dye or contrast
• Cant be used in patients with renal disease
• Some MM

6
PIOPED in brief

• Your pre-test clinical suspicion matters
• Diagnostic accuracy was greatest when the V/Q
  scan was combined with clinical probability
• In patients with a low pre-test suspicion, having
  a low or near normal scan result was helpful,
  missing only 4 and 2 respectively
• In patients with a high pre-test suspicion, a
  HIGH scan probability detected 96 of PEs, but a
  LOW probability scan detected roughly 40 of PEs
• So if you have a high suspicion, a low
  probability scan is not that helpful to you

Pioped investigators. Value of the
Ventilation/Perfusion Scan in Acute Pulmonary
Embolism. JAMA May 23/30 1990 vol 263 no 20
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Quantifying your clinical suspicion
Modified Wells criteria clinical assessment for
pulmonary embolism
Data from van Belle, A, et al. JAMA 2006
295172.
8
Clinical Question

• What are the options if you still are still
  worried about PE in your patient, but the VQ scan
  was low prob?

9
2 options Take your pick

• At study by Kearon, et al found that it was safe
  to withhold anticoagulation after obtaining
  normal results on initial US, followed by repeat
  US 1 week later
• Study design randomized, multi-center
• 810 patients w/ normal initial compression US
  studies for proximal veins
• Interventions D-dimer testing followed by no
  further testing if the result was negative and
  venography if the result was positive
  (experimental) or ultrasonography
• US repeated after 1 week in all patients
  (control).
• Measurements Symptomatic DVT diagnosed initially
  and DVT during 6 months of follow-up
• Conclusion In outpatients with suspected deep
  venous thrombosis who initially had normal
  results on ultrasonography of the proximal veins,
  a strategy based on D-dimer testing followed by
  no further testing if the result was negative and
  venography if the result was positive had
  acceptable safety and did not differ from the
  safety of a strategy based on withholding
  anticoagulant therapy and routinely repeating
  ultrasonography after 1 week.

Kereon, et al. A Randomized Trial of Diagnostic
Strategies after Normal Proximal Vein
Ultrasonography for Suspected Deep Venous
Thrombosis D-Dimer Testing Compared with
Repeated Ultrasonography. Ann Intern Med.
2005142490-496
10
More literature on this

• Study Design retrospective chart review on 662
  PIOPED patients
• Results Single noninvasive leg test in patients
  with nondiagnostic VQ scans picks up DVT in 11
  of patients who would otherwise require
  angiography
• Serial noninvasive leg tests in patients w/
  normal initial test either picks up the DVT or
  excludes it in 47 of patients
• Using serial dopplers decreases the need for
  invasive angiography to 29 from 63 for 1
  Doppler study
• Additionally, using NO Doppler study has a
  baseline angiography requirement in 71 of
  patients
• Clearly 1 is not good enough and 2 is a lot
  better
• Conclusion A noninvasive strategy that includes
  VQ scans, single noninvasive leg tests, and
  serial noninvasive leg tests would permit a
  diagnosis of thromboembolic disease or a safe
  exclusion of thromboembolic disease in 71 of
  patients with suspected acute pulmonary embolism.

Stein, Paul, et al. Strategy That Includes Serial
Noninvasive Leg Tests for Diagnosis of
Thromboembolic Disease in Patients With Suspected
Acute Pulmonary Embolism Based on Data From
PIOPED. Arch Int Med. Volume 155(19), 23 October
1995, pp 2101-2104.