Upload
driainduncan
View
1.140
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Citation preview
Lungs ScansLungs Scans
Their role in diagnosis of Their role in diagnosis of Pulmonary EmbolismPulmonary Embolism
Suspect PE?Suspect PE?
Investigation of patients with suspected pulmonary emboli (PE) remains problematic and controversial
there are several ways to “rule in” and “rule out” the diagnosis (or, more importantly, to make a decision about anticoagulation or not)
At least 70% of patients with suspected PE don’t have it
PE is nearly always a complication of (proximal) DVT
Investigation of PEInvestigation of PE
Not every PE can (or needs to) be diagnosed. The clinical priorities in the investigation of patients with suspected PE include:
1. Diagnosis of extensive PE
2. Diagnosis of PE in patients with severe symptoms and/or poor cardiopulmonary reserve
3. Diagnosis of any PE when associated with symptomatic or asymptomatic proximal DVT
4. Diagnosis in patients presenting with possible recurrent PE
D-dimerD-dimer
Although most patients with PE and DVT have an elevated D-dimer result, D-dimer is also elevated in many other conditions
D-dimer raised in recent injury or surgery, cancer, inflammatory diseases, healthy elderly, etc
Therefore, a positive test result is not helpful. A negative result, using a sensitive D-dimer assay, helps to rule out PE.
Clinical Probability (Wells’) ScoreClinical Probability (Wells’) Score
Clinical symptoms and signs of DVT 3.0 No alternative diagnosis is more likely than PE 3.0 Heart rate > 100 beats/min 1.5 Immobilization or surgery previous 4 weeks 1.5 Previous DVT/PE 1.5 Hemoptysis 1.0 Malignancy (treated within previous 6 mos or palliative) 1.0
Total points ______
Clinical pretest probability of PE High >6 Moderate 2-6 Low <2
Wells PS, et al. Ann Intern Med 2001;135:98
Which scan?Which scan?
Choose V/Q 1. Normal CXR
2. Patient is otherwise healthy
3. CTPA is contraindicated because of contrast allergy Poor renal function
4. Young & pregnant patients
Choose CTPA1. Abnormal CXR2. Respiratory disease3. Critical care patient4. Suspect massive PE
If the CXR is normal the V/Q scan will be diagnostic >94% of the time
Anticipating the traps Anticipating the traps and pitfallsand pitfalls
<6% of V/Q scans are non-diagnostic >6% of V/Q scans are non-diagnostic without
background clinical data, CXR, etc V/Q scans do not help to identify an alternate
diagnosis in the large proportion of patients who don’t have PE.
Not as readily available
V/Q scan advantagesV/Q scan advantages
1. a normal V/Q scan rules out PE>99% negative predictive value
2. the radiation dose is low
3. iodine-based contrast is not used
SUSPECT PEClinical assessment
LOW
D-dimer
Intermediate or HIGH
HIGHNormal Non-diagnosticPOSITIVENegative
DVT Study
VQ scan and/or CTPA
PositiveNegative
PE Excluded
Treat
All clear now?
NORMAL SCAN
RPO: ant & lat basal segments RLL
RAO: inf lingula; ant segment RUL
POSITIVE SCAN
POSITIVE SCAN
NON-DIAGNOSTIC SCAN
V/Q lung scanV/Q lung scan
1. A normal perfusion scan rules out PE.2. Most patients with a positive V/Q scan (one or more,
segmental or larger, perfusion defects) have PE and they can be treated without further testing.
3. All other lung scan abnormalities are non-diagnostic. Modern imaging techniques and good clinical communication
can keep this number <10% Further testing is required in patients with this V/Q scan
pattern. (CTPA, doppler legs)
Recommended reference: Management of Suspected Acute Pulmonary Embolism in the era of CT Pulmonary Angiography. A Statement from the Fleischer Society. Remy-Jardin et al. Radiology 2007;245:315-329.
Thankyou