Definitions for the strength of evidence (Class I-III) and strength of recommendations (Level A-C) are repeated at the end of the Major Recommendations.
- Can a negative D-dimer exclude pulmonary embolism (PE)?
Level A recommendations. None specified.
Level B recommendations. In patients with a low pretest probability of PE, use the following tests to exclude PE:
- A negative quantitative D-dimer assay
(turbidimetric or enzyme-linked immunosorbent assay [ELISA]).
- A negative whole blood cell qualitative D-dimer assay in conjunction with a Wells’ score of 2 or less.
Level C recommendations. In patients with a low pretest probability of PE, negative findings on a whole blood D-dimer assay (when not used with Wells’ scoring system) or immunofiltration D-dimer assay can be used to exclude PE.
- When can ventilation-perfusion (V/Q) scan alone or in combination with venous ultrasonography and/or D-dimer assay exclude PE?
Level A recommendations. In patients with a low-to-moderate pretest probability of PE, a normal perfusion scan reliably excludes clinically significant PE.
Level B recommendations. In patients with a low-to-moderate pretest probability of PE and a non-diagnostic V/Q scan, use 1 of the following tests instead of pulmonary arteriogram to exclude clinically significant PE:
- A negative quantitative D-dimer assay
(turbidimetric or ELISA).
- A negative whole blood cell qualitative D-dimer
assay in conjunction with a Wells’ score of 4 or less.
- A negative single bilateral venous ultrasonographic
scan for low-probability patients.
- A negative serial* bilateral venous ultrasonographic scan for moderate-probability patients (*serial venous ultrasonography refers to scheduling a patient for follow-up examination in the emergency department within 3 to 7 days or referring to a primary care physician for follow-up).
Level C recommendations. In patients with a low-to-moderate pretest probability of PE and a nondiagnostic V/Q scan, use a negative whole blood D-dimer assay (when not used with Wells’ scoring system) or immunofiltration D-dimer assay to exclude PE.
- Can spiral computed tomography (CT) replace V/Q scanning in the diagnostic evaluation of PE?
Level A recommendations. None specified.
Level B recommendations. Thin collimation spiral CT scan of the thorax with 1- to 2-mm image reconstruction may be used as an alternative to V/Q scan during the diagnostic evaluation of patients with suspected PE.
Level C recommendations. Spiral CT scan of the thorax with delayed CT venography may be used for increased detection of patients with significant thromboembolic disease.
- What are the indications for fibrinolytic therapy in patients with PE?
Level A recommendations. None specified.
Level B recommendations. Consider fibrinolytic therapy in hemodynamically unstable patients with confirmed PE.
Level C recommendations. Consider fibrinolytic therapy in:
- Hemodynamically stable patients with confirmed PE
and right ventricular (RV) dysfunction on echocardiography.
- Unstable patients with high clinical index of suspicion (especially if RV dysfunction can be demonstrated on bedside echocardiography).
Definitions:
Strength of Evidence
Literature Classification
Schema*
Design/Class 1
- Therapy#: Randomized,
controlled trials or meta-analyses of randomized controlled trials
- Diagnosis&:
Prospective cohort using a criterion standard
- Prognosis**: Population prospective cohort
Design/Class 2
- Therapy#: Nonrandomized trial
- Diagnosis&: Retrospective observational
- Prognosis**: Retrospective cohort, case control
Design/Class 3
- Therapy#: Case
series, case report, other (e.g., consensus, review)
- Diagnosis&: Case
series, case report, other (e.g., consensus, review)
- Prognosis**: Case series, case report, other (e.g., consensus, review)
*Some designs (e.g., surveys) will not fit this schema and should be assessed individually.
#Objective is to measure therapeutic efficacy comparing >2 interventions.
&Objective is to determine the sensitivity and specificity of diagnostic tests.
**Objective is to predict outcome including mortality and morbidity.
Strength of Recommendations
Level A recommendations. Generally accepted principles for patient management that reflect a high degree of clinical certainty (i.e., based on "strength of evidence class I" or overwhelming evidence from "strength of evidence class II" studies that directly address all the issues).
Level B recommendations. Recommendations for patient management that may identify a particular strategy or range of management strategies that reflect moderate clinical certainty (i.e., based on "strength of evidence class II" studies that directly address the issue, decision analysis that directly addresses the issue, or strong consensus of "strength of evidence class III" studies).
Level C recommendations. Other strategies for patient management based on preliminary, inconclusive, or conflicting evidence or, in the absence of any published literature, based on panel consensus.