What test to order to rule in/out pulmonary embolism?

[donkeykong1]

I've been getting conflicting advice on rotations and on uworld on what to order when. I know it depends on the situation so here are a couple of scenarios I need advice on what test to order first:

1- PE like symptoms+clinical history supporting PE=spiral ct?

2- PE like symptoms+clinical history supporting PE+leg swelling=LE doppler? to r/o clot in the leg?

3-PE like symptoms+no clinical history supporting PE=d-dimer? since once its neg, you dont need to pursue it fruther

Also for scenario 1,2,3 do we just start heparin before even ordering the tests?

*By supportive clinical history I mean lying in a hospital bed for a week or traveling on a airplane etc...

MTB states v/q is #1 in pregnancy. Also gold standard is an angiogram, though I've never seen one ordered b/c of the .5% mortality rate

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[Phloston]

If the patient is likely to have PE, do spiral CT. If negative --> no further testing. If positive --> Tx.

If the patient is unlikely to have PE, do D-dimer. If negative (i.e., <500 ng/mL) --> no further testing. If positive --> spiral CT.

If spiral CT is contraindicated (e.g., renal failure, morbid obesity, contrast allergy) or is inconclusive but not negative, do V/Q scan.

Spiral CT and V/Q scan, in a randomized trial of 1417 patients, concluded that spiral CT is non-inferior to V/Q scan.

"Likely to have PE" = age >50, HR >100, O2 sats <95%, hemoptysis, estrogen use, Hx of DVT/PE, unilateral leg swelling, surgery/trauma requiring hospitalization in past 4 weeks, or patient who was previously considered unlikely to have PE who had >500 ng/mL D-dimer.

Pulmonary angiography is gold standard, as you've said, but yeah, it has high mortality (<2%) and morbidity (5%) rates.

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In patients without hemodynamic compromise (i.e., systolic BP >90 or not decreased by >40 from baseline), Tx with heparin (or instead with IVC filter if anticoagulation is contraindicated or fails, or minor subsequent PE would likely be lethal due to severe respiratory compromise). Do NOT give thrombolysis to these patients.

In patients with hemodynamic compromise (i.e., systolic BP <90 or fallen >40 from baseline), Tx with thrombolysis and heparin. If thrombolysis is contraindicated or fails, do surgical embolectomy.

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In pregnancy:

If PE is suspected, first do CXR. If normal --> V/Q Scan. If abnormal --> spiral CT.

The risks from radiation are

If she has PE, Tx with LMWH, not unfractionated heparin, and continue 6 weeks postpartum or for 3-6 total duration (whichever ends later). Avoid direct-thrombin or Xa inhibitors. Reserve thrombolysis for life-threatening situations only.

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All of this research is from UpToDate btw.

 

[donkeykong1]

so if the patient has unilateral leg swelling and a supporting clinical picture of PE, so dont do LE doppler, instead go with spiral ct?

 

[Phloston]

UpToDate says that if you specifically think DVT is the culprit, do the Doppler before the CXR.

 

[donkeykong1]

UpToDate says that if you specifically think DVT is the culprit, do the Doppler before the CXR.

seems like ct>>>>doppler even if dvt is thought to be the cause since that is included in the likeliness of PE

(Christopher Study; JAMA 2006;295:172-179)
TABLE 3 -- DICHOTOMIZED CLINICAL DECISION RULE FOR SUSPECTED ACUTE PULMONARY EMBOLISM[*]

Variable

Points

Symptoms and signs of deep venous thrombosis[†]

3.0

Alternative diagnosis less likely than pulmonary embolism[‡]

3.0

Heart rate >100 beats/min

1.5

Immobilization (>3 days) or surgery in previous 4 weeks

1.5

Previous deep venous thrombosis or pulmonary embolism

1.5

Hemoptysis

1.0

Malignancy (current therapy, or in previous 6 months, or palliative)

1.0

 

[Phloston]

seems like ct>>>>doppler even if dvt is thought to be the cause since that is included in the likeliness of PE

(Christopher Study; JAMA 2006;295:172-179)
TABLE 3 -- DICHOTOMIZED CLINICAL DECISION RULE FOR SUSPECTED ACUTE PULMONARY EMBOLISM[*]

Variable

Points

Symptoms and signs of deep venous thrombosis[†]

3.0

Alternative diagnosis less likely than pulmonary embolism[‡]

3.0

Heart rate >100 beats/min

1.5

Immobilization (>3 days) or surgery in previous 4 weeks

1.5

Previous deep venous thrombosis or pulmonary embolism

1.5

Hemoptysis

1.0

Malignancy (current therapy, or in previous 6 months, or palliative)

1.0

I was talking about in pregnancy since doppler becomes most relevant when you're trying to get around doing a CT.

If you're not a pregger and high-risk, CT is needed. If you're low-risk, D-dimer before CT.

 

[Instatewaiter]

LE ultrasound can be used to risk stratify people who have RV strain. If the patient has a PE and significant RV strain on echo AND still has clot in his leg, you'd put in a IVC filter (because if they have another PE, they're dead).