Why CARE!? Such a high FALSE POSITIVE rate for subsegmental PEs on CTA is 60%!!! Studies with multiple blinded radiology reads. Segmental FALSE positives = 25%. 

Not a benign evaluation: Contrast risk of infiltration or anaphylactoid reaction. Malignancy risk from radiation is 1/100 for women and 1/500. Increased risk of repeat CT imaging in the future 7x!!

PE: 1/400 or 1/1500 incidence of PE total for ED presentations in US

Mortality: 8% (30 day mortality after PE diagnosis). On autopsy up to 30% found to have PE (unknown other cause of death)

Vital Signs:

SpO2: <95% (94 and below)

HR: >100 at ANY time per guidelines

RR: No recognized agreement (triage RR often blanket value – 20 for all. Some say 20 vs 24, etc.)

Temp: >102.5 F, less likely to be PE (wash between 100.4 and 102.5)

Risk Factors: 

Prior VTE (PE/DVT): Unprovoked  vs. provoked. Unprovoked is more concerning, even with normal coagulopathy panel

Malignancy History: Definition of active cancer – metastatic disease state and/or active treatment within 6 months. High risk – pancreatic, Multiple myeloma, colon, glioblastoma, melanoma. Some chemo treatments more risk inducing (eg. ALL chemo)

Immobility: Casting, trauma patients in particular, no necessarily hospitalization. 6 hours of continuous seated position. Surgery: with intubation/general anesthesia and/or epidural. Knee, abdominal, neurological. 

OCPs: estrogen of any form. Not really men. 

Pregnancy: postpartum, way increased risk. Symptomatic patients = 70% risk. 

Increased risk at age 50: Perpetually increases with age.

Symptoms:

Pleuritic chest pain: suggest peripheral PEs (65%)

Hemoptysis: hemorrhage, not infarct

Exertional Dyspnea: Subacute = 3-7ish days, insidious increase (often do not reports CP, usually central clot). vs. Acute

Calf pain/Calf swelling: symptom and PE finding

Syncope: large clot burden

Anticoagulation: Compliance = less likely. NOACs, if compliant, they are therapeutic. Coumadin, variable levels 

Not significant: orthopnea, palpitations, anxiety, dizziness

Physical Exam Findings:

Abnormal pulmonary exam – decreases likelihood

Calf edema – increases likelihood

STEP 1: Do you, based on the information above, feel that a PE is possible? Meaning, it is ABOVE the 2% threshold for PE. (if you have less than a 2% clinical suspicion for PE, STOP. You do NOT think there is a PE and you do not evaluate further. I repeat – STOP! Evaluate for other suspected pathologies).

ACEP Guidelines: 2% is an acceptable cutoff recognizing limitations of testing and risk of false positives

So nowwwwww, clinically feel that PE is possible. 

STEP 2: RISK STRATIFY

Wells Score vs. Geneva vs. Gestalt: all relatively equivalent

These are NOT used to rule out. They are only to RISK STRATIFY, meaning that you clinically have a suspicion of said disease so then you risk stratify. 

Low – Moderate – High

STEP 3: Based on risk, apply appropriate next evaluation steps (imaging, lab test, or clinical decision tool)

High: Wells, Geneva, Gestalt High -> CTA. Can consider empiric heparin pre CTA or post.

Moderate: D-dimer. Value cutoff chosen to have <2% of PE. Yes, do age adjusted cutoffs. Look at the units (Hx10 fibrinogen unit. Ddimer unit Hx5). Starts at age 50 and above. (NOT a screen for people who you think do not have a PE. You have a clinical concern for PE, they are moderate or low risk).

Low: PERC – only patient population because the inclusion criteria is only low risk for PE. If PERC+, then you d-dimer. 

If limited CTA with inadequate imaging obtained and VSS, expert recommendation is to obtain a ddimer if not done so. If negative, discharge. If ddimer positive, obtain LE ultrasounds. If no DVT, discharge +/- anticoagulation for PE based on actual risk factors and follow up. (Look at age/real risk factors/trop/BNP/echo/PESI score).

Disposition:

Stable vs. Unstable. 

Unstable: hypotensive -> tPa and MICU

Stable: BNP/trop/echo R heart strain -> heparin +/- half dose tPa and admit to ICU/tele

If normal BNP/trop/echo -> PESI Score -> HIGH gets heparin to floor. Low PESI give lovenox shots and discharge (no evidence/FDA approval for NOACs). 

Subsegmental PEs: ACEP – No risk factors for recurrence, no DVT on b/l US -> can be sent home on no AC and refer to PCP for PE surveillance for symptoms of PE. 

Young and VSS with subsegmental PE: really low risk for negative outcome for PE