Pulmonary Embolism - Problem Based Study

A 32-year- female who presents to you with shortness of breath. she mentions that she became acutely short of breath and her symptom is associated with some moderately sharp chest pain located along the left side of her chest. The pain seems worse when she attempts to breathe deeply.
On further questioning she mentions she she takes low-dose estrogen for birth control and has no significant past medical history. She has recently returned from visiting her sister and had a long duration flight.
Her vitals are (temperature 37.1◦C, heart rate 92, blood pressure 129/68, respiratory rate 21, SpO2 95% on room air) and on examination you notice that she appears mildly uncomfortable but is in no acute distress.
The rest of the physical exam is unremarkable.

Q 1. What is your most probable diagnosis?

Answer: Pulmonary embolism
(risk factors of long duration travel and taking low dose estrogen for birth control. Symptoms are acute in onset)

Q 2. An ECG and Chest X ray were done. What would you suspect?

Answer: The most common ECG finding associated with the diagnosis of PE remains normal sinus rhythm. With that said, the most common arrhythmia found in patients with a PE is sinus tachycardia but this patient's vitals indicate that she is not tachycardic.
S1Q3T3 ECG rarely occurs in patients that had massive pulmonary emboli. Even if you do
spot this pattern on an ECG, it is not specific enough to confirm the diagnosis.

The specific findings on chest X ray in PE may include: ( but seen infrequently)

•  Westermark sign (loss of peripheral vascular markings) and 
• Hampton hump (a wedge-shaped opacity due to pulmonary infarction) 

Both signs have a low sensitivity and low specificity for the diagnosis of PE.

Q 3. What is the Wells criteria for diagnosis of Pulmonary Embolism ?

Answer : Wells criteria include:

• Pulse >100.
• Previous history of veno thromboembolism.
• Clinical symptoms and signs consistent with PE.
• Hemoptysis.
• History of surgery or 3 days immobilization in the last 4 weeks 
• History of malignancy treated in the last 6 months.

Q 4. What are  PERC rules (pulmonary embolism rule-out criteria)

Answer: The PERC rules (pulmonary embolism rule-out criteria) are a validated set of rules that allow categorization of a patient into a low-risk group to rule out PE clinically. If the patient meets all of the following, PE is ruled out assuming you believe the patient is low risk.

PERC rules:

1) Age <50.

2) Heart rate <100.

3) SaO2 >94%.

4) No unilateral leg swelling.

5) No hemoptysis.

6) No recent history of trauma or surgery.

7) No prior DVT or PE.

8) No hormone use.

Q 5 . What Diagnsotic study is of choice for Pulmonary embloism ? 

Answer: The American College of Radiology (ACR) lists the CT scan of the chest with contrast (i.e., CT angiography or CTA) as the modality of choice in stable patients with a suspected PE.

Its benefits include the fact that it is noninvasive, cheaper than pulmonary angiography, and far

more available than VQ scans. It should be noted that pulmonary angiography still remains the “gold standard” for diagnosing pulmonary emboli, but that is more of an academic point. As for VQ scans, they are not available in many locales and often return nondiagnostic. However, they can be used in a patient with a normal chest x-ray. A chest CT without contrast will not enhance the pulmonary arteries, making the diagnosis of a PE far more difficult, if not impossible.