What further evaluation is warranted in a tachypneic patient with COPD and lobar pneumonia, despite initial treatment and low suspicion for Pulmonary Embolism (PE)?

From the Guidelines

No further testing is recommended for this patient. Given the low Wells score of 0 and low clinical suspicion of PE, along with the patient's improvement after initial treatment, the risk of PE is considered low 1. The Pulmonary Embolism Rule-Out Criteria (PERC) can be applied in this scenario to help guide the decision to not pursue further testing, including D-dimer or imaging studies 1. The PERC have been shown to be effective in identifying low-risk patients in whom the risks of testing outweigh the risk of PE, with a pooled sensitivity of 97% and a low rate of missed PEs (0.3%) 1. In this case, the patient's symptoms are largely explained by the COPD exacerbation and pneumonia, and the persistent tachypnea may be attributed to these conditions rather than PE.

Some key points to consider in this decision include:

• The patient's low Wells score and low clinical suspicion for PE
• The effectiveness of the PERC in identifying low-risk patients
• The potential risks and benefits of further testing, including radiation exposure from a CT scan
• The patient's underlying conditions, including COPD and pneumonia, which may contribute to the persistent tachypnea.

By not pursuing further testing, we can avoid unnecessary radiation exposure and potential complications, while also providing appropriate care for the patient's underlying conditions.

From the Research

Patient Assessment

The patient is a 68-year-old male with severe COPD, presenting with increased sputum production and wheezing, and diagnosed with lobar pneumonia. The patient has been started on prednisone, antibiotics, and bronchodilators. With a Wells Score of 0 and low clinical suspicion of PE, the patient's symptoms have improved but still exhibits tachypnea.

Diagnostic Considerations

Given the patient's low clinical suspicion of PE, as indicated by a Wells Score of 0, the following options can be considered:

• D-dimer testing: According to 2, a d-dimer level of less than 1000 ng per milliliter can rule out pulmonary embolism in patients with a low clinical pretest probability.
• Further testing may not be necessary if the d-dimer level is below the threshold, as suggested by 3 and 4.
• The use of D-dimer testing in conjunction with clinical assessment can facilitate safe discharge and limit unnecessary investigation, as noted in 4.

Recommended Course of Action

Based on the evidence, the most appropriate next step would be to perform a D-dimer test, as it can help rule out pulmonary embolism in patients with a low clinical pretest probability, as stated in 2 and 4. If the D-dimer level is below the threshold, no further testing may be necessary.

Key Points to Consider

• The patient's low Wells Score and low clinical suspicion of PE suggest a low pretest probability.
• D-dimer testing can be used to rule out pulmonary embolism in patients with a low clinical pretest probability, as indicated by 2 and 4.
• The results of the D-dimer test should be interpreted in conjunction with the patient's clinical assessment, as noted in 3 and 4.