Can a computed tomography pulmonary embolism (CT PE) scan adequately reassess left lobe consolidation in a patient with suspected chronic obstructive pulmonary disease (COPD) exacerbation and hypoxia?

From the Guidelines

A CT pulmonary embolism (CT PE) study can adequately reassess the previously noted left lobe consolidation in a patient with suspected chronic obstructive pulmonary disease (COPD) exacerbation and hypoxia, as it provides comprehensive imaging of the entire chest with contrast enhancement, allowing for evaluation of both pulmonary vasculature and lung parenchyma. This approach is supported by the most recent and highest quality study, which highlights the importance of careful monitoring and management of patients with COPD exacerbations 1. The CT PE protocol will clearly show the area of previous consolidation, enabling comparison with the prior chest CT, and the contrast enhancement may provide additional information about the consolidation, potentially helping to distinguish between infectious processes, malignancy, or resolution of the previous finding.

Key Considerations

• The primary purpose of the CT PE is to rule out pulmonary embolism in this hypoxic, tachycardic patient with suspected COPD exacerbation, but the same images can be used to reassess the left lobe consolidation.
• The radiologist should be specifically asked to comment on the previously identified left lobe consolidation in the CT PE order to ensure this area receives particular attention during interpretation.
• This approach is efficient as it avoids subjecting the patient to two separate CT scans, reducing radiation exposure and healthcare costs while still providing the necessary diagnostic information for both clinical concerns.
• The management of COPD exacerbations should focus on careful monitoring for hypercapnic respiratory failure, avoiding excessive oxygen use, and targeting oxygen saturation ranges based on individual patient needs, as outlined in the BTS guideline for oxygen use in adults in healthcare and emergency settings 1.

Additional Evidence

• A study from 2015 highlights the importance of computed tomography (CT) in estimating the degree of emphysema and its distribution, and identifying bronchial wall thickening and gas trapping in patients with COPD 1.
• However, the most recent and highest quality study, from 2017, provides the most relevant guidance for the management of COPD exacerbations and the use of CT PE studies in this context 1.

From the Research

CT PE Scan for Left Lobe Consolidation Reassessment

• A CT PE scan is primarily used for detecting pulmonary embolism, but its ability to reassess left lobe consolidation in patients with suspected COPD exacerbation and hypoxia is not directly addressed in the provided studies 2, 3, 4, 5, 6.
• However, studies suggest that CT scans can provide valuable information on lung density and perfusion, which may be useful in assessing consolidation 2.
• The use of CT scans in patients with COPD exacerbation has been explored, particularly in the context of diagnosing pulmonary embolism 3, 4.
• A study comparing CT scans and ventilation-perfusion lung scans for detecting pulmonary embolism found that CT scans have high sensitivity and specificity for central and peripheral PE combined 5.
• Another study on triple rule-out CT in patients with suspected acute pulmonary embolism found that the scan can reveal a wide range of vascular and non-vascular chest disease, including pneumonia and other non-vascular conditions 6.

Limitations and Considerations

• The provided studies do not directly address the use of CT PE scans for reassessing left lobe consolidation in patients with COPD exacerbation and hypoxia.
• The diagnostic performance of CT PE scans for consolidation may depend on various factors, including the specific scan protocol and the patient's underlying condition 2, 6.
• Further studies are needed to determine the efficacy and safety of using CT PE scans for reassessing left lobe consolidation in this patient population 3, 4.