Lung Ultrasound Versus Chest Radiography for Detection of Pneumothorax

Comparative Evaluation of Novice-Performed Lung Ultrasound vs. Chest X-Ray for Pneumothorax Detection Post-Chest Tube Removal in Cardiac Surgery and Trauma Patients

Sunnybrook Health Sciences Center annually provides assistance to approximately 600 cardiac surgeries and 1500 trauma patients, many of whom require chest tubes to prevent blood and fluids from accumulating in the pleural cavities surrounding the heart. During the removal of chest tubes, there is a risk of air leaking into these cavities, leading to pneumothorax, a critical condition occurring in approximately 5-26% of cases, associated with increased complications and mortality.

Currently, the diagnosis of pneumothorax is primarily based on chest X-rays (CXR), despite their limitations and low reliability. As an alternative method, lung ultrasound (LUS) offers several advantages: it is safer, less expensive, and less painful for patients compared to CXR. However, there is a lack of comparative data on the accuracy and interrater reliability of these two diagnostic approaches after chest tube removal.

This study aims to evaluate the accuracy of lung ultrasound performed by medical trainees in diagnosing pneumothorax in cardiac and trauma patients. By comparing LUS to CXR, the investigators seek to determine if LUS provides a more reliable and precise diagnosis. This study has the potential to enhance patient care by establishing a more effective and accessible method for diagnosing pneumothorax post-chest tube removal.

Diagnosing and promptly treating pneumothorax (PNX) is critical, as it is associated with increased morbidity, mortality, and hospital stay for patients. Following cardiac surgery, timely identification of PNX is particularly vital due to patients' reduced cardiopulmonary reserve, which can rapidly lead to life-threatening situations. While computed tomography (CT) is highly accurate in diagnosing PNX, its routine use for screening is impractical due to high radiation exposure, cost, and limited availability. Currently, the standard method for PNX detection is chest X-ray (CXR), but its reliability is suboptimal, resulting in potential misdiagnoses and delays in patient care.

An alternate method for detecting PNX is using lung ultrasound (LUS). LUS is safe, portable compared to CXR, has the potential for faster results and higher accuracy relative to CXR. LUS can also be carried out by appropriate trained nurses and medical trainees, instead of requiring an expert radiographer. This prospective, single-center, observational, cross-sectional, cohort, feasibility pilot trial assesses trainee-performed bedside lung ultrasound (LUS) for detecting PNX and testing feasibility for a multicenter observational prospective study.

The investigators will also compare PNX detection using LUS by novices compared to experts, interrater reliability and the time required from chest/mediastinal tube removal to diagnostic report for LUS. All participants will undergo assessment for PNX using both LUS and CXR completed independently (by study-trained critical care nurse/surgical trainee or an expert radiologist, respectively) and results will be compared between the two modalities.

The successful implementation of LUS could lead to streamlined patient care and improved outcomes for cardiac surgery and trauma patients.

Inclusion Criteria:

• Age ≥ 18 years old.
• Cardiac and trauma patients who have had a chest/mediastinal tube removed within the past two hours in the CVICU, trauma bay, or ward.

Exclusion Criteria:

• Patients who had a PNX prior to mediastinal chest tube removal that required intervention.
• Patients on mechanical ventilation.
• Patients with subcutaneous emphysema due to impaired pleural line visualization.