What are the indications for a chest ultrasound?

From the Guidelines

Chest ultrasound is a highly recommended imaging technique for evaluating pleural effusions and pneumothorax, as well as guiding procedures like thoracentesis, due to its high sensitivity and specificity, portability, and lack of radiation exposure. The procedure involves placing a transducer on the chest wall that emits sound waves, which bounce off tissues and return as echoes that are converted into images.

Key Benefits of Chest Ultrasound

• High sensitivity and specificity for diagnosing pleural effusions and pneumothorax, with a sensitivity of 84% and specificity of 100% for pleural effusions 1, and a sensitivity of 89% and specificity of 99% for pneumothorax 1
• Portability and ability to perform at the bedside, making it ideal for critically ill patients who cannot be transported
• Lack of radiation exposure, making it a safer alternative to chest X-rays and CT scans
• Ability to detect smaller amounts of pleural fluid, as little as 5-50 mL, compared to 200-300 mL needed for detection on X-ray

Guidelines for Use

• Ultrasound should be used to complement physical examination and conventional chest radiography to diagnose and localize a pleural effusion, with a Grade 1A recommendation 1
• Ultrasound guidance should be used to assist in drainage, particularly of small or loculated effusions, with a Grade 1B recommendation 1
• The sonographic features of a pleural effusion and pneumothorax are basic and objective, and can be appreciated by intensivists who may perform the examination at the patient’s bedside 1

Procedure

• The patient typically sits upright or lies in a position that allows access to the area of interest
• Gel is applied to the skin to improve sound wave transmission
• The examination usually takes 15-30 minutes and causes minimal discomfort

Advantages

• Chest ultrasound has advantages over chest X-rays and CT scans for certain conditions, including the ability to detect smaller amounts of pleural fluid and lack of radiation exposure 1
• Can be performed at the bedside for critically ill patients who cannot be transported
• Provides real-time imaging, allowing for guided procedures like thoracentesis.

From the Research

Chest Ultrasound Applications

• Chest ultrasound is a valuable tool for diagnosing and treating pleural disease, as well as guiding interventional procedures such as thoracentesis and chest tube insertion 2.
• It can be used to identify artifacts such as A lines, B lines, sliding sign, and lung point, which are essential for discriminating between normal pleural appearance and pleural effusion, pneumothorax, thickenings, and tumors 2.
• Chest ultrasound has also gained clinical significance in the diagnosis of various pulmonary, pleural, cardiac, and mediastinal emergency conditions, including pulmonary embolism, pneumothorax, pneumonia, and pleural effusion 3.

Benefits of Chest Ultrasound

• The use of portable devices promotes patient's bedside evaluation, providing rapid, real-time, and low-cost diagnostic information 2.
• Chest ultrasound can detect minute pleural fluids, fractures of the ribs and sternum, and inflammatory lung diseases such as pleuritis and pneumonia 4.
• It can also differentiate between cardiogenic pulmonary edema and chronic obstructive lung disease, and guide clinical management in emergency and intensive care medicine 4.

Indications for Chest Ultrasound

• The most common indication for chest ultrasound is to assess pleural effusion, but other indications include diaphragmatic function, pleural thickening, and chest wall masses 5.
• Chest ultrasound can significantly alter patient management by resolving equivocal chest radiograph findings, excluding pathology, detecting effusions not visible on chest radiograph, and localizing a safe site for medical thoracoscopy 5.

Safety and Efficacy of Chest Ultrasound

• The use of ultrasound guidance during thoracentesis can reduce the rate of pneumothorax and tube thoracostomy, improving safety in patients with malignant pleural effusion 6.
• A study of 445 consecutive patients with advanced cancer found that pneumothorax occurred in 0.97% of procedures performed with ultrasound guidance, compared to 8.89% without ultrasound guidance 6.