Post Number 3: E-FAST and Pneumothora

           

Normal lung sliding shown through ultrasound

            Hello and welcome back :) After briefly summarizing the FAST exam last week, this week I will talk a bit about the extended FAST Exam (e-FAST) and how it is used to diagnose lung issues like pneumothorax.

            Firstly, the extended FAST exam is when an ultrasound of the lungs is taken and it is usually added to the ultrasound examination of a trauma patient who has lung issues or experienced trauma from a lot of force, like car accidents.

            There are many complications of the lungs that can be found using an ultrasound, however, today I will focus on one major issue: Pneumothorax.

            To give some background information, normal lungs have a membrane that folds onto itself to create two layers: the visceral pleura, which covers the lungs and adjoining structures, and the parietal pleura which is attached to the chest wall. In between these layers is a miniscule layer of pleural fluid (lung fluid essentially). This small layer of fluid aids respiration, which results in these two layers sliding against one another (‘lung-sliding’).

            Pneumothorax (a collapsed lung) occurs when air invades the small pleural space between the layers and into the chest cavity where it ‘pushes’ against the lung effectively stopping ‘lung sliding’. Because air is detected by ‘white’ on an ultrasound versus ‘black’ indicating fluid, this disruption in normal lung respiration can be detected.

            Before ultrasounds, A CT scan was needed to identify pneumothorax, which made bedside care by doctors and nurses limited because you had to put a patient through the CT machine and leave the room. Now, through the e-FAST exam, pneumothorax can be quickly identified beside the patient while the patient is being simultaneously examined and treated by doctors.

            Along with limited accessibility in caring for a trauma patient, CT scans and x-rays have trouble detecting pneumothorax because the amount of air pressing on the lung is miniscule; however, pneumothorax can be double checked using the M-mode of an ultrasound (detects movement).

            For further explanation, I will reference ultrasound images. In a depiction of a normal lung, you can see a grainy layer called the ‘seashore sign’ in M-mode that indicates the sliding (movement) of the lungs which is what you want to see. The layers above the arrow indicate ‘superficial’ layers (the skin) and it travels deeper, the arrow showing the layer of lung.

Arrow shows grainy layer know as 'seashore sign' which indicates lung movement.

            If pneumothorax occurs, straight lines deemed as ‘barcode lines’ indicates that the lungs are not sliding properly.

Full pneumothorax (lung collapse)

         In this next picture, there is a small segment of the ‘seashore sign’ indicating lung sliding in a small part of the lungs while  the ‘bar-code sign’ indicates the absence of lung sliding on other parts of the lung. 

The area between the arrows indicates ‘lung point’—the presence of pneumothorax on only a part of the lung (partial lung collapse).

           Thank you for stopping by to check out this latest blog post! I hope you have a great rest of the day.